Myocardial Protective Effects of L-Carnitine on Ischemia-Reperfusion Injury in Patients With Rheumatic Valvular Heart Disease Undergoing Cardiac Surgery.

OBJECTIVES

The authors used L-carnitine as an ingredient in cardioplegic solution during valve replacement surgery to investigate the protective effect of L-carnitine on myocardial ischemia-reperfusion injury (MIRI) and its possible mechanism.

DESIGN

Prospective, randomized study.

SETTING

A tertiary-care hospital.

PARTICIPANTS

The study comprised 90 patients undergoing valve replacement under cardiopulmonary bypass.

INTERVENTIONS: Patients were divided randomly into 3 groups. L-carnitine was added to the crystalloid cardioplegic solution for experimental group 1 (3 g/L) and experimental group 2 (6 g/L), whereas no L-carnitine was used in the control group. The remainder of the treatment was identical for all 3 groups.

MEASUREMENTS AND MAIN

RESULTS

Serum was collected from each patient 1 hour before the surgery and at 2, 6, 24, and 72 hours after unclamping the aorta, and tissue samples were obtained before cardiac arrest and after unclamping the aorta. The postoperative levels of serum aspartate aminotransferase, creatine kinase, creatine kinase-MB isozyme, and lactic acid dehydrogenase and the apoptotic index were all lower in the 2 experimental groups than those in the control group. In addition, each of the aforementioned serum enzyme levels and the apoptotic index in all 3 groups significantly increased after unclamping the aorta compared with baseline levels taken before surgery. Bcl-2 expression was higher and Bax was lower in the 2 experimental groups compared with those of the control group after unclamping the aorta. However, there was no significant difference in all the postoperative indices between the 2 experimental groups.

CONCLUSION

L-carnitine may reduce cardiopulmonary bypass-induced myocardial apoptosis through modulating the expressions of Bcl-2 and Bax, resulting in a protective effect from MIRI.