Comparative use of cold blood potassium cardioplegia in coronary bypass patients necessitating long (2.5-6 h) versus short (less than 1.5 h) aortic cross-clamp times.

In symptomatic patients with severe diffuse multivessel coronary disease undergoing bypass surgery, complete revascularization with multiple bypass grafts using saphenous vein and internal mammary conduits, and multiple endarterectomies may be necessary. Such complex surgeries may require long aortic cross-clamp times in excess of 2.5 h. To evaluate the myocardial preservation provided by cold potassium blood cardioplegia, two groups of consecutive patients using nearly similar surgical techniques were compared. Group A consisted of 100 patients who received an average of 3.8 grafts per patient and had a mean aortic cross-clamp time of 66 (range 15-90) min. Group B was comprised of 100 patients who received an average of 9.3 grafts per patient and had a mean cross-clamp time of 187 (range 150-351) min. Operative mortality and perioperative myocardial infarction were low (0-2%) and were not significantly different between the groups. In addition, the postoperative creatine kinase-MB isoenzyme levels, use of pharmacologic and/or mechanical (i.e., intra-aortic balloon) support, and follow-up exercise treadmill tests were not significantly different in the two groups. These findings suggest that cold potassium blood cardioplegia is equally protective of the myocardium during surgical revascularization in patients with short aortic cross-clamp times (less than 1.5 h) as in those with severe diffuse multivessel coronary artery disease requiring long cross-clamp times exceeding 2.5 h and up to 6 h.