Echocardiography in Myocardial Infarction

Abstract

Among the earliest detectable changes in myocardial ischemia or an acute MI are regional LV and potentially also right ventricular wall motion abnormalities. The LV can be divided into 17 anatomic segments, which can be viewed as a composite from the standard echocardiographic views, and have standardized nomenclature as recommended by the American Heart Association (AHA) (it see Chapter 5, Figs. 1 and 10). Normal wall motion (normally kinetic segments) is seen as wall thickening, caused by the contraction of individual myocardial fibers; on echocardiography, this is seen as the radial distance between the epi- and endocardial borders, which increases by at least 10–20% during systole. Abnormal wall motion owing to insufficient blood supply to the myocardium may be graded as hypokinetic (thickening, but less than normal), akinetic (no thickening), and dyskinetic or aneurysmal (no thickening, with outward movement of the segment during systole, owing to increased intraventricular pressure on a scarred and noncontractile area of myocardial fibrosis). In general, myocardium that is transmurally infarcted tends to have more severe dysfunction, with akinetic or dyskinetic motion.