Subendocardial ischaemia & infarction

· subendocardial infarcts occur in the subendocardial muscle even when the epicardial portions of the muscle remain uninfarcted

· most infarcts are regional, intramural infarcts (subepicardial or transmural)

· Subendocardial infarcts are relatively rare, and zonal

· Occur especially when the diastolic arterial pressure is very low or the diastolic intraventricular pressure is very high

- as most of the blood flow into the subendocardium ( via subendocardial plexus) occurs during diastole, therefore if diastolic BP is very low (eg AR, patent ductus arteriosus, arteriosclerosis), see increased incidence of subendocardial MI

· Subendocardial necrosis 2° continuous coronary perfusion technique to preserve myocardium during Cardiac surgery was seen especially in hypertrophied hearts due to combination of poor coronary blood flow associated with VF