[Three cardiac mysteries--stunning, hibernation and ischemic preconditioning]

Cardiovascular research has led to the identification of three new and important phenomena: myocardial stunning, myocardial hibernation, and ischaemic preconditioning. Myocardial stunning is characterised by transient contractile dysfunction that persists after reperfusion despite the absence of irreversible damage and despite restoration of normal or near normal coronary blood flow. Myocardial hibernation is a condition of sustained reduction of contractile function in hypoperfused but viable myocardium, which recovers completely upon reperfusion. Ischaemic preconditioning refers to a phenomenon by which one or more brief periods of myocardial ischaemia increases the ischaemic tolerance against infarction by endogenous adaptive mechanisms.

Current relevant literature obtained through PubMed search is reviewed with emphasis on occurrence of the phenomena, the therapeutic potential, and the underlying mechanisms.

Several observations indicate that myocardial stunning, myocardial hibernation, and ischaemic preconditioning may occur in patients with coronary heart disease. Actually, an increasing amount of evidence indicates that these phenomena are of major importance with regard to myocardial ischaemic tolerance. The mechanisms underlying these phenomena are, however, not yet clarified.

A better understanding of the mechanisms underlying myocardial stunning, myocardial hibernation, and ischaemic preconditioning may provide a rational basis for development of therapeutic interventions that increase myocardial ischaemic tolerance.