Effects of acute coronary occlusion on the motion and perfusion of the normal and ischemic interventricular septum.

To establish the effect of local and remote myocardial ischemia on interventricular septal motion, 27 open-chest dogs were studied using ultrasound and radioactive microspheres. In 14 dogs the left anterior descending coronary artery was ligated. If the ultrasound beam traversed ischemic septum (proximal LAD occlusion), significant (P less than 0.05) declines in systolic septal velocity (26.4 +/- 2.9 to 6.4 +/- 1.8 mm/sec), and excursion (2.6 +/- 0.3 to 0.7 +/- 0.2 mm) occurred, and systolic thickening was reduced. Similar significant changes were seen when the ultrasound beam traversed nonischemic septum adjacent to the ischemic area (distal LAD occlusion). In 13 additional dogs, circumflex coronary ligation produced posterior ischemia. The mean septal velocity for this group increased significantly (21.8 +/- 2.6 to 26.5 +/- 3.3 mm/sec), as did the septal excursion (2.5 +/- 0.2 to 3.1 +/- 0.4 mm). We conclude that acute LAD occlusion causes a reduction in systolic velocity, excursion, and thickening of both the involved ischemic and the adjacent nonischemic septum. When myocardial ischemia was produced in a part of the ventricle remote from the septum, septal velocity and excursion increased.