Functional anatomy in arrhythmias and vascular support of the conduction system

Abstract

The cardiac conduction system is composed of the sinoatrial node (SAN), the atrioventricular node (AVN), the His bundle, the right and left bundle branches, the fascicles, and the Purkinje fibers. Spreading of the pacemaking impulse from atrial to ventricular myocardium is delayed at the AVN located at the base of the interatrial septum. From the AV node, the propagation of the pacemaking impulse accelerates along the AV bundle and bundle branches, finally activating ventricular muscle via the Purkinje fiber network system. The atrioventricular node (AVN) and bundle (AVB) normally penetrate the right fibrous trigone (central fibrous body) at the atrioventricular junction. The SAN artery comes off of either the proximal right coronary artery (60-70 %) or the proximal circumflex artery. Alternative sources of arterial supply to the atrioventricular-conducting pathway include the descending septal artery, the first septal perforating artery, and anterior atrial branches inclusively the Kugel anastomotic artery. Anatomic structures related to arrhythmias include cavotricuspid isthmus, subthebesian pouch, septal isthmus, and pulmonary veins. Other anatomic arrhythmogenic elements are the ligament of Marshall, lipomatous hypertrophy of the interatrial septum, and cardiac autonomic nervous system.