“Time is Muscle”
Coronary Circulation is a Determinant of Myocardial Ischemic Injury.
The perfusion territory of the coronary artery distal to the site of the occlusion is the area at risk of infarction because the coronary arteries are functional end arteries.
Within a given area at risk, both the duration and the severity of coronary blood flow reduction determines the nature and amount of injury.
Complete coronary occlusion of <20-minute duration results in reversible injury, that is, contractile dysfunction with a slow, but complete recovery during reperfusion, a phenomenon called myocardial stunning. Repeated coronary occlusion of short duration or prolonged moderate reduction in coronary blood flow results in hibernating myocardium, a phenomenon of reduced contractile function with retained viability and thus eventual recovery after reperfusion. Hibernating myocardium displays signs of both injury (loss of contractile proteins, small doughnut-like mitochondria, and fibrosis) and adaptation (Short-term energetic recovery, altered expression of mitochondrial proteins, and proteins related to Cardioprotection). When the reduction in coronary blood flow is severe and lasts longer than 20 to 40 minutes cause significant cardiac muscle damage resulting in contractile dysfunction and conduction dysfunction, presenting as various cardiovascular emergencies.
The emergency medicine department at AIG Hospital works for hand in glove with the Eminent cardiology team that is headed by Dr B. Somaraju, understanding the importance of time in cardiac emergencies. The standard door to needle time is 20 min, door to balloon time is 25min the AIG ACS protocol.