NON-RHEUMATIC CARDITIS IN THE CHILDREN
Importance of the subject.
Non-rheumatic carditis is a group of the inflammatory diseases of the heart predominantly affecting myocardium. Non-rheumatic carditis is the disease of infectious and allergic origin. These lesions are caused by various infectious agents, predominantly by viruses. Non-rheumatic cardites are difficult for diagnosing. Their prevalence in the children exceeds that in the adults. In the children with the syndrome of the sudden death within the first year of the life, the prevalence of the cardites amounts to 17%. In the children of the school age, the prevalence of the cardites is about 21%. No more than 55-60% of the children recover after non-rheumatic carditis. In 30% of the patients, cardiodilatation remains, while in 15-20% of the patients myocardiofibrosis persists. The mortality rate ion-rheumatic carditis assessed in different studies varies from 2.2% to 11.4%. The course of the disease is polymorphous. The latent and low symptomatic as well as severe and recurrent forms are recorded. The tendency for the transition to the chronic form of the disease is evident. Since non-rheumatic carditis is resistance to the treatment, this pathology is the topical problem in the pediatric practice.
Classification of non-rheumatic cardites (after N. Bielokon and M. Kuberger, 1987)
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According to the time of origin |
Congenital (antenatal): early, late Acquired |
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Etiology |
Viral, viral-bacterial, bacterial, parasitogenic, mycotic, caused by Yersinia sp., allergic (iatrogenic, postvaccinal, serum-mediated), idiopathic |
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Predominant location of the lesion |
Carditis (myo-, endo- or pericarditis or their combination). Lesions affecting the conducting system of heart |
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Course of the disease |
Acute (up to 3 months), subacute (up to 18 months), chronic (more than 18 months): recurrent, primary chronic (congestive, hypertrophic, restrictive variants) |
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Severity |
Mild, moderately severe, severe |
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Form and grade of the heart insufficiency |
Left-ventricular, grade I, IIA, IIB, III Right-ventricular, grade I, IIA, IIB, III Total |
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Outcome and complications |
Cardiosclerosis, hypertrophy of myocardium, disorders of rhythm and conduction, pulmonary hypertension, lesions of the heart valves, constrictive myopericarditis, thromboembolic syndrome |
The grades of the heart insufficiency ion-rheumatic cardites in the children (after N. Bielokon and M. Kuberger, 1987)
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Grade |
Right-ventricular insufficiency |
Left-ventricular insufficiency |
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I |
The signs of the insufficient circulation at rest are not evident and appear only after the physical activity manifesting as tachycardia or dyspnea, the liver size is within the normal values |
The same |
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IIA |
Heart rate increases by 15-30% per minute, respiration rate increases by 30-50% per minute as compared to the physiological values |
The liver extends from the edge of the costal arch by 2-3 cm |
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IIB |
Heart rate increases by 30-50% per minute, respiration rate increases by 50-70% per minute as compared to the physiological values. The obtrusive cough, the bubbling rales, and acrocyanosis are possible |
The liver extends from the edge of the costal arch by 3-5 cm. The pastosity is observed. The jugular venous distention may be recorded. |
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III |
Heart rate increases by 50-60% per minute, respiration rate increases by 70-100% per minute as compared to the physiological values. The characteristic clinical conditions of pre-edema and edema of lungs are evident |
Hepatosplenomegalia, ascites, hydrothorax |
The criteria of diagnosing non-rheumatic carditis in the children (after I. Vorontsov et al., 1982)
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The signs of high significance (scored as 4 points) |
The signs of medium significance (scored as 2 points) |
The signs of low significance (scored as 1 point) |
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Increased size of the heart or its cavities. Decreased contractility of myocardium. |
The absence of the signs indicating the control of heart functions by the autonomic nervous system. The detection of the cardiac antigen and anticardial antibody in the blood. The increased blood level of cardiospecific fraction of isozymes: lactate dehydrogenase, malate dehydrogenase, creatine phosphokinase, etc. ECG signs of heart hypertrophy. ECG signs of heart ischemia. |
Heart pain. Diminution of the intensity of the heart sound I Tachycardia or bradycardia. The gallop rhythm. The apical systolic murmur. Sinoauricular blockade. The impairment of the atrioventricular conduction. The ectopic rhythm. Extrasystoles. The displacement of S-T interval The alteration of T wave. |
The diagnosis of the carditis is regarded as the reliable one when the sum of the scores is 5 points and more (with at least one sign of high or medium significance being present). The diagnosis is regarded as the probable one when the sum of the scores is 3 points.
