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

Right ventricular arrhythmogenic cardiomyopathy is a rare disease of unclear etiology, characterized by a progressive replacement of the right ventricle myocytes with fatty or fibrous fat tissue leading to atrophy and thinning of the ventricular wall, its dilatation accompanied by ventricular rhythm disturbances of varying severity, including ventricular fibrillation.

Epidemiology of arrhythmogenic cardiomyopathy of the right ventricle

The prevalence of arrhythmogenic cardiomyopathy of the right ventricle is unknown, or, to be more precise, little studied due to the fact that the onset of the disease often occurs asymptomatically. In addition, there is little information about the natural course of this disease, the effect on long-term clinical course and the survival of patients. However, it is believed that arrhythmogenic cardiomyopathy of the right ventricle causes sudden death in 26% of children and adolescents who died from cardiovascular diseases.

Causes and pathogenesis of arrhythmogenic cardiomyopathy of the right ventricle

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

• In accordance with one of them, arrhythmogenic cardiomyopathy of the right ventricle is a congenital disorder of myocardium development of the right ventricle (dysplasia). The appearance of ventricular tachyarrhythmias can 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 occurrence 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 fibrous-fat tissue, which is a substrate for ventricular arrhythmias.

Symptoms of arrhythmogenic cardiomyopathy of the right ventricle

For a long time the disease is asymptomatic. During this period, the organic damage underlying the arrhythmogenic cardiomyopathy of the right ventricle is slowly progressing. Clinical signs of arrhythmogenic cardiomyopathy of the right ventricle (palpitation, paroxysmal tachycardia, dizziness or fainting) usually appear in adolescence or adolescence. The leading clinical manifestations are life-threatening arrhythmias: ventricular extrasystole or tachycardia (usually has a block diagram of the left leg of the His bundle), episodes of ventricular fibrillation, and less frequently supraventricular disorders (atrial tachyarrhythmias, flicker or atrial flutter). The first manifestation of the disease can be a sudden stoppage of blood circulation, occurring during physical exertion or intense sports activity.

Diagnosis of arrhythmogenic cardiomyopathy of the right ventricle

Clinical examination

In general, the clinical examination is poorly informative due to the different causes of this condition, and precise identification is only possible with long-term follow-up. Sometimes the disease can be suspected in the absence of an increase in the size of the heart on the radiograph.

Instrumental methods

Electrocardiography

ECG at rest in patients with arrhythmogenic cardiomyopathy of the right ventricle has characteristic features that allow one to assume the presence of the disease. Thus, the duration of the ventricular complexes in the right thoracic leads can exceed the duration of QRS-complexes in the left thoracic leads. The duration of the QRS complex in lead VI exceeds 110 ms with a sensitivity of 55% and a specificity of 100%. The long duration of QRS- complexes in the right thoracic leads, in comparison with the left ones, is also preserved in cases of blockade of the right leg of the bundle.

Very different ectopic ventricular arrhythmias, up to a persistent ventricular tachycardia, in which the ventricular complexes usually have the form of a blockade of the left leg of the bundle, and the electric axis of the heart can be rejected both to the right and to the left. Paroxysmal ventricular tachycardia in most cases occurs in the right ventricle and is easily induced by electrophysiological examination.

Chest X-ray examination

Radiologic examination of the chest organs in a large percentage of cases reveal normal morphometric parameters.

Echocardiography

Echocardiographic criteria for arrhythmogenic cardiomyopathy of the right ventricle:

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

Magnetic resonance imaging

MRI is considered the most promising visualizing method for diagnosis of arrhythmogenic cardiomyopathy of the right ventricle, which allows to detect structural disorders, such as focal wall thinning and local aneurysms.

Radiocontrast ventriculography

Valuable information is provided by radiocontrast ventriculography. This is characterized by dilatation of the right ventricle in combination with segmental impairment of its contraction, protrusion of the contour in the areas of dysplasia and an increase in trabecularity.

Differential diagnostics

Differential diagnosis of arrhythmogenic right ventricular dysplasia is performed with dilated cardiomyopathy with predominant right ventricular lesion, in which symptoms of right ventricular failure prevail, and in ventricular arrhythmogenic dysplasia, ventricular arrhythmias. It is suggested that endomyocardial biopsy allows differentiating dilated cardiomyopathy and arrhythmogenic right ventricular dysplasia. Histological examination of biopsies and autopsies reveals changes characteristic of right ventricular arrhythmogenic 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 in biopsy notes marked hypertrophy, partial atrophy and interstitial fibrosis.

Treatment of arrhythmogenic cardiomyopathy of the right ventricle

Treatment for arrhythmogenic cardiomyopathy of the right ventricle is aimed at eliminating cardiac arrhythmias. To do this, antiarrhythmic drugs of different groups are used: sotalol, amiodarone, verapamil, etc. With stable ventricular tachycardia, catheter destruction of the arrhythmogenic focus or implant cardioverter defibrillator is performed.

Forecast

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

[1], [2], [3], [4], [5]