Low myocardial temperatures are associated with postoperative conduction defects after coronary artery bypass surgery.

The incidence and significance of postoperative conduction defects after coronary artery bypass surgery were investigated prospectively in 181 patients. Several pre- and perioperative variables, especially the temperature in three regions of the myocardium, were recorded as explanatory variables. The incidence of conduction defect(s) in the immediate postoperative electrocardiogram (ECG) was 55.8%, and 35.9% of the patients had a conduction defect when leaving hospital. Two patients had a permanent third degree atrioventricular (AV) block. Five pacemakers were implanted. Left main coronary artery stenosis was more common (P < 0.01), and the perioperative myocardial temperatures (P < 0.05-0.01) were lower in patients with conduction defects. These patients had also low postoperative cardiac output more often (P < 0.001), their creatine kinase myocardial (MB) fraction values were higher (P < 0.01), and they stayed in hospital longer (P < 0.05). Right bundle branch block had no significant association with the studied variables.

Procaine and timing of aortic declamping affect ventricular reperfusion fibrillation.

Both ventricular fibrillation and electric defibrillation are detrimental to the myocardium. Therefore, we studied the effect of procaine hydrochloride during crystalloid cardioplegia and the effect of performing all central anastomoses before aortic declamping in an attempt to prevent ventricular reperfusion fibrillation during coronary bypass operation. Seventy-four patients were randomised, first to receive procaine hydrochloride or saline during cardioplegia, and secondly, to have central anastomoses performed before and after aortic declamping. In patients receiving procaine in cardioplegic solution (n = 37), the mean ventricular fibrillation time was shorter (27 +/- 79 sec. vs 205 +/- 161 sec., P < 0.0001), the proportion of patients spontaneously achieving stable rhythm was higher (67.6% vs 13.5%, P < 0.0001) and the mean number of defibrillations was lower (0.3 +/- 0.7 vs 2.4 +/- 1.7, P < 0.0001) than in patients receiving placebo (n = 37). Although the aortic occlusion time was longer (112 +/- 28 min vs 91 +/- 26 min, P = 0.0015) in patients with central anastomoses made during cardiac arrest (n = 35) and the mean fibrillation time was shorter (53 +/- 87 sec. vs 173 +/- 179 sec., P = 0.0006) than compared with patients with central anastomoses made after declamping the aorta (n = 39), the mean number of defibrillations (1.2 +/- 1.7 vs 1.4 +/- 1.7, P = 0.59) and the cardiopulmonary bypass time (138 +/- 29 min vs. 132 +/- 34 min, P = 0.47) were not statistically different between these groups. There were no differences in arrhythmias, conduction defects or postoperative recovery between the study groups. We conclude that both procaine hydrochloride during cardioplegia and the performance of central anastomoses of vein grafts during aortic occlusion effectively reduce reperfusion ventricular fibrillation.