Catecholamine release and ventricular arrhythmias during coronary occlusion and reperfusion in the dog.

Abstract

In anesthetized dogs, 60-min occlusions of either the proximal (n = 14), distal (n = 8) left circumflex (LCX), or left anterior descending (LAD, n = 10) arteries were followed by reperfusion. Coronary sinus and aortic norepinephrine and epinephrine plasma concentrations were measured. The ventricular arrhythmias were ventricular premature depolarizations (VPDs), unsustained ventricular tachycardia (VT) (greater than or equal to 3 and less than 20 VPDs), sustained VT (greater than or equal to 20 VPDs), and ventricular fibrillation (VF). A gradual twofold increase (p less than 0.05) in myocardial norepinephrine overflow followed occlusion in all three groups. The increases in the amounts of norepinephrine released in the coronary sinus blood during reperfusion were significant and proportional to the size of the occluded area: proximal LCX, from 0.236 +/- 0.038 to 1.528 +/- 0.490 ng/mL of plasma (p less than 0.001); LAD, from 0.180 +/- 0.027 to 0.795 +/- 0.286 ng/mL (p less than 0.05); distal LCX, from 0.215 +/- 0.039 to 0.404 +/- 0.110 ng/mL (p less than 0.05). Aortic epinephrine concentrations were significantly increased only by LAD occlusion; at 15 min, the value had increased to 0.187 +/- 0.053 ng/mL from an initial value of 0.069 +/- 0.029 ng/mL (p less than 0.001). Two phases of ventricular arrhythmias followed both occlusion and reperfusion. Phase 1 postocclusion was characterized by VPDs and phase 2 by VPDs and unsustained VT. Sustained VT was seen only in phase 1 postreperfusion, whereas unsustained VT was seen in phase 2. VF was seen in 50, 35, and 25% of the dogs with proximal LCX, LAD, and distal LCX occlusion and reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)