Effects of different cardioplegic solutions on nitric oxide release from coronary vasculature in diabetic patients undergoing coronary artery bypass surgery.

Objective: The aim of this study was to compare the effects of two different cardioplegic solutions on nitric oxide (NO) release from coronary vasculature in patients with type II diabetes mellitus undergoing coronary artery bypass grafting (CABG) surgery.
Methods: Forty patients undergoing elective CABG surgery were randomized to be given crystalloid (Group 1) or blood (Group 2) cardioplegia. Aortic and coronary sinus blood samples were taken at three different time periods and the release of NO from the coronary vasculature was determined by measuring its stable end-products, nitrite and nitrate. The difference between the aortic and coronary sinus concentrations of nitrite and nitrate represents the amount of NO released by coronary vascular bed.
Results: Before application of aortic cross-clamp, at T1 period, the levels of nitrite/nitrate from the coronary vasculature were similar in both groups (6.53+/-1.21 microM vs 6.07+/-1.24 microM , p>0.05). However after the removal of cross-clamp, a significant decrease in NO was observed in Group 1 as compared with Group 2 (4.21+/-0.73 microM vs 4.92+/-1.02 microM, p<0.01) . This decrease persisted at T3 period, after 30 minutes of reperfusion in group 1 being significantly different from group 2 (3.86+/-0.49 vs 4.37+/-0.72 microM, p<0.05).
Conclusion: This study has shown that in patients with type II diabetes mellitus crystalloid cardioplegia causes a decrease in the release of NO from coronary vascular bed during aortic cross-clamp and reperfusion period whereas more physiologic blood cardioplegia did not. Our findings indicate that blood cardioplegia protects endothelial function better than crystalloid cardioplegia in diabetic patients.