Diagnosis of dilated cardiomyopathy in children

Diagnosis of dilated cardiomyopathy in a child is difficult, since the disease has no specific criteria. The final diagnosis of dilated cardiomyopathy is established by excluding all diseases that can lead to enlargement of the heart cavities and circulatory failure. The most important element of the clinical picture in patients with dilated cardiomyopathy is episodes of embolism, which very often lead to death of patients.

The survey plan is as follows.

• Collection of life history, family history, and disease history.
• Clinical examination.
• Laboratory research.
• Instrumental studies (echocardiography, ECG, Holter monitoring, chest X-ray, ultrasound examination of the abdominal organs and kidneys).

The doctor should take into account that children rarely complain. However, when questioned, parents note a lag in weight gain and physical development. It turns out that children have difficulty participating in active games, climbing stairs, young children quickly get tired during feeding, note increased sweating, anxiety. Often, changes in the lungs and cough are incorrectly interpreted as "frequent pneumonia", anorexia, abdominal pain, vomiting, dyspepsia, syncope are possible. It is necessary to clarify whether there were cases of sudden death or death at a young age in the family, whether there are heart defects or other diseases of the cardiovascular system in close relatives. It is important how the child developed, what diseases he suffered from.

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Clinical examination in dilated cardiomyopathy

The clinical picture of dilated cardiomyopathy is variable and depends on the severity of circulatory failure. Hemodynamic disorders are caused by decreased myocardial contractility and the pumping function of the heart. This leads to increased pressure in the cavities of the heart, primarily in the left, then in the right. During examination, clinical manifestations of congestive heart failure are detected. The most important and constant diagnostic signs of dilated cardiomyopathy include: cardiomegaly, left displacement and weakening of the apical impulse, chest deformation in the form of a cardiac hump, lethargy, pale skin, delayed physical development (cachexia), swelling of the jugular veins, cyanosis, acrocyanosis, enlarged liver (in children under 1 year - and spleen), ascites, edema in the lower extremities. Auscultation reveals weakening of the 1st tone at the apex, systolic murmur of relative mitral and/or tricuspid valve insufficiency, the intensity of which varies; the 2nd tone over the pulmonary artery is accentuated and bifurcated. Tachycardia, extrasystole, and rarely bradycardia are characteristic.

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Laboratory diagnostics of dilated cardiomyopathy

When cardiomegaly is detected for the first time, it is advisable to conduct a comprehensive serological, immunological and biochemical blood test to exclude acute myocarditis.

• Conducting immunological studies allows us to identify a decrease in the activity of natural killers, an increase in the content of tumor necrosis factor, the presence of specific circulating antibodies (anti-myosin antibodies to the a- and beta-heavy chains of myosin, anti-mitochondrial antibodies, antibodies to beta-adrenergic receptors) - important markers of dilated cardiomyopathy.
• The detection of elevated CPK and CPK-MB activity may indicate acute myocarditis and neuromuscular disease.
• Elevated iron and transferrin levels in the blood may indicate hemochromatosis as a cause of dilated cardiomyopathy.
• Hyponatremia in combination with increased creatinine and urea levels (signs of impaired renal function), decreased fibrinogen, albumin, cholinesterase levels, increased transaminase activity, and bilirubin concentrations (signs of impaired liver function) reflect severe hemodynamic disturbances.

Instrumental diagnostics of dilated cardiomyopathy

Electrocardiography

The ECG results are very important, but they are non-specific and reflect the severity of myocardial damage and the degree of its hemodynamic overload. ECG data:

• rhythm disturbances (sinus tachycardia, ventricular arrhythmia, supraventricular and ventricular extrasystole);
• conduction disturbances (left bundle branch block, right bundle branch block, distal AV conduction disturbances);
• signs of hypertrophy, more often of the left ventricle, less often of both ventricles, and overload of the left atrium;
• low QRS voltage in standard leads;
• non-specific changes in the T wave.

