Sudden death in an adult with a small ventricular septal defect and an aneurysmal membranous septum

An apparently healthy man of 26 years of age suddenly died. He was known to have had a small ventricular septal defect and complete right bundle branc h block from early childhood. At post-mortem examination the small ventricu lar septal defect was found associated with an aneurysm of the membranous s eptum. Histological examination showed a normal atrioventricular node and b undle, adjacent to the aneurysm. There was fibrous interruption at the comm encement of the right bundle branch, which was considered the basis of the bundle branch block. It was also considered that the right bundle branch bl ock was of the hereditary type and that this, rather than the aneurysm of t he membranous septum, was responsible for the unexpected death.