The AV Conduction System in Bicuspid Aortic Valve (BAV)

Patients with BAV may be associated with atrioventricular (AV) conduction system disease requiring pacemaker. Knowledge of spatial relationship between the valve cusps, commissures, raphe and AV conduction system is crucial for avoiding conduction disturbances during surgical and transcatheter procedures. In the normal heart the AV node is located within the triangle of Koch and the His bundle runs underneath the membranous septum, in correspondence of the interleaflet triangle between the posterior non coronary and right anterior cusps. In BAV, by fusion of the posterior non coronary and right coronary anterior cusps, the raphe is just above the membranous septum and His bundle. On the opposite in BAV by fusion of the anterior coronary right and left cusps, the membranous septum and His bundle are far from the raphe. Calcification is the cause of BAV stenosis and raphe is particularly prone to mineralization. According to Lev, the natural occurrence of progressive AV block is ascribable to calcification involving His bundle and bifurcation.