Restrictive cardiomyopathy in children: causes, symptoms, diagnosis, treatment

Restrictive cardiomyopathy in children is a rare myocardial disease characterized by impaired diastolic function and increased ventricular filling pressure with normal or slightly changed systolic myocardial function and the absence of significant hypertrophy. The phenomena of circulatory failure in such patients are not accompanied by an increase in the volume of the left ventricle.

ICD 10 code

• 142.3. Endomyocardial (eosinophilic) disease.
• 142.5. Other restrictive cardiomyopathy.

Epidemiology

The disease occurs in various age groups, both among adults and children (4 to 63 years). However, children, teenagers and young men are more often affected, the disease begins earlier and is more severe in them. Restrictive cardiomyopathy accounts for 5% of all cases of cardiomyopathy. Familial cases of the disease are possible.

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Causes of restrictive cardiomyopathy

The disease may be idiopathic (primary) or secondary, caused by infiltrative systemic diseases (e.g., amyloidosis, hemochromatosis, sarcoidosis, etc.). The disease is assumed to be genetically determined, but the nature and localization of the genetic defect underlying the fibroplastic process have not yet been clarified. Sporadic cases may be a consequence of autoimmune processes provoked by previous bacterial (streptococcal) and viral (enteroviruses Coxsackie B or A) or parasitic (filariasis) diseases. One of the identified causes of restrictive cardiomyopathy is hypereosinophilic syndrome.

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Pathogenesis of restrictive cardiomyopathy

In the endomyocardial form, the leading role in the development of restrictive cardiomyopathy belongs to immune disorders with hypereosinophilic syndrome, against the background of which, due to the infiltration of degranulated forms of eosinophilic granulocytes into the endomyocardium, gross morphological abnormalities of the heart structure are formed. Deficiency of T-suppressors is important in pathogenesis, leading to hypereosinophilia, degranulation of eosinophilic granulocytes, which is accompanied by the release of cationic proteins that have a toxic effect on cell membranes and enzymes involved in mitochondrial respiration, as well as a thrombogenic effect on the damaged myocardium. Damaging factors of eosinophilic granulocyte granules have been partially identified; they include neurotoxins, eosinophilic protein, which has a major reaction, apparently damaging epithelial cells. Neutrophilic granulocytes can also have a damaging effect on myocytes.

As a result of endomyocardial fibrosis or infiltrative myocardial damage, ventricular compliance decreases, their filling is impaired, which leads to an increase in end-diastolic pressure, overload and dilation of the atria, and pulmonary hypertension. Systolic function of the myocardium is not impaired for a long time, and ventricular dilation is not observed. The thickness of their walls is usually not increased (with the exception of amyloidosis and lymphoma).

Subsequently, progressive endocardial fibrosis leads to impairment of diastolic function of the heart and the development of treatment-resistant chronic heart failure.

Symptoms of Restrictive Cardiomyopathy in Children

The disease has a subclinical course for a long time. The pathology is detected due to the development of pronounced symptoms of heart failure. The clinical picture depends on the severity of chronic heart failure, usually with a predominance of congestion in the systemic circulation; heart failure progresses rapidly. Venous congestion of blood is detected in the inflow pathways to the left and right ventricles. Typical complaints in restrictive cardiomyopathy are as follows:

• weakness, increased fatigue;
• shortness of breath with minor physical exertion;
• cough;
• abdominal enlargement;
• swelling of the upper half of the body.

Classification of restrictive cardiomyopathy

Of the two forms of restrictive cardiomyopathy identified in the new classification (1995): the first, primary myocardial, occurs with isolated myocardial damage similar to those in dilated cardiomyopathy, the second, endomyocardial, is characterized by thickening of the endocardium and infiltrative, necrotic and fibrous changes in the heart muscle.

In the case of the endomyocardial form and detection of eosinophilic infiltration of the myocardium, the disease is assessed as Löffler's fibroplastic endocarditis. In the absence of eosinophilic infiltration of the myocardium, they speak of Davis's endomyocardial fibrosis. There is a point of view that eosinophilic endocarditis and endomyocardial fibrosis are stages of the same disease, which occurs mainly in tropical countries of South Africa and Latin America.

At the same time, primary myocardial restrictive cardiomyopathy, which is not characterized by endocardial changes and eosinophilic infiltration of the heart muscle, has been described in countries of other continents, including our country. In these cases, careful examination, including myocardial biopsy and coronary angiography, or autopsy failed to reveal any specific changes, there was no atherosclerosis of the coronary arteries and constrictive pericarditis. Histological examination of such patients revealed interstitial myocardial fibrosis, the mechanism of its development remains unclear. This form of restrictive cardiomyopathy is found in both adults and children.

