Myocardial protection in operations requiring more than 2 h of aortic cross-clamping

Objective: Long periods of aortic cross-clamping time during cardiac surger y are associated with high rates of morbidity and mortality because of dama ge to the myocardium. Recently, we have used a method of myocardial protect ion based on the principles of hyperkalemic cardioplegic arrest. We use ant egrade administration of warm, undiluted blood followed by continuous retro grade infusion of tepid, undiluted blood supplemented with potassium and ma gnesium. In this study, we have retrospectively reviewed our experience wit h this method of cardioprotection in operations requiring more than 2 h of cross-clamp time. Methods: We retrospectively reviewed the medical records of 1280 patients who underwent myocardial revascularization, valve repair o r replacement, or a combination of both operations between January 1, 1994 and December 31, 1997. Patients were divided into two groups: the short cro ss-clamp group (SXC) (n = 1144) had cross-clamp times <120 min (mean, 78 +/ - 20 min; range, 35-119 min) and the long cross-clamp group (LXC) (n = 136) had cross-clamp times > 120 min (mean, 154 +/- 31 min; range, 120-277 min) . We compared preoperative, operative, and postoperative variables between the two groups. Results: Significantly more patients in the long cross-clam p group (43.4%) underwent the combined operation than in the short cross-cl amp group (2.3%), and the rate of reoperation was significantly higher in t he long cross-clamp group (12%) than in the short cross-clamp group (5%). D espite these differences in operative complexity, we found no difference in hospital mortality rates between the two groups. The only significant post operative differences were that the long cross-clamp group had a greater ne ed for inotropic agents (43 vs. 29%), higher serum levels of creatine kinas e (880 +/- 583 vs. 613 +/- 418) and CK-MB (10.9 +/- 6.4 vs. 5.9 +/- 5.2), a nd a longer hospital stay (9.6 vs. 6.1 days). Conclusion: Long, complex ope rations requiring more than 2 h of cross-clamping can be performed safely w ith our method of cardioprotection based on continuous retrograde infusion of tepid, hyperkalemic, undiluted blood. (C) 1999 Elsevier Science B.V. All rights reserved.