Congestive heart failure (CHF) in medical practice GPFM: diagnosis, etiologic and pathogenetic features, classification of heart failure, clinical treatment protocols. Identification of heart murmurs and heart defects. Clinical examination, MPE.
Terms of issuing documents certifying the disability. Question ITU at a family doctor.
Definition
Heart failure is a condition in which the heart has lost the ability to pump enough blood to the body’s tissues. With too little blood being delivered, the organs and other tissues do not receive enough oxygen and nutrients to function properly.
Description
According to the American Heart Association, about 4.9 million Americans are living with congestive heart failure. Of these, 2.5 million are males and 2.4 million are females. Ten of every 1,000 people over age 65 have this condition. There are about 400,000 new cases each year.
Heart failure happens when a disease affects the heart’s ability to deliver enough blood to the body’s tissues. Often, a person with heart failure may have a buildup of fluid in the tissues, called edema. Heart failure with this kind of fluid buildup is called congestive heart failure. Where edema occurs in the body depends on the part of the heart that is affected by heart failure. Heart failure caused by abnormality of the lower left chamber of the heart (left ventricle) means that the left ventricle cannot pump blood out to the body as fast as it returns from the lungs. Because blood cannot get back to the heart, it begins to back up in the blood vessels of the lungs. Some of the fluid in the blood is forced into the breathing space of the lungs, causing pulmonary edema. A person with pulmonary edema has shortness of breath, which may be acute, severe and life threatening. A person with congestive heart failure feels tired because not enough blood circulates to supply the body’s tissues with the oxygen and nutrients they need. Abnormalities of the heart structure and rhythm also can be responsible for left ventricular congestive heart failure.
In right-sided heart failure, the lower right chamber of the heart (right ventricle) cannot pump blood to the lungs as fast as it returns from the body through the veins. Blood then engorges the right side of the heart and the veins. Fluid backed up in the veins is forced out into the tissues, causing swelling (edema), usually in the feet and legs. Congestive heart failure of the right ventricle often is caused by abnormalities of the heart valves and lung disorders.
When the heart cannot pump enough blood, it tries to make up for this by becoming larger. By becoming enlarged (hypertrophic) the ventricle can contract more strongly and pump more blood. When this happens, the heart chamber becomes larger and the muscle in the heart wall becomes thicker. The heart also compensates by pumping more often to improve blood output and circulation. The kidneys try to compensate for a failing heart by retaining more salt and water to increase the volume of blood. This extra fluid also can cause edema. Eventually, as the condition worsens over time these measures are not enough to keep the heart pumping enough blood needed by the body. Kidneys often weaken under these circumstances, further aggravating the situation and making therapy more difficult.
For most people, heart failure is a chronic disease with no cure. However, it can be managed and treated with medicines and changes in diet, exercise, and life-style habits. Heart transplantation is considered in some cases.
Causes and symptoms
The most common causes of heart failure are:
· coronary artery disease and heart attack (which may be “silent”)
· high blood pressure (hypertension)
· heart valve disease
· congenital heart disease
· alcoholism and drug abuse
The most common cause of heart failure is coronary artery disease. In coronary artery disease, the arteries supplying blood to the heart become narrowed or blocked. When blood flow to an area of the heart is completely blocked, the person has a heart attack. Some heart attacks go unrecognized. The heart muscle suffers damage when its blood supply is reduced or blocked. If the damage affects the heart’s ability to pump blood, heart failure develops.
Cardiomyopathy is a general term for disease of the heart muscle. Cardiomyopathy may be caused by coronary artery disease and various other heart problems. Sometimes the cause of cardiomyopathy cannot be found. In these cases the heart muscle disease is called idiopathic cardiomyopathy. Whatever the cause, cardiomyopathy can weaken the heart, leading to heart failure.
High blood pressure is another common cause of heart failure. High blood pressure makes the heart work harder to pump blood. After a while, the heart cannot keep up and the symptoms of heart failure develop.
Defects of the heart valves, congenital heart diseases, alcoholism, and drug abuse cause damage to the heart that can all lead to heart failure.
A person with heart failure may experience the following:
· frequent coughing, especially when lying down
· swollen feet, ankles, and legs
· abdominal swelling and pain
· fatigue
· sudden death
A person with left-sided heart failure may have shortness of breath and coughing caused by the fluid buildup in the lungs. Pulmonary edema may cause the person to cough up bubbly phlegm that contains blood. With right-sided heart failure, fluid build-up in the veins and body tissues causes swelling in the feet, legs, and abdomen. When body tissues, such as organs and muscles, do not receive enough oxygen and nutrients they cannot function as well, leading to tiredness and dizziness.
Diagnosis
Diagnosis of heart failure is based on:
· symptoms
· medical history
· electrocardiogram (ECG; also called EKG)
· other imaging tests
A person’s symptoms can provide important clues to the presence of heart failure. Shortness of breath while engaging in activities and episodes of shortness of breath that wake a person from sleep are classic symptoms of heart failure. During the physical examination, the physician listens to the heart and lungs with a stethoscope for telltale signs of heart failure. Irregular heart sounds, “gallops,” a rapid heart rate, and murmurs of the heart valves may be heard. If there is fluid in the lungs a crackling sound may be heard. Rapid breathing or other changes in breathing may also be present. Patients with heart failure also may have a rapid pulse.
By pressing on the abdomen, the physician can feel if the liver is enlarged. The skin of the fingers and toes may have a bluish tint and feel cool if not enough oxygen is reaching them.
A chest x ray can show if there is fluid in the lungs and if the heart is enlarged. Abnormalities of heart valves and other structures also may be seen on chest x ray.
An electrocardiogram gives information on the heart rhythm and the size of the heart. It can show if the heart chamber is enlarged and if there is damage to the heart muscle from blocked arteries.
Besides chest x ray, other imaging tests may help make a diagnosis. Echocardiography uses sound waves to make images of the heart. These images can show if the heart wall or chambers are enlarged and if there are any abnormalities of the heart valves. An echocardiogram also can be used to find out how much blood the heart is pumping. It determines the amount of blood in the ventricle (ventricular volume) and the amount of blood the ventricle pumps each time it beats (called the ejection fraction). A healthy heart pumps at least one-half the amount of blood in the left ventricle with each heartbeat. Radionuclide ventriculography also measures the ejection fraction by imaging with very low doses of an injected radioactive substance as it travels through the heart.
A new test that measures the level of a particular hormone in the blood was introduced in 2003 and researchers said the test may be useful for testing for heart failure in physicians’ offices because it could provide results in 15 minutes.
Cardiac catheterization involves using a small tube (catheter) that is inserted through a blood vessel into the heart. It is used to measure pressure in the heart and the amount of blood pumped by the heart. This test can help find abnormalities of the coronary arteries, heart valves, and heart muscle, and other blood vessels. Combined with echocardiography and other tests, cardiac catheterization can help find the cause of heart failure. It is not always necessary, however.
Treatment
Heart failure usually is treated with lifestyle changes and medicines. Sometimes surgery is needed to correct abnormalities of the heart or heart valves. Heart transplantation is a last resort to be considered in certain cases.
Dietary changes to maintain proper weight and reduce salt intake may be needed. Reducing salt intake helps to lessen swelling in the legs, feet, and abdomen. Appropriate exercise also may be recommended, but it is important that heart failure patients only begin an exercise program with the advice of their doctors. Walking, bicycling, swimming, or low-impact aerobic exercises may be recommended. There are good heart rehabilitation programs at most larger hospitals.
Other lifestyle changes that may reduce the symptoms of heart failure include stopping smoking or other tobacco use, eliminating or reducing alcohol consumption, and not using harmful drugs.
One or more of the following types of medicines may be prescribed for heart failure:
· digitalis
· beta blockers
· angiotensin converting enzyme inhibitors (ACE inhibitors)
· angiotensin receptor blockers (ARBs)
· calcium channel blockers
Diuretics help eliminate excess salt and water from the kidneys by making patients urinate more often. This helps reduce the swelling caused by fluid buildup in the tissues. Digitalis helps the heart muscle to have stronger pumping action. Vasodilators, ACE inhibitors, ARBs, and calcium channel blockers lower blood pressure and expand the blood vessels so blood can move more easily through them. This action makes it easier for the heart to pump blood through the vessels. Cholesterol-lowering drugs called statins can help prevent death from heart failure. A 2003 study showed a 62% drop in mortality rate among patients with severe heart failure who took statin therapy.
In 2003, a new noninvasive procedure was being tested for patients with congestive heart failure. Called enhanced external counterpulsation (EECP), it consisted of inflating three sets of pneumatic cuffs attached to the patient’s legs. The therapy had positive effects on the blood pressure and reduced frequency of episodes of angina (pain) in a clinical trial by as much as 70%.
Surgery is used to correct certain heart conditions that cause heart failure. Congenital heart defects and abnormal heart valves can be repaired with surgery. Blocked coronary arteries usually can be treated with angioplasty or coronary artery bypass surgery.
With severe heart failure, the heart muscle may become so damaged that available treatments do not help. Patients with this stage of heart failure are said to have end-stage heart failure. Heart transplant usually is considered for patients with end-stage heart failure when all other treatments have stopped working.
Prognosis
Most patients with mild or moderate heart failure can be successfully treated with dietary and exercise programs and the right medications. In fact, in 2003, the American Heart Association said that even those awaiting heart transplants could benefit from exercise. Many people are able to participate iormal daily activities and lead relatively active lives.
Patients with severe heart failure may eventually have to consider heart transplantation. Approximately 50% of patients diagnosed with congestive heart failure live for five years with the condition. Women with heart failure usually live longer than men with heart failure.
Prevention
Heart failure usually is caused by the effects of some type of heart disease. The best way to try to prevent heart failure is to eat a healthy diet and get regular exercise, but many causes of heart failure cannot be prevented. People with risk factors for coronary disease (such as high blood pressure and high cholesterol levels) should work closely with their physician to reduce likelihood of heart attack and heart failure.
heart failure,
a condition in which the heart cannot pump enough blood to meet the metabolic requirements of body tissues. Many of the symptoms associated with heart failure are caused by the dysfunction of organs other than the heart, especially the lungs, kidneys, and liver. Ventricular dysfunction is usually the basic disorder in congestive heart failure. It often triggers compensatory mechanisms that preserve cardiac output but produce symptoms and signs such as dyspnea, orthopnea, rales, and edema. Heart failure is closely associated with many forms of heart disease, most of which initially affect the left side of the heart. Hence, clinicians commonly divide associated heart failure into left-sided heart failure and right-sided heart failure. Peripheral edema is associated with right-sided heart failure, and dyspnea and other respiratory disorders with left-sided heart failure. Heart failure in infants and children is usually the result of congenital heart disease but also may be caused by myocarditis and ectopic tachycardia. Rheumatic mitral disease and aortic valve disease frequently cause congestive heart failure in young adults. Mitral valve disease, especially mitral stenosis, is the most common cause of heart failure in young adults and affects more young women than men. The common causes of heart failure after 40 years of age are coronary atherosclerosis with myocardial infarction, anemia, diastolic hypertension, hypervolemia, valvular heart disease, pulmonary disease, renal disease, and diffuse myocardial disease. Some individuals may suffer heart failure caused by a combination of congenital heart disease and acquired disease. After 50 years of age, a common cause of heart failure, especially in men, is calcific aortic stenosis. Some of the extracardiac signs of heart failure are ascites, bronchial wheezing, hydrothorax, edema, liver enlargement, moist rales, and splenomegaly. Cardiac signs associated with heart failure are abnormalities in the jugular venous pulsation, the carotid pulse, and the apex wave on cardiographic tracings. Treatment for heart failure commonly involves reduction of the heart’s workload, administration of drugs such as beta-blockers, digitalis to increase myocardial contractility and cardiac output, salt-restricted diet, diuretics, angiotensin-converting enzymes to decrease afterload, and surgical intervention. Also called cardiac failure. See also compensated heart failure, congestive heart failure.
Heart failure inability of the heart to maintain cardiac output sufficient to meet the body’s needs; it most often results from myocardial failure affecting the right or left ventricle.
backward heart failure a concept of heart failure emphasizing the resultant passive engorgement of the systemic venous system that.
congestive heart failure (CHF) that which occurs as a result of impaired pumping capability of the heart that is not keeping up with the metabolic needs of body tissues and organs; it is associated with abnormal retention of water and sodium. It ranges from mild congestion with few symptoms to life-threatening fluid overload and heart failure. Congestive heart failure results in an inadequate supply of blood and oxygen to the body’s cells. The decreased cardiac output causes an increase in the blood volume within the vascular system. Congestion within the blood vessels interferes with the movement of body fluids in and out of the various fluid compartments, so that fluid accumulates in the tissue spaces, causing edema.
There are three general kinds of pathologic conditions that can bring about congestive heart failure: (1) ventricular failure, in which the contractions of the ventricles become weak and ineffective, as in myocardial ischemia from coronary artery disease; (2) mechanical failure of the ventricles to fill with blood during the diastole phase of the cardiac cycle, which can occur when the mitral valve is narrowed, as in rheumatic mitral stenosis, or when there is an accumulation of fluid within the pericardial sac (cardiac tamponade) pressing against the ventricles, preventing them from accepting a full load of blood; and (3) an overload of blood in the ventricles during the systole phase of the cycle. High blood pressure, aortic stenosis, and aortic regurgitation are some of the conditions that can cause ventricular overload.
Compensatory Mechanisms. In an attempt to compensate for inadequate pumping of the heart, the body uses three basic adaptive mechanisms which, though they are effective for a brief period of time, will eventually become insufficient to meet the oxygeeeds of the body. These mechanisms are also responsible for many of the symptoms experienced by the patient with congestive heart failure.
First, the failing heart attempts to maintain a normal output of blood by enlarging its pumping chambers so that they are capable of holding a greater volume of blood. This increases the amount of blood ejected from the heart, but it also leads to fluid overload within the blood vessels and excessive accumulation of body fluids in all of the fluid compartments.
Second, the heart begins to increase its muscle mass in order to strengthen the force of its contractions. This results in ventricular hypertrophy and a need for more oxygen. Eventually, the coronary arteries cao longer meet the oxygen demands of the enlarged myocardium and the patient experiences angina pectoris owing to ischemia.
Third, there is a response from the sympathetic nervous system. The involuntary muscle of the heart is regulated by autonomic, or involuntary, innervation. In response to failing contractility of the myocardial cells, the sympathetic nervous system activates adaptive processes that increase the heart rate, redistribute peripheral blood flow, and retain urine. These mechanisms are responsible for the symptoms of diaphoresis, cool skin, tachycardia, cardiac arrhythmias, and oliguria.
The combined efforts of these three compensatory mechanisms achieve a fairly normal level of cardiac output for a period of time. During this phase of congestive heart failure, the patient is said to have compensated CHF. When these mechanisms are no longer effective the disease progresses to the final stage of impaired heart function and the patient has decompensated CHF.
Clinical Symptoms. Left-sided heart failure produces dyspnea of varying intensity. In the early stages, shortness of breath occurs only when the patient is physically active. Later, as the heart action becomes more seriously impaired, the dyspnea is present even when the patient is resting. In advanced cases, the patient must sit up in order to breathe (orthopnea). Attacks of breathlessness severe enough to wake the patient frequently occur during sleep (paroxysmal nocturnal dyspnea). These attacks usually are accompanied by coughing and wheezing, and the patient seeks relief by sitting upright. Orthopnea and paroxysmal nocturnal dyspnea are related to congestion of the pulmonary blood vessels and edema of the lung tissues. They are aggravated by lying down because in the prone position quantities of blood in the lower extremities move upward into the blood vessels of the lungs.
Fluid retention is another common symptom of congestive heart failure. In left-sided failure there is higher thaormal pressure of blood in the pulmonary vessels. This increased pressure forces fluid out of the intravascular compartment and into the tissue spaces of the lungs, causing pulmonary edema. Right-sided failure causes congestion in the capillaries of the peripheral circulation and results in edema and congestion of the liver, stomach, legs, and feet, and in the sacral region in bedridden patients.
