Activation of the Ischemic Ventricle and Acute Peri-Infarction Block in Experimental Coronary Occlusion

Changes in left ventricular activation during the first 10 min. following occlusion of the anterior descending branch of the left coronary artery of dogs were studied by using multiple intramural electrodes. Intramural block and an increase in the amplitude of R were observed routinely in the outermost layers of muscle in the central zone of maximal ischemia as long as the occlusion was maintained. The changes were distinct from those produced by left bundle-branch block. Failure to propagate the accession process in normal fashion seems to be characteristic of ischemic heart muscle.