Importance of internal mammary artery perfusion in cardiac ischemia and reperfusion

Our purpose was to investigate the changes in antioxidant defense systems due to internal mammary artery (IMA) perfusion during coronary artery bypass graft (CABG) operations in which proximal anastomoses were completed under partial bypass with the aid of a side-biting clamp.

Twenty-five patients to be studied were divided into two groups according to the criterion of whether during proximal anastomoses left internal mammary artery (LIMA) perfusion was applied (n = 15, LIMA group) or not (n = 10, non-LIMA group). The erythrocyte catalase (CAT), superoxide dismutase (SOD), serum lipid peroxidation (LPO) products and whole blood reduced glutathione (GSH) levels were measured in the blood samples taken from the coronary sinus before cardiopulmonary bypass (CPB) (t1), before declamping (t2), at the 5th min after declamping (t3), at the 5th (t4) and 15th (t5) min after removing the side-biting clamp.

While erythrocyte CAT enzyme activity decreases in both groups after the basal measurements, no significant difference was detected between the groups. Although the GSH levels did not differ at t1, t2 and t3, they were found to be higher in the LIMA group at t4 (p = 0.006) and t5 (p = 0.021). The erythrocyte SOD enzyme activity decreased after the basal measurements in both groups, but this reduction was less in the LIMA group at t4 (p = 0.034) and t5 (p = 0.018) compared to the other group. LPO products rose in both groups when reperfusion started after declamping. The levels of LPO products were significantly higher at t4 and t5 in the non-LIMA group than the other group (p = 0.011 and p = 0.008).

If proximal anastomoses of coronary grafts are completed under partial bypass, permitting LIMA perfusion during this procedure will be beneficial to antioxidant defense systems.