[Arrhythmogenic cardiomyopathies of the right ventricle]

Arrhythmogenic cardiomyopathies of the right ventricle (ACRV) are defined by an association of left delayed type ventricular arrhythmias, ranging from apparently uncomplicated extrasystoles to more severe or even potentially lethal arrhythmias such as polymorphous VT and ventricular fibrillation, with an anatomical substrate consisting of adipose or fibro-adipose degeneration of the myocytes of the free wall of the ventricle, which may be either focal (in particular: apex, anterior surface of the infundibulum and the sub-tricuspid region), or more diffuse. It is then accompanied by RV systolic dysfunction with dilatation of the cavity. This apparently well defined clinico-pathological entity is in fact more complex, if only because of the existence of associated lesions of the left ventricle in 1/3 of cases. The distinction from Uhl disease remains blurred, in particular in diffuse forms. It is most probable that more than one etiology is involved. A dysgenetic mechanism with probable autosomal dominant transmission has apparently been shown in familiar forms which are associated with a particularly severe risk of progression. The hypothesis of sequelae of multifocal myocarditis appears to be the most probable in sporadic forms. In the absence of histological criteria, which it is difficult to demand in view of the variability of results and potential dangers of endomyocardial biopsy involving such thin and fragile ventricular walls, the diagnosis of ACRV is based upon the concomitant existence of: (1) electrophysiological criteria: ventricular arrhythmias, in particular sustained monomorphous VT, with the particular feature of a very high degree of sensitivity to adrenergic stimulation (exercise), the existence of late potentials on the high amplification ECG, a highly specific sign, though unfortunately of poor sensitivity in localized froms, those which are most difficult to identify (2); segmentary morphological and kinetic RV abnormalities, most often resulting in localized akinetic or dyskinetic parietal vaulting, with stasis "in situ". Modern imaging methods (echocardiography, angioscintigraphy with phase analysis, nuclear magnetic resonance imaging, etc.) unfortunately do not yet offer an alternative to selective cineangiography of the RV which is the reference investigation when it is performed and interpreted under strict conditions. Several reports of sudden death or of ventricular fibrillation seen in confirmed cases of ACRV, as well as the publication of a number of autopsy registers indicating that this condition is one of the primary causes of sudden death in young individuals and in athletes, have cast doubt on the benign prognosis initially attributed to this condition.(ABSTRACT TRUNCATED AT 400 WORDS)