Torsades de Pointes in a case of hypertrophic cardiomyopathy with special reference to the pathologic findings of the heart including the conduction system

A clinicopathologic study was performed in a 77-year-old female with hypert rophic cardiomyopathy who had experienced recurrent syncopal attacks due to Torsades de Pointes (TdP) following QT prolongation and atrioventricular b lock. She died suddenly two years later while eating dinner. Pathologic fin dings of the heart showed a dilated and hypertrophied left ventricle. The h eart weighed 550 g. There were two foci of localized endocardial fibroelast osis (EFE) beneath the aortic valve, one with a size of 3.5 x 3.5 cm, and t he other (2 x 1 cm) located on the upper ventricular septum. Histologic fin dings showed hypertrophy and disarray in the left ventricular myocardium. T he conduction system using serial sectioning revealed remarkable bilateral bundle branch fibrosis and hypertrophied Purkinje fibers in the left bundle branch adjacent to the EFE on the ventricular septum. These findings were thought to be related to the occurrence of TdP.