STUNNED AND HIBERNATING MYOCARDIUM - AN UPDATE FOR THE ANESTHETISTS

Stunned and hibernating myocardium are both responsible for hypocontra ctility secondary to an ischaemic event. No cellular necrosis occurs i n pure stunned or hibernating myocardium. In case of myocardial stun n ing, ischaemia is usually severe but of short duration, followed by pe rsisting hypocontractility after revascularization proportional to the severity of the ischaemia. Stunned myocardium can be observed after c ardiopulmonary bypass in cardiac surgery myocardial recovery ad integr um should be allowed by use of positive inotropic agents and possibly mechanical circulatory assistance for several days. Rahimtoola describ ed myocardial hibernation as a chronic hypoperfusion insufficient to p roduce a necrosis. This hypoperfusion leads to an adaptive steady stat e characterised by a reduced contractile function (perfusion, metaboli sm and contractile function matching). After reperfusion, hypocontract ility can remain during weeks or months before reversing itself. Howev er, no animal model of chronic hibernation is vet available. The new c oncept of ''chronic stunning'' map explain long term hibernating obser vations. Some patients with ischaemic cardiomyopathy can benefit from surgical revascularization or PTCA. Positron emission tomography, sing le photon emission tomography, dobutamine echocardiography allow diffe rentiation between hibernating myocardium and scar tissue after myocar dial infarction and help to select patients who would benefit most fro m revascularization.