The peculiar features of the various variants of non-rheumatic carditis in the children
Acute carditis develops directly at the time of viral infection or the infection of other etiology or soon after such infection, often in the children with the non-favorable premorbid state (allergic or lymphatic diathesis; in the children with recurrent diseases). The severe forms are observed predominantly at the age below 3 years. The forms of the moderate severity may be observed both in the children of early age and in preschool and school age children. The mild forms are recorded predominantly in preschool and school age children.
Subacute carditis is characteristic of the preschool and school age children. The signs of the heart insufficiency become evident in 4-6 months after the acute respiratory viral infection. At the first stage, the clinical manifestation may be insignificant. Then the following signs become evident: the cardiac hump, the systolic murmur of mitral valve insufficiency, the persistent accent of the second sound over the pulmonary artery. The treatment-resistant cardiac insufficiency develops.
Chronic carditis occurs in the children of the school age. The primarily chronic carditis with the clinically asymptomatic onset is possible. Otherwise, the chronic carditis may be a consequence of the acute or subacute process. The congestive or dilatation carditis, the hypertrophic carditis and the restrictive carditis with the drastically decreased volume of the left ventricle may be distinguished as the clinical variants. Since the heart insufficiency develops later in the course of the disease, such condition is often missed for being diagnosed early.
Clinical manifestations of non-rheumatic myocarditis.
The extracardial signs of the heart lesion become evident: the decreased appetite, the flabbiness, the anxiety with groaning in the night, the irritability, the nausea, and the vomiting. The signs of the congestive cardiac insufficiency are also apparent: the cough, which increases upon the change of the body position, the cyanosis attacks, the dyspnea; the rales in the lungs (the asthmatic components in the left-ventricular insufficiency), the increased liver size (in the right-ventricular insufficiency), the pastosity of the tissues, the decreased diuresis. The apical beat is weakened, the borders of the heart are moderately broadened, the tachycardia appears, the first sound over the apex is muted, the gallop rhythm is possible as well as tachycardia, bradycardia, tachyarrhythmia or bradyarrhythmia.
The following variants of the course may be distinguished: low-symptomatic, pseudocoronary (painful), decompensated (with impaired blood circulation), arrhythmical, pseudovalvular (with the signs of the dysfunction of the heart valves, often mitral valve), thromboembolic, and mixed.
The peculiar features of endocarditis in the children. Frequently, the onset of the disease is without peculiar symptoms except for the rapid fatigability. The low febricity, the general weakness is possible. The classic signs of the endocarditis may be absent. Among the characteristic features are cardio- and splenomegaly, petechias, the loss of body mass, the finger deformities in the shape of the drumstick fingers. If the adequate treatment has not been provided, the retinal hemorrhages (Roth spots), the erythematous painful spots in the palms and the soles, and the painful nodules in the skin in the finger cushions (Osler’s nodules) develop.
The peculiar features of pericarditis in the children. For the pericarditis the following signs are typical: the pain in the left shoulder and the back, which decrease in sitting position, the frequent fevers, tachypnea, tachycardia, the cough, the muted heart sounds due to the pericardial effusion, the pericardial friction rub. The extensive effusion may be a cause of the heart tamponade. The jugular venous distention in the course of breath-in may be recorded with the paradoxic pulse (the decrement in the arterial blood pressure in the breath-in exceeds the physiological values, while the decrement in the venous blood pressure in the breath-in is lower than the corresponding physiological values).
The peculiar features of congenital carditis in the children. The intrauterine carditis may be detected antenatally. Nevertheless, more frequently this condition is diagnosed within the first postnatal weeks or months. According to the term of the origin, early and late carditis may be delineated. The early carditis originates on the months 4th-7th antenatally and is manifested by the growth of the fibrous tissue in the subendocardial layers of myocardium resulting in fibroelastosis of endocardium or the predominant growth of the elastic tissue resulting in elastofibrosis of endo- and myocardium without the overt features of the inflammation.
The first symptoms of the disease that become evident in the first postnatal months comprise the decrease appetite, the delay in the physical development, the flabbiness, the paleness of the skin and the mucosa, the fatigability in the course of the sucking, the extension of the heart borders, the early development of the cardiac hump, the muted heart sounds. The coarse murmurs are not detectable. Nevertheless, sometimes the systolic murmur of the relative mitral insufficiency may be heard. The insufficiency of the left ventricle, which is resistant to the treatment, prevails. The ECG findings are such as follows: the rapid rhythm, the high voltage of QRG complex, the hypertrophy of the left ventricle. On X-ray pictures, the shape of the heart in spherical in the case of the fibroelastosis and trapezoid in the case of the elastofibrosis.
