Sinoatrial nodal artery variant in approximately 10% of human hearts. This artery is larger than normal and supplies a good part of the left atrium, but also right sided structures like part of the sinoatrial node and the atrioventricular nodal areas. In this variant, the artery courses in the sulcus between the left superior pulmonary vein and the left atrial appendage where it could be susceptible to injury during catheter or surgical ablation procedures on the left atrium, especially for atrial fibrillation ablation or open heart cardiac surgery. Sinoatrial nodal artery The sinoatrial nodal artery (or sinuatrial nodal artery or sinoatrial artery) is
Heart block the atrioventricular node ("AV node") which also contains a secondary "pacemaker" that acts as a backup for the SA nodes, then to the bundle of His and then via the bundle branches to the point of the apex of the fascicular branches. Blockages are therefore classified based on where the blockage occurs - namely the SA node ("Sinoatrial block"), AV node ("AV block" or AVB), and at or below the bundle of His ("Intra-Hisian" or "Infra-Hisian block" respectively). Infra-Hisian blocks may occur at the left or right bundle branches ("bundle branch block") or the fascicles of the left bundle branch