PRECONDITIONING AND ITS POTENTIAL ROLE IN MYOCARDIAL PROTECTION DURING CARDIAC-SURGERY

Myocardial preconditioning is the phenomenon whereby a brief stress to the heart (e.g., ischemia, hypoxia, etc.) prior to a prolonged period of ischemia renders the heart more resistant to ischemic injury. The cardioprotective effects of preconditioning include reduced infarct si ze and reduced ventricular arrhythmias. Preconditioning also is associ ated with beneficial metabolic effects during the prolonged ischemia, effects that also are observed during intermittent cardioplegia. Howev er, there are conflicting reports about the effects of preconditioning on postischemic ventricular function. Although adenosine is thought t o be the endogenous mediator of ischemic preconditioning, there are so me important differences between adenosine and ischemic preconditionin g mediated cardioprotection.