In order to observe the changes in left ventricular function during coronary artery occlusion and reperfusion, left anterior descending (LAD) coronary arteries in the anesthetized dogs were occluded for 1 hour and then reperfused for 4 hours. Hemodynamic indexes of global systolic and diastolic function and regional wall thickness changes as a regional contractile index were measured during occlusion and reperfusion. The results were as follows; 1) Indexes of global systolic function (left ventricular peak systolic pressure, peak positive dP/dt) and global diastolic function (peak negative dP/dt, time constant, left ventricular end-diastolic pressure) showed deterioration in early occlusion period (10-30 minutes) but gradually improved even if coronary occlusion persisted. Reperfusion did not induce significant changes except that peak positive dP/dt transiently deteriorated 30 minutes after reperfusion and left ventricular end-diastolic pressure decreased 1.5-2 hours after reperfusion. 2) Indexed of regional function (i.e, end-diastolic thickness and % systolic thickening of anterior left ventricular wall) deteriorated by 10 minutes' occlusion which persisted during the entire occlusion period. Reperfusion induced no significant improvement in regional contractile function compared with occlusion 60 minutes' data, which suggested reperfusion for 4 hours after 1 hour's LAD occlusion may be insufficient for the ischemic region to recover its contractility. 3) Reperfusion arrhythmia (ventricular tachycardia) was noted in most (6/9) of the dogs, one of which deteriorated into ventricular fibrillation and the others spontaneously converted to normal sinus rhythm.
Animals ; Arrhythmias, Cardiac ; Blood Pressure ; Coronary Occlusion ; Coronary Vessels* ; Dogs ; Hemodynamics ; Reperfusion* ; Ventricular Fibrillation ; Ventricular Function, Left*