Decreased cardiac output also affects the kidneys by reducing their blood supply, which in turn causes a decrease in the rate of glomerular filtration of plasma from the renal blood vessels into the renal tubules. Sodium and water not excreted in the urine are retained in the vascular system, adding to the blood volume. The diminished blood supply to the kidney also causes it to secrete renin, which indirectly stimulates the secretion of aldosterone from the adrenal gland. Aldosterone in turn acts on the renal tubules, causing them to increase reabsorption of sodium and water, and thus to further increase the volume of body fluids.
Treatment. Medical management of congestive heart failure is aimed at improving contractility of the heart, reducing salt and water retention, and providing rest for the heart muscle. Drugs used to accomplish these goals include digitalis glycosides to slow and strengthen the heartbeat,vasodilators such as nitroprusside and phentolamine to reduce resistance to the flow of blood being pumped from the heart, diuretics to assist in the elimination of water and sodium in the urine, and angiotensin converting enzyme inhibitors to reduce blood pressure, inhibit aldosterone release, and reduce peripheral arterial resistance. beta-blockers are an important adjunct in treatment of heart failure, helping to decrease the sympathetic response. Electroconversion of atrial fibrillation enlists the help of the atria to fill the ventricles to maximum capacity. Biventricular pacing or restoration of cardiac synchrony is helpful for patients with interventricular conduction delay and a wide QRS complex.
Patient Care. Hospitalized patients with severe congestive heart failure present problems related to their needs for physical and mental rest, adequate aeration of the lungs and oxygenation of the tissues, prevention of circulatory stasis, maintenance of the integrity of the skin, restoration and maintenance of fluid and electrolyte balances, and adequate nutrition. The care plan should include frequent monitoring of the vital signs, intake and output, daily weight, serum electrolyte and blood gas levels, and nutritional intake. Patients are placed on sodium-restricted diets and limited fluid intake; they should have a good understanding of the reason for this before leaving the hospital. They should also have a plan for regular exercise as tolerated. Since it is likely that they will continue taking several kinds of medications after returning home, patients or family members should be taught about the pharmacologic action of each drug, the need for taking it exactly as prescribed, any precautions to be taken, and any untoward reactions that warrant notification of the physician, nurse practitioner, or physician’s assistant
Clinical portrait of congestive heart failure. (SOBOE=shortness of breath on exertion) From Jarvis, 1996.
forward heart failure a concept of heart failure emphasizing the inadequacy of cardiac output as the primary cause.
high-output heart failure that in which cardiac output remains high, associated with conditions such as hyperthyroidism, anemia, and emphysema.
left-sided heart failure (left ventricular heart failure) failure of the left ventricle to maintain a normal output of blood; it does not empty completely and thus cannot accept all the blood returning from the lungs via the pulmonary veins, which become engorged. Fluid seeps out of the veins through the pulmonary capillaries and collects in the interstitial tissue of the lung, causing pulmonary edema that eventually leads to right ventricular heart failure as well.
low-output heart failure that in which cardiac output is diminished, associated with cardiovascular diseases such as coronary artery disease, hypertension, and cardiomyopathy.
right-sided heart failure (right ventricular heart failure) failure of proper functioning of the right ventricle, with subsequent engorgement of the systemic veins, producing pitting edema, enlargement of the liver, and ascites.
Heart failure is the pathophysiologic state in which the heart, via an abnormality of cardiac function (detectable or not), fails to pump blood at a rate commensurate with the requirements of the metabolizing tissues and/or pumps only from an abnormally elevated diastolic filling pressure.
Heart failure may be caused by myocardial failure but may also occur in the presence of near-normal cardiac function under conditions of high demand. Heart failure always causes circulatory failure, but the converse is not necessarily the case because various noncardiac conditions (eg, hypovolemic shock, septic shock) can produce circulatory failure in the presence of normal, modestly impaired, or even supranormal cardiac function.
Sex: Men and women have equivalent incidence and prevalence of CHF. CHF in women tends to occur later in life compared to men.
Age: The prevalence of CHF increases with age, being most common in individuals older than 65 years. In the United States, CHF is the most common reason for hospital admission in patients older than 65 years.
A classification of patients with heart disease based on the relation between symptoms and the amount of effort required to provoke them has been developed by the NYHA.
Class I: No limitations. Ordinary physical activity does not cause undue fatigue, dyspnea, or palpitations.
Class II: Slight limitation of physical activity. Such patients are comfortable at rest. Ordinary physical activity results in fatigue, palpitations, dyspnea, or angina.
Class III: Marked limitation of physical activity. Although patients are comfortable at rest, less-than-ordinary activity leads to fatigue, dyspnea, palpitations, or angina.
Class IV: Symptomatic at rest. Symptoms of CHF are present at rest; discomfort increases with any physical activity.
Management of patients with heart murmurs
Acquired Valvular Heart Disease
Primary valvular heart disease ranks well below coronary heart disease, stroke, hypertension, obesity, and diabetes as major threats to the public health. Nevertheless, it is the source of significant morbidity and mortality. Rheumatic fever is the dominant cause of valvular heart disease in developing countries. Its prevalence has been estimated to range from as low as 1.0 per 100,000 school-age children in Costa Rica to as high as 150 per 100,000 in China. Rheumatic heart disease accounts for 12–65% of hospital admissions related to cardiovascular disease and 2–10% of hospital discharges in some developing countries. Prevalence and mortality rates vary among communities even within the same country as a function of crowding and the availability of medical resources and population-wide programs for detection and treatment of Group A streptococcal pharyngitis. In economically deprived areas, tropical and subtropical climates (particularly on the Indian subcontinent), Central America, and the Middle East, rheumatic valvular disease progresses more rapidly than in more-developed nations and frequently causes serious symptoms in patients <20 years of age. This accelerated natural history may be due to repeated infections with more virulent strains of rheumatogenic streptococci.
TS, a relatively uncommon valvular lesion in North America and Western Europe, is more common in tropical and subtropical climates, especially in southern Asia and in Latin America.
As of the year 2000, worldwide death rates for rheumatic heart disease approximated 5.5 per 100,000 population (n = 332,000), with the highest rates reported from Southeast Asia. Although there have been reports of recent isolated outbreaks of streptococcal infection in North America, valve disease in developed countries is now dominated by degenerative or inflammatory processes that lead to valve thickening, calcification, and dysfunction. The prevalence of valvular heart disease increases with age. Important left-sided valve disease may affect as many as 12–13% of adults over the age of 75.
The incidence of infective endocarditis has increased with the aging of the population, the more widespread prevalence of vascular grafts and intracardiac devices, the emergence of more virulent multidrug-resistant microorganisms, and the growing epidemic of diabetes. Infective endocarditis has become a more frequent cause of acute valvular regurgitation.
Bicuspid aortic valve disease affects as many as 1–2% of the population, and an increasing number of childhood survivors of congenital heart disease present later in life with valvular dysfunction. The past several years have witnessed significant improvements in surgical outcomes with progressive refinement of relatively less-invasive techniques. Percutaneous heart valve replacement or repair is under active clinical investigation.
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Note: AV, atrioventricular; HOCM, hypertrophic obstructive cardiomyopathy; HTN, hypertension; IE, infective endocarditis; LV, left ventricular; MI, myocardial infarction; MVP, mitral valve prolapse; RA, rheumatoid arthritis; RV, right ventricular; SAM, systolic anterior motion of the anterior mitral valve leaflet; SLE, systemic lupus erythematosus; TVP, tricuspid valve prolapse. |
Mitral regurgitation
Mitral regurgitation affects more than 2 million people in the USA. The main causes are classified as degenerative (with valve prolapse) and ischaemic (ie, due to consequences of coronary disease) in developed countries, or rheumatic (in developing countries). This disorder generally progresses insidiously, because the heart compensates for increasing regurgitant volume by left-atrial enlargement, causes left-ventricular overload and dysfunction, and yields poor outcome when it becomes severe. Doppler-echocardiographic methods can be used to quantify the severity of mitral regurgitation. Yearly mortality rates with medical treatment in patients aged 50 years or older are about 3% for moderate organic regurgitation and about 6% for severe organic regurgitation. Surgery is the only treatment proven to improve symptoms and prevent heart failure. Valve repair improves outcome compared with valve replacement and reduces mortality of patient with severe organic mitral regurgitation by about 70%. The best short-term and long-term results are obtained in asymptomatic patients operated on in advanced repair centres with low operative mortality (<1%) and high repair rates (≥80—90%). These results emphasise the importance of early detection and assessment of mitral regurgitation.
Mitral regurgitation is defined as systolic retrograde flow from the left ventricle into the left atrium. Although a trivial form of this valve disease is often seen in healthy people, epidemiological data show that moderate or severe regurgitation is the most frequent valve disease in the USA and is the second most common form of valvular heart disease needing surgery in Europe. Despite substantial reduction in the incidence of rheumatic heart disease, mitral regurgitation is a growing public health problem. Moderate or severe regurgitation is frequent, its prevalence increases with age, and it was estimated to affect 2·0—2·5 million people in the USA in 2000—a number expected to almost double by 2030 because of population ageing and growth. Although no large epidemiological studies are available, mitral regurgitation is prevalent in young adults in countries with endemic rheumatic fever. Substantial progress has been achieved to improve its diagnosis, quantification, and surgical treatment. Improved knowledge of clinical outcome of patients with mitral regurgitation resulted in refined surgical indications. Hence, mitral regurgitation is a disease in which restoration of life expectancy can often be achieved, an encouraging outcome that emphasises the importance of early detection, assessment, and prompt consideration for treatment of patients with this condition. Challenges in management of patients with mitral regurgitation remain—elderly patients and those with disease due to ischaemic heart disease are ofteot offered surgery; valve repair—the preferred surgical method—is insufficiently done; new interventional techniques—minimally invasive or percutaneous—are under investigation. However, the general absence of clinical trials means evidence to guide treatment is weak.
All lesions that cause mitral regurgitation do so by reduction or elimination of the normal systolic coaptation between anterior and posterior mitral leaflets, which normally ensures mitral competence. Consistent anatomical and functional descriptors of mitral lesions are essential to assess surgical reparability but overlapping and poorly defined terminology has caused confusion. Causes and mechanisms are not synonymous and a particular cause might produce regurgitation by different mechanisms (table). Surgical correction of this valve disease is dependent on both cause and mechanism, which affect reparability. Causes are generally classified as ischaemic (mitral regurgitation due to consequences of coronary disease, not fortuitous association of both) and non-ischaemic (all other causes). Mechanisms are grossly classified as functional (mitral valve is structurally normal and disease results from valve deformation caused by ventricular remodelling) or organic (intrinsic valve lesions). They can be subclassified by leaflet movement (Carpentier’s classification)—type I (normal valve movement, such as annular dilatation or leaflet perforation); type II (excessive movement); and type III (restrictive movement: IIIa—diastolic restriction such as rheumatic disease; IIIb—systolic restriction as in functional disease). Carpentier also proposed a simple lesion localisation classification.
Causes and mechanisms of mitral regurgitation
MR=mitral regurgitation. PM=papillary muscle. RF=rheumatic fever.
* Mechanism involves normal leaflet movement.
† Mechanism involves excessive valve movement.
‡ Restricted valve movement, IIIa in diastole, IIIb in systole.
Schematic anatomical mitral-valve presentation
(A) Atrial view of a healthy mitral valve. Posterior leaflet has a shorter length but occupies a longer circumference than the anterior leaflet. Mitral annulus around the leaflet is part of the aortic-mitral fibrosa superiorly, is asymmetric, and short in its anteroposterior dimension. Leaflet segmentation starts with A1—P1 close to the anterolateral commissure, with A2—P2 centrally, and A3—P3 close to the posteromedial commissure. The normally apposing leaflets make up the mitral smile. (B) Example of a flail posterior leaflet affecting the P2 segment with ruptured chordae. Note the bulge and excess tissue of the flail segment and the annular enlargement mostly along the posterior part of its circumference. (C) Initial step of surgical valve repair. Resection of the flail segment can be triangular (as shown) or quadrangular and leaves the healthy P1 and P3 segments available for reattachment and repair. (D) Posterior leaflet has been restored by approximation of the remaining segment after resection of the flail segment and the mitral annular dimensions have been restored by an annuloplasty ring. In this example an incomplete ring has been used with its extremities sutured to the trigonal regions of the aortic-mitral fibrosa. The mitral smile and competence have been restored.
Major causes of surgical mitral regurgitation in western countries are degenerative (primary myxomatous disease, primary flail leaflets, annular calcification), representing 60—70% of cases, followed by ischaemic mitral regurgitation (20%), endocarditis (2—5%), rheumatic (2—5%), and miscellaneous causes (cardiomyopathies, inflammatory diseases, drug-induced, traumatic, congenital). Ischaemic disease probably represents a large proportion of the non-surgical disease burden. Nomenclature and mechanisms of major causes are summarised below.
Degenerative mitral regurgitation is usually related to mitral-valve prolapse and rarely to isolated mitral annular calcification. Mitral-valve prolapse is an abnormal systolic valve movement into the left atrium (≥2 mm beyond saddle-shaped annular level). This excessive movement can be seen with other causes such as endocarditis. Prolapse might be of moderate magnitude (leaflet tips remain in the left ventricle—ie, billowing mitral valve) or can be severe (eversion of leaflet tip into left atrium—ie, flail leaflet—usually caused by ruptured chordae). The main phenotypes of mitral prolapse are diffuse myxomatous degeneration (mitral-valve prolapse syndrome or Barlow’s disease, sometimes with posterior annular translocation into left atrium) or primary flail leaflets with ruptured chordae affecting the posterior leaflet in 70% of cases, and accompanied by myxomatous degeneration localised to the flail segment and generally normal valve morphology elsewhere. Myxomatous degeneration remodels valve tissue by increasing the spongiosa layer and valve water content and thickness, with mucopolysaccharide and matrix changes, as a functional manifestation of metalloproteinase alterations. These mitral tissue changes and prolapse might be genetically transmitted and X-chromosome linked. Degenerative mitral regurgitation is the most reparable form, warranting early and careful assessment.
Echocardiographic appearance of the two main anatomical types of mitral regurgitation from apical views centred on the mitral valve
(A) An example of a flail posterior leaflet with the tip of the leaflet floating in the left atrium. Note the otherwise grossly normal anterior leaflet. (B) An example of functional mitral regurgitation. Strut chordae (long arrows) to the anterior and posterior leaflets exert an abnormal traction on the body of the leaflets, which displaces (arrowheads) the leaflets towards the ventricular apex, creating an area of tenting above the mitral annulus and an incomplete coaptation. LA=left atrium. LV=left ventricle.
The ischaemic form of this disease rarely results from an organic mechanism (papillary-muscle rupture) and is rarely acute. Frequently, it is functional (structurally normal leaflets) and chronic, epitomising left-ventricular disease that causes valvular dysfunction. Papillary-muscle dysfunction plays little part in the generation of functional mitral regurgitation, which is mostly caused by apical and inferior-papillary-muscle displacement due to ischaemic left-ventricular remodelling. Because chordae are non-extensible, papillary-muscle displacement exerts traction on leaflets through strut chordae implanted on the body of leaflets, resulting in tethered and apically displaced leaflets (tenting). Coupled with annular flattening, enlargement, and decreased contraction, mitral valve tenting results in coaptation loss that yields functional mitral regurgitation. Asymmetric tenting due to regional scarring (inferior infarction) might explain commissural jets of ischaemic disease. Rheumatic mitral regurgitation—past the acute phase—causes chordal and leaflet retraction, which, amplified by annular dilatation, results in coaptation loss. Postinflammatory and postradiation mitral regurgitations have similar mechanisms. Retraction of tissue is a major limitation to successful valve repair.
