[Myocardial protective effect of L-carnitine in cardioplegia solution on patients undergoing heart valve replacement...

To investigate the myocardial protective effect of L-carnitine as an ingredient of cardiac arresting solution in the process of heart valve replacement operation.

69 cases undergoing heart valve replacement with cardiopulmonary bypass (CPB), 47 males and 22 females, aged 48.17 +/- 14.22 (16 approximately 74 years), were divided into 3 groups: test group I (n = 22, 12 g/L L-carnitine was put in the St. Thomas II cold crystal cardiac arresting liquid), test group II (n = 24, 6 g/L L-carnitine was put in the St. Thomas II cold crystal cardiac arresting liquid), and control group (n = 23, no L-carnitine was put in the St. Thomas II cold crystal cardiac arresting liquid). Before operation, 20 minutes after the beginning of shunt, after the finish of shunt, and 8 hours, one day, 3 days, and 7 days after operation venous blood was drawn to test the serum cardial tropnin I (cTnI), aspartate transaminase, lactate dehydrogenase, creatine kinase (CK) and CK-MB isozyme. Heart color ultrasonography was conducted to test the cardiac index (CI) and left heart ejecting fraction (EF) one day before operation and 7 days after operation. Before shunt and by the end of intracardiac procedure a bit of myocardial tissue was taken to undergo electron microscopy. The amounts of vaso-active drugs, such as dopamine and dobutamine, used postoperatively, and the postoperative cardiac auto-rebeating rate were recorded.

The Amounts of vaso-active drugs used after operation was 329 +/- 54 mg in the test group I and 339 +/- 47 mg in the test group II, both significantly less than in the control group (669 +/- 56 mg, both P < 0.01) without a significant difference between the 2 test groups. Since the end of CPB to 3 days after operation, the serum levels of cTnI, aspartate transaminase, lactate dehydrogenase, CK and CK-MB isozyme were significantly lower in the 2 test groups than in the control group (P < 0.05 or P < 0.01). The serum level of cTnI in test group I was significantly lower than in the test group II (5.71 +/- 1.14 ng/ml vs 7.87 +/- 1.89 ng/ml 1 day postoperatively (P < 0.05), and 5.01 +/- 0.89 ng/ml vs 7.53 +/- 1.43 ng/ml 3 days postoperatively (P < 0.05). The postoperative cardiac auto-rebeating rate was 87.9% in the test group I and 74.3% in the test group II, both significantly higher than that in the control group (45.7%, P < 0.05 and P < 0.01). Heart color ultrasonogram showed that 7 days postoperatively the CI index was 2.86 +/- 0.55 and 2.74 +/- 0.56 in the 2 test groups, significantly higher than that in the control group (2.11 +/- 0.35, both P < 0.05), and the left heart EF were 64.3 +/- 8.6 and 59.1 +/- 6.7 in the 2 test groups, both significantly higher than that in the control group (51.7 +/- 4.9, both P < 0.05). Electron microscopy showed only slight swelling of mitochondria in the cardial cell and the myocardial fiber was intact by the end of operation in the 2 test groups without significant difference between these 2 groups, however, in the control group swelling of mitochondria with vesicle formation, fissure of part of mitochondrial ridges, and disappearance of glycogen particles were found.

Antegrade coronary perfusion of L-carnitine has a good protective effect on myocardium and is worth spreading for heart valve replacement patients with cardiopulmonary bypass.