Coronary artery bypass surgery with intermittent aortic cross-clamping

Abstract

Despite the generally accepted use of cardioplegia for myocardial protection during cardiac revascularization and other operations, non-cardioplegic methods have been used by many surgeons throughout the world. We have prospectively studied 229 patients consecutively subjected to isolated coronary artery bypass surgery from March 1990 to February 1991 by a single surgeon who used intermittent aortic cross-clamping for construction of the distal anastomoses. The mean age of the patients was 58.9 + 8.9 years. One hundred and nine patients (47.6%) with unstable angina were subjected to urgent or emergent surgery and 129 (56.3%) had a previous myocardial infarction. The mean number of grafts per patient was 3.0. The ischaemic time per graft was 6.5 + 1.4 min. At least one internal mammary artery was used in 98% of the cases (1.4 internal mammary artery grafts/patient). Hospital mortality was 0.9% (two patients, in neither case related to the procedure). Only nine patients (3.9%) required inotropes and none needed intra-aorti@counterpulsation. The analysis of serum enzymes specific of myocardial lesion showed a CPK-MB/CPK ratio of 10.5 f 10.2 after surgery, 6.4 f 6.6% at 24 h after surgery, and 6.9 f 2.6% by the 5th day. Only four patients (1.7%) had ECG criteria of myocardial infarction. These results were compared retrospectively with those of the 40 immediately preceding patients (December 1989 to February 1990), in whom crystalloid cardioplegia had been used. There were no differences between the two groups with regard to age, prevalence of unstable angina and of previous myocardial infarction, and technique used. The mean aortic cross-clamp time was 50.0 + 11.5 min. There was no mortality in this group and four patients (10% ; p = NS) required inotropic support. One patient (2.5%) sustained a myocardial infarction. There were no differences in enzyme levels to those in the former group. These results, in a non-selected group of patients, appear to demonstrate that intermittent aortic cross-clamping for short periods (< 10 min) affords good myocardial protection and is a simple and safe method to use during revascularization procedures