The late carditis originates after the 7th month of the antenatal development. This form is characterized by the substantial inflammatory alterations in myocardium involving two or three heart envelopes, the conducting system, sometimes the coronary vessels with the resulting sclerosis of the blood vessels and the hypertrophy of myocardium without the growth of the elastic and fibrous tissue. When the cords and the valves of the heart are involved into the process, the congenital heart disease develops.
The clinical and instrumental symptoms of the disease are similar top that in the severe form of the chronic non-rheumatic carditis with the delay in the gain of body mass after 3-5 months of the postnatal life, the fatigability during the feeding, the sweating. The apical beat is slightly enhanced, the borders of the heart are extended moderately, the heart sounds are clear, the murmurs are not heard, the cardiac insufficiency is less pronounced as compared to the early carditis. Tachy- and bradycardia, bradyarrhythmia are detectable. In ECG: arrhythmia, atrioventricular blockade, the overloading of the left ventricle and the atria. X-ray findings: the shadow of the heart increased less than in the variant described above.
Idiopathic myocarditis (Abramov-Fidler) represents the most severe acute form of the disease accompanied by the deep diffuse lesion of the myocardium. The following features are typical for this condition: the pronounced intoxication syndrome, cardialgia, dyspnea, cardiomegalia with the relative insufficiency of the mitral valve (less frequently other valves are also involved), the sounds are muted significantly, and ECG pathology varies. Sometimes the cardiac fibrillation is evident. The circulatory insufficiency may progress and the thromboembolic syndrome may develop. According to the predominant symptoms, the following variants may be distinguished: stenocarditic, arrhythmic, asystolic, and thromboembolic. The laboratory findings usually are not changed. The prognosis is unfavorable and most patients die. In many cases, the use of prednisolone is advantageous for attaining the significant improvement (starting from 30-50 mg daily followed by the decrease in the daily dose). The pathogenetic therapy is performed taking into account the clinical variant of the disease.
Supplementary techniques for diagnosing non-rheumatic carditis in the children
Laboratory examinations
The most reliable technique for confirming the diagnosis of the acute non-rheumatic carditis in the children consists in detecting the infectious agent in the blood, the nasopharyngeal mucus, and the feces as well as identifying the high titers of the corresponding antibodies in the paired sera of the patients (four-fold increment in 2-4 weeks) followed by the decrease in the titer.
The changes of the parameters of the general blood test and the biochemical parameters of the blood such as the increased ESR, leukocytosis or leucopenia, the increased content of alpha-2 and gamma-globulins, C-reactive protein, DPA assay are associated with the viral or bacterial infection. In most cases including those with the severe course of the disease with cardiomegaly, the activities of the organ-specific enzymes (creatine phosphatase, lactate dehydrogenase) remain unchanged.
Electrocardiography. The following ECG signs may be detectable for diagnosing non-rheumatic carditis in the children: the impaired conduction (the atrioventricular blockade grade II-III, the blockade of Gis bundle), extrasystoles, the paroxysmal tachycardia with the extended and deformed QRS complex, the alterations in ST segment, the inversion of T wave, the hypertrophy of the chambers of the heart.
X-ray examination. The following signs are detectable: the extension of the heart borders with the cardiac index exceeding 50, the alteration of the contours of the heart and the large vessels, the increased pulmonary X-ray pattern.
Echography of the heart
This technique allows one for detecting the hypertrophy of the heart chambers, the dilatation of the heart cavities. Doppler echography is the useful technique for assessing the state of the valves of the heart.
Treatment of non-rheumatic carditis in the children
The treatment depends on the etiology of the disease, the peculiar features of the immune reactivity of the child, the course of the disease, and the grade of the cardiovascular insufficiency. The treatment comprises the hospital period (acute disease or the acute condition of the disease), the outpatient period, and the sanatorium treatment period (the maintenance treatment).
Principles of the hospital treatment of non-rheumatic carditis in the children
1. The limitation of the movements for 2-4 weeks. The treatment exercises are performed after the decrease in body temperature with the exercise load selected according to the results of the functional tests (after Shalkov).
