Журнал «Здоровье ребенка» 2 (45) 2013

Arrhythmogenic right ventricular dysplasia (ARVD) belongs to primary cardiomyopathy (CM). This pathology of unclear etiology is usually an isolated impairment of the right ventricle (RV), often running in the family, characterized by fatty or fibrofatty infiltration of ventricular myocardium accompanied by heart rhythm disorders (HRD) of the ventricles of various severity, including ventricular fibrillation. Prevalence of ARVD has been studied not enough due to the fact that the onset of the disease is often asymptomatic. In 80% of cases it is revealed under the age of 40, more frequently in males [1,2,4]. Some authors consider ARVD to be the cause of sudden cardiac death (SCD) in 26% of children and adolescents. SCD may be the first and the only manifestation of ARVD, particularly in young people and sportsmen. According to the data by the American authors, ARVD is diagnosed posthumously approximately in 5% of SCD cases in people younger than 65 years of age and in 3-4% cases of death in young sportsmen during competitions [4]. Opinions as to pathogenesis of the disease come to two theories: ARVD is a congenital anomaly of development of RV myocardium called dysplasia [1,3,4]. The onset of tachycardia may be postponed for many years until RV is considerably enlarged and the size of arrhythmogenic substrate is big enough to cause persistent ventricular tachyarrhythmia (VT). The second theory connects the onset of RV dysplasia with metabolic disturbances involving RV and causing progressing myocyte replacement (apoptosis) [3,9]. Islets of fibrofatty tissue revealed in ARVD form arrhythmogenic substrate carrying electrophysiological conditions for development of reentry underlying malignant VT. There distinguish 4 different forms of clinical course of ARVD: latent form in which the first and the only manifestation of the disease is SCD due to ventricular fibrillation; arrhythmic form characterized by proved symptomatic VT (ventricular extrasystolia and VT) with QRS complex configuration of the left bundle branch block (LBBB) type; “paucisymptomatic form” manifested through such symptoms as palpitations, pain in the heart area; the form appearing as heart failure (HF), predominantly of the right ventricle, with or without HRD [1,2,4,5,8]. In 1994 McKenna W.J. et al. [14] elaborated the criteria for ARVD diagnosis (table 1).

The diagnosis of ARVD is considered reliable in combination of two major criteria, or one major and two minor criteria, or four minor criteria.

There are data on the hereditary character of ARVD: in 1988 A.Nava et al. suggested a hypothesis on autosome-dominant type of inheritance with different degrees of manifestation [6,7].  Indeed, patients with ARVD and their relatives often have syncope of undetermined origin in their history. Faints as a manifestation of severe arrhythmic events may appear long before development of characteristic clinical-instrumental signs of ARVD.

Our clinical example illustrates the theory by F.I. Marcus et al. (1982) on the familial character of arrhythmogenic RV dysplasia. The patient V. with severe HRD, frequent pre-syncope and later on syncope events was followed-up by at first children and then adult cardiologists for 12 years (9 to 21 yr. of age). The diagnosis of ARVD, arrhythmic form with frequent attacks of ventricular tachycardia was made in patient V. on basis of one major and four minor criteria by McKenna W.J. et al.: segmental RV impairment with LV involvement; familial case of ARVD confirmed clinically; frequent ventricular extrasystoles (>1000/24h); episodes of monomorphic VT with morphology of left bundle branch block; mild RV dilatation without reduction of ejection fraction (figures 1, 2).

Family history is aggravating. During the first examination of the girl, her mother was 40 and she also had severe HRD (figure 3) with frequent pre-syncope and syncope conditions. At the age of 30, after clinical death, the patient’s mother was examined at Research Centre of Cardiovascular Surgery named after N. Amosov (the city of Kiev) where she was suggested an implantation of a pacemaker but the woman refused to be treated.

Arrhythmia was induced in the child on physical exertion. While analysing Holter ECG monitoring, it was noted higher sinus rhythm preceding VT paroxysm as reflection of activation of the sympathoadrenal system. At first VT in the patient had ECG-morphology of LBBB which indicated the origin of arrhythmia from RV myocardium. However, with time several morphologies of VT were registered which was the evidence of formation of multiple arrhythmogenic foci. The girl often had syncope conditions which required implantation of a cardioverter-defibrillator. It was implanted at the age of 14 in Federal Children Centre of Arrhythmias (Moscow). While checking the work of the cardioverter-defibrillator in patient V., frequent ventricular paroxysms controlled by the discharge of the defibrillator were registered during several years. At the age of 17 the patient got married and became pregnant at the age of 18 in spite of doctors’ warning about undesirability of pregnancy. She registered with the obstetrician on the 22nd week of gestation at Centre for Maternity and Childhood Protection (the city of Simferopol). There the echocardiogram of the fetus revealed severe congenital heart defect (CHD) (hypoplastic left heart syndrome (HLHS)). The parents were referred to the State Institution Research and Practical Centre for Children Cardiology and Cardiosurgery under Ministry of Health of Ukraine (the city of Kiev) where the fetus was diagnosed not only CHD, but also complete atrioventricular block, fetal heart rate being 40-45 beats/min (Fig. 4).

The high risk of abortion caused the parents to refuse to make such an operation. At the term of 28 weeks of gestation the patient was seen by Head of the Department of Arrhythmias of Research Centre of Cardiovascular Surgery named after N. Amosov (the city of Kiev) V.P. Zalevsky who reprogrammed the cardioverter-defibrillator and gave recommendations as to the delivery at the specialized maternity home No. 5 (the city of Kiev). The childbirth was timely. At the age of 2 hours the infant was moved to State Institution Research and Practical Centre for Children Cardiology and Cardiosurgery under Ministry of Health of Ukraine with the diagnosis: moderate valve aortic stenosis (systolic pressure gradient 54 mmHg). Aortic arch hypoplasia with critical coarctation of aorta (COA). Mitral valve and left ventricle hypoplasia. Patent ductus arteriosus (PDA). During the first 24 h roentgen-endovascular balloon angioplasty of critical COA was performed to the infant. The result of the intervention was satisfactory; systolic pressure gradient reduced. However, the baby’s complete AV block aggravated and this, together with CHD, led to the fatal outcome within a few days.

In spite of all the efforts of the doctors, patient V. died at the age of 21 yr. because of her refusal to replace the cardioverter-defibrillator which had been far beyond its service life. The diagnosis of ARVD was confirmed on autopsy. The patient’s mother is still alive.

Thus, the young age of the patient, marked and poorly tolerated VT (particularly polymorphic), frequent episodes of syncope, severe RV dysfunction, HF, relatives with arrhythmia or those who died at the early age, refusal of treatment, - all these factors are predictors of unfavourable prognosis. That is why all the patients with diagnosis of ARVD or suspected of it have a high risk of SCD even in absence of confirmed ventricular HRD. Reduction of SCD risk is the main task in treating ARVD. One of the most recommended medical approaches is implantation of a cardioverter-defibrillator which prevents effectively development of SCD in such patients, lessens progressing contractive myocardial dysfunction, reduces the risk of HF development and improves long-term prognosis.