[Myocardial viability. The concept of myocardial viability].
Certain zones of ischemic, akinetic or severely hypokinetic myocardium are capable of recovering normal contractile function. This is termed myocardial viability and occurs in two different situations: myocardial stunning and myocardial hibernation. This term designates temporary but prolonged impairment of myocardial function resulting from a brief episode of ischemia before reperfusion. Hibernation designates prolonged but potentially reversible myocardial contractile dysfunction caused by chronic myocardial ischemia and persisting at least until blood flow is restored. Theoretically reversible, myocardial stunning or hibernation can have devastating effects if they persist too long. Revascularization with angioplasty or bypass surgery is indicated. The degree of myocardial viability in akinetic zones can be determined by assessing preserved inotropic capacity with stress echocardiography and/or evidencing metabolic activity with isotopic techniques (myocardial scintigraphy, positron emission tomography).