In a healthy cardiac cycle, electrical conduction is initiated by the sinoatrial (SA) node - the pacemaker of the heart. From this location, a wave of depolarization travels through the myocardium of the atria and eventually arrives at the atrioventricular (AV) node. At this point, there is a slight delay in electrical conduction. The next structure which conducts the impulse is the bundle of His, which gives rise to two bundle branches - a left and right. The final structures of the cardiac conduction system are the Purkinje fibers, which rapidly disperse the wave of depolarization to the myocardium of the ventricles.