Congenital aneurysm of the membranous septum associated with bundle branch block

An aneurysm of the membranous portion of the interventricular septum in a 69 year old man with right bundle branch block and A-V dissociation is reported. The pertinent literature dealing with this rare cardiac anomaly is briefly reviewed. More widespread use of angiocardiography and awareness of the existence of this lesion should increase the frequency of in vivo diagnosis of congenital ventricular septal aneurysm.