Endocarditic mitral regurgitation might be caused by ruptured chordae or perforations. In all causes, annular enlargement is common, is located mostly or exclusively on the posterior part of the annular circumference, and surgical repair almost always requires annuloplasty.
Pathophysiology and progression
The degree of mitral regurgitation is defined by lesion severity (measured as effective regurgitant orifice [ERO] area) and the yielding volume overload (measured as regurgitant volume[RVol]), but it is also affected by the driving force (left-ventricular systolic pressure) and left-atrial compliance.5 Thus, in acute disease, the large regurgitant orifice converts ventricular energy mostly into potential energy (left-atrial pressure V-wave) due to non-compliant left atrium. In chronic regurgitation, the enlarged left atrium is compliant, the V-wave is often small, and ventricular energy is converted mostly into kinetic energy (large RVol). This process of atrial enlargement and increased compliance probably explains atrial pressure reduction and clinical improvement after initial heart failure caused by acute mitral regurgitation.
The ERO area is not necessarily fixed and can be dynamic. Increased loading or contractility can cause the ERO area to increase or decrease slightly. With valve prolapse, the area is very dynamic, increasing progressively during systole, and is sometimes purely end-systolic. In functional mitral regurgitation, ERO area is dynamic during systole, with large area during short isovolumic contraction and relaxation phases caused by lesser ventricular pressure apposing leaflets. This type of regurgitation is also dynamic with decreased loading or inotrope administration, and might disappear with these interventions, whereas exercise most often results in augmentation of ERO area. Long-term progression of organic disease is about 5—7 mL per year for RVol and is determined by ERO area progression caused by new lesions or annular enlargement. Thus, mitral regurgitation is self-sustained, causing atrial and annular enlargement, which in turn leads to increased ERO area.
The ventricular and atrial consequences of organic mitral regurgitation are initiated by volume overload with increased preload and left-ventricular and left-atrial enlargement. Impedance to ejection is reduced despite normal or increased vascular resistances, whereas myocardial afterload (end-systolic wall stress) is normal with an end-systolic volume that is normal to slightly increased. Thus, in organic disease, altered left-ventricular function might coexist with normal or high ejection fraction. Borderline normal ejection fraction, between 50—60%, already implies overt left-ventricular dysfunction. Ventricular dysfunction should be suspected when end-systolic dimensions are large but is often masked by a large ejection volume and is revealed after surgical elimination of mitral regurgitation, with a postoperative average immediate ejection fraction drop of about 10%. Diastolic ventricular dysfunction is difficult to characterise, but seems to reduce exercise capacity.
Physiology of functional mitral regurgitation is even more complex than that of organic mitral regurgitation since ventricular dysfunction predates the regurgitation. Nevertheless, functional mitral regurgitation further increases atrial pressure, which leads to pulmonary hypertension and heart failure. With increased atrial pressure and low driving force, functional regurgitation often has low RVol and can be silent.
Whether functional regurgitation affects remodelling and dysfunction is uncertain but is suspected because of the high mortality associated with increased severity of mitral regurgitation.
Progression or recurrence after annuloplasty is weakly related to annular enlargement but strongly to increased mitral tenting caused by ventricular remodelling, papillary-muscle displacement, and increased chordal traction; however, rates of progression are unknown.
Assessment
Initial clinical assessment looks for symptoms, signs of heart failure, and physical signs of severe mitral regurgitation—ie, displaced apical impulse, systolic thrill, loud systolic murmur, S3, early diastolic rumble, and cardiomegaly with left-atrial enlargement on chest radiography and atrial fibrillation. These signs are important but not specific enough to rely solely on them to suggest surgery.
Doppler echocardiography is the main method for assessment of patients with mitral regurgitation. Transthoracic or transoesophageal echocardiography provides functional anatomical information that is crucial for assessment of reparability by defining cause, mechanism, presence of calcification, and localisation of lesions. Transoesophageal echocardiography provides better imaging quality than transthoracic echocardiography but its ability to detect details such as ruptured chordae rarely changes management. Transoesophageal echocardiography essentially provides incremental clinically meaningful information (such as reparability) when transthoracic echocardiography is of poor quality or when complex, calcified, or endocarditic lesions are suspected. Thus, transoesophageal echocardiography is rarely used on an outpatient basis and is mostly used intraoperatively for lesion verification and to monitor surgical results. Real-time three-dimensional echocardiography has at present insufficient image resolution but pilot data suggest that it allows quantitative assessment of structures that are not easily measurable by two-dimensional echocardiography, such as mitral annulus. Although emerging technologies such as transoesophageal echocardiography three-dimensional imaging have great potential, they need to be rigorously tested.
Doppler echocardiography provides crucial information about mitral regurgitation severity (table). Comprehensive integration of colour-flow imaging and pulsed and continuous wave doppler echocardiography is necessary because jet-based assessment has major limitations (figure). Quantitative assessment of regurgitation is feasible by three methods—quantitative doppler echocardiography based on mitral and aortic stroke volumes, quantitative two-dimensional echocardiography based on left-ventricular volumes, and flow-convergence analysis measuring flow with colour-flow imaging proximal to the regurgitant orifice (proximal isovelocity surface area method; figure ). These methods allow measurement of ERO area and RVol and have important prognostic value. Severe mitral regurgitation is diagnosed with an ERO area of at least 40 mm2 and RVol of at least 60 mL per beat; and moderate regurgitation with ERO area 20—39 mm2 and RVol 30—59 mL per beat. Outcome data suggest that a smaller volume mitral regurgitation and smaller ERO area (≥30 mL and ≥20 mm2, respectively) are associated with severe outcome in patients with ischaemic disease; therefore, thresholds for severe disease are cause-dependent. Consistency in all measures of mitral regurgitation severity is essential to appropriately grade disease severity (table ). Haemodynamic assessment is completed with doppler measurement of cardiac index and pulmonary pressure.
Gradation of mitral regurgitation by doppler echocardiography
Modified from Zoghbi and colleagues.5 ERO=effective regurgitant orifice area. LA=left atrium. LV=left ventricle. MR=mitral regurgitation. RF=regurgitant fraction. RVol=regurgitant volume.
Use of colour-flow imaging for assessment of mitral regurgitation
(A) Jet imaging in left atrium. The jet is eccentric and is displayed with mosaic colours, whereas the normal flow is of uniform colour. It fills only part of the left atrium and might underestimate the regurgitation. The observation of a large flow convergence should lead to suspicion of severe regurgitation. (B) Measurement of the flow convergence with colour-flow imaging. The baseline of the colour scale has been brought down to decrease the aliasing velocity to 53 cm/s (velocity at the blue-yellow border), which allows the flow convergence (yellow) to be seen. The radius (r) of the flow convergence is used in the formula for calculation of the instantaneous regurgitant flow (258 mL/s). Flow=6·28×Valiasing×r2=6·28×53×0·882=258 mL/s. Division of this value by the jet velocity allows calculation of the effective regurgitant orifice of mitral regurgitation. LA=left atrium. LV=left ventricle.
Doppler echocardiography also measures left-ventricular and left-atrial consequences of mitral regurgitation. End-diastolic left-ventricular diameter and volume indicate volume overload whereas end-systolic dimension shows volume overload and ventricular function. Patients with left-ventricular ejection fraction less than 60% or end-systolic diameter of at least 40—45 mm are regarded as having overt left-ventricular dysfunction. Left-atrial diameter indicates volume overload but also conveys important prognostic information. Left-atrial volume was recommended as the preferred measure of atrial overload, (at least 40 mL/m2 for severe dilatation) and predicts the occurrence of atrial fibrillation.
Exercise tests are used to define functional capacity. One in five asymptomatic patients shows severe functional limitations during cardiopulmonary exercise. Peak oxygen consumption compared with that expected for age, sex, and weight objectively measures functional limitations versus normal reference values. Other exercise modalities, such as supine-bike exercise, examine changes in severity of mitral regurgitation with activity, especially seen in ischaemic and functional disease and might reveal poor prognosis when ERO area increases. Standard postexercise echocardiography was used to detect exertional ventricular volume increase as a predictor of postoperative left-ventricular dysfunction, but difficulties in measurement of monoplane ventricular volumes hinder this approach. Other stress tests are rarely used. Dobutamine echocardiography reduces mitral regurgitation universally, but in selected patients with ischaemic disease it might reveal viability and ischaemia.
MRI shows mitral regurgitation jets, with limitations similar to those of colour-flow imaging; quantitative measurements are possible but validation studies are few. This imaging method is unique in revealing ventricular scars and in assessment of viability in ischaemic disease and is useful in measurement of ventricular volumes but its incremental diagnostic role remains unknown.
Detection of hormonal activation is important in many cardiac diseases. Atrial natriuretic peptide has little specificity for mitral regurgitation and is strongly activated by arrhythmias, irrespective of mitral regurgitation severity. B-type natriuretic peptide is of greater value than atrial natriuretic peptide in patients with regurgitation. Its activation in organic disease is determined by the consequences—mostly left-atrial enlargement, symptoms, rhythm, and left-ventricular function—rather than the severity of regurgitation. Importantly, its activation is associated with poor outcome and should alert clinicians. Strong B-type natriuretic peptide activation is noted in functional mitral regurgitation linked to the severity of end-systolic ventricular changes and of mitral regurgitation. Subtle sympathetic activation and altered β receptors in organic disease might indicate left-ventricular dysfunction but are usually less prominent than in functional disease.
Cardiac catheterisation is not consistently used by institutions and might be overused in some.3 In academic centres, it is rarely used to define haemodynamics, which are usually provided by doppler echocardiography. Left ventriculography and right-heart catheterisation are rarely needed for assessment of mitral regurgitation. Conversely, in most patients aged 45 years or older, coronary angiography is routinely done preoperatively.
Natural history and clinical outcome
Although a few prospective studies are available, most data for mitral regurgitation outcome are extracted from observational series. Clinical outcome under medical management and after surgery is different in organic and functional disease.
Natural history of organic regurgitation has been poorly defined, largely because of limitations in severity assessment. Old studies, before echocardiography, showed a wide range in 5-year survival rates from 27% to 97%, probably related to variations in severity. Most data (table) were from studies of patients diagnosed with mitral regurgitation due to flail leaflets, most of whom had severe regurgitation. Such patients have ventricular enlargement causing the notable volume overload and incur excess mortality overall; mortality was especially high in patients with class III—IV symptoms but also notable in those with no or minimum symptoms. A sudden death rate of 1·8% per year overall varied from as high as 12·0% per year in patients with class III—IV symptoms who had not undergone surgery to 0·8% per year in asymptomatic patients with normal ejection fraction and sinus rhythm. Patients in some mitral regurgitation subsets have low mortality, such as young patients (<50 years) even with severe mitral regurgitationor those of all ages with initially a moderate disorder. Conversely, in a prospective study of asymptomatic patients with long-term follow-up, those with severe regurgitation proven by quantitative measurements showed increased mortality under medical management.9 Thus, older patients (≥50 years) with severe (defined as ERO area ≥40 mm2) organic mitral regurgitation are at increased risk of mortality (yearly rates of about 3% for moderate regurgitation vs 6% for the severe organic form). For morbid complications, all studies substantiated the adverse effect of severe regurgitation. Patients with flail leaflet and in general those with severe mitral regurgitation had, under medical management, yearly cardiac event rates of 10—12%—including about 9% for heart failure and 5% for atrial fibrillation. Within 10 years of diagnosis, cardiac events arise in most patients with severe mitral regurgitation, and death occurs or cardiac surgery is needed in at least 90%, making surgery an almost unavoidable consideration in such patients. The risk of stroke is low, but in excess of that expected in old patients and is strongly linked to occurrence of atrial fibrillation, and thus to left-atrial size. Predictors of reduced survival under medical management are symptoms (class III or IV), even if transient, reduced ejection fraction, severe mitral regurgitation with ERO area of 40 mm2 or more, and hormonal activation, although not as well substantiated. Predictors of cardiac events are atrial fibrillation, left-atrial enlargement of at least 40—50 mm diameter, , flail leaflet or large ERO area—all markers of severe mitral regurgitation—and, during exercise, reduced peak oxygen consumption and possibly reduced right ventricular function.
Clinical outcome after surgery depends on patient-specific, disease-related, and surgery-related factors. Early postoperative mortality is largely affected by age, but improvement of surgical results reduced the risk to about 1% for patients younger than 65 years, 2% for those aged 65—75 years, and 4—5% for older than 75 years. Increased surgical risk is also linked to preoperative severe symptoms or heart failure whereas ejection fraction has less effect. Surgery-related determinants of operative risk are governed by mitral reparability, which ensures reduced risk, whereas risk is increased with concomitant coronary artery bypass grafting. Other associated procedures, such as tricuspid repair or replacement, or those aimed at treatment or prevention of atrial fibrillatioeed a longer bypass time, which can increase risk. Long-term, patient-related factors continue to affect outcome, particularly coronary disease or reduced renal function. Age determines mortality but restoration of life expectancy is similar in young and old patients. After surgery, patients with severe symptoms before surgery continue to have increased mortality despite symptom relief, whereas in those with no or few symptoms, restoration of life expectancy can be achieved. Similarly, patients with overt preoperative ventricular dysfunction have increased postoperative mortality, especially with ejection fraction less than 50%. Generally, a 10% early postoperative reduction in ejection fraction happens after elimination of volume overload, whereas end-systolic characteristics (volume, wall stress) are unchanged. This reduction is lowest after valve repairand is minimised by preservation of subvalvular apparatus during valve replacement. Nevertheless, 25—30% of patients with mitral regurgitation present with postoperative left-ventricular dysfunction, especially those with preoperative ejection fraction of less than 60% or end-systolic diameter at least of 40—45 mm. Occasional unexpected ventricular dysfunctions arise in patients with ejection fraction greater than 60% and no perfect predictor has been identified. Hence, in some centres, prevention of postoperative left-ventricular dysfunction relies on performance of early surgery wheo sign of left-ventricular alteration is present.
Coronary disease (even in the absence of angina) increases the risk of left-ventricular dysfunction despite the performance of coronary artery bypass grafting.79 Although no clinical trial has compared outcomes of patients randomised to repair versus replacement, observational evidence suggests that the major surgical determinant of improved long-term outcome is valve repair, which allows restoration of life expectancy and reduces the risk of heart failure after surgery. Although mitral regurgitation can recur after repair, reoperation rates do not differ after repair compared with replacement. Thus, mitral valve repair is widely regarded as the preferred mode of correction of organic mitral regurgitation, especially degenerative.
For ischaemic mitral regurgitation, the natural history of the functional form is incompletely definedwhereas that of papillary-muscle rupture is known to be rapidly fatal. Whether functional regurgitation intrinsically causes poor outcome, or whether it indicates left-ventricular alterations, is still disputed. However, association of severe ischaemic mitral regurgitation with severe outcomes, independent of ejection fraction, age, and presentation, suggests that the regurgitation is indeed causal of the poor outcome. This prognostic role of mitral regurgitation is now substantiated by results from studies of patients with acute or chronic myocardial infarction, by clinical trials and by population studies. Another important concept is that even modest regurgitation is associated with substantially increased mortality, a fact proved by quantitative data. ERO area of ischaemic mitral regurgitation independently predicts excess mortality. Patients with an area larger than 20 mm2 incur about a two-fold increase in mortality risk and about a four-fold increase in the risk of heart failure compared with those with a similar ischaemic left-ventricular dysfunction but no mitral regurgitation. The better predictive value of ERO area than that of RVol is explained by the strong link between ERO area and filling pressure. Increase in ERO area with exercise might additionally affect clinical outcome, survival, and heart failure. Nevertheless, a clinical trial is needed to determine whether surgical correction of the valvular consequence (ischaemic mitral regurgitation) improves mortality and heart failure in this mainly ventricular disease. Clinical outcome of functional disease caused by cardiomyopathy is not well defined but few data suggest that mitral regurgitation yields poor outcomes.
