Warm Cardioplegia Study:
INTRODUCTION: The present study is a prospective, randomized trial of warm induction, cold maintenance, warm reperfusion, substrate-enriched, blood (Buckberg) cardioplegia compared to standard cold blood cardioplegia.
METHODS: Sixty-seven patients scheduled for elective CABG surgery were studied after giving informed consent. Measurements included left ventricular systolic and diastolic function (measured by left ventricular Millar® and volume conductance catheters, echocardiography, and MUGA scanning), and myocardial ischemia (determined by lactate extraction, continuous Holter ECG, and transesophageal echocardiographic wall-motion monitoring). Warm cardioplegia consisted of 37° C substrate-enriched [glutamate (13 mM/L), aspartate (13 mM/L)], hyperkalemic (25 mEQ/L) anterograde and retrograde blood cardioplegic solution. Followed by non-substrate enriched cardioplegic solution substituted at 4 - 8° C (750 ml). Prior to unclamping the aorta, warm (37° C) substrate-enriched cardioplegic solution was again infused. Cold cardioplegic induction consisted of 4 - 8° C, hyperkalemic (20 mEq/L) blood anterograde and retrograde cardioplegic solution without substrate. No reperfusion cardioplegia was given in the cold group.
RESULTS: The end-systolic pressure-volume relationship (EES) was improved postbypass in the warm group (cold 1.5±0.74 vs. warm 2.1±1.2, p=0.042). The postoperative EF% was better preserved in the cold group (cold 65±11.53 vs. warm 58.62±11.75, p<0.04)
DISCUSSION: Our results demonstrate improved preservation of left ventricular systolic function in the immediate postbypass period in CABG patients in the warm group. The intraoperative benefits of the warm technique did not persist in the postoperative period.
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