Original Article

Intermittent Ischemia: An Alternative to Cardioplegic Arrest during Myocardial Revascularization Surgery

Lancaster, PA

^* Direct communications to: George D. Galbraith, B.S., C.C.P., Division of Cardiothoracic Surgery, Lancaster General Hospital, 555 North Duke Street, P.O. Box 3555, Lancaster, PA 17603

Abstract

Cardioplegic myocardial protection has become the standard for myocardial revascularization surgery (MRS). In contrast, our group performed 500 consecutive MRS' with intermittent aortic cross-clamping for distal anastomoses, left ventricular venting, and systemic hypothermia. Average patient age was 62 years (range: 30-89 years). 194 patients (38.8%) had urgent or emergent MRS. 251 patients (50.2%) had unstable angina and 123 others (24.6%) had preinfarction angina (rest pain in the hospital); 27 (5.4%) had evolving myocardial infarctions (MI). 174 patients (34.8%) had ejection fractions (EF) <0.50 including 75 patients (15.0%) with EFs <0.40; 16 patients (3.2%) had left ventricular aneurysms. Average number of grafts was 3.3 per patient and average ischemic time was 7.6 minutes per graft.

There were five hospital deaths (1.0%), none due to poor myocardial protection and low cardiac output. Only three survivors (0.6%) required an intra-aortic balloon pump (IABP) to wean from cardiopulmonary bypass (CPB): two had acute MIs preoperatively; the other had EF <0.30 and intractable atrial arrhythmias. Only two other patients (0.4%) received any inotropic infusions postoperatively. 18 patients (3.6%) had perioperative MIs.

These results, particularly the virtual absence of postoperative inotropic support, in unselected patients of whom 80% had acute coronary syndromes, indicate that intermittent ischemia (II) can provide excellent myocardial protection for MRS. Brief periods of II alleviate concerns about cardioplegic protection via occluded coronary arteries or internal mammary artery grafts. II provides a simple and safe alternative to cardioplegic arrest for myocardial protection during MRS.