Acute regional left atrial ischemia causes acceleration of atrial drivers during atrial fibrillation

Background The mechanisms by which acute left atrial ischemia (LAI) leads to atrial fibrillation (AF) initiation and perpetuation remain unclear. Objective To investigate the electrophysiological mechanisms of AF perpetuation in the presence of regional atrial ischemia. Methods LAI (90-minute ischemia) was obtained in isolated sheep hearts by selectively perfusing microspheres into the left anterior atrial artery. Two charge-coupled device cameras and several bipolar electrodes enabled recording from multiple atrial locations: with a dual-camera setup (protocol 1, n = 10, and protocol 1′, n = 4, for biatrial or atrioventricular camera setups, respectively), in the presence of propranolol/atropine (1 μM) added to the perfusate after LAI (protocol 2, n = 3) and after a pretreatment with glibenclamide (10 μM; protocol 3, n = 4). Results Spontaneous AF occurred in 41.2% (7 of 17) of the hearts that were in sinus rhythm before LAI. LAI caused action potential duration shortening in both the ischemic (IZ) and nonischemic (NIZ) zones by 21%±8% and 34%±13%, respectively (pacing, 5 Hz; P