Echocardiographic criteria to distinguish reversible from irreversible myocardial ischaemia.

This treatise reviews two-dimensional echocardiographic criteria which have been developed to describe and distinguish reversible vs irreversible myocardial ischaemia. It also discusses the new pathophysiologic concepts such as 'hibernating' and 'decapitated' myocardium, and also 'reperfusion injury' and 'stunned' myocardium, complications which may supervene following reperfusion of jeopardized ischaemic myocardium. Computerized regional and global wall-motion analysis is now usually measured from enhanced endocardial edges. Provocative interventions can contribute information regarding viability of jeopardized ischaemic regions by testing contractile response of the myocardium to afterload reducing agents such as nitroglycerine or nitroprusside. They can also validate viability by demonstrating that post-extrasystolic beats can still cause potentiation. Ultrasonic contrast washout half-life of the myocardium which is compromised by stenotic coronary arteries provides a promising method for supplying information about the coronary perfusion defects and flow reserve. The decrease in global or regional ejection fraction following exercise echocardiography may show if jeopardized ischaemic myocardium is irreversibly damaged. A new hypercontractility phenomenon is described following brief coronary occlusions such as during percutaneous transluminal angioplasty, or after sudden release of angiospasm, and this should be considered a sign of viability. Increase in end-diastolic wall thickness and echo amplitudes immediately after reperfusion of ischaemic segments is often associated with reversibly damaged myocardium.