Antegrade/retrograde cardioplegia in arterial bypass grafting: Metabolic randomized clinical trial

The metabolic effects of combined antegrade/retrograde and antegrade cardioplegia on myocardial protection were evaluated and compared in 30 patients who underwent myocardial revascularization. All patients had three-vessel coronary artery disease, and the revascularization was done with exclusive use of arterial grafts (internal mammary artery, gastroepiploic artery). Myocardial protection consisted of oxygenated crystalloid cardioplegia, topical slushed ice, and moderate systemic hypothermia (34°C). The patients were randomly separated into two groups: group A (n = 15), who received antegrade cardioplegia, and group A/R (n = 15), who received combined antegrade/retrograde cardioplegia. There was no significant difference between the two groups concerning preoperative and intraoperative data. After the first dose of cardioplegia, right ventricular temperature was significantly lower in group A/R (15 ± 2° versus 19 ± 5°C; p < 0.05), and there was no significant difference between the two groups in left ventricular temperature. Coronary sinus blood samples were obtained before bypass and 5, 10, and 15 minutes after reperfusion; there was no difference between the two groups concerning lactates, superoxide dismutase, and gluthatione peroxidase. After reperfusion, malondialdehyde levels increased significantly in group A and there was no change in group A/R, with a significant difference between the two groups (at 10 minutes after reperfusion, 0.80 ± 0.20 versus 0.53 ± 0.16 μmol/L; p < 0.05). Right and left ventricular myocardial biopsies were performed before bypass and 15 minutes after reperfusion; there was no significant difference between the two groups concerning adenosine triphosphate and creatine phosphate myocardial concentrations. After reperfusion, spontaneous recovery of heart activity without defibrillation occurred in 14 patients in group A/R and in 9 patients in group A (p < 0.05); there was no atrioventricular block in group A/R and 26% in group A (p < 0.05). Postoperative release of creatine kinase isoenzyme was higher in group A than in group A/R (6 postoperative hours, 21 ± 12 versus 15 ± 5 μg/L; 12 postoperative hours, 20 ± 14 versus 12 ± 5 μg/L; p < 0.05). We conclude that combined antegrade/retrograde cardioplegia provides better and more homogeneous myocardial protection than does antegrade cardioplegia in patients with three-vessel coronary artery disease who undergo myocardial revascularization with exclusive use of arterial grafts.