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Chest X-ray

In all cases, X-ray examination reveals an increase in the size of the heart (cardiothoracic index over 0.60). The shape of the heart is often spherical, mitral or trapezoidal. In the pulmonary circulation, children often show signs of venous congestion, and less often moderate signs of pulmonary hypertension.

Echocardiography

EchoCG is the most important non-invasive diagnostic method for dilated cardiomyopathy. EchoCG helps to exclude heart defects, pericardial effusion, and other causes of cardiomegaly. In dilated cardiomyopathy, echocardiographic examination reveals a sharp dilation of the heart cavities, especially the left ventricle, often in combination with dilation of the atria. Intact heart valves, a decrease in the amplitude of the mitral valve opening due to impaired compliance of the dilated left ventricle, and an increase in end-diastolic pressure in its cavity are determined. A quantitative analysis of the functional state of the left ventricle is characterized by a significant increase in its end-diastolic and systolic diameters, as well as a decrease in left ventricular contractility (left ventricular ejection fraction below 30-40%). Doppler echoCG helps to detect mitral and tricuspid regurgitation. This method helps to identify a violation of the diastolic function of the left ventricle (its isometric relaxation phase is extended and the final diastolic pressure in its cavity increases). It is possible to detect an intracavitary thrombus and signs of pulmonary hypertension.

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Radionuclide research methods

• Radionuclide ventriculography reveals the following changes:
  • dilation of the heart cavities;
  • violation of local contractility against the background of a diffuse decrease in myocardial contractility;
  • significant decrease in the ejection fraction of the left and right ventricles.
• Myocardial scintigraphy with thallium-201 reveals diffuse and focal defects in drug accumulation.
• In myocardial scintigraphy with gallium-67, the isotope accumulates in inflammatory foci in myocarditis and does not accumulate in dilated cardiomyopathy.

Puncture (catheter, endomyocardial) biopsy

In our country, this method is not used for dilated cardiomyopathy in children due to its invasive nature, risk of complications, and high cost. In addition, the diagnostic value of endomyocardial biopsy for dilated cardiomyopathy is limited by the lack of pathognomonic morphological criteria for this disease. However, the study allows us to exclude the clinical diagnosis of dilated cardiomyopathy in the case of detection of pathohistological changes specific to such myocardial diseases as myocarditis, amyloidosis, sarcoidosis, and cardiac hemochromatosis.

Differential diagnosis of dilated cardiomyopathy in children

Differential diagnosis of dilated cardiomyopathy in children should be carried out with congenital heart defects, chronic myocarditis, arrhythmogenic myocardial dysfunction, rheumatic carditis, exudative pericarditis and specific cardiomyopathies.

Differential diagnostics with recurrent rheumatic carditis (against the background of formed mitral and aortic heart defects) is based on the absence of a characteristic rheumatic anamnesis, extracardiac manifestations of rheumatism, increased body temperature and humoral activity, persistent and more intense murmur of rheumatic defects in dilated cardiomyopathy. Rheumatism proceeds for many years without signs of congestive heart failure and has positive dynamics against the background of therapy, while the clinical manifestation of dilated cardiomyopathy is manifested by pronounced signs of heart failure, often refractory to the treatment.

Differential diagnostics with congenital heart defects (coarctation of the aorta, abnormal origin of the coronary artery from the pulmonary trunk, mitral valve insufficiency, etc.), pericarditis and other diseases accompanied by the development of heart failure are carried out using echocardiography.

Differential diagnostics with chronic myocarditis is difficult and in world practice is based on the results of endomyocardial biopsy. Due to the fact that in our country this method is not used in children, it is necessary to take into account the anamnesis data (connection with a previous viral infection, increased body temperature, humoral activity), the effectiveness of anti-inflammatory and symptomatic therapy, against the background of which positive dynamics are noted in chronic myocarditis.

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