[Aortocoronary bypass. Intermittent clamping of the aorta versus cardioplegia]

Cardioplegia is the standard method of myocardial protection during aorto-coronary bypass surgery. However, there are other alternatives which the authors intend to test.

Forty consecutive, non-selected cases of coronary artery bypass surgery done with intermittent aortic crossclamping (Group A) are compared with the 40 preceding consecutive cases where cardioplegia was used (Group B).

The mean age of the patients of group A was 57.5 years (range 42-69 years) and that of group B was 57.1 years (range 39-76 years). Patients of group A had an incidence of previous myocardial infarct of 42.5% against 65.0% in group B. Chronic angina led to surgery in 33 cases of group A and in 32 of group B. The remainder (18.8%) had unstable angina.

The mean number of grafts per patient was 2.9 in group A and 3.2 in group B. Internal mammary arteries were used in most patients of both groups, with 61 anastomoses in group A (1.5/patient) and 57 in group B (1.4/patient). The mean ischaemic time per graft was 7.4 min (range 5.5-11 min) in group A and 15.6 min (8.5-22 min) for group B.

Serial analysis of myocardium-specific serum enzymes and the CPK-MB/total CPK ratio has not evidenced perioperative infarction in any patient of either group. Although enzyme levels were slightly higher in group A, the difference has not reached statistical significance. However, the electrocardiograms have shown one perioperative infarct in each group. Vasodilators were generally used in the 2 groups, for a mean of 16.8 hours, while inotropic drugs were required in only 4 cases of group A and 3 of group B. There has been no hospital mortality in either group.

These results, in a series of non selected patients, demonstrate that intermittent crossclamping may be an acceptable alternative method of myocardial protection during aorto-coronary bypass surgery thus made simple, quick and secure.