Protecting the heart from ischemia: an update on ischemic and pharmacologic conditioning

The attempt to find treatments that will reduce myocardial cell death during periods of ischemia and subsequent reperfusion has spanned nearly 40 years. Although many therapies have shown promise in animal models, relatively few have been successful in clinical trials. Some of the most effective clinical therapies involve techniques designed to elicit the heart's own innate capacity to protect itself. The ability of the heart to render itself more resistant to ischemia/reperfusion injury was not appreciated until the description of ischemic preconditioning in 1986. Following the discovery that brief, nonlethal episodes of ischemia conditioned the heart to better tolerate a subsequent prolonged episode of ischemia, alternative ways of evoking this endogenous cardioprotection were described. Ischemic postconditioning and remote conditioning are potentially useful tools for protecting ischemic myocardium, and have been shown to be beneficial in small clinical trials. Several pharmacologic agents have the ability to mimic the effects of ischemic conditioning and can also reduce the amount of cell death during ischemia/reperfusion. This article provides the clinician with an overview of the different techniques of ischemic conditioning and how they can protect the myocardium from ischemia/reperfusion injury. Additionally, several pharmacologic agents that can protect the heart in a similar manner are discussed.