Right ventricular dysplasia: morphological findings in 13 cases.

To characterize the pathological features of right ventricular dysplasia (RVD). Retrospective morphological case study. Three referral-based university medical centres. Thirteen subjects (one female) aged 16 to 55 years including 10 necropsy hearts from sudden deaths out of hospital, one explant heart and two partial right ventricular resections from patients with intractable ventricular tachycardia. Most hearts showed hypertrophy and localized or generalized dilatation of the right ventricle. Transillumination revealed myocardial thinning of variable configuration usually conforming to regions of dilatation. Common sites of involvement were apex, infundibular region and posterobasal wall. Histologically, focal or extensive segments of right ventricular myocardium were absent or replaced. Three patterns were found: right ventricle markedly thinned, epicardium and endocardium contiguous, virtually no intervening tissue; wall normal thickness or thinned, myocardium almost totally replaced by fat; and wall normal or thin, myocardium largely replaced by fat with scattered residual myocardial cells and fibrous tissue (the predominant pattern). Endocardial fibrosis was present in eight cases and focal mononuclear cell infiltrates in 10. Electron microscopy in two cases showed nonspecific findings. RVD has gross and microscopic features which permit its recognition. While a majority of cases are likely congenital (genetic or acquired in utero), the possibility of postnatally acquired conditions (inflammatory, toxic, ischemic) inducing RVD must be explored. The incidence and importance of RVD as a cause of sudden death can only be assessed by continued systematic and detailed studies of patients with recurrent ventricular tachycardia and of hearts, especially from sudden death victims. Although uncommon, RVD should be considered in the differential diagnosis of arrhythmia and sudden death by both clinicians and pathologists.