Myocardial stunning is the reversible reduction of function of heart contraction after reperfusion not accounted for by tissue damage or reduced blood flow.
After total ischemia occurs, the myocardium switches immediately form 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.
Clinical situations of stunned myocardium are:
- acute myocardial infarction (AMI)
- after percutaneous transluminal coronary angioplasty (PTCA)
- after cardiac surgery
- 'neurogenic' stunned myocardium following an acute cerebrovascular event such as a subarachnoid hemorrhage
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—Robert Benchley (1889–1945)