Outcomes after surgery for functional disease remain suboptimum. Operative mortality is still high despite definite surgical improvements. Long-term mortality and heart failure rates are high, although not unexpected in patients with coronary disease, previous myocardial infarction, reduced ventricular function, and vascular comorbidity. These suboptimum outcomes explain uncertainties in surgical indications. The value of mitral repair compared with replacement is also debated because mitral regurgitation often recurs after repair as a consequence of continued ventricular remodelling, which results in recurrent valve tenting. Determinants of postoperative outcome are myocardial viability, preserved mitral competence, and absence of sustained or advanced ventricular remodelling. Postoperative outcome of functional mitral regurgitation due to cardiomyopathy is mediocre and whether it is improved compared with outcome under medical management is doubtful. However, with low operative mortality, postoperative heart failure and symptomatic improvements are possible.
Treatment
The natural history of untreated organic and functional mitral regurgitation emphasises the importance of treatment of patients with severe regurgitation. Because the effects of various treatments on survival have not been tested in randomised clinical trials, the value of any approach is estimated on the basis of outcome studies.
Management strategy for patients with chronic severe mitral regurgitation. *Mitral valve (MV) repair may be performed in asymptomatic patients with normal left ventricular (LV) function if performed by an experienced surgical team and if the likelihood of successful MV repair is >90%. AF, atrial fibrillation; Echo, echocardiography; EF, ejection fraction; ESD, end-systolic dimension; eval, evaluation; HT, hypertension; MVR, mitral valve replacement. (From Bonow et al.)
Medical treatment aims to prevent progression of organic disease. Prevention of endocarditis is directed at forestalling catastrophic infectious complications and sudden mitral regurgitation progression associated with endocarditis. Diuretics often reduce or eliminate symptoms of disease but such improvement should not unduly reassure physicians. Patients who had transiently severe symptoms and improved with treatment continue to be at high risk and should be promptly assessed for surgery.
Treatment of organic mitral regurgitation with vasodilators has been advocated on the basis of experimental studies showing reductions in acute RVol and even ERO area with blood pressure reduction. Acutely ill patients with mitral regurgitation benefit from vasodilator treatment. However, despite some encouraging data, translation to chronic treatment of organic disease is unresolved because reported series were small, rarely randomised, and contradictory in conclusions. Activation of the tissue (not systemic) renin-angiotensin myocardial system was shown in organic mitral regurgitation. Consistent pilot studies suggest potential of drugs blocking tissue renin-angiotensin system to stabilise organic disease severity and consequences. The effect of such treatments on clinical outcome remains to be shown. β blockade in organic mitral regurgitation has only been tested in animal models and remains conjectural. Conversely, in functional disease, medical treatment has been better studied than in organic disease. Maximum medical treatment of patients with heart failure and left-ventricular dysfunction reduces functional mitral regurgitation. Specifically β blockade—with carvedilol or long-acting metoprolol—and inhibition of angiotensin-converting enzyme reduce functional mitral regurgitation severity. These therapies are recommended for treatment of left-ventricular dysfunction. Thus, non-urgent surgical indications should be reviewed after maximum medical treatment has taken effect.
Interventional treatment is not yet approved for clinical use and remains investigational. Percutaneous revascularisation of patients with ischaemic regurgitation is possible but patients are often left with residual regurgitation that affects prognosis so that more effective treatment is necessary. Resynchronisation treatment in left-ventricular dysfunction with delayed conduction might improve functional mitral regurgitation. Two specific interventional approaches to treatment are discussed here.
Valvular edge-to-edge attachment mimics the surgical procedure proposed by Alfieri and colleagues, creating a tissue bridge between anterior and posterior leaflets. Percutaneously, this technique uses a clip or sutures deployed through trans-septal catheterisation. Experimental studies have shown success and reliable clip or suture placement through the trans-septal approach (figure). Early trials also suggest safety and feasibility with close echocardiographic guidance in centres with much experience of interventional valvular procedures. Data for how well this intervention works are preliminary but encouraging,128 suggesting that more than 80% of patients can be discharged from hospital with a clip, and mild or little mitral regurgitation. A randomised trial comparing percutaneous clip and surgery is in progress. The edge-to-edge technique has important limitations. First, the application of this technique is restricted to localised prolapse of the central segment of the anterior and posterior leaflets. Second, annular dilatation is not addressed by the procedure and might cause residual regurgitation.
Percutaneous devices used for treatment of mitral regurgitation
(A) Percutaneous clip introduced by venous and trans-septal approach into the left atrium and through the mitral orifice. The clip then grabs both leaflets, resuspending them with prolapse. (B) Percutaneous coronary sinus cinching device introduced through the jugular vein into the coronary sinus. The distal stent (smallest) then the proximal stent are deployed. With time the bridge shrinks and cinches the annulus.
Annuloplasty aimed at reduction of annular dilatation is under investigation mostly with coronary sinus cinching. Technically, stabilisation of material with sufficient constraining force to obtain more than 20% diameter reduction is a challenge. Most devices are composed of anchoring devices placed in the distal and proximal coronary sinus and an intermediate tensioning or supporting element. Experimentally, reduction of mitral regurgitation is achievable, but clinical results are preliminary. Feasibility through a jugular approach and safety seem to be acceptable. Potential limitations are those of annuloplasty (incomplete valve tenting correction) and those of coronary sinus approach that might reduce only part of the annular circumference with an effectiveness limited by the 1—2 cm sinus-annular distance. Because of safety concerns related to proximity of the coronary sinus and circumflex artery with potential artery compression, non-coronary sinus approaches to annuloplasty and percutaneous ventricular remodelling-constraint devices are being investigated.
On the basis of the success of balloon valvuloplasty for mitral stenosis, percutaneous treatment of mitral regurgitation is expected to be successful but this success will necessitate complex development that needs strong cardiologist—engineer collaboration and rigorous assessment.
Surgical treatment of mitral regurgitation is the only approach with defined clinical success, providing sustained relief of symptoms or heart failure. However, no randomised trial has been done to prove mortality or cardiac event reduction. The standard surgical approach is a median sternotomy, but sometimes only partial sternotomy or minimally invasive surgery through thoracoscopic approach can be used.
Valve repair includes an array of valvular, subvalvular, and annular procedures aimed at restoration of leaflet coaptation (ie, valvular normal function) and elimination of mitral regurgitation. These surgical techniques are more successful with redundant than with retracted or calcified leaflets. For valve prolapse, typical repair is resection (triangular or quadrangular) of the prolapsed posterior leaflet segment whereas the anterior leaflet is rarely resected. Subvalvular support can be obtained by chordal transfer or artificial chords rather than chordal shortening. Annuloplasty is routinely used with annular bands or flexible or rigid rings. Many additional technical procedures might be used at the surgeon’s discretion to restore coaptation and valve competence. Conversely, in functional mitral regurgitation, valve repair is rather uniform with restrictive annuloplasty substantially reducing the anteroposterior annular diameter. New rings aimed at annular reshaping, specific to each cause of functional regurgitation (ischaemic disease or cardiomyopathy) are now available but their incremental value (compared with traditional rings) is not defined. Valve repair is done in about half of patients who undergo surgery for mitral regurgitation in the USA and Europe. In centres with surgeons proficient in valve repair, more than 80—90% repair rates are achieved. A failed repair is caused rarely by systolic anterior motion of the mitral valve due to excessively redundant tissue or by stenosis, but more often by insufficient correction of a prolapse, recurrence of ruptured chords, and excessive tissue retraction or resection. Overall, reoperation after 10 years is necessary in 5% of patients with repaired posterior leaflet prolapse and 10% of those with anterior leaflet interventions. 20—30% of patients with repaired functional mitral regurgitation are estimated to have recurrent regurgitation. Reoperation rate is not greater after valve repair than after replacement and because of the morbidity and mortality advantages, valve repair is the preferred method of surgical correction of mitral regurgitation.
Valve replacement involves insertion of a biological or mechanical prosthesis. Bioprosthetic valve replacement is associated with low embolic risk but shorter durability, whereas mechanical valve replacement is associated with high risk of embolism and haemorrhagic complications (due to intensive warfarin treatment) but has potential for long-lasting durability. Results of randomised trials showed that within 10 years of surgery these risks are balanced. Older age determines the probability that bioprosthetic durability will be longer than life expectancy, and is the main bioprosthesis insertion indication (usually >65 years of age). Ability to achieve high-quality anticoagulation and patient’s desire also affect the choice of prosthesis. Irrespective of the prosthesis selected, conservation of subvalvular apparatus is essential for preservation of ventricular function. The risk of prosthetic complications makes surgical indications more restrictive when valve replacement is likely.
Controversies and guidelines for treatment
In view of the experimental nature of medical and interventional treatments for mitral regurgitation, surgery is the only treatment recommended by management guidelines. Because surgery is associated with small but definite risks, those patients with a higher risk of spontaneous complications than of surgery-related complications are selected. Guidelines should, in our opinion, be interpreted as a minimum to be applied by all physicians but should not deter centres with better results than those of other centres from providing advanced care to patients with mitral regurgitation. Furthermore, the absence of clinical trials and few prospective studies create ample controversy, which should be addressed in future studies.
The natural history of mitral regurgitation has been described in individual centre studies, which have provided discordant data, most of which is explained by differences in age, disease severity, and referral biases. Thus, multicentre data are essential to reconcile these discordant results. Assessment of the severity of mitral regurgitation is not uniform between centres, especially with use of qualitative assessment. The generalisability of quantitative assessment should be assessed in a multicentre study to provide benchmarks for the American Society of Echocardiography guidelines/ Moderate regurgitation represents a wide range of clinical situations. Selection of patients who need treatment and the potential role of medical and percutaneous interventional treatments should be assessed prospectively. Improved characterisation of functional mitral-regurgitation grading and the effect on outcome is needed. Specifically, the effect of surgical correction on outcome remains disputed. The benefit of early surgery (ie, valve repair in asymptomatic patients) versus a watchful wait was suggested in observational studies but is controversial. To resolve these issues, clinical trials of surgery for mitral regurgitation will be necessary.
Although approaches to surgical indications are detailed in clinical guidelines, they are summarised here. Rescue surgical indications—class I by guidelines—are compulsory. Patients with organic mitral regurgitation who have developed severe symptoms (class III or IV), heart failure, or signs of overt left-ventricular dysfunction (ejection fraction <60% or end-systolic dimension ≥40—45 mm) have an immediate high risk and therefore prompt surgery—repair (preferable) or replacement—is indicated. Even with advanced heart failure or ventricular dysfunction, contraindications to surgery are rare as long as mitral regurgitation remains severe, emphasising the importance of quantitative assessment of disease. Such rescue surgery is indispensable, but is not the preferred timing for surgery in organic disease. Indeed, patients who need to be operated on at such a late stage of their disease have increased mortality after surgery. This outcome emphasises the importance of early detection and assessment of mitral regurgitation. In functional regurgitation, rescue surgery is the most frequent surgical indication, but consideration should be given to surgery in symptomatic patients before heart failure becomes intractable.
Restorative surgical indications—class II by guidelines—are optional. Patients with no or minimum symptoms at baseline cannot expect substantial symptomatic improvement. Those with functional mitral regurgitation are rarely candidates for restorative surgery while asymptomatic but might be suitable for valve repair if coronary artery bypass grafting is necessary independently of the mitral regurgitation. In organic regurgitation, postoperative outcome studies in patients with no or minimum symptoms before surgery show restoration of life expectancy, emphasising the importance of this approach. Patients who are asymptomatic but had either reduced functional capacity by objective exercise testing, hormonal activation, or paroxysmal atrial fibrillation are specific but not exclusive candidates for restorative surgery. To ensure success of such restorative surgery, important requirements form the basis of advanced mitral-valve-repair centres. First, surgical risk should be very low, below 1% in asymptomatic patients. Second, high-quality non-invasive mitral-regurgitation assessment should be available with complete description of causes, mechanisms, localisation of lesions, and quantitative assessment of regurgitation. Third, high repair rates of at least 80% of patients with mitral regurgitation are essential to qualify as an advanced repair centre. Last, high quality intraoperative assessment of disease and of surgical results is essential to avoid residual disease. In such centres, many indications for surgery in asymptomatic patients are supported by most guidelines.
Mitral stenosis
Etiology and Pathology
Rheumatic fever is the leading cause of mitral stenosis (MS) (Table). Other less common etiologies of obstruction to left atrial outflow include congenital mitral valve stenosis, cor triatriatum, mitral annular calcification with extension onto the leaflets, systemic lupus erythematosus, rheumatoid arthritis, left atrial myxoma, and infective endocarditis with large vegetations. Pure or predominant MS occurs in approximately 40% of all patients with rheumatic heart disease and a history of rheumatic fever. In other patients with rheumatic heart disease, lesser degrees of MS may accompany mitral regurgitation (MR) and aortic valve disease. With reductions in the incidence of acute rheumatic fever, particularly in temperate climates and developed countries, the incidence of MS has declined considerably over the past few decades. However, it remains a major problem in developing nations, especially in tropical and semitropical climates.
In rheumatic MS, the valve leaflets are diffusely thickened by fibrous tissue and/or calcific deposits. The mitral commissures fuse, the chordae tendineae fuse and shorten, the valvular cusps become rigid, and these changes, in turn, lead to narrowing at the apex of the funnel-shaped (“fish-mouth”) valve. Although the initial insult to the mitral valve is rheumatic, the later changes may be a nonspecific process resulting from trauma to the valve caused by altered flow patterns due to the initial deformity. Calcification of the stenotic mitral valve immobilizes the leaflets and narrows the orifice further. Thrombus formation and arterial embolization may arise from the calcific valve itself, but in patients with atrial fibrillation (AF), thrombi arise more frequently from the dilated left atrium (LA), particularly the left atrial appendage.
Pathophysiology
Iormal adults, the area of the mitral valve orifice is 4–6 cm2. In the presence of significant obstruction, i.e., when the orifice area is reduced to < ~2 cm2, blood can flow from the LA to the left ventricle (LV) only if propelled by an abnormally elevated left atrioventricular pressure gradient, the hemodynamic hallmark of MS. When the mitral valve opening is reduced to <1 cm2, often referred to as “severe” MS, a LA pressure of ~25 mmHg is required to maintain a normal cardiac output (CO). The elevated pulmonary venous and pulmonary arterial (PA) wedge pressures reduce pulmonary compliance, contributing to exertional dyspnea. The first bouts of dyspnea are usually precipitated by clinical events that increase the rate of blood flow across the mitral orifice, resulting in further elevation of the LA pressure (see below).
To assess the severity of obstruction hemodynamically, both the transvalvular pressure gradient and the flow rate must be measured. The latter depends not only on the CO but on the heart rate as well. An increase in heart rate shortens diastole proportionately more than systole and diminishes the time available for flow across the mitral valve. Therefore, at any given level of CO, tachycardia including that associated with AF augments the transvalvular pressure gradient and elevates further the LA pressure. Similar considerations apply to the pathophysiology of tricuspid stenosis.
The LV diastolic pressure and ejection fraction (EF) are normal in isolated MS. In MS and sinus rhythm, the elevated LA and PA wedge pressures exhibit a prominent atrial contraction (a wave) and a gradual pressure decline after mitral valve opening (y descent). In severe MS and whenever pulmonary vascular resistance is significantly increased, the pulmonary arterial pressure (PAP) is elevated at rest and rises further during exercise, often causing secondary elevations of right ventricular (RV) end-diastolic pressure and volume.
Cardiac Output
In patients with moderate MS (mitral valve orifice 1.0 cm2–1.5 cm2), the CO is normal or almost so at rest but rises subnormally during exertion. In patients with severe MS (valve area< 1.0 cm2), particularly those in whom pulmonary vascular resistance is markedly elevated, the CO is subnormal at rest and may fail to rise or may even decline during activity.
