Reperfusion is when the blocked artery is “unblocked” so that myocardial perfusion is restored (may not be to 100%). Severe ischaemia does not cause cell death instantly. It takes about 40 minutes, before reversible damage becomes irreversible. Reperfusion (i.e.: using thrombolytic therapy, or angioplasty, CABG) within 15-20 minutes after onset of ischaemia may prevent necrosis altogether. If done later, it may not prevent necrosis, but will salvage the ischaemic myocytes will necrose if nothing is done about them. Gross appearance is haemorrhagic because vasculature injured during ischaemic period starts leaking after reperfusion. Microscopically, you see exaggerated contraction of myofibrils in response to reperfusion .
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Pathology Notes
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