Histopathological analysis of surgically resected myocardium in patients with sustained ventricular tachycardia.

Surgical resection of the endocardium and subendocardium often abolishes sustained ventricular tachycardia (VT) in patients with old myocarcial infarct (OMI), unknown myocardial disease, and arrhythmogenic right ventricular dysplasia (ARVD), presumably by interrupting the reentrant pathway. In order to define the morphologic characteristics of histologic components in the reentrant pathway, we carried out histopathological analysis of surgically resected specimens from 17 patients who underwent this procedure. Bundles of apparently viable and hydropic myocardial fibers embedded in dense fibrous and adipose tissues were identified throughout the specimens obtained from OMI, ARVD and idiopathic VT cases. In 3 patients with idiopathic VT, most of the resected areas were composed of ventricular muscle, the components of which appeared histologically similar to Purkinje fibres. In all patients, the abnormal muscle cells were characterized by a loss of contractile elements, hydropic cytoplasm and an elliptic shape. Such an abnormal structure and arrangement of surviving cardiac fibers following tissue injury might play an important role in creating abnormalities of transmembrane potential, leading to the micro-reentrant circuits that give rise to ventricular tachycardias.