The clinical and hemodynamic features of MS are influenced importantly by the level of the PAP. Pulmonary hypertension results from: (1) passive backward transmission of the elevated LA pressure; (2) pulmonary arteriolar constriction, which presumably is triggered by LA and pulmonary venous hypertension (reactive pulmonary hypertension); (3) interstitial edema in the walls of the small pulmonary vessels; and (4) organic obliterative changes in the pulmonary vascular bed. Severe pulmonary hypertension results in RV enlargement, secondary tricuspid regurgitation (TR) and pulmonic regurgitation (PR), as well as right-sided heart failure.
In temperate climates, the latent period between the initial attack of rheumatic carditis (in the increasingly rare circumstances in which a history of one can be elicited) and the development of symptoms due to MS is generally about two decades; most patients begin to experience disability in the fourth decade of life. Studies carried out before the development of mitral valvotomy revealed that once a patient with MS became seriously symptomatic, the disease progressed continuously to death within 2–5 years.
In patients whose mitral orifices are large enough to accommodate a normal blood flow with only mild elevations of LA pressure, marked elevations of this pressure leading to dyspnea and cough may be precipitated by sudden changes in the heart rate, volume status, or CO, as for example with severe exertion, excitement, fever, severe anemia, paroxysmal AF and other tachycardias, sexual intercourse, pregnancy, and thyrotoxicosis. As MS progresses, lesser stresses precipitate dyspnea, and the patient becomes limited in daily activities, and orthopnea and paroxysmal nocturnal dyspnea develop. The development of permanent AF often marks a turning point in the patient’s course and is generally associated with acceleration of the rate at which symptoms progress.
Hemoptysis results from rupture of pulmonary-bronchial venous connections secondary to pulmonary venous hypertension. It occurs most frequently in patients who have elevated LA pressures without markedly elevated pulmonary vascular resistances and is almost never fatal. Recurrent pulmonary emboli, sometimes with infarction, are an important cause of morbidity and mortality late in the course of MS. Pulmonary infections, i.e., bronchitis, bronchopneumonia, and lobar pneumonia, commonly complicate untreated MS, especially during the winter months. Infective endocarditis is rare in isolated MS.
In addition to the aforementioned changes in the pulmonary vascular bed, fibrous thickening of the walls of the alveoli and pulmonary capillaries occurs commonly in MS. The vital capacity, total lung capacity, maximal breathing capacity, and oxygen uptake per unit of ventilation are reduced. Pulmonary compliance falls further as pulmonary capillary pressure rises during exercise.
Thrombi may form in the left atria, particularly in the enlarged atrial appendages of patients with MS. Systemic embolization, the incidence of which is 10–20%, occurs more frequently in patients with AF, in older patients, and in those with a reduced CO. However, systemic embolization may be the presenting feature in otherwise asymptomatic patients with only mild MS.
In patients with severe MS, there may be a malar flush with pinched and blue facies. In patients with sinus rhythm and severe pulmonary hypertension or associated tricuspid stenosis (TS), the jugular venous pulse reveals prominent a waves due to vigorous right atrial systole. The systemic arterial pressure is usually normal or slightly low. An RV tap along the left sternal border signifies an enlarged RV. A diastolic thrill may be present at the cardiac apex, with the patient in the left lateral recumbent position.
The first heart sound (S1) is usually accentuated and slightly delayed. The pulmonic component of the second heart sound (P2) also is often accentuated, and the two components of the second heart sound (S2) are closely split. The opening snap (OS) of the mitral valve is most readily audible in expiration at, or just medial to the cardiac apex. This sound generally follows the sound of aortic valve closure (A2) by 0.05–0.12 s. The time interval between A2 and OS varies inversely with the severity of the MS. The OS is followed by a low-pitched, rumbling, diastolic murmur, heard best at the apex with the patient in the left lateral recumbent position. It is accentuated by mild exercise (e.g., a few rapid sit-ups) carried out just before auscultation. In general, the duration of this murmur correlates with the severity of the stenosis in patients with preserved CO. In patients with sinus rhythm, the murmur often reappears or becomes louder during atrial systole (presystolic accentuation). Soft grade I or II/VI systolic murmurs are commonly heard at the apex or along the left sternal border in patients with pure MS and do not necessarily signify the presence of MR. Hepatomegaly, ankle edema, ascites, and pleural effusion, particularly in the right pleural cavity, may occur in patients with MS and RV failure.
With severe pulmonary hypertension, a pansystolic murmur produced by functional TR may be audible along the left sternal border. This murmur is usually louder during inspiration and diminishes during forced expiration (Carvallo’s sign). When the CO is markedly reduced in MS, the typical auscultatory findings, including the diastolic rumbling murmur, may not be detectable (silent MS), but they may reappear as compensation is restored. The Graham Steell murmur of PR, a high-pitched, diastolic, decrescendo blowing murmur along the left sternal border, results from dilatation of the pulmonary valve ring and occurs in patients with mitral valve disease and severe pulmonary hypertension. This murmur may be indistinguishable from the more common murmur produced by aortic regurgitation (AR), though it may increase in intensity with inspiration and is accompanied by a loud P2.
In MS and sinus rhythm, the P wave usually suggests LA enlargement . It may become tall and peaked in lead II and upright in lead V1 when severe pulmonary hypertension or TS complicates MS and right atrial (RA) enlargement occurs. The QRS complex is usually normal. However, with severe pulmonary hypertension, right axis deviation and RV hypertrophy are often present.
Transthoracic two-dimensional echocardiography (TTE) with color flow Doppler imaging provides critical information, including an estimate of the transvalvular peak and mean gradients and of mitral orifice size, the presence and severity of accompanying MR, the extent of restriction of valve leaflets and their thickness, the degree of distortion of the subvalvular apparatus, and the anatomic suitability for percutaneous mitral balloon valvotomy (PMBV; see below). In addition, TTE provides an assessment of the size of the cardiac chambers, an estimation of LV function, an estimation of the pulmonary artery pressure (PAP), and an indication of the presence and severity of associated valvular lesions. Transesophageal echocardiography (TEE) provides superior images and should be employed when TTE is inadequate for guiding therapy. TEE is especially indicated to exclude the presence of left atrial thrombi prior to PMBV.
The earliest changes are straightening of the upper left border of the cardiac silhouette, prominence of the main pulmonary arteries, dilatation of the upper lobe pulmonary veins, and posterior displacement of the esophagus by an enlarged LA. Kerley B lines are fine, dense, opaque, horizontal lines that are most prominent in the lower and mid-lung fields and that result from distention of interlobular septae and lymphatics with edema when the resting mean LA pressure exceeds approximately 20 mmHg.
Like MS, significant MR may also be associated with a prominent diastolic murmur at the apex due to increased flow, but in MR this diastolic murmur commences slightly later than in patients with MS, and there is often clear-cut evidence of LV enlargement. An apical pansystolic murmur of at least grade III/VI intensity as well as an S3 suggests significant associated MR. Similarly, the apical mid-diastolic murmur associated with severe AR (Austin Flint murmur) may be mistaken for MS but can be differentiated from it because it is not intensified in presystole. TS, which occurs rarely in the absence of MS, may mask many of the clinical features of MS or be clinically silent.
Atrial septal defect may be mistaken for MS; in both conditions there is often clinical, ECG, and chest x-ray evidence of RV enlargement and accentuation of pulmonary vascularity. However, the absence of LA enlargement and of Kerley B lines and the demonstration of fixed splitting of S2 all favor atrial septal defect over MS.
Left atrial myxoma may obstruct LA emptying, causing dyspnea, a diastolic murmur, and hemodynamic changes resembling those of MS. However, patients with an LA myxoma often have features suggestive of a systemic disease, such as weight loss, fever, anemia, systemic emboli, and elevated serum IgG and interleukin 6 (IL-6) concentrations. The auscultatory findings may change markedly with body position. The diagnosis can be established by the demonstration of a characteristic echo-producing mass in the LA with TTE.
Left and right heart catheterization is useful when there is a discrepancy between the clinical and TTE findings that cannot be resolved with either TEE or cardiac magnetic resonance (CMR) imaging. The growing experience with CMR for the assessment of patients with valvular heart disease may decrease the need for invasive catheterization. Catheterization is helpful in assessing associated lesions such as aortic stenosis (AS) and AR. Catheterization and coronary arteriography are not usually necessary to aid in the decision about surgery in younger patients, with typical findings of severe obstruction on clinical examination and TTE. In males over 45 years of age, females over 55 years of age, and younger patients with coronary risk factors, especially those with positive noninvasive stress tests for myocardial ischemia, coronary angiography is advisable preoperatively to detect patients with critical coronary obstructions that should be bypassed at the time of operation. Computed tomographic angiography (CTA) is now used in some centers to screen preoperatively for the presence of coronary artery disease (CAD) in patients with valvular heart disease. Catheterization and left ventriculography are also indicated in most patients who have undergone PMBV or previous mitral valve surgery and who have redeveloped serious symptoms, if questions remain after both TTE and TEE.
Treatment
Management strategy for patients with mitral stenosis (MS) and mild symptoms. There is controversy as to whether patients with severe MS (MVA <1.0 cm2) and severe pulmonary hypertension(PH) (PASP >60 mmHg) should undergo percutaneous mitral balloon valvotomy (PMBV) or mitral valve replacement (MVR) to prevent right ventricular failure. CXR, chest x-ray; ECG, electrocardiogram; echo, echocardiography; LA, left atrial; MR, mitral regurgitation; MVA, mitral valve area; MVG, mean mitral valve pressure gradient; NYHA, New York Heart Association; PASP, pulmonary artery systolic pressure; PAWP, pulmonary artery wedge pressure; 2D, 2-dimensional. (From Bonow et al.)
Penicillin prophylaxis of Group A -hemolytic streptococcal infections to prevent rheumatic fever is important for at-risk patients with MS. Recommendations for infective endocarditis prophylaxis have recently changed. In symptomatic patients, some improvement usually occurs with restriction of sodium intake and maintenance doses of oral diuretics. Digitalis glycosides usually do not benefit patients with MS and sinus rhythm, but they are helpful in slowing the ventricular rate of patients with AF. Beta blockers and nondihydropyridine calcium channel blockers (e.g., verapamil or diltiazem) are also useful in this regard. Warfarin to an international normalized ration (INR) of 2–3 should be administered indefinitely to patients with MS who have AF or a history of thromboembolism. The routine use of warfarin in patients in sinus rhythm with LA enlargement (maximal dimension >5.5 cm) with or without spontaneous echo contrast is more controversial.
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If AF is of relatively recent onset in a patient whose MS is not severe enough to warrant PMBV or surgical commissurotomy, reversion to sinus rhythm pharmacologically or by means of electrical countershock is indicated. Usually, cardioversion should be undertaken after the patient has had at least 3 consecutive weeks of anticoagulant treatment to a therapeutic INR. If cardioversion is indicated more urgently, then intravenous heparin should be provided and a TEE performed to exclude the presence of left atrial thrombus before the procedure. Conversion to sinus rhythm is rarely successful or sustained in patients with severe MS, particularly those in whom the LA is especially enlarged or in whom AF has been present for more than 1 year.
Unless there is a contraindication, mitral valvotomy is indicated in symptomatic [New York Heart Association (NYHA) Functional Class II–IV] patients with isolated MS whose effective orifice (valve area) is < ~1.0 cm2/m2 body surface area, or <1.5 cm2 iormal-sized adults. Mitral valvotomy can be carried out by two techniques: PMBV and surgical valvotomy. In PMBV a catheter is directed into the LA after transseptal puncture, and a single balloon is directed across the valve and inflated in the valvular orifice. Ideal patients have relatively pliable leaflets with little or no commissural calcium. In addition, the subvalvular structures should not be significantly scarred or thickened and there should be no left atrial thombus. The short- and long-term results of this procedure in appropriate patients are similar to those of surgical valvotomy, but with less morbidity and a lower periprocedural mortality rate. Event-free survival in younger (<45 years) patients with pliable valves is excellent, with rates as high as 80–90% over 3–7 years. Therefore, PMBV has become the procedure of choice for such patients when it can be performed by a skilled operator in a high-volume center.
Inoue balloon technique for mitral balloon valvotomy. A. After transseptal puncture, the deflated balloon catheter is advanced across the inter-atrial septum, then across the mitral valve and into the left ventricle. B-D. The balloon is then inflated stepwise within the mitral orifice.
Transthoracic echocardiography is helpful in identifying patients for the percutaneous procedure, and TEE is performed routinely to exclude left atrial thrombus. An “echo score” has been developed to help guide decision-making. The score accounts for the degree of leaflet thickening, calcification, and mobility, and for the extent of subvalvular thickening. A lower score predicts a higher likelihood of successful PMBV.
In patients in whom PMBV is not possible or unsuccessful, or in many patients with restenosis, an “open” valvotomy using cardiopulmonary bypass is necessary. In addition to opening the valve commissures, it is important to loosen any subvalvular fusion of papillary muscles and chordae tendineae and to remove large deposits of calcium, thereby improving valvular function, as well as to remove atrial thrombi. The perioperative mortality rate is ~2%.
Successful valvotomy is defined by a 50% reduction in the mean mitral valve gradient and a doubling of the mitral valve area. Successful valvotomy, whether balloon or surgical, usually results in striking symptomatic and hemodynamic improvement and prolongs survival. However, there is no evidence that the procedure improves the prognosis of patients with slight or no functional impairment. Therefore, unless recurrent systemic embolization or severe pulmonary hypertension has occurred (PA systolic pressures >50 mmHg at rest or >60 mmHg with exercise), valvotomy is not recommended for patients who are entirely asymptomatic and/or who have mild stenosis (mitral valve area >1/5 cm2). When there is little symptomatic improvement after valvotomy, it is likely that the procedure was ineffective, that it induced MR, or that associated valvular or myocardial disease was present. About half of all patients undergoing surgical mitral valvotomy require reoperation by 10 years. In the pregnant patient with MS, valvotomy should be carried out if pulmonary congestion occurs despite intensive medical treatment. PMBV is the preferred strategy in this setting and is performed with TEE and no or minimal x-ray exposure.
Mitral valve replacement (MVR) is necessary in patients with MS and significant associated MR, those in whom the valve has been severely distorted by previous transcatheter or operative manipulation, or those in whom the surgeon does not find it possible to improve valve function significantly. MVR is now routinely performed with preservation of the chordal attachments to optimize LV functional recovery. Perioperative mortality rates with MVR vary with age, LV function, the presence of CAD, and associated comorbidities. They average 5% overall but are lower in young patients and may be twice as high in older patients with comorbidities. Since there are also long-term complications of valve replacement, patients in whom preoperative evaluation suggests the possibility that MVR may be required should be operated on only if they have severe MS—i.e., an orifice area 1 cm2—and are in NYHA Class III, i.e., symptomatic with ordinary activity despite optimal medical therapy. The overall 10-year survival of surgical survivors is ~70%. Long-term prognosis is worse in older patients and those with marked disability and marked depression of the CO preoperatively. Pulmonary hypertension and RV dysfunction are additional risk factors for poor outcome.
Aortic stenosis
Aortic stenosis (AS) most often is due to calcification of a congenitally bicuspid or normal trileaflet valve. Calcific changes are due to an active disease process characterized by lipid accumulation, inflammation, and calcification. Once initiated, progressive leaflet calcification and fibrosis eventually result in reduced leaflet motion with obstruction to left ventricular (LV) outflow . Aortic stenosis often is first diagnosed by the finding of a murmur on auscultation. However, while a soft murmur with a physiologic split S2 reliably excludes severe stenosis and a grade 4 murmur with diminished carotid upstrokes confirms severe obstruction, between these extremes physical examination is not accurate for evaluation of disease severity.
AS occurs in about one-fourth of all patients with chronic valvular heart disease; approximately 80% of adult patients with symptomatic valvular AS are male.
