OBJECTIVE:

Endothelial dysfunction with decreased nitric oxide (NO) levels has been implicated on reperfusion injury. Although L-arginine has been shown to diminish reperfusion injury in in vitro studies, clinical studies were very limited.

METHODS:

Forty patients with acute myocardial ischemia undergoing CABG were randomized to a study and a control group. L-Arginine was added to cardioplegia solutions in study group. A non-cardioplegic warm blood solution with 8 mmol/l L-arginine infused for controlled reperfusion. Control patients received same protocol without L-arginine. Myocardial O2, lactate, nitrite and malondialdehyde extractions were measured in addition to calculation of CK-MB/CPK ratio and hemodynamic data.

RESULTS:

While there was no mortality in study group, one patient in control group died. Overall and nitrite (P=0.01) and lactate extractions (P=0.04) was higher in study and control groups, respectively. Myocardial O2 uptake was higher and malondialdehyde extraction was lower in study group. CK-MB/CPK ratio at postoperative sixth hour was also significantly lower in study group. Ninety percent of the study group had spontaneous return of the sinus rhythm, while 80% of the control patients required defibrillation (P<0.0001). In addition to significantly better hemodynamics, perioperative myocardial infarction incidence was lower (P=0.037), the length of intensive care unit (P=0.009) and hospital (0.014) stays were shorter in study group.

CONCLUSIONS:

Use of L-arginine for protection of acutely ischemic myocardium appears to be a safe technique. L-Arginine supplementation increased NO levels and attenuated free O2 radical mediated myocardial injury. Controlled reperfusion with l-arginine enriched non-cardioplegic blood could be a new therapeutic entity to diminish ischemia/reperfusion injury.

Copyright 2003 Elsevier Ireland Ltd.