Myocardial stunning or transient post-ischemic myocardial dysfunction is a state of mechanical cardiac dysfunction that can occur in a portion of myocardium without necrosis after a brief interruption in perfusion, despite the timely restoration of normal coronary blood flow. In this situation, even after ischemia has been relieved (by for instance angioplasty or coronary artery bypass surgery) and myocardial blood flow (MBF) returns to normal, myocardial function is still depressed for a variable period of time, usually days to weeks. This reversible reduction of function of heart contraction after reperfusion is not accounted for by tissue damage or reduced blood flow, but rather, its thought to represent a perfusion-contraction "mismatch". Myocardial stunning was first described in laboratory canine experiments in the 1970s where LV wall abnormalities were observed following coronary artery occlusion and subsequent reperfusion.