AS in adults may be due to degenerative calcification of the aortic cusps. It may be congenital in origin or it may be secondary to rheumatic inflammation. Age-related degenerative calcific AS (also known as senile or sclerocalcific AS) is now the most common cause of AS in adults in North America and Western Europe. About 30% of persons >65 years exhibit aortic valve sclerosis; many of these have a systolic murmur of AS but without obstruction, while 2% exhibit frank stenosis. Aortic sclerosis is defined echocardiographically as focal thickening or calcification of the valve cusps with a peak Doppler transaortic velocity of 2.5 m/s. Aortic sclerosis appears to be a marker for an increased risk of coronary heart disease events. On histologic examination these valves frequently exhibit changes similar to those seen with atherosclerosis and vascular inflammation. Interestingly, risk factors for atherosclerosis, such as age, male sex, smoking, diabetes mellitus, hypertension, chronic kidney disease, increased LDL, reduced HDL cholesterol, and elevated C-reactive protein are all risk factors for aortic valve calcification.
The congenitally affected valve may be stenotic at birth and may become progressively more fibrotic, calcified, and stenotic. In other cases the valve may be congenitally deformed, usually bicuspid [bicuspid aortic valve (BAV)], without serious narrowing of the aortic orifice during childhood; its abnormal architecture makes its leaflets susceptible to otherwise ordinary hemodynamic stresses, which ultimately lead to valvular thickening, calcification, increased rigidity, and narrowing of the aortic orifice.
Rheumatic disease of the aortic leaflets produces commissural fusion, sometimes resulting in a bicuspid-appearing valve. This condition in turn makes the leaflets more susceptible to trauma and ultimately leads to fibrosis, calcification, and further narrowing. By the time the obstruction to LV outflow causes serious clinical disability, the valve is usually a rigid calcified mass, and careful examination may make it difficult or even impossible to determine the etiology of the underlying process. Rheumatic AS is almost always associated with involvement of the mitral valve and with AR.
Other Forms of Obstruction to Left Ventricular Outflow
Besides valvular AS, three other lesions may be responsible for obstruction to LV outflow: hypertrophic obstructive cardiomyopathy, discrete congenital subvalvularAS, and supravalvularAS. The causes of left ventricular outflow obstruction can be differentiated on the basis of the cardiac examination and Doppler echocardiographic findings.
The obstruction to LV outflow produces a systolic pressure gradient between the LV and aorta. When severe obstruction is suddenly produced experimentally, the LV responds by dilatation and reduction of stroke volume. However, in some patients the obstruction may be present at birth and/or increase gradually over the course of many years, and LV output is maintained by the presence of concentric LV hypertrophy. Initially, this serves as an adaptive mechanism because it reduces toward normal the systolic stress developed by the myocardium, as predicted by the Laplace relation (S = Pr/h, where S = systolic wall stress, P = pressure, r = radius, and h = wall thickness). A large transaortic valvular pressure gradient may exist for many years without a reduction in CO or LV dilatation; ultimately, however, excessive hypertrophy becomes maladaptive, and LV function declines.
A mean systolic pressure gradient >40 mmHg with a normal CO or an effective aortic orifice area < ~1.0 cm2 (or ~<0.6 cm2/m2 body surface area in a normal-sized adult)—i.e., less than approximately one-third of the normal orifice—is generally considered to represent severe obstruction to LV outflow. The elevated LV end-diastolic pressure observed in many patients with severe AS signifies the presence of LV dilatation and/or diminished compliance of the hypertrophied LV wall. Although the CO at rest is withiormal limits in most patients with severe AS, it usually fails to rise normally during exercise. Loss of an appropriately timed, vigorous atrial contraction, as occurs in AF or atrioventricular dissociation, may cause rapid progression of symptoms. Late in the course, the CO and LV–aortic pressure gradient decline, and the mean LA, PA, and RV pressures rise.
The hypertrophied LV elevates myocardial oxygen requirements. In addition, even in the absence of obstructive CAD, there may be interference with coronary blood flow. This is because the pressure compressing the coronary arteries exceeds the coronary perfusion pressure, often causing ischemia (especially in the subendocardium), both in the presence and in the absence of coronary arterial narrowing.
AS is rarely of clinical importance until the valve orifice has narrowed to approximately 1.0 cm2. Even severe AS may exist for many years without producing any symptoms because of the ability of the hypertrophied LV to generate the elevated intraventricular pressures required for a normal stroke volume.
Most patients with pure or predominant AS have gradually increasing obstruction for years but do not become symptomatic until the sixth to eighth decades. Exertional dyspnea, angina pectoris, and syncope are the three cardinal symptoms. Often there is a history of insidious progression of fatigue and dyspnea associated with gradual curtailment of activities. Dyspnea results primarily from elevation of the pulmonary capillary pressure caused by elevations of LV diastolic pressures secondary to reduced left ventricular compliance. Angina pectoris usually develops somewhat later and reflects an imbalance between the augmented myocardial oxygen requirements and reduced oxygen availability; the former results from the increased myocardial mass and intraventricular pressure, while the latter may result from accompanying CAD, which is not uncommon in patients with AS, as well as from compression of the coronary vessels by the hypertrophied myocardium. Therefore, angina may occur in severe AS even without obstructive epicardial CAD. Exertional syncope may result from a decline in arterial pressure caused by vasodilatation in the exercising muscles and inadequate vasoconstriction ionexercising muscles in the face of a fixed CO, or from a sudden fall in CO produced by an arrhythmia.
Since the CO at rest is usually well maintained until late in the course, marked fatigability, weakness, peripheral cyanosis, cachexia, and other clinical manifestations of a low CO are usually not prominent until this stage is reached. Orthopnea, paroxysmal nocturnal dyspnea, and pulmonary edema, i.e., symptoms of LV failure, also occur only in the advanced stages of the disease. Severe pulmonary hypertension leading to RV failure and systemic venous hypertension, hepatomegaly, AF, and TR are usually late findings in patients with isolated severe AS.
When AS and MS coexist, the reduction in CO induced by MS lowers the pressure gradient across the aortic valve and thereby masks many of the clinical findings produced by AS.
The rhythm is generally regular until late in the course; at other times, AF should suggest the possibility of associated mitral valve disease. The systemic arterial pressure is usually withiormal limits. In the late stages, however, when stroke volume declines, the systolic pressure may fall and the pulse pressure narrow. The peripheral arterial pulse rises slowly to a delayed sustained peak (pulsus parvus et tardus. In the elderly, the stiffening of the arterial wall may mask this important physical sign. In many patients the a wave in the jugular venous pulse is accentuated. This results from the diminished distensibility of the RV cavity caused by the bulging, hypertrophied interventricular septum.
The LV impulse is usually displaced laterally. A double apical impulse may be recognized, particularly with the patient in the left lateral recumbent position. A systolic thrill is generally present at the base of the heart, in the suprasternal notch, and along the carotid arteries.
An early systolic ejection sound is frequently audible in children and adolescents with congenital noncalcific valvular AS. This sound usually disappears when the valve becomes calcified and rigid. As AS increases in severity, LV systole may become prolonged so that the aortic valve closure sound no longer precedes the pulmonic valve closure sound, and the two components may become synchronous, or aortic valve closure may even follow pulmonic valve closure, causing paradoxic splitting of S2. The sound of aortic valve closure can be heard most frequently in patients with AS who have pliable valves, and calcification diminishes the intensity of this sound. Frequently, an S4 is audible at the apex and reflects the presence of LV hypertrophy and an elevated LV end-diastolic pressure; an S3 generally occurs late in the course, when the LV dilates.
A. Schematic representation of ECG, aortic pressure (AOP), left ventricular pressure (LVP), and left atrial pressure (LAP). The shaded areas indicate a transvalvular pressure difference during systole. HSM, holosystolic murmur; MSM, midsystolic murmur. B. Graphic representation of ECG, aortic pressure (AOP), left ventricular pressure (LVP), and left atrial pressure (LAP) with shaded areas indicating transvalvular diastolic pressure difference. EDM, early diastolic murmur; PSM, presystolic murmur; MDM, middiastolic murmur.
The murmur of AS is characteristically an ejection (mid) systolic murmur that commences shortly after the S1, increases in intensity to reach a peak toward the middle of ejection, and ends just before aortic valve closure. It is characteristically low-pitched, rough and rasping in character, and loudest at the base of the heart, most commonly in the second right intercostal space. It is transmitted upward along the carotid arteries. Occasionally it is transmitted downward and to the apex, where it may be confused with the systolic murmur of MR (Gallavardin effect). In almost all patients with severe obstruction and preserved CO, the murmur is at least grade III/VI. In patients with mild degrees of obstruction or in those with severe stenosis with heart failure in whom the stroke volume and therefore the transvalvular flow rate are reduced, the murmur may be relatively soft and brief.
In most patients with severe AS there is LV hypertrophy.
Left ventricular hypertrophy (LVH) increases the amplitude of electrical forces directed to the left and posteriorly. In addition, repolarization abnormalities may cause ST-segment depression and T-wave inversion in leads with a prominent R wave. Right ventricular hypertrophy (RVH) may shift the QRS vector to the right; this effect usually is associated with an R, RS, or qR complex in lead V1. T-wave inversions may be present in right precordial leads.
In advanced cases, ST-segment depression and T-wave inversion (LV “strain”) in standard leads I and aVL and in the left precordial leads are evident. However, there is no close correlation between the ECG and the hemodynamic severity of obstruction, and the absence of ECG signs of LV hypertrophy does not exclude severe obstruction.
The key findings are LV hypertrophy and, in patients with valvular calcification (i.e., most adult patients with symptomatic AS), multiple, bright, thick, echoes from the valve.
Still frame two-dimensional echocardiographic image from the parasternal long axis view of a patient with aortic stenosis. The aortic valve is calcified with restricted opening during systole. Ao, aorta; RV, right ventricle; LA, left atrium; LV, left ventricle.
Standard evaluation of aortic stenosis (AS) severity is based on measurement of left ventricular outflow tract (LVOT) diameter (D) in a parasternal long-axis view for calculation of a circular cross-sectional area (CSA), outflow tract velocity (V) from an apical approach using pulsed Doppler, and the maximum aortic jet (AS-Jet, Vmax) from the continuous-wave Doppler recording. Either velocity-time integrals (VTIs) or maximum velocities can be used in the continuity equation for aortic valve area (AVA).
Aortic valve area (AVA) is calculated based on the principle that volume flow proximal to the valve equals volume flow through the narrowed orifice . Volume flow is calculated as the cross-sectional area (CSA) of flow times the velocity-time integral (VTI) of flow at that site. In the left ventricular outflow tract (LVOT), flow just proximal to the stenotic valve is relatively laminar with a flat velocity profile. Thus: or
In clinical practice, maximum velocities often are substituted for VTIs, in the simplified continuity equation:
A further simplification of the continuity equation is the dimensionless ratio of outflow tract to aortic velocity:
This ratio reflects the relative valve size compared with the area of the patient’s outflow track (i.e., is effectively indexed for body size) and is particularly useful when images of outflow tract diameter are suboptimal. This ratio approaches 1 with a normal valve. A ratio <0.25 indicates a valve area 25% of expected, corresponding to severe stenosis. The accuracy of all these Doppler measures of stenosis severity is highly dependent on meticulous attention to technical details and a comprehensive examination by an experienced echocardiographer.
Eccentricity of the aortic valve cusps is characteristic of congenitally bicuspid valves. TEE imaging usually displays the obstructed orifice extremely well, but it is not routinely required for adequate characterization. The valve gradient and aortic valve area can be estimated by Doppler measurement of the transaortic velocity. Severe AS is defined by a valve area <1.0 cm2, whereas moderate AS is defined by a valve area of 1.0–1.5 cm2 and mild AS by a valve area of 1.5–2.0 cm2. LV dilatation and reduced systolic shortening reflect impairment of LV function.
Echocardiography is useful for identifying coexisting valvular abnormalities such as MS and AR, which sometimes accompany AS; for differentiating valvular AS from other forms of outflow obstruction; and for measurement of the aortic root. Aneurysmal enlargement (maximal dimension >4.5 cm) of the root or ascending aorta can occur in up to 20% of patients with bicuspid aortic valve disease, independent of the severity of the valve lesion. Dobutamine stress echocardiography is useful for the evaluation of patients with severe AS and severe LV systolic dysfunction (EF< 0.35).
The chest x-ray may show no or little overall cardiac enlargement for many years. Hypertrophy without dilatation may produce some rounding of the cardiac apex in the frontal projection and slight backward displacement in the lateral view; severe AS is often associated with poststenotic dilatation of the ascending aorta. As noted above, however, aortic enlargement may be an independent process and mediated by the same type of structural changes that occur in patients with Marfan syndrome. Aortic calcification is usually readily apparent on fluoroscopic examination or by echocardiography; the absence of valvular calcification in an adult suggests that severe valvular AS is not present. In later stages of the disease, as the LV dilates there is increasing roentgenographic evidence of LV enlargement, pulmonary congestion, and enlargement of the LA, PA, and right side of the heart.
Right and left heart catheterization for invasive assessment of AS is performed infrequently but can be useful when there is a discrepancy between the clinical and echocardiographic findings. Concerns have been raised that attempts to cross the aortic valve for measurement of left ventricular pressures are associated with a risk of cerebral embolization. Catheterization is also useful in three distinct categories of patients: (1) patients with multivalvular disease, in whom the role played by each valvular deformity should be defined to aid in the planning of definitive operative treatment; (2) young, asymptomatic patients with noncalcific congenital AS, to define with precision the severity of obstruction to LV outflow, since operation [which does not usually require aortic valve replacement (AVR)] or PABV may be indicated if severe AS is present, even in the absence of symptoms; balloon valvotomy may follow left heart catheterization immediately; and (3) patients in whom it is suspected that the obstruction to LV outflow may not be at the aortic valve but rather in the sub- or supravalvular regions.
Coronary angiography is indicated to detect or exclude CAD in patients >45 years old with severe AS who are being considered for operative treatment. The incidence of significant CAD for which bypass grafting is indicated at the time of AVR exceeds 50% among adult patients.
Death in patients with severe AS occurs most commonly in the seventh and eighth decades. Based on data obtained at postmortem examination in patients before surgical treatment became widely available, the average time to death after the onset of various symptoms was as follows: angina pectoris, 3 years; syncope, 3 years; dyspnea, 2 years; congestive heart failure, 1.5–2 years. Moreover, in >80% of patients who died with AS, symptoms had existed for <4 years. Among adults dying with valvular AS, sudden death, which presumably resulted from an arrhythmia, occurred in 10–20%. However, most sudden deaths occurred in patients who had previously been symptomatic; thus, sudden death is very uncommon (<1% per year) in asymptomatic adult patients with severe AS. Obstructive calcific AS is a progressive disease, with an annual reduction in valve area averaging 0.1 cm2/year and an annual increase in mean gradient averaging 7 mmHg/year.
Medical Treatment
Management strategy for patients with severe aortic stenosis. Preoperative coronary angiography should be performed routinely as determined by age, symptoms, and coronary risk factors. Cardiac catheterization and angiography may also be helpful when there is discordance between clinical findings and echocardiography. AVA, aortic valve area; BP, blood pressure; CABG, coronary artery bypass graft surgery; echo, echocardiography; LV, left ventricle; Vmax, maximal velocity across aortic valve by Doppler echocardiography. (From Bonow et al. Modified from CM Otto: J Am Coll Cardiol 47:2141, 2006.)
In patients with severe AS (<1.0 cm2), strenuous physical activity should be avoided, even in the asymptomatic stage. Care must be taken to avoid dehydration and hypovolemia to protect against a significant reduction in CO. Medications used for the treatment of hypertension or CAD, including beta blockers and ACE inhibitors, are generally safe for asymptomatic patients with preserved left ventricular systolic function. Nitroglycerin is helpful in relieving angina pectoris. Retrospective studies have shown that patients with degenerative calcific AS who receive HMG-CoA reductase inhibitors (“statins”) exhibit slower progression of leaflet calcification and aortic valve area reduction than those who do not. One prospective randomized clinical trial using high-dose atorvastatin failed to show a measurable benefit, although a more recent trial using rosuvastatin did show a beneficial effect. The role of statin medications may be more clearly defined with further study.
