ObjectiveTo study the protective effect of coenzyme complex on myocardium under cardiopulmonary bypass in open heart surgery.MethodsForty patients with congenital heart disease scheduled for open heart surgery under cardiopulmonary bypass (CPB) were evenly randomized into 2 groups. Coenzyme complex (1 bottle/10 kg) was given to the experimental group but not to the control group. The venous blood samples were collected at following time points. T1: during anesthetic induction period (baseline), T2: half an hour after aorta clamp, T3: one hour after aorta clamp opened, T4: 24 h after operation, T5: 48 h after operation, T6:72 h after operation, and T7:one week after operation. The levels of cardiac troponin I (CTnI), interleukin-8(IL-8) and maleic dialdehyde (MDA) were measured. Right atrial appendage specimen was taken and processed for transmission electron microscope observation of myocardial ultrastructure.ResultsThe levels of CTnI, IL-8, and MDA were significantly increased in the two groups during CPB, but the values in the experimental group were lower than those in the control group at following time points: (CTnI) one hour after aorta clamp opened and 24 h, 48 h, 72 h after operation (P<0.05 or 0.01); (IL-8) half an hour after aorta clamp, one hour after aorta clamp opened and 24 h, 48 h, 72 h after operation (P<0.01); and (MDA) one hour after aorta clamp opened and 24 h, 48 h after operation (P<0.05 or 0.01). The injury of myocardial cellular ultrastructure was seen in each group after aorta clamp was opened by different extents. However, more severe disorganization of myocardial cellular ultrastructure could be seen in the control group. ConclusionCoenzyme complex may reduce the production of oxygen free radical and inflammatory factor, subsequently reduce the release of CTnI, protecting myocardium under cardiopulmonary bypass in the open heart surgery.