2. The diet (ration No. 10) demands the limitation of the volume of liquid (the daily liquid consumption should be inferior to the diuresis volume by 200-300 mL). The ration should comprise the food rich in potassium such as the raisins, the dried apricots, and the baked potato.
3. Antiviral and antibacterial therapies are provided. The duration of the antibacterial therapy should be not less than 3-4 weeks.
4. The antibacterial therapy with Penicillins is performed on the Weeks 2-3 of the hospital treatment as to eliminate the chronic infectious foci present in most patients with carditis.
5. The non-steroid anti-inflammatory drugs are prescribed for 4-6 weeks in the acute carditis (acetylsalicylic acid at a dose of 0.2 g per one year of life; Indometacin at a dose 1-2 mg per 1 kg of body mass; Voltaren at a dose of 0.5 mg per 1 kg of body mass daily). Then the drugs are used for further 2-3 months at a half-dose. In the cases of the subacute course or the recurrence of the chronic carditis, the full doses of the drugs stated above are prescribed for 6-8 weeks.
6. Glucocorticoids are indicated in the severe course of the disease with the signs of the cardiac insufficiency (often in the young children and in the children of the school age with Abramov-Fidler myocarditis), in the cases involving the conduction system, and when the danger of the transition to the chronic course of the disease is significant. Prednisolon is prescribed at a dose of 1-1.5 mg per 1 kg of body mass daily for one month followed by the gradual dose reduction by 2.5 mg for 3-4 days in the children of the school age and 1.2-1.5 mg for 3-4 days in the young children. When the effect is insufficient, the maintenance dose of 0.5 mg per 1 kg of body mass daily is provided.
7. In the case of the cardiac insufficiency, the diuretics are used daily for 1-1.5 months. In the case of the left-ventricular insufficiency grade I-IIA, Veroshpiron is used at a dose of 1-4 mg per 1 kg of body mass daily; in the case of the left-ventricular insufficiency grade IIA with the concomitant right-ventricular insufficiency grade Iia-IIB, Verospiron is used in the combination with Furosemid (2-4 mg per 1 kg of body mass daily); in the case of the total insufficiency grade IIB-III, Lasix or Furosemid are administered parenterally in combination with Verospiron; wheecessary Brinaldix or Uregit (1-2 mg per 1 kg of body mass daily) are used. Upon the discharge from the hospital, the drugs are taken 2-3 times a week.
8. The desensitizing drugs are indicated only in the acute or subacute course of the carditis.
9. The anticoagulant therapy is administered in the cases of the thromboembolic variant of the disease: Heparin is used at a dise of 120-150 U per 1 kg of body mass; Curantil or Dipiridamol is used as a dose of 5 mg per 1 kg of body mass daily.
10. Antikinin therapy is provided in the cases of the utmost acute course of the disease (Parmidine, Arginine, Predectin, Contrical).
11. In the cases of cardiac insufficiency, the cardiac glycosides are provided.
12. Cardiometabolic drugs are used intravenously as the polarizing mixture (10% glucose solution –10-15 mL per 1 kg of body mass, 1 U of insulin per 5 g of glucose, Panangin – 1 mL per each year of the life, 2-5 mL of 0.25% solution of Novocain). Riboxin is used per os for one month. In addition, the following drugs are used: potassium orotate, Panangin, vitamin B12 with folic acid, calcium pangamate (vitamin B15), calcium pantotenate (vitamin B5), L-carnitine or Mildronate, non-steroid anabolic hormones (Retabolyl, Nerobol, Femobolyn, Metandrostendiol).
13. Antiarrhythmic drugs are used depending on the form of arrhythmia.
14. In the subacute or chronic course of the disease, the drugs belonging to Aminoquinolines are indicated: Delalgil, Plaquenil (3 mg per 1 kg of body mass daily) for a long period, 3-6 months and more.
Principles of the treatment of cardiac insufficiency. The acute cardiac insufficiency is the insufficiency of blood circulation due to non-efficient pumping ability of the heart resulting in decreasing cardiac output or inability to pump the whole venous inflow per unit of time. Clinically, the acute cardiac insufficiency is manifested as the syndrome of low cardiac discharge.
The following elements of the therapy of cardiac insufficiency are to be followed:
– The adequacy of the venous inflow to the heart should be provided. This aim is attained by the use of diuretics (Lasix intravenously at a dose of 1-2 mg per 1 kg of body mass for one injection, 2-3 injections a day) and the respiratory therapy with breathing in the oxygen with the positive pressure at the end of expiration.