Asymptomatic patients with calcific AS and severe obstruction should be followed carefully for the development of symptoms and by serial echocardiograms for evidence of deteriorating LV function. Operation is indicated in patients with severe AS (valve area <1.0 cm2 or 0.6 cm2/m2 body surface area) who are symptomatic, those who exhibit LV dysfunction (EF <50%), as well as those with an aneurysmal or expanding aortic root (maximal dimension >4.5 cm or annual increase in size >0.5 cm/year), even if they are asymptomatic. In patients without heart failure, the operative risk of AVR is approximately 3% . It is prudent to postpone operation in patients with severe calcific AS who are truly asymptomatic and who exhibit normal LV function, i.e., EF >50%, since they may continue to do well for years. However, some advocate AVR in patients with severe valve calcification and rapid progression of obstruction. The risk of surgical mortality exceeds that of sudden death in asymptomatic patients. Exercise testing is employed in many centers to assess objectively the functional capacity of asymptomatic patients for whom the history is ambiguous. As many as one-third of patients will show signs of functional impairment during exercise for which AVR should be considered. AVR is carried out in asymptomatic patients with severe or moderately severe stenosis who undergo coronary artery bypass grafting. AVR is also routinely performed in patients with moderate AS who are undergoing coronary bypass grafting or aortic root reconstruction.
Operation should, if possible, be carried out before frank LV failure develops; at this late stage, the aortic valve pressure gradient declines as the CO, stroke volume, and EF decline (low gradient, low output AS). In such patients the perioperative risk is high (15–20%), and evidence of myocardial disease may persist even when the operation is technically successful. Furthermore, long-term postoperative survival also correlates inversely with preoperative LV dysfunction. Nonetheless, in view of the even worse prognosis of such patients when they are treated medically, there is usually little choice but to advise surgical treatment, especially in patients in whom contractile reserve can be demonstrated by dobutamine echocardiography (defined by a 20% in stroke volume after dobutamine challenge). In patients in whom severe AS and CAD coexist, relief of the AS and revascularization of the myocardium by means of aortocoronary bypass grafting may result in striking clinical and hemodynamic improvement.
Because many patients with calcific AS are elderly, particular attention must be directed to the adequacy of hepatic, renal, and pulmonary function before AVR is recommended. Age alone is not a contraindication to AVR for AS. The mortality rate depends to a substantial extent on the patient’s preoperative clinical and hemodynamic state. The 10-year survival rate of patients with AVR is approximately 60%. Approximately 30% of bioprosthetic valves evidence primary valve failure in 10 years, requiring re-replacement, and an approximately equal percentage of patients with mechanical prostheses develop significant hemorrhagic complications as a consequence of treatment with anticoagulants.
Percutaneous Balloon Aortic Valvuloplasty
This procedure is preferable to operation in children and young adults with congenital, noncalcific AS. It is not commonly used in adults with severe calcific AS because of a very high restenosis rate and the risk of procedural complications, but on occasion it has been used successfully as a “bridge to operation” in patients with severe LV dysfunction and shock who are too ill to tolerate surgery.
Aortic Regurgitation
In approximately two-thirds of patients with valvular AR, the disease is rheumatic in origin, resulting in thickening, deformity, and shortening of the individual aortic valve cusps, changes that prevent their proper opening during systole and closure during diastole. A rheumatic origin is much less common in patients with isolated AR who do not have associated mitral valve disease. Patients with congenital BAV disease may develop predominant AR. Congenital fenestrations of the aortic valve occasionally produce mild AR. Membranous subaortic stenosis often leads to thickening and scarring of the aortic valve leaflets with secondary AR. Prolapse of an aortic cusp, resulting in progressive chronic AR, occurs in approximately 15% of patients with ventricular septal defect but may also occur as an isolated phenomenon or as a consequence of myxomatous degeneration sometimes associated with mitral and/or tricuspid valve involvement.
AR may result from infective endocarditis, which can develop on a valve previously affected by rheumatic disease, a congenitally deformed valve, or, rarely, on a normal aortic valve, and may lead to perforation or erosion of one or more leaflets. The aortic valve leaflets may become scarred and retracted during the course of syphilis or ankylosing spondylitis and contribute further to the AR that derives primarily from the associated root disease. Although traumatic rupture or avulsion of the aortic valve is an uncommon cause of acute AR, it does represent the most frequent serious lesion in patients surviving nonpenetrating cardiac injuries. The coexistence of hemodynamically significant AS with AR usually excludes all the rarer forms of AR because it occurs almost exclusively in patients with rheumatic or congenital AR. In patients with AR due to primary valvular disease, dilatation of the aortic annulus may occur secondarily and intensify the regurgitation.
AR may also be due entirely to marked aortic dilatation, i.e., aortic root disease, without primary involvement of the valve leaflets; widening of the aortic annulus and separation of the aortic leaflets are responsible for the AR. Cystic medial degeneration of the ascending aorta, which may or may not be associated with other manifestations of Marfan syndrome; idiopathic dilatation of the aorta; annulo-aortic ectasia; osteogenesis imperfecta; and severe hypertension may all widen the aortic annulus and lead to progressive AR. Occasionally AR is caused by retrograde dissection of the aorta involving the aortic annulus. Syphilis and ankylosing spondylitis, both of which may affect aortic valves, may also be associated with cellular infiltration and scarring of the media of the thoracic aorta, leading to aortic dilatation, aneurysm formation, and severe regurgitation. In syphilis of the aorta, now a very rare condition, the involvement of the intima may narrow the coronary ostia, which in turn may be responsible for myocardial ischemia.
The total stroke volume ejected by the LV (i.e., the sum of the effective forward stroke volume and the volume of blood that regurgitates back into the LV) is increased in patients with AR. In patients with wide-open (free) AR, the volume of regurgitant flow may equal the effective forward stroke volume. In contrast to MR, in which a fraction of the LV stroke volume is delivered into the low-pressure LA, in AR the entire LV stroke volume is ejected into a high-pressure zone, the aorta. An increase in the LV end-diastolic volume (increased preload) constitutes the major hemodynamic compensation for AR. The dilatation and eccentric hypertrophy of the LV allow this chamber to eject a larger stroke volume without requiring any increase in the relative shortening of each myofibril. Therefore, severe AR may occur with a normal effective forward stroke volume and a normal left ventricular EF [total (forward plus regurgitant) stroke volume/end-diastolic volume], together with an elevated LV end-diastolic pressure and volume. However, through the operation of Laplace’s law, LV dilatation increases the LV systolic tension required to develop any given level of systolic pressure. Chronic AR is thus a state in which LV preload and afterload are both increased. Ultimately, these adaptive measures fail. As LV function deteriorates, the end-diastolic volume rises further and the forward stroke volume and EF decline. Deterioration of LV function often precedes the development of symptoms. Considerable thickening of the LV wall also occurs with chronic AR, and at autopsy the hearts of these patients may be among the largest encountered, sometimes weighing> 1000 g.
The reverse pressure gradient from aorta to LV, which drives the AR flow, falls progressively during diastole, accounting for the decrescendo nature of the diastolic murmur. Equilibration between aortic and LV pressures may occur toward the end of diastole in patients with chronic severe AR, particularly when the heart rate is slow. In patients with acute severe AR, the LV is unprepared for the regurgitant volume load. LV compliance is normal or reduced, and LV diastolic pressures rise rapidly, occasionally to levels >40 mmHg. The LV pressure may exceed the LA pressure toward the end of diastole, and this reversed pressure gradient closes the mitral valve prematurely.
In patients with chronic severe AR, the effective forward CO usually is normal or only slightly reduced at rest, but often it fails to rise normally during exertion. Early signs of LV dysfunction include reduction in the EF. In advanced stages there may be considerable elevation of the LA, PA wedge, PA, and RV pressures and lowering of the forward CO at rest.
Myocardial ischemia may occur in patients with AR because myocardial oxygen requirements are elevated by LV dilatation, hypertrophy, and elevated LV systolic tension. However, a large fraction of coronary blood flow occurs during diastole, when arterial pressure is subnormal, thereby reducing coronary perfusion pressure. This combination of increased oxygen demand and reduced supply may cause myocardial ischemia, particularly of the subendocardium, even in the absence of concomitant CAD.
Approximately three-fourths of patients with pure or predominant valvular AR are males; females predominate among patients with primary valvular AR who have associated mitral valve disease. A history compatible with infective endocarditis may sometimes be elicited from patients with rheumatic or congenital involvement of the aortic valve, and the infection often precipitates or seriously aggravates preexisting symptoms.
In patients with acute severe AR, as may occur in infective endocarditis, aortic dissection, or trauma, the LV cannot dilate sufficiently to maintain stroke volume, and LV diastolic pressure rises rapidly with associated marked elevations of LA and PA wedge pressures. Pulmonary edema and/or cardiogenic shock may develop rapidly.
Chronic severe AR may have a long latent period, and patients may remain relatively asymptomatic for as long as 10–15 years. However, uncomfortable awareness of the heartbeat, especially on lying down, may be an early complaint. Sinus tachycardia, during exertion or with emotion, or premature ventricular contractions may produce particularly uncomfortable palpitations as well as head pounding. These complaints may persist for many years before the development of exertional dyspnea, usually the first symptom of diminished cardiac reserve. The dyspnea is followed by orthopnea, paroxysmal nocturnal dyspnea, and excessive diaphoresis. Anginal chest pain occurs frequently in patients with severe AR, even in younger patients, and it is not necessary to invoke the presence of CAD to explain this symptom in patients with severe AR. Anginal pain may develop at rest as well as during exertion. Nocturnal angina may be a particularly troublesome symptom, and it may be accompanied by marked diaphoresis. The anginal episodes can be prolonged and often do not respond satisfactorily to sublingual nitroglycerin. Systemic fluid accumulation, including congestive hepatomegaly and ankle edema, may develop late in the course of the disease.
In chronic severe AR, the jarring of the entire body and the bobbing motion of the head with each systole can be appreciated, and the abrupt distention and collapse of the larger arteries are easily visible. The examination should be directed toward the detection of conditions predisposing to AR, such as Marfan syndrome, ankylosing spondylitis, and ventricular septal defect.
A rapidly rising “water-hammer” pulse, which collapses suddenly as arterial pressure falls rapidly during late systole and diastole (Corrigan’s pulse), and capillary pulsations, an alternate flushing and paling of the skin at the root of the nail while pressure is applied to the tip of the nail (Quincke’s pulse), are characteristic of free AR. A booming “pistol-shot” sound can be heard over the femoral arteries (Traube’s sign), and a to-and-fro murmur (Duroziez’s sign) is audible if the femoral artery is lightly compressed with a stethoscope.
The arterial pulse pressure is widened, and there is an elevation of the systolic pressure, sometimes to as high as 300 mmHg, and a depression of the diastolic pressure. The measurement of arterial diastolic pressure with a sphygmomanometer may be complicated by the fact that systolic sounds are frequently heard with the cuff completely deflated. However, the level of cuff pressure at the time of muffling of the Korotkoff sounds (Phase IV) generally corresponds fairly closely to the true intraarterial diastolic pressure. As the disease progresses and the LV end-diastolic pressure rises, the arterial diastolic pressure may actually rise as well, since the aortic diastolic pressure cannot fall below the LV end-diastolic pressure. For the same reason, acute severe AR may also be accompanied by only a slight widening of the pulse pressure. Such patients are invariably tachycardic as the heart rate increases in an attempt to preserve the CO.
In patients with chronic severe AR, the LV impulse is heaving and displaced laterally and inferiorly. The systolic expansion and diastolic retraction of the apex are prominent. A diastolic thrill is often palpable along the left sternal border, and a prominent systolic thrill may be palpable in the suprasternal notch and transmitted upward along the carotid arteries. This systolic thrill and the accompanying murmur do not necessarily signify the coexistence of AS. In many patients with pure AR or with combined AS and AR, the carotid arterial pulse is bisferiens, i.e., with two systolic waves separated by a trough.
In patients with severe AR, the aortic valve closure sound (A2) is usually absent. An S3 and systolic ejection sound are frequently audible, and occasionally an S4 also may be heard. The murmur of chronic AR is typically a high-pitched, blowing, decrescendo diastolic murmur, heard best in the third intercostal space along the left sternal border.
A. Schematic representation of ECG, aortic pressure (AOP), left ventricular pressure (LVP), and left atrial pressure (LAP). The shaded areas indicate a transvalvular pressure difference during systole. HSM, holosystolic murmur; MSM, midsystolic murmur. B. Graphic representation of ECG, aortic pressure (AOP), left ventricular pressure (LVP), and left atrial pressure (LAP) with shaded areas indicating transvalvular diastolic pressure difference. EDM, early diastolic murmur; PSM, presystolic murmur; MDM, middiastolic murmur.
In patients with mild AR, this murmur is brief but, as the severity increases, generally becomes louder and longer, indeed holodiastolic. When the murmur is soft, it can be heard best with the diaphragm of the stethoscope and with the patient sitting up, leaning forward, and with the breath held in forced expiration. In patients in whom the AR is caused by primary valvular disease, the diastolic murmur is usually louder along the left than the right sternal border. However, when the murmur is heard best along the right sternal border, it suggests that the AR is caused by aneurysmal dilatation of the aortic root. “Cooing” or musical diastolic murmurs suggest eversion of an aortic cusp vibrating in the regurgitant stream.
A mid-systolic ejection murmur is frequently audible in isolated AR. It is generally heard best at the base of the heart and is transmitted along the carotid vessels. This murmur may be quite loud without signifying aortic obstruction. A third murmur frequently heard in patients with severe AR is the Austin Flint murmur, a soft, low-pitched, rumbling mid-diastolic murmur. It is probably produced by the diastolic displacement of the anterior leaflet of the mitral valve by the AR stream but does not appear to be associated with hemodynamically significant mitral obstruction. The auscultatory features of AR are intensified by strenuous handgrip, which augments systemic resistance.
In acute severe AR, the elevation of LV end-diastolic pressure may lead to early closure of the mitral valve, an associated mid-diastolic sound, a soft or absent S1, a pulse pressure that is not particularly wide, and a soft, short diastolic murmur of AR.
In patients with chronic severe AR, the ECG signs of LV hypertrophy become manifest . In addition, these patients frequently exhibit ST-segment depression and T-wave inversion in leads I, aVL, V5, and V6 (“LV strain”). Left axis deviation and/or QRS prolongation denote diffuse myocardial disease, generally associated with patchy fibrosis, and usually signify a poor prognosis.
The extent and velocity of wall motion are normal or even supernormal, until myocardial contractility declines. A rapid, high-frequency fluttering of the anterior mitral leaflet produced by the impact of the regurgitant jet is a characteristic finding. The echocardiogram is also useful in determining the cause of AR, by detecting dilatation of the aortic annulus and root or aortic dissection. Thickening and failure of coaptation of the leaflets also may be noted. Color flow Doppler echocardiographic imaging is very sensitive in the detection of AR, and Doppler echocardiography is helpful in assessing its severity. With severe AR, the central jet width exceeds 65% of the left ventricular outflow tract, the regurgitant volume is 60 ml/beat, the regurgitant fraction is 50%, and there is diastolic flow reversal in the proximal descending thoracic aorta. The continuous wave Doppler profile shows a rapid deceleration time in patients with acute severe AR, due to the rapid increase in LV diastolic pressure. Serial two-dimensional echocardiography is valuable in assessing LV performance and in detecting progressive myocardial dysfunction.
In chronic severe AR, the apex is displaced downward and to the left in the frontal projection. In the left anterior oblique and lateral projections, the LV is displaced posteriorly and encroaches on the spine. When AR is caused by primary disease of the aortic root, aneurysmal dilatation of the aorta may be noted, and the aorta may fill the retrosternal space in the lateral view. Echocardiography and CT angiography are more sensitive than the chest x-ray for the detection of aortic root enlargement.
