Comparison of two-dimensional echocardiographic wall motion and wall thickening abnormalities in relation to the myocardium at risk

Abstract

Previous 2DE studies have suggested that left ventricular wall thickening determinants of regional left ventricular function may be more precise than left ventricular wall motion parameters in the assessment of myocardial ischemia and infarction. To study the relationship between regional wall motion and regional wall thickening abnormalities relative to myocardial ischemia, we performed 2DE in 27 dogs at baseline and following 1 hour of circumflex coronary occlusion. A 2DE circumferential map of regional wall motion and regional wall thickening was generated at 22.5-degree intervals over 360 degrees using a fixed centroid. With the use of three consecutive beats, 95% normal tolerance levels were derived for each individual left ventricular function map. The circumferential extent of left ventricular dysfunction was measured at the curve intercepts of the occluded and normal maps. The left ventricular ischemic area at risk for the corresponding 2DE slice was determined by technetium-99 autoradiography