The results of electrophysiologic studies made at the time of operation were compared with histologic and ultrastructural observations made on surgically resected ventricular aneurysms from 3 patients with Chagasic cardiomyopathy. Electrophysiologic mapping studies indicated that refractory ventricular arrhythmias in all 3 patients originated from regions adjacent to the aneurysms. Morphologic studies reveal focal changes, the most important of which consisted of loss of myofibrils, mitochondrial damage and thickening of the basement membranes. It was concluded that the mixture of normal and damaged myocytes provided the anatomic basis for a reentry type of arrthymia.
