Protection of the myocardium during ischemic arrest: possible toxicity of carnitine in cardioplegic solutions.

Carnitine has been suggested as an agent for the protection of the myocardium during regional ischemia and it might therefore be able to reduce tissue injury during surgically induced global ischemia. Using an isolated working rat heart model we have assessed the way in which various concentrations of carnitine infuence the efficacy of the St. Thomas' Hospital Cardioplegic Solution. Carnitine was found to exert a dose-dependent detrimental effect upon the ischemic myocardium, with high concentrations abolishing all the protective properties of the cardioplegic solution. Furthermore, this compound appeared to promote the occurrence of reperfusion dysrhythmias.