L-arginine supplemented nondiluted blood cardioplegia: a clinical trial

L-arginine was shown to improve protection of the myocardium during coronary artery bypass graft (CABG) surgery. The objective of the present study was to determine the concentration of L-arginine to obtain the most effective protection of the myocardium during CABG surgery.

Seventy-five patients undergoing CABG surgery were randomized in 3 groups. The first group (N.=25) was administered a placebo injection in the blood cardioplegic solution, the second group (N.=25) received an injection of 4 mmol/L of L-arginine and a third group (N.=25) an injection of 6 mmol/L of L-arginine in the blood cardioplegic solution. Blood samples from the ascending aorta and the coronary sinus catheter were collected before, immediately after and at 20 minutes after aortic cross-clamping. Total plasmatic nitrite and nitrate ratio and lactate release from the myocardium in the collected blood samples were measured.

Seventy-five patients averaging 62+/-7 years of age and undergoing 3.1+/-1 coronary bypass grafts during 41+/-17 minutes of aortic cross clamping time were recruited. Values of total plasmatic nitrite and nitrate ratio remains non-significant before and after aortic clamping and also between groups (P=0.9812 and 0.3573 respectively). Myocardial lactate release was statistically different before and after cross clamping (P=0.0002) and also between the 3 groups (P=0.0311).

Nondiluted blood cardioplegic solution supplemented with 4 mmol/L of L-arginine was associated with a significant decrease of myocardial lactate release after aortic cross-clamping and reperfusion during CABG surgery.