Cardiac Catheterization and Angiography
Wheeeded, right and left heart catheterization with contrast aortography can provide accurate confirmation of the magnitude of regurgitation and the status of LV function. Coronary angiography is performed routinely in appropriate patients prior to surgery.
Evaluation
Classifying the severity of regurgitation is the first step in evaluating patients with aortic regurgitation (Table 1).
Clinically, bounding arterial pulses, a widened pulse pressure, a loud diastolic murmur, and a third heart sound are signs of severe regurgitation but are not always specific. Doppler echocardiography has become the mainstay of the assessment of the severity of aortic regurgitation. Suggestive of severe regurgitation are signs of a broad jet width on color-flow imaging, steep jet velocity deceleration (reflecting equalization of aortic and ventricular pressure), and prolonged diastolic flow reversal in the aorta. The use of Doppler echocardiography makes it possible to quantify the effective regurgitant orifice (severe if 0.30 cm2) and regurgitant volume (severe if 60 ml per beat)
Echo-Doppler imaging of aortic regurgitation (video)
Example of a Jet of Aortic Regurgitation, as Shown by Color-Flow Imaging.
The three components of the regurgitant flow (flow convergence above the orifice, vena contracta through the orifice, and the jet below the orifice) are shown. The width of the vena contracta (as indicated by crosses) can be measured as a surrogate for the regurgitant orifice.
A simple, reliable measurement is the “vena contracta” — that is, the width of the regurgitant flow at the orifice, a surrogate measurement for the size of the orifice. Measurements that are 0.5 cm or more have a high sensitivity for the diagnosis of severe regurgitation, and measurements that are 0.7 cm or more have a high specificity for the diagnosis. On rare occasions, this approach is inconclusive, and either transesophageal echocardiography or angiography of the aortic root is necessary to determine the severity of aortic regurgitation. Left ventricular size and function (particularly, the end-systolic diameter and ejection fraction) should be routinely assessed, as should dilatation of the ascending aorta. If transthoracic imaging is suboptimal for the latter, transesophageal echocardiography, computed tomography, or magnetic resonance imaging can be used. Exercise testing may be warranted in asymptomatic patients with limited physical activity to evaluate functional limitations and may also provide information about changes of left ventricular function with stress.
Example of Quantitation of Aortic Regurgitation by the Convergence of the Proximal Flow.
Panel A is a color-flow image of the aortic valve; the measured radius of the proximal flow convergence (R) is 0.74 cm, and the regurgitant flow is calculated as 138 ml per second. The “aliasing” velocity of 0.40 m per second (modified by baseline displacement) is the blood velocity at the junction of the orange and blue flows. Panel B shows a continuous-wave Doppler measurement of regurgitant blood velocity, at 455 cm per second (arrow). The effective regurgitant orifice area is determined by dividing the flow by the velocity, which in this case is 0.30 cm2.
Treatment
Management strategy for patients with chronic severe aortic regurgitation. Preoperative coronary angiography should be performed routinely, as determined by age, symptoms, and coronary risk factors. Cardiac catheterization and angiography may also be helpful when there is discordance between clinical findings and echocardiography. “Stable” refers to stable echocardiographic measurements. In some centers, serial follow-up may be performed with radionuclide ventriculography (RVG) or magnetic resonance imaging (MRI) rather than echocardiography (echo) to assess left ventricular (LV) volume and systolic function. AVR, aortic valve replacement; DD, end-diastolic dimension; EF, ejection fraction; eval, evaluation; SD, end-systolic dimension. (Modified from Bonow et al.)
Acute Aortic Regurgitation
Patients with acute severe AR may respond to intravenous diuretics and vasodilators (such as sodium nitroprusside), but stabilization is usually short-lived and operation is indicated urgently. Intraaortic balloon counterpulsation is contraindicated. Beta-blockers are also best avoided so as not to reduce the CO further or slow the heart rate, which might allow proportionately more time in diastole for regurgitation to occur. Surgery is the treatment of choice.
Early symptoms of dyspnea and effort intolerance respond to treatment with diuretics and vasodilators (ACE inhibitors, dihydropyridine calcium channel blockers, or hydralazine) may be useful as well. Surgery can then be performed in more controlled circumstances. The use of vasodilators to extend the compensated phase of chronic severe AR before the onset of symptoms or the development of LV dysfunction is more controversial. Expert consensus is strong regarding the need to control systolic blood pressure (goal <140 mmHg) in patients with chronic AR, and vasodilators are an excellent first choice as antihypertensive agents. It is often difficult to achieve adequate control in such patients because of the increased stroke volume. Cardiac arrhythmias and systemic infections are poorly tolerated in patients with severe AR and must be treated promptly and vigorously. Although nitroglycerin and long-acting nitrates are not as helpful in relieving anginal pain as they are in patients with ischemic heart disease, they are worth a trial. Patients with syphilitic aortitis should receive a full course of penicillin therapy. Beta blockers may be useful to retard the rate of aortic root enlargement in young patients with Marfan syndrome and aortic root dilatation with no or only mild AR. Patients with severe AR should avoid isometric exercises.
In deciding on the advisability and proper timing of surgical treatment, two points should be kept in mind: (1) patients with chronic severe AR usually do not become symptomatic until after the development of myocardial dysfunction; and (2) when delayed too long (defined as >1 year from onset of symptoms or LV dysfunction), surgical treatment often does not restore normal LV function. Therefore, in patients with chronic severe AR, careful clinical follow-up and noninvasive testing with echocardiography at approximately 6-month intervals are necessary if operation is to be undertaken at the optimal time, i.e., after the onset of LV dysfunction but prior to the development of severe symptoms. Operation can be deferred as long as the patient both remains asymptomatic and retains normal LV function.
AVR is indicated for the treatment of severe AR in symptomatic patients irrespective of LV function. In general, operation should be carried out in asymptomatic patients with severe AR and progressive LV dysfunction defined by an LVEF <50%, an LV end-systolic dimension >55mm or end-systolic volume >55 mL/m2, or an LV diastolic dimension >75 mm. Smaller dimensions may be appropriate thresholds in individuals of smaller stature. Patients with severe AR without indications for operation should be followed by clinical and echocardiographic examination every 3–12 months.
Surgical options for management of aortic valve and root disease have expanded considerably over the past decade. AVR with a suitable mechanical or tissue prosthesis is generally necessary in patients with rheumatic AR and in many patients with other forms of regurgitation. Rarely, when a leaflet has been perforated during infective endocarditis or torn from its attachments to the aortic annulus by thoracic trauma, primary surgical repair may be possible. When AR is due to aneurysmal dilatation of the annulus and ascending aorta rather than to primary valvular involvement, it may be possible to reduce the regurgitation by narrowing the annulus or by excising a portion of the aortic root without replacing the valve. Resuspension of the native aortic valve leaflets is possible in approximately 50% of patients with acute AR in the setting of Type A aortic dissection. In other conditions, however, regurgitation can be eliminated only by replacing the aortic valve, excising the dilated or aneurysmal ascending aorta responsible for the regurgitation, and replacing it with a graft. This formidable procedure entails a higher risk than isolated AVR.
As in patients with other valvular abnormalities, both the operative risk and the late mortality are largely dependent on the stage of the disease and on myocardial function at the time of operation. The overall operative mortality for isolated AVR is about 3%. However, patients with marked cardiac enlargement and prolonged LV dysfunction experience an operative mortality rate of approximately 10% and a late mortality rate of approximately 5% per year due to LV failure despite a technically satisfactory operation. Nonetheless, because of the very poor prognosis with medical management, even patients with LV failure should be considered for operation.
Patients with acute severe AR require prompt surgical treatment, which may be lifesaving.
Tricuspid stenosis
TS, much less prevalent than MS in North America and Western Europe, is generally rheumatic in origin and is more common in females than in males. It does not occur as an isolated lesion and is usually associated with MS. Hemodynamically significant TS occurs in 5–10% of patients with severe MS; rheumatic TS is commonly associated with some degree of TR. Nonrheumatic causes of TS are rare.
A diastolic pressure gradient between the RA and RV defines TS. It is augmented when the transvalvular blood flow increases during inspiration and declines during expiration. A mean diastolic pressure gradient of 4 mmHg is usually sufficient to elevate the mean RA pressure to levels that result in systemic venous congestion. Unless sodium intake has been restricted and diuretics administered, this venous congestion is associated with hepatomegaly, ascites, and edema, sometimes severe. In patients with sinus rhythm, the RA a wave may be extremely tall and may even approach the level of the RV systolic pressure. The y descent is prolonged. The CO at rest is usually depressed, and it fails to rise during exercise. The low CO is responsible for the normal or only slightly elevated LA, PA, and RV systolic pressures despite the presence of MS. Thus, the presence of TS can mask the hemodynamic and clinical features of the MS, which usually accompanies it.
Since the development of MS generally precedes that of TS, many patients initially have symptoms of pulmonary congestion. Spontaneous improvement of these symptoms should raise the possibility that TS may be developing. Characteristically, patients complain of relatively little dyspnea for the degree of hepatomegaly, ascites, and edema that they have. However, fatigue secondary to a low CO and discomfort due to refractory edema, ascites, and marked hepatomegaly are common in patients with TS and/or TR. In some patients, TS may be suspected for the first time when symptoms of right-sided failure persist after an adequate mitral valvotomy.
Since TS usually occurs in the presence of other obvious valvular disease, the diagnosis may be missed unless it is considered and searched for. Severe TS is associated with marked hepatic congestion, often resulting in cirrhosis, jaundice, serious malnutrition, anasarca, and ascites. Congestive hepatomegaly and, in cases of severe tricuspid valve disease, splenomegaly are present. The jugular veins are distended, and in patients with sinus rhythm there may be giant a waves. The v waves are less conspicuous, and since tricuspid obstruction impedes RA emptying during diastole, there is a slow y descent. In patients with sinus rhythm there may be prominent presystolic pulsations of the enlarged liver as well.
On auscultation, an OS of the tricuspid valve may occasionally be heard approximately 0.06 s after pulmonic valve closure. The diastolic murmur of TS has many of the qualities of the diastolic murmur of MS, and since TS almost always occurs in the presence of MS, the less-common valvular lesion may be missed. However, the tricuspid murmur is generally heard best along the left lower sternal margin and over the xiphoid process, and it is most prominent during presystole in patients with sinus rhythm. The murmur of TS is augmented during inspiration, and it is reduced during expiration and particularly during the strain phase of the Valsalva maneuver, when tricuspid blood flow is reduced.
The ECG features of RA enlargement include tall, peaked P waves in lead II, as well as prominent, upright P waves in lead V1. The absence of ECG evidence of right ventricular hypertrophy (RVH) in a patient with right-sided heart failure who is believed to have MS should suggest associated tricuspid valve disease. The chest x-ray in patients with combined TS and MS shows particular prominence of the RA and superior vena cava without much enlargement of the PA and with less evidence of pulmonary vascular congestion than occurs in patients with isolated MS. On echocardiographic examination, the tricuspid valve is usually thickened and domes in diastole; the transvalvular gradient can be estimated by Doppler echocardiography. TTE provides additional information regarding mitral valve structure and function, LV and RV size and function, and PA pressure.
Patients with TS generally exhibit marked systemic venous congestion; intensive salt restriction, bed rest, and diuretic therapy are required during the preoperative period. Such a preparatory period may diminish hepatic congestion and thereby improve hepatic function sufficiently so that the risks of operation, particularly bleeding, are diminished. Surgical relief of the TS should be carried out, preferably at the time of surgical mitral valvotomy or MVR, in patients with moderate or severe TS who have mean diastolic pressure gradients exceeding ~4 mmHg and tricuspid orifice areas <1.5–2.0 cm2. TS is almost always accompanied by significant TR. Operative repair may permit substantial improvement of tricuspid valve function. If repair cannot be accomplished, the tricuspid valve may have to be replaced with a prosthesis, preferably a large bioprosthetic valve. Mechanical valves in the tricuspid position are more prone to thromboembolic complications than in other positions.
Tricuspid regurgitation
Most commonly, TR is functional and secondary to marked dilatation of the tricuspid annulus. Functional TR may complicate RV enlargement of any cause, including inferior wall infarcts that involve the RV. It is commonly seen in the late stages of heart failure due to rheumatic or congenital heart disease with severe pulmonary hypertension (pulmonary artery systolic pressure >55 mmHg), as well as in ischemic heart disease and dilated cardiomyopathy. It is reversible in part if pulmonary hypertension is relieved. Rheumatic fever may produce organic (primary) TR, often associated with TS. Infarction of RV papillary muscles, tricuspid valve prolapse, carcinoid heart disease, endomyocardial fibrosis, infective endocarditis, and trauma all may produce TR. Less commonly, TR results from congenitally deformed tricuspid valves, and it occurs with defects of the atrioventricular canal, as well as with Ebstein’s malformation of the tricuspid valve. TR also develops eventually in patients with chronic RV apical pacing.
As is the case for TS, the clinical features of TR result primarily from systemic venous congestion and reduction of CO. With the onset of TR in patients with pulmonary hypertension, symptoms of pulmonary congestion diminish, but the clinical manifestations of right-sided heart failure become intensified. The neck veins are distended with prominent v waves and rapid y descents, marked hepatomegaly, ascites, pleural effusions, edema, systolic pulsations of the liver, and a positive hepatojugular reflux. A prominent RV pulsation along the left parasternal region and a blowing holosystolic murmur along the lower left sternal margin, which may be intensified during inspiration and reduced during expiration or the strain of the Valsalva maneuver (Carvallo’s sign), are characteristic findings; AF is usually present.
The ECG usually shows changes characteristic of the lesion responsible for the enlargement of the RV that leads to TR, e.g., inferior wall myocardial infarction or severe RVH. Echocardiography may be helpful by demonstrating RV dilatation and prolapsing, flail, scarred, or displaced tricuspid leaflets; the diagnosis of TR can be made by color flow Doppler echocardiography, and its severity can be estimated by Doppler examination.
Continuous-wave Doppler of tricuspid regurgitation in a patient with pulmonary hypertension. There is an increase in the velocity of flow from the right ventricle into the right atrium to 5.4 m/s. Using the modified Bernoulli equation, the peak pressure gradient between the right ventricle and right atrium during systole is 120 mmHg. Assuming a right atrial pressure of 10 mmHg, the right ventricular systolic pressure is 130 mmHg. In the absence of right ventricular outflow tract obstruction, this indicates there is severe pulmonary hypertension with a pulmonary artery systolic pressure of 130 mmHg.
Severe TR is accompanied by hepatic vein systolic flow reversal. Continuous wave Doppler is also useful in estimating PA pressure. Roentgenographic examination usually reveals enlargement of both the RA and RV.
In patients with severe TR, the CO is usually markedly reduced, and the RA pressure pulse may exhibit no x descent during early systole but a prominent c-v wave with a rapid y descent. The mean RA and the RV end-diastolic pressures are often elevated.
Tricuspid Regurgitation: Treatment
Isolated TR, in the absence of pulmonary hypertension, such as that occurring as a consequence of infective endocarditis or trauma, is usually well tolerated and does not require operation. Indeed, even total excision of an infected tricuspid valve may be well tolerated for several years if the PA pressure is normal. Treatment of the underlying cause of heart failure usually reduces the severity of functional TR, by reducing the size of the tricuspid annulus. In patients with mitral valve disease and TR secondary to pulmonary hypertension and massive RV enlargement, effective surgical correction of the mitral valvular abnormality results in lowering of the PA pressures and gradual reduction or disappearance of the TR without direct treatment of the tricuspid valve. However, recovery may be much more rapid in patients with severe secondary TR if, at the time of mitral valve surgery, and especially when there is measurable enlargement of the tricuspid valve annulus, tricuspid annuloplasty (generally with the insertion of a plastic ring), open tricuspid valve repair, or, in the rare instance of severe organic tricuspid valve disease, tricuspid valve replacement is performed. Tricuspid annuloplasty or replacement may be required for severe TR with primary involvement of the valve.
