Arrhythmogenic right ventricular cardiomyopathy in children: causes, symptoms, diagnosis, treatment

Arrhythmogenic right ventricular cardiomyopathy is a rare disease of unknown etiology, characterized by progressive replacement of right ventricular myocytes with fatty or fibro-fatty tissue, leading to atrophy and thinning of the ventricular wall, its dilation, accompanied by ventricular rhythm disturbances of varying severity, including ventricular fibrillation.

Epidemiology of arrhythmogenic right ventricular cardiomyopathy

The prevalence of arrhythmogenic right ventricular cardiomyopathy is unknown, or rather poorly understood, due to the fact that the onset of the disease is often asymptomatic. In addition, there is little information about the natural history of this disease, the impact on the long-term clinical course and survival of patients. However, it is believed that arrhythmogenic right ventricular cardiomyopathy is the cause of sudden death in 26% of children and adolescents who die from cardiovascular diseases.

Causes and pathogenesis of arrhythmogenic right ventricular cardiomyopathy

The cause of this cardiomyopathy remains unclear to this day and is the subject of numerous discussions. Heredity, chemical, viral and bacterial agents, and apoptosis are considered as possible etiological factors. Judgments about the pathogenesis of myopathic shifts and arrhythmogenesis in arrhythmogenic cardiomyopathy of the right ventricle are reduced to several basic assumptions.

• According to one of them, arrhythmogenic right ventricular cardiomyopathy is a congenital disorder of the right ventricular myocardium (dysplasia). The appearance of ventricular tachyarrhythmia may be delayed for 15 years or more until the size of the arrhythmogenic substrate becomes sufficient for the occurrence of persistent ventricular arrhythmias.
• Another variant of the development of dysplasia is associated with metabolic disorders that cause progressive replacement of myocytes.

The end result of one or more of the above processes is the replacement of the myocardium of the right and/or left ventricles with fatty or fibro-fatty tissue, which is a substrate for ventricular arrhythmias.

Symptoms of arrhythmogenic right ventricular cardiomyopathy

The disease is asymptomatic for a long time. During this period, the organic damage underlying arrhythmogenic right ventricular cardiomyopathy slowly progresses. Clinical signs of arrhythmogenic right ventricular cardiomyopathy (palpitations, paroxysmal tachycardia, dizziness or fainting) usually appear in adolescence or young adulthood. The leading clinical manifestations in this case are life-threatening arrhythmias: ventricular extrasystole or tachycardia (usually has a left bundle branch block pattern), episodes of ventricular fibrillation, and less commonly, supraventricular disorders (atrial tachyarrhythmias, atrial fibrillation or flutter). The first manifestation of the disease may be sudden circulatory arrest that occurs during physical exertion or intense sports activity.

Diagnosis of arrhythmogenic right ventricular cardiomyopathy

Clinical examination

In general, clinical examination is of little information due to the various causes of this condition, and accurate identification is possible only with long-term observation. Sometimes the disease can be suspected in the absence of an increase in the size of the heart on the radiograph.

Instrumental methods

Electrocardiography

Resting ECG in patients with arrhythmogenic right ventricular cardiomyopathy has characteristic features that suggest the presence of the disease. Thus, the duration of ventricular complexes in the right chest leads may exceed the duration of QRS complexes in the left chest leads. The duration of the QRS complex in lead VI exceeds 110 ms with a sensitivity of 55% and a specificity of 100%. A longer duration of QRS complexes in the right chest leads compared to the left ones also persists in cases of right bundle branch block.

Very characteristic are various ectopic ventricular arrhythmias, up to persistent ventricular tachycardia, in which ventricular complexes usually have the appearance of a left bundle branch block, and the electrical axis of the heart can be deviated both to the right and to the left. Paroxysmal ventricular tachycardia in most cases occurs in the right ventricle and is easily induced during electrophysiological examination.

X-ray examination of the chest organs

In X-ray examination of the chest organs, normal morphometric parameters are revealed in a large percentage of cases.

Echocardiography

Echocardiographic criteria for arrhythmogenic right ventricular cardiomyopathy:

• moderate dilation of the right ventricle;
• local protrusion and dyskinesia of the lower wall or apex of the heart;
• isolated dilation of the right ventricular outflow tract;
• increased intensity of reflected signals from the right ventricle;
• increased trabecularity of the right ventricle.

Magnetic resonance imaging

MRI is considered the most promising imaging method for diagnosing arrhythmogenic right ventricular cardiomyopathy, allowing the detection of structural abnormalities such as focal wall thinning and local aneurysms.

X-ray contrast ventriculography

Valuable information is provided by radiocontrast ventriculography. In this case, dilation of the right ventricle is characteristic in combination with segmental disturbances of its contraction, protrusions of the contour in areas of dysplasia and an increase in trabecularity.

Differential diagnostics

Differential diagnostics of arrhythmogenic right ventricular dysplasia is performed with dilated cardiomyopathy with predominant damage to the right ventricle, in which symptoms of right ventricular failure predominate, and in arrhythmogenic right ventricular dysplasia - ventricular arrhythmias. It is assumed that endomyocardial biopsy allows differentiating dilated cardiomyopathy and arrhythmogenic right ventricular dysplasia. Histological examination of biopsy specimens and autopsies reveals changes characteristic of arrhythmogenic right ventricular dysplasia: fatty infiltration (replacement) of the myocardium, atrophic or necrotic changes in cardiomyocytes, interstitial fibrosis, interstitial infiltrates from mononuclear cells. In the case of right ventricular dilated cardiomyopathy, biopsy specimens show noticeable hypertrophy, partial atrophy and interstitial fibrosis.

Treatment of arrhythmogenic right ventricular cardiomyopathy

Treatment for arrhythmogenic right ventricular cardiomyopathy is aimed at eliminating cardiac arrhythmias. For this purpose, antiarrhythmic drugs of different groups are used: sotalol, amiodarone, verapamil, etc. In case of persistent ventricular tachycardia, catheter destruction of the arrhythmogenic focus is performed or a cardioverter-defibrillator is implanted.

Forecast

The prognosis of arrhythmogenic right ventricular dysplasia is often unfavorable. Every 5th young patient who dies suddenly suffers from this pathology, every 10th patient suffering from arrhythmogenic right ventricular dysplasia dies from congestive heart failure and thromboembolic complications. The leading cause of death is electrical instability of the myocardium.

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