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Diagnosis of restrictive cardiomyopathy in children

The diagnosis of restrictive cardiomyopathy is based on family history, clinical presentation, physical examination, ECG, echocardiography, chest radiography, CT or MRI, cardiac catheterization and endomyocardial biopsy. Laboratory tests are not helpful. Restrictive myocardial disease should be suspected in patients with chronic heart failure in the absence of left ventricular dilation and severe impairment of contractile function.

For a long time, the disease progresses gradually, slowly and unnoticed by others and parents. Children do not complain for a long time. The manifestation of the disease is caused by decompensation of cardiac activity. The longevity of the disease is indicated by a significant lag in physical development.

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Clinical examination

Clinical manifestations of the disease are caused by the development of circulatory failure, mainly of the right ventricular type, and disturbances in the venous inflow pathways to both ventricles are accompanied by increased pressure in the pulmonary circulation. During examination, a cyanotic blush and swelling of the jugular veins are noted, which is more pronounced in the horizontal position. The pulse is weakly filled, systolic arterial pressure is reduced. The apical impulse is localized, the upper border is shifted upward due to atriomegaly. A "gallop rhythm" is often heard, in a significant number of cases - a low-intensity systolic murmur of mitral or tricuspid insufficiency. Hepatomegaly is significantly expressed, the liver is dense, the edge is sharp. Peripheral edema and ascites are often noted. In cases of severe circulatory failure, auscultation reveals fine bubbling rales over the lower parts of both lungs.

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Electrocardiography

ECG shows signs of hypertrophy of the affected sections of the heart, especially pronounced overload of the atria. Often, a decrease in the ST segment and inversion of the T wave are noted. Heart rhythm and conduction disturbances are possible. Tachycardia is not typical.

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Chest X-ray

On chest X-ray, the heart size is slightly enlarged or unchanged, with enlarged atria and venous congestion in the lungs.

Echocardiography

Echocardiographic signs are as follows:

• systolic function is not impaired;
• dilation of the atria is pronounced;
• reduction of the cavity of the affected ventricle;
• functional mitral and/or tricuspid regurgitation;
• restrictive type of diastolic dysfunction (shortening of isovolumic relaxation time, increase in peak early filling, decrease in peak late atrial ventricular filling, increase in the ratio of early to late filling);
• signs of pulmonary hypertension;
• The thickness of the heart walls is usually not increased.

EchoCG allows to exclude dilated and hypertrophic cardiomyopathy, but is not informative enough to exclude constrictive pericarditis.

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Computed tomography and magnetic resonance imaging

These methods are important for the differential diagnosis of restrictive cardiomyopathy with constrictive pericarditis, allow one to assess the condition of the pericardial leaflets and exclude their calcification.

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Endomyocardial biopsy

This study is performed to clarify the etiology of restrictive cardiomyopathy. It allows to identify myocardial fibrosis in idiopathic myocardial fibrosis, characteristic changes in amyloidosis, sarcoidosis and hemochromatosis.

The technique is rarely used due to its invasive nature, high cost and the need for specially trained personnel.

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Differential diagnosis of restrictive cardiomyopathy

RCM is differentiated primarily from constrictive pericarditis. For this purpose, the condition of the pericardial leaflets is assessed and their calcification is excluded using CT. Differential diagnostics are also performed between RCM caused by different reasons (in storage diseases - hemochromatosis, amyloidosis, sarcoidosis, glycogenoses, lipidoses).

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Treatment of restrictive cardiomyopathy restrictive cardiomyopathy in children

Treatment of restrictive cardiomyopathy in children is ineffective, temporary improvement occurs when therapeutic measures are carried out early from the onset of the disease. Symptomatic therapy is carried out in accordance with the general principles of treating heart failure depending on the severity of clinical manifestations, if necessary - stopping heart rhythm disturbances.

In hemochromatosis, improvements in cardiac function are achieved by influencing the underlying disease. Therapy for sarcoidosis using glucocorticosteroids does not affect the pathological process in the myocardium. In endocardial fibrosis, endocardial resection with mitral valve replacement sometimes improves the condition of patients.

The only radical method of treating idiopathic restrictive cardiomyopathy is heart transplantation. In our country, it is not performed on children.

Prognosis for restrictive cardiomyopathy in children

The prognosis for restrictive cardiomyopathy in children is often unfavorable; patients die from refractory chronic heart failure, thromboembolism, and other complications.