– The improvement of the inotropic activity of myocardium, in other words – the increase in the strength of heart contractions. This aim is attained by the use of adrenomimetics of fast action (Dopamine, Dobutamine, Adrenalin hydrochloride).
– In the case of the supraventricular tachycardia in the congestive cardiac insufficiency, Digoxin is used intravenously at a dose of 0.03-0.05 mg per 1 kg of body mass. In tachyarrhythmia, the drugs for the normalization of heart rhythm are provided (Quinidine, Novocainamde, Isoptin, Anaprilin, Cordaron, Ornid, Verapamil, etc.). In bradyarrhythmia, the drugs, which do not affect the heart rhythm, are prescribed (Adonis, Taluzin).
– The cardiotrophic drugs are used (potassium and magnesium-containing drugs, pyridoxal phosphate, Phosphaden, ATP-long, Riboxin, Inosin-F).
– Vasodilating drugs are also advantageous for decreasing the venous inflow to the heart due to the decrease in the peripheral resistance of blood vessels. With this aim in view, Nanipruss (Nitroglycerin) is administered in microstream mode or ACE inhibitors such as Captopril or Enalapril are used (1-2 times a day at a dose 0.5-0.6 mg per 1 kg of body mass for the patients aged below 3 years and 12.5 mg for the patients of the preschool age).
The regular medical check-up of the children with non-rheumatic carditis (outpatient and sanatorium phases)
Following the acute carditis, the child should be observed on the outpatient basis by cardiorheumatologist for 5 years. Upon the discharge from the hospital, the child should be examined monthly for three months, then one time in three months for further one year, and then twice a year with the obligatory record of ECG. Once or twice a year, X-ray examination of the chest is performed.
At this phase of the treatment, the drugs improving the myocardial metabolism are used 2-4 courses every year (potassium orotate, Panangin, vitamin B12 with folic acid, calcium pangamate, calcium pantotenate, L-carnitine or Mildronate), non-steroid anabolic hormones (Retabolyl, Nerobol, Femobolyn, Metandrostendiol). When indicated, the cardiac glycosides are prescribed at the maintenance doses. In addition, antiarrhythmic drugs, diuretics are used 1-3 times a week. Aminoquinolines are used for 3-6 months. The sedatives are administered for preventing the stress, which may result in cardiogenic shock.
In the case of the acute intercurrent diseases, the non-steroid anti-inflammatory drugs for 2-3 weeks are useful. Bicillin is used in the cases of the chronic tonsillitis for one year. The question on whether tonsillectomy should be performed in resolved on an individual basis. The child should be exempted from the physical exercises at school except for graduated walking.
The vaccination is performed one year after the acute process has calmed down. At the same term, the sanatorium treatment is indicated.
When the disease becomes chronic, the child should remain at the dispensary registry and the regular examinations are performed once a month. Once in three months, ECG should be recorded. Once or twice a year, X-ray examination of the heart is performed. When cardiosclerosis develops, the child also should remain at the dispensary registry and the regular check-ups are performed 3-4 times a year. For the patients with the cardiac insufficiency, the physical and psychic loads should be limited. The scope of the treatment depends on the individual course of the disease. The planned vaccination is not performed.
Cardiomyopathy
Definition
Cardiomyopathy is a disease of the myocardium resulting in thickening of the myocardial fibers or fibrosis. Hypertrophic cardiomyopathy is characterized by thickening of the muscular walls of the ventricles, typically involving the ventricular septum. Dilated cardiomyopathy may also cause hypertrophy of the ventricular walls, however due to severe dilation of the ventricular chambers, they appear thin and stretched.
Incidence
Cardiomyopathy is a chronic and variably progressive disease of the heart muscle that can present in various forms and in severe cases can lead to heart failure and sudden death. According to the Pediatric Cardiomyopathy Registry, 1 in 100,000 children are diagnosed with symptoms each year, with 30,000 children in the US affected annually if all forms of cardiomyopathy are considered together. However, it has to be noted that many asymptomatic and undiagnosed cases are unaccounted for in this survey. Infants less than a year old are ten times more likely to develop cardiomyopathy compared to children aged 2–18 years. Hypertrophic cardiomyopathy occurs at a rate of 5 per million children.
