The Efficacy and Safety of Extending the Ischemic Time with a Modified Cardioplegic Technique for Coronary Artery Surgery

Abstract

The need to intermittently discontinue the administration of cardioplegia in order to complete the surgical procedure is a major drawback of antegrade warm blood cardioplegia. An ischemic time of 15 minutes is generally considered safe based on empirical observation. The aim of this study was the evaluation of the efficacy and safety of an intermittent warm blood cardioplegia with intervals between administrations prolonged to 25 minutes. Ninety-seven patients undergoing primary elective coronary artery revascularization were prospectively randomized into two groups. The first, Intermittent Antegrade Warm Blood Cardioplegia (IAWBC) group, comprising 49 patients, received standard intermittent antegrade warm blood cardioplegia repeated every 15 minutes. The second, Modified Intermittent Antegrade Warm Blood Cardioplegia (M-IAWBC) group, comprising 48 patients, received intermittent antegrade warm blood cardioplegia supplemented with magnesium sulfate (MgSO(4)), delivered in volumes proportional to the ventricular mass and repeated every 25 minutes. The clinical outcomes were evaluated. The levels of creatine kinase-MB (CK-MB) isoenzyme, in addition to the echocardiographic assessment of septal dyskinesia and tricuspid annulus plane systolic excursion (TAPSE), have been used as markers of myocardial damage. There were no statistically significant differences in clinical outcomes, need for inotropes and vasodilators, length of stay in the intensive care unit, and postoperative levels of CK-MB between the two groups. Likewise, postoperative echocardiographic assessment showed no relevant differences. Administration of warm antegrade cardioplegic solution supplemented with MgSO(4), delivered in volumes proportional to ventricular mass every 25 minutes, provides adequate myocardial protection for coronary artery surgery.