A clinical trial of blood and crystalloid cardioplegia

Abstract

Although experimental studies suggest that blood cardioplegia provides better protection than crystalloid cardioplegia, clinical studies have been inconclusive. Ninety patients undergoing coronary bypass grafting were randomized to receive either blood (n = 43) or crystalloid cardioplegia (n = 47). The incidence of perioperative myocardial infarction was lower with blood cardioplegia (blood, n = 0; crystalloid, n = 5; p = 0.06), and the maximum MB isoenzyme of creatine kinase was significantly less with blood cardioplegia (blood, 26.3 +/- 12.6 U/L; crystalloid, 35.6 +/- 17.0 U/L, mean +/- standard deviation; p less than 0.02.) Sixty patients (blood cardioplegia, n = 28; crystalloid cardioplegia, n = 32) had more sensitive measurements to assess the metabolic response to aortic occlusion and to compare the metabolic and functional recovery from the operation. Coronary sinus blood flow (by the continuous thermodilution technique) was significantly lower after cross-clamp removal with blood cardioplegia (blood, 160 +/- 100 ml/min; crystalloid, 220 +/- 120 ml/min; p less than 0.05), indicating less reactive hyperemia. The cardiac production of lactate was significantly less with blood cardioplegia during aortic occlusion (blood, -0.5 +/- 0.9 mmol/L; crystalloid, -0.9 +/- 0.9 mmol/L; p less than 0.05) and immediately after aortic declamping (blood, -0.2 +/- 0.4 mmol/L; crystalloid, -0.7 +/- 0.7 mmol/L; p less than 0.01). Thermodilution cardiac output measurements permitted calculation of the left ventricular stroke work index, and nuclear ventriculograms permitted calculation of the left ventricular end-diastolic volume index and end-systolic volume index. Myocardial performance, systolic elastance, and diastolic compliance were determined from volume loading studies (250 to 500 ml colloid) performed 2 to 4 hours postoperatively. Myocardial performance (the left ventricular stroke work index-left ventricular end-diastolic volume index relation) and systolic elastance (the systolic blood pressure-left ventricular end-systolic volume index relation) were significantly better with blood cardioplegia (p less than 0.01 by multivariate analysis); diastolic compliance (the left atrial pressure-left ventricular end-diastolic volume index relation) was similar. Blood cardioplegia reduced ischemic injury, decreased anaerobic metabolism during arrest, and permitted better functional recovery. Blood cardioplegia provides superior protection for elective coronary bypass grafting and may improve the clinical results in patients with unstable angina and in other high-risk patients.