Pathology
Hypertrophic cardiomyopathy is characterized by abnormal growth and arrangement of muscle fibers, termed muscle disarray. The process starts in the ventricles and in severe cases can involve the wall of the atria. It can be acquired, secondary to a viral infection or chemotherapy, or inherited as an autosomal dominant, autosomal recessive, or X-linked disease such as the Barth Syndrome. Cardiomyopathy could also be secondary to a more generalized metabolic, mitochondrial, or multisystem disorder.
Cardiomyopathy can be mainly divided into two types: ischemic and nonischemic. Pediatric cardiomyopathy is almost exclusively nonischemic which is further divided into four types by the World Health Organization depending on the type of muscle damage:
• Dilated cardiomyopathy (58%)
• Hypertrophic (30%)
• Restrictive (5%)
• Arrhythmogenic Right Ventricular Cardiomyopathy, or ARVC (5%)
Dilated cardiomyopathy is most commonly idiopathic. Other cases are caused by viral infections such as coxsackie virus or HIV, secondary to toxins such as doxorubicin, or related to severe anemia or nutritional deficiencies.
In hypertrophic cardiomyopathy most commonly the left ventricle is the more affected chamber with the septum showing the most growth. The term for this phenomenon is the asymmetric hypertrophic cardiomyopathy. The thickening can sometimes be symmetric or concentric involving the entire left ventricular wall or localized to the apex in rare cases.
ARVC is an extremely rare disorder in children in which the muscles in the right ventricle become disorganized and are replaced with fibrous tissue. After starting as a patchy lesion, the process can gradually spread to involve the entire right ventricle and then to the left ventricle. The disorganization of the cells leads to arrhythmias and poor contractility.
Pathophysiology
Dilated cardiomyopathy leads to dilation and poor contractility of the ventricles. There is progressive mitral and tricuspid regurgitation. Eventually the patient develops signs of CHF and fluid overload.
Hypertrophic cardiomyopathy causes abnormal relaxation of the heart during diastole and secondary obstruction to venous return. In the terminal stages of this disease, the heart resembles those seen in a dilated cardiomyopathy.
In restrictive cardiomyopathy there is normal systolic function but abnormal relaxation. The ventricles turn rigid and show poor flexibility to expand. While the ventricles do not show any enlargement, the atria are grossly enlarged. The blood flow to the heart is restricted.
Dilated Cardiomyopathy
This most frequent of the childhood cardiomyopathies occurs with an annual incidence of 4–8 cases per 100,000 population in the United States and Europe. Although usually idiopathic, diagnosable causes include acute or chronic myocarditis, long-standing untreated tachyarrhythmias, left heart obstructive lesions, congenital abnormalities of the coronary arteries, anthracycline toxicity, and genetic and metabolic diseases (inborn errors of fatty acid oxidation and mitochondrial oxidative phosphorylation defects). Genetic causes include abnormalities of the dystrophin gene as occur in Duchenne and Becker muscular dystrophy.
Clinical Findings
Signs and Symptoms
As the heart dilates, cardiac output falls, and affected children develop heart failure (HF) with decreased exercise tolerance, failure to thrive, diaphoresis, and tachypnea. As the heart deteriorates, pulses and perfusion become weaker, hepatomegaly and rales develop, and the cardiac examination shows a prominent gallop. The initial diagnosis in a previously healthy child can be difficult, as presenting symptoms can resemble a viral respiratory infection, pneumonia, or asthma.
Imaging
Chest radiograph shows generalized cardiomegaly with or without pulmonary venous congestion.
Electrocardiography
Sinus tachycardia with ST-T segment changes is commonly seen on ECG. The criteria for right and left ventricular hypertrophy may also be met. One must ensure that a narrow complex tachycardia is in fact sinus tachycardia with a normal P-wave axis as opposed to an atrial or junctional tachyarrhythmia that may be the underlying cause of the cardiomyopathy.
Echocardiography
The echocardiogram shows LV and left atrial enlargement with decreased LV shortening fraction and ejection fraction. The calculated end-diastolic and end-systolic dimensions are increased. With more advanced disease, mitral insufficiency will occur as the LV dilates. A careful evaluation for evidence of structural abnormalities (especially coronary artery anomalies) must be performed in infant patients.
Other Testing
Cardiac catheterization is useful to evaluate the hemodynamic status and the coronary artery anatomy. Endomyocardial biopsies can be obtained in those with idiopathic disease. Biopsy specimens may show acute myocarditis, abnormal myocyte architecture, and myocardial fibrosis. Electron micrographs may reveal evidence of mitochondrial or other metabolic disorders. Polymerase chain reaction testing may be performed on biopsies to detect viral genome products in infectious myocarditis. Skeletal muscle biopsy may be helpful in those with evidence of possible skeletal muscle myopathy. Cardiopulmonary stress testing is useful in cardiomyopathy for measuring response to medical therapy and as an objective assessment of the cardiac limitations to exercise.
