An ultrastructural study on arrhythmogenic right ventricular dysplasia with special reference to lipid droplets.

Myocardial tissues in arrhythmogenic-right ventricular dysplasia (ARVD), which were surgically resected from the site of origin of ventricular tachycardia (VT), were investigated optically and electron-microscopically. The site of origin was found to be occupied by an abundance of adipose cells. In the marginal zone, lipid droplets were obviously increased in count in the cytoplasm of both myocytes and blood capillary-endothelium, rather more than in distant areas. Lipid droplets in the endothelial cells also occurred at a higher frequency in the ARVD group than in any other myocardial disease showing VT. A mechanism which increases lipid droplets in the cytoplasm of cardiomyocytes and endothelial cells operates at the VT origin site in ARVD. Intraendothelial lipids may be an important diagnostic finding in the histology of ARVD.