ischemic preconditioning
A protective mechanism whereby brief episodes of ischemia make the myocardium more resistant to subsequent prolonged ischemic injury.
Full Definition
Ischemic preconditioning is an endogenous cardioprotective phenomenon where short periods of ischemia followed by reperfusion render the heart more tolerant to subsequent sustained ischemic insults. This adaptive response involves multiple molecular pathways including adenosine receptors, protein kinase C activation, and mitochondrial ATP-sensitive potassium channels. The protection manifests as reduced infarct size, decreased arrhythmias, and improved functional recovery when prolonged ischemia occurs. Clinical evidence of preconditioning includes the observation that patients with preinfarction angina often have smaller myocardial infarctions and better outcomes. This natural protective mechanism has inspired research into pharmacological preconditioning agents and remote ischemic preconditioning protocols.
Usage
Usage note: Distinguish from postconditioning, which refers to protection applied after the onset of ischemia.
In Context
- "The patient's history of unstable angina prior to STEMI may have provided ischemic preconditioning, explaining the smaller than expected infarct size." — Cardiology consultation note
- "Research protocols investigated whether remote ischemic preconditioning could reduce periprocedural myocardial injury." — Clinical trial methodology