One hundred patients underwent coronary artery bypass grafting and thirty patients underwent replacement of mitral valve were included in this study, and patients were randomized to two groups. Adenosine group (group I):6 mg adenosine was diluted with physiological saline and injected from the root of the ascending aorta after blocking it. The aorta was then perfused with high-potassium cold-blood cardioplegia. Control group (group II):the aorta was just perfused with high-potassium cold-blood cardioplegia. Adenosine was only added in first perfusion in adenosine group. Both groups were reperfused half-amount of cold-blood cardioplegia containing potassium every 30 minutes. Relevant clinical indexes and myocardial enzymological determination were compared between two groups. Results For patients who underwent CABG, the cardiac arrest induced time,ICU dwell and assisted ventilation time after surgery and dopamine usage were all less in adenosine group than those of control group (P < 0.05). There were no significant differences in the total number of cardioplegia of perfusion fluid, the total amount of perfusion, clamping aorta and assisting circulation times and automatic rebeating between two groups (P>0.05). For patients who underwent MVR, the cardiac arrest induced time and dopamine usage were all less in adenosine group than those of control group (P<0.05). There were no significant differences in times and total number of cardioplegia of perfusion fluid, clamping aorta and assisting circulation times, ICU dwell and assisted ventilation time after surgery automatic rebeating between two groups (P>0.05). For both operations, 4 hours after clamping aorta, creatine kinase isoenzyme (CK-MB) was less in adenosine group than that of control group (P<0.01 or P<0.05), and 4 hours and 24 hours after bypass, cardiac troponin I (cTnI) was significantly higher in control group than that of adenosine group (P < 0.05). Conclusion After aorta is clamped, immediate injection of adenosine diluent and cold-blood cardioplegia containing potassium from the root of the ascending aorta can lead to quick heart arrest, reduce the release of myocardial enzymes and dosage of vasoactive agents, and shorten ICU dwell and assisted ventilation time.