Treatment& Prognosis
Patients with dilated cardiomyopathy may require in-hospital management of HF – either on initial presentation or with a heart failure exacerbation. As outpatients they are treated with various combinations of digoxin, diuretics, and afterload-reducing agents (see section on Heart Failure). There is an ongoing multicenter, placebo-controlled, double-blind trial of carvedilol use in children with heart failure that will help determine the efficacy of -blocker therapy as an adjunct in these patients. Aspirin or warfarin may be used to prevent thrombus formation in the dilated and poorly contractile cardiac chambers. Arrhythmias are more common in dilated hearts. Antiarrhythmic agents that do not suppress myocardial contractility, such as digoxin and amiodarone, may be used. Internal defibrillators are used in some patients with dilated cardiomyopathy and life-threatening ventricular arrhythmias.
Therapy directed at the cause of cardiomyopathy is always indicated if available. Treatment of carnitine deficiency may result in improved cardiac function. Antiarrhythmic therapy in patients with arrhythmia-induced cardiomyopathy is often curative. Unfortunately despite complete evaluation, a diagnosis is discovered in less than 30% of patients with dilated cardiomyopathy. If medical management is unsuccessful, cardiac transplantation is considered.
Hypertrophic Cardiomyopathy
The most common cause of hypertrophic cardiomyopathy (HCM) is familial hypertrophic cardiomyopathy, which is found 1 in 500 individuals. It is the leading cause of sudden cardiac death. It most commonly presents in the older child, adolescent, or adult, although it may be seen in the neonatal period. Other causes of HCM ieonates and children include glycogen storage disease, Noonan syndrome, Friedreich ataxia, mitochondrial disorders, and other metabolic disorders.
Familial Hypertrophic Cardiomyopathy
In the familial form, HCM is most commonly caused by a mutation in several genes that encode proteins of the cardiac sarcomere (B-myosin heavy chain, cardiac troponin T or I, A-tropomyosin, and myosin-binding protein C).
Clinical Findings
Patients may be asymptomatic despite having significant hypertrophy, or may present with symptoms of inadequate coronary perfusion such as angina, syncope, palpitations, or exercise intolerance. Patients may experience sudden cardiac death, often precipitated by sporting activities. Although the cardiac examination may be normal early, eventually patients develop a left precordial bulge with a diffuse point of maximal impulse. LV heave may be present. A palpable or audible S4 may be present. If outflow tract obstruction is present, a systolic ejection murmur will be audible. A murmur may not be audible at rest but is easily provoked with exercise or positional maneuvers that decrease left ventricular volume (standing) thereby increasing the outflow tract obstruction. Although the older patient with HCM typically has disease primarily in the LV, right ventricular hypertrophy, either alone or in association with LVH, may be seen in the neonate. Affected neonates may be cyanotic if RV outflow tract obstruction is significant.
Echocardiography
The diagnosis of HCM is usually made by echocardiography that demonstrates asymmetrical septal hypertrophy. Young patients may have concentric hypertrophy, which makes the diagnosis less obvious. Systolic anterior motion of the mitral valve leaflet may occur and contribute to LV outflow tract obstruction. The mitral valve leaflet may become distorted and cause mitral insufficiency. LV outflow tract obstruction may be present at rest. Provocable outflow tract obstruction can be assessed with either amyl nitrate or monitored exercise. Systolic function is most often hypercontractile in young children but may deteriorate over time, often in association with a change in morphology as hypertrophy develops into LV dilation. Diastolic function is often impaired. Patients are at risk for myocardial ischemia, possibly as a result of systolic compression of the intramyocardial septal perforators, myocardial bridging of epicardial coronary arteries, or an imbalance of coronary artery supply and demand due to the presence of massive myocardial hypertrophy.
Electrocardiography
The ECG may be normal, but more typically demonstrates deep Q waves in the inferolateral leads (II, III, aVF, V5, and V6) secondary to the increased mass of the hypertrophied septum. ST segment abnormalities may be seen in the same leads. Age-dependent criteria for LVH are often present as are criteria for left atrial enlargement.
Other Testing
Cardiopulmonary stress testing is a valuable tool to check for provocable LV outflow tract obstruction, ischemia, and arrhythmias, and to determine prognosis. A blunted blood pressure response and ventricular arrhythmias with exercise have both been associated with increased mortality in children. Nuclear stress testing allows for assessment of myocardial perfusion defects.
Cardiac Catheterization
Cardiac catheterization should be performed in patients with HCM who have angina, syncope, resuscitated sudden death, or a worrisome stress test. Hemodynamic findings include elevated left atrial pressure secondary to impaired diastolic filling. If midcavitary LV outflow tract obstruction is present, an associated pressure gradient will be evident. Provocation of LV outflow tract obstruction with either rapid atrial pacing or isoproterenol may be sought. Angiography demonstrates a “ballerina slipper” configuration of the LV secondary to the midcavitary LV obliteration during systole. Coronary angiography should be performed to evaluate possible associated myocardial bridging, which may be an important source of myocardial ischemia in these patients. Angiography will show systolic obliteration, typically of the middle left anterior descending coronary artery.
Treatment& Prognosis
The prognosis depends on the degree of hypertrophy, the degree of outflow tract obstruction, the particular genetic defect, and the presence of coronary compression. Patients may be restricted from strenuous athletics and isometric exercise. Patients with resting or latent LV outflow tract obstruction may be treated with either -blockers, verapamil, or disopyramide with good, albeit temporary, relief of obstruction. Patients with persistent symptoms despite medical therapy and an LV outflow tract gradient greater than 30 mm Hg may require additional intervention. Surgical myectomy with resection of part of the hypertrophied septum has been used with good results. At the time of myectomy, the mitral valve may require repair or replacement in patients with a long history of systolic anterior motion of the mitral valve. Ethanol ablation is being used with increasing frequency in adults with HCM and LV outflow tract obstruction. This procedure involves the selective infiltration of ethanol in a coronary septal artery branch, thereby inducing a small myocardial infarction. This leads to a reduction in septal size and improvement of obstruction. The long-term effects of this procedure are unknown and it is not currently employed in children. Surgical unroofing of a myocardial bridge may improve prognosis in those with myocardial ischemia secondary to epicardial coronary compression. Although dual-chamber pacing has been used in some children with good relief of obstruction, larger series demonstrate no significant improvement in obstruction. Internal defibrillators are being placed in patients with documented ventricular arrhythmias, resuscitated sudden death, or a strong family history of HCM with associated sudden death.
Restrictive Cardiomyopathy
Restrictive cardiomyopathy is a rare entity in the pediatric population, accounting for less than 5% of all cases of cardiomyopathy. Constrictive pericarditis can have a similar presentation and must be considered in the differential diagnosis of a patient with suspected restrictive cardiomyopathy.
Clinical Findings
Patients present with signs of heart failure as outlined previously. Physical examination is remarkable for a prominent S4 and jugular venous distention.
Electrocardiography
ECG demonstrates marked right and left atrial enlargement with normal ventricular voltages. ST-T–wave abnormalities may be present.
Echocardiography
The diagnosis is confirmed echocardiographically by the presence of normal sized ventricles with massively dilated atria. Due to infiltration of the ventricular myocardium, the LV becomes “restrictive,” and atrial emptying is impaired.
Course& Prognosis
The condition is usually idiopathic. Endocardial fibroelastosis, a histologic diagnosis, may be noted. The endocardium has marked milky white thickening, as do the subendocardial layers of the LV and left atrium. The mitral valve may be involved. Regardless of cause, the prognosis is poor. Anticongestive therapy may be tried, but many patients will require cardiac transplantation.
REFERENCES
1. Abdulla Ra-id. Heart diseases in children: a pediatrician’s guide / R. Abdulla, 2011. – New York: Springer. – 486 p.
2. Pediatrics / Edited by O.V. Tiazhka, T.V. Pochinok, A.M. Antoshkina/ – Vinnytsa: Nova Knyha Publishers, 2011. – 584 p.
3. Nelson Textbook of Pediatrics, 19th Edition. – Expert Consult Premium Edition – Enhanced Online Features and Print / by Robert M. Kliegman, MD, Bonita M.D. Stanton, MD, Joseph St. Geme, Nina Schor, MD, PhD and Richard E. Behrman, MD. – 2011. – 2680 p.
4. Pediatrics / Edited by O.V. Tiazhka, T.V. Pochinok, A.M. Antoshkina/ – Vinnytsa: Nova Knyha Publishers, 2011. – 584 p.
5. www.tdmu.edu.ua
