Arrhythmogenic dysplasia of the right ventricle

In Russia, arrhythmogenic dysplasia of the right ventricle was first described by G.I. Storozhakov et al.

Arrhythmogenic right ventricular cardiomyopathy (ARVC), or arrhythmogenic right ventricular dysplasia, is a disease in which the normal myocardium of the right ventricle is replaced by fatty or fibro-fatty tissue. Usually, the right ventricle is affected isolated, but the interventricular septum and myocardium of the left ventricle may be involved in the process.

ICD-10 code

142.8. Other cardiomyopathies.

Epidemiology

The incidence in the population depends on the region and ranges from 6 to 44 cases per 10,000 population. Arrhythmogenic right ventricular dysplasia is most common in Mediterranean regions. In 80% of cases, it is detected before the age of 40, more often in men.

Arrhythmogenic right ventricular dysplasia is the cause of 5-20% of cases of sudden death in young people (second only to HCM).

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Causes of arrhythmogenic right ventricular dysplasia

The cause of the disease remains unclear to this day. There is evidence of the hereditary nature of APFD. Genetic abnormalities of several chromosomes have been established in familial cases of arrhythmogenic right ventricular dysplasia.

It is assumed that changes in chromosomes lead to pathology of proteins that form intercellular connections. Disturbances in these connections lead to death of cardiomyocytes and their fibrous-fatty replacement. Genetic disorders in arrhythmogenic right ventricular dysplasia (ESC, 2008) are associated with a family gene, a mutation of the intercalated disk protein (plakoglobin, desmoplakin, plakophilin 2, desmoglein 2, desmocollin 2). There is also an inflammatory theory of the formation of arrhythmogenic right ventricular dysplasia as a result of viral myocarditis in genetically predisposed individuals with altered myocardium.

Macroscopically, patients with APVC show local or generalized dilation of the right ventricle with myocardial thinning. Typical localization of changes is the apex, infundibular and subtricuspid region ("dysplasia triangle").

The microscopic criterion for diagnosis is the presence of foci of fibro-fatty tissue interspersed with unchanged myocardium.

Symptoms of arrhythmogenic right ventricular dysplasia

Symptoms of arrhythmogenic right ventricular dysplasia range from asymptomatic forms to cases of sudden death or severe biventricular heart failure.

Arrhythmogenic right ventricular dysplasia usually debuts with ventricular heart rhythm disturbances: extrasystole of various gradations, short "runs" of ventricular tachycardia, and in some cases paroxysms of sustained ventricular tachycardia. Since the arrhythmogenic focus is located in the right ventricle, ectopic ventricular complexes look like a block of the left leg of the His bundle.

There may be atypical chest pain, weakness, increased fatigue, episodes of rapid heartbeat during physical exertion. Arrhythmogenic collapses occur during exertion or spontaneously.

In half of the cases, physical examination reveals no abnormalities.

In later stages, patients may develop circulatory failure, which causes serious difficulties in the differential diagnosis of APHD with dilated cardiomyopathy.

Diagnosis of arrhythmogenic right ventricular dysplasia

A number of international cardiology societies have adopted the diagnostic criteria for arrhythmogenic right ventricular dysplasia proposed by WJ McKenna. Major and minor criteria are distinguished. The presence of arrhythmogenic right ventricular dysplasia is indicated by the establishment of 2 major criteria, 1 major and 2 minor criteria, or 4 minor criteria from different groups.

Diagnostic criteria for arrhythmogenic right ventricular dysplasia (McKenna WJ et al., 1991)

Criteria	Big signs	Minor signs
Global and/or regional dysfunction and structural changes	Significant dilation and decrease in the ejection fraction of the right ventricle with no changes (or minor changes) in the left ventricle Local aneurysms of the right ventricle Significant segmental dilation of the right ventricle	Moderate dilatation of the right ventricle and/or decreased ejection fraction with a normal left ventricle Moderate segmental dilatation of the right ventricle Regional hypokinesia of the right ventricle
Characteristics of wall fabric	Fibro-fatty degeneration of the myocardium in endomyocardial biopsy	-
Repolarization abnormalities	-	T-wave inversion in the right V2 and V3 chest leads in patients over 12 years of age without right bundle branch block
Depolarization/conduction abnormalities on ECG	Epsilon waves or local increase in QRS complex duration (>110 ms) in the right chest leads (V1-V3)	Late ventricular potentials on high-resolution ECG
Arrhythmias	-	Sustained or non-sustained ventricular tachycardia (with complexes of the left bundle branch block type) according to ECG, daily monitoring and exercise testing Frequent ventricular extrasystoles (>1000/day)
Family history	Familial nature of the disease, confirmed by autopsy or surgery	Sudden death in relatives younger than 35 years with suspected arrhythmogenic right ventricular dysplasia Family history (clinical diagnosis based on current criteria)

To clarify the nature of rhythm disturbances and assess the risk of fatal arrhythmias, an electrophysiological study is performed.

Visualization methods are of great importance for the diagnosis of arrhythmogenic right ventricular dysplasia.

Echocardiography (including contrast) reveals abnormalities in the contractility of the right ventricle.

Magnetic resonance imaging helps to detect increased levels of fatty tissue in the myocardium.

The “gold standard” for diagnosing arrhythmogenic right ventricular dysplasia is ventriculography.

Reliable diagnostic signs of arrhythmogenic right ventricular dysplasia can be determined by endomyocardial biopsy, which is performed in the area of the interventricular septum and free wall of the right ventricle. The sensitivity of the method is about 20%, since it is not always possible to take a biopsy from the affected area.

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Treatment of arrhythmogenic right ventricular dysplasia

The disease has a steadily progressive nature, but with timely diagnosis and adequate treatment, the prognosis can be significantly improved.

The treatment of APHC is aimed at preventing sudden death and treating heart failure.

Treatment of CHF in APHC involves the standard use of diuretics, ACE inhibitors, digoxin and, if indicated, anticoagulants.

Among antiarrhythmics, the greatest experience has been accumulated with respect to amiodarone and sotalol. The latter has the greatest effectiveness, therefore, for the purpose of treating ventricular arrhythmias and preventing sudden death, it is recommended to begin treatment with sotalol. If it is ineffective, non-drug methods should be used, in particular, implantation of a cardioverter-defibrillator.

Radiofrequency ablation has low efficiency, as relapses of arrhythmia develop, caused by the activation of new foci.

The only treatment for arrhythmogenic right ventricular dysplasia in patients refractory to conservative treatment is heart transplantation.