Hibernating Myocardium "Hibernating myocardium" is a state of persistently impaired myocar- dial and left ventricular function at rest due to reduced coronary blood flow that can be paially or completely restored to normal if the myocardial oxygen supply demand relationship is ourably allered either by improving blood flow and/ or by reducing demand - Hibernation is a response to chronic reduction in resting coronary blood flow, leading to a new equilibrium where myocardial metabolism was altered with a subsequent reduction in energy production and myocardial contractility The initial triggering event i.e., reduction the blood flow was followed by a downregulation in cardiac function to a point at which the limited Oxygen supply enabled the maintenance of biochemical functions that sustained cell integrity - If the myocardial oxygen supply/demand was subsequently altered either temporarily or permanently then symptoms or signs of ischemia and/or necrosis might- occur - The hibernating response of the hea, namely a reduction of cardiac .function to cope with a reduced myocardial blood flow was considered an act of self preservation (Little blood, Little work) This chronic adaption occurs in the absence of angina (the lack of resting pain is a unique sign of chronic hibernation) or electrocardiographic evidence of ischemia and was thought to be a protective mechanism reducing the oxygen demand of hypoperfused myocardium and preserving long term bility On imaging, the hea is presented as area of left ventricular wall that could have been hypokinetic, akinetic dyskinetic Myocardial stunning This describes a clinical state where after a period of "transient ischemia" the hea goes into period of "Persistent dysfunction" even after the flow is reversed The impoant point to note in myocardial stunning is that the left ventricular dysfunction persisted after reperfusion despite the absence of irreversible damage and despite the restoration of normal or near normal coronary blood flow. It is believed or proposed that due to ischemia the hea is stunned .for a period of time. So even after the blood flow is restored the hea will not regain its function immediately. It will remain in its dysfunctional state for a ceain period of time and then resumes its normal activity. Its should be noted that myocardial stunning is a fully reversible abnormally, provided of course that sufficient time is allowed for myocardiunt to recover. Hibernating and stunned myocardium are clinically very impoant conditions of contractile asynergy, since they are potentially reversible Hibernating myocardium is similar to stunned myocardium in that both are characterized by ble myocardial cell with depressed function. When ischemia is relieved the hibernating myocardium exhibits nearly "immediate return" of function where as stunned myocardium exhibit "gradual recovery"