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. Cause Clinical situations associated with myocardial stunning include: acute myocardial infarction (AMI) with early reperfusion unstable angina after percutaneous transluminal coronary angioplasty (PTCA) after cardiac surgery 'neurogenic' stunned myocardium following an acute cerebrovascular event such as a subarachnoid hemorrhage in patients undergoing chronic hemodialysis, chronic myocardial stunning may lead to heart failure Myocardial stunning has been implicated in the development of Takotsubo (Stress) cardiomyopathy. Pathophysiology The underlying mechanisms of myocardial stunning have remained the subject of debate for several decades. Two leading hypotheses implicate reperfusion-induced oxygen free-radical damage and altered calcium flux resulting in intracellular hypercalcemia and desensitization of myofilaments. After total ischemia occurs, the myocardium switches immediately from aerobic glycolysis to anaerobic glycolysis resulting in the reduced ability to produce high energy phosphates such as ATP and Creatinine Phosphate. At this point, the lack of the energy and lactate accumulation results in cessation of contraction within 60 seconds of ischemia (i.e. Vessel Occlusion). Subsequent to this is a period of "myocardial stunning," in which reversible ischemic damage is taking place. At approximately 30 minutes after the onset of total ischemia the damage becomes irreversible, thereby ending the phase of myocardial stunning. The generation of oxygen-derived [free radicals] during the initial period of reperfusion after ischemia is believed to contribute to the pathogenesis of myocardial stunning. Some evidence suggests that brief, repetitive episodes of myocardial ischemia may result in chronic myocardial stunning and ventricular contractile impairment. Diagnosis Imaging techniques such as echocardiography, ventriculography, and nuclear imaging can be used to detect a contractile dysfunction following reperfusion after an episode of ischemia. The area of dysfunction