Excerpt

With the increasing acceptability and use of catheterization ablation for ventricular tachycardia, detailed anatomic studies have been done to improve the safety and efficacy for energy delivery in and around critical cardiac structures [1‐7]. More recently, ventricular fibrillation and certain forms of monomorphic ventricular tachycardia have required ablation in either the infrahisian conduction system or endocavitary cardiac structure, such as the papillary muscle, false tendons, and the right ventricular moderator band [8‐13]. In this review, we explain the critical details of structure and structure–function relations of the infrahisian tissue and the cardiac endocavitary structures. We approach the structures as a single unit with endocavitary structures routinely having a rich network of the distal His-Purkinje system. In addition, several commonly applied cardiac mapping maneuvers, including parahisian pacing and pacemapping, rely on understanding conduction tissue anatomy and active myocardium within the cavity for correct interpretation. Throughout the text are interspersed boxes that tabulate and summarize key anatomic pieces of information for the invasive electrophysiologist. …