The significance of stenotic lesion in an unoccluded coronary artery. A manifestation of myocardial "ischemia at a distance" during acute coronary occlusion.
This study was undertaken to investigate the significance of stenotic lesion of an unoccluded vessel in a manifestation of myocardial "ischemia at a distance" during acute coronary occlusion. The left anterior descending artery (LAD) was ligated in dogs in which constriction of the circumflex artery (LCx) of different degrees was carried out beforehand. Ischemic changes were detected by epicardial and intramyocardial electrocardiograms. Systemic and coronary hemodynamics were monitored. In dogs without LCx constriction (Group-I) and those with LCx constriction of such a degree as to reduce the percent repayment of the blood flow debt to 150% (Group-II), the LAD-ligation produced no ischemic changes in the LCx area. In dogs with severe constriction of LCx such as eliminating reactive hyperemia (Group-III), an expansion of ischemic damage to the LCx area was observed. Ventricular fibrillation was observed more frequently in Group-III as compared to Group-I and Group-II. After LAD-ligation LCx blood flow was increased in Group-I and Group-II, but remained unchanged in Group-III. After LAD ligation, distal coronary perfusion pressure (DCPP) of LCx remained unchanged in Group-I, while further decrease of DCPP was observed in both Group-II and Group-III. Some dogs in Group-III showed a sudden reduction of the flow associated with a decrease of DCPP after the ligation. These results show that hemodynamic changes, especially a sudden decrease in coronary perfusion pressure after LAD-ligation, play a significant role in inducing ischemic changes in the area perfused by the unoccluded coronary artery with severe stenosis (LCx).
D000818:Animals; D003251:Constriction, Pathologic; D003326:Coronary Circulation; D003327:Coronary Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000503:physiopathology / Q000601:surgery; D004285:Dogs; D004562:Electrocardiography; D006439:Hemodynamics; D008026:Ligation; D010477:Perfusion; D014655:Vascular Resistance