Sudden death caused by benign tumor of the atrioventricular node

Mesothelioma of the atrioventricular (AV) node, although a benign tumor, is a known cause of sudden cardiac death.1This association is surprising, in that the tumor location should produce a site of block proximal to the His bundle, which is ordinarily consistent with a favorable clinical course.2-6 The present report concerns a 16-year-old girl with acquired heart block, sudden death, and pathological studies demonstrating a mesothelioma of the AV node. The case is unique in that His-bundle recordings were obtained that verified a localized site of AV block consistent with the location of the tumor. This case is of particular interest, since previous correlative studies of His-bundle recording and serial section of the conduction system have been attempted generally in patients with multiple electrophysiologic and pathologic sites of conduction disease,7-12rather than with a localized site as in our patient. PATIENT SUMMARY The patient was a gravida