Arrhythmogenic right ventricular dysplasia（不整脈を伴う右心室異形成症）の1例—心筋生検による病理組織像を中心に

A case of arrhythmogenic right ventricular dysplasia with special refrence to endomyocardial biopsy study

　Arrhythmogenic right ventricular dysplasia （不整脈を伴う右心室異形成症，ARVD）は心室頻拍（VT）発作をくり返す，右心室に限局した原因不明の心筋疾患としてFontaine^1）が1977年に報告したもので，症例数は少なく，その病因に未だ定説はない。われわれは特発性VTと紛らわしく，心筋生検により診断しえたARVDを経験したので，その診断・病因・治療に関する考察を加え報告する。

A 42-year-old male dental technician was refer-red to the hospital for evaluation of recurrent ven-tricular tachycardia (VT). He had been well until 6 months previously to admission when he began having bouts of sustained VT at the rate of 250/ min with a QRS configuration of left bundle branch block type. These episodes made the patient com-plaining only of palpitation and light-headedness. Following conversion to sinus rhythm by lidocaine infusion, the ECG demonstrated no abnormalities such as bundle branch block, prolonged QT-inter-val, or T-wave inversion at the anterior precordial leads. Physical examination, chest roentgenograms, echocardiograms and laboratory findings were not contributory. Right and left heart pressure studies were normal. The coronary arteriograms and the left ventriculograms were also normal, but the right ventriculograms showed slight hypokinesis at the apical segment. His bundle electrograms disclosed no abnormality. VT could not be initiated by a programmed single ventricular-extrastimulus. Right ventricular endomyocardial biopsy was performed. Two samples were taken from the apical portion, one for light microscopy (LM) and the other for electron microscopy (EM). Marked vacuolation of myocytes with fatty infiltration in and around myo-cytes was noted by LM. A large number of lipid droplets were found in the myocytes and vascular endothelial cells by EM. A diagnosis of arrhythmo-genic right ventricular dysplasia (ARVD) was made. Proprano/ol has been given to prevent the VT episodes.

Endomyocardial biopsy study was useful in differ-entiating ARVD with less remarkable right ven-tricular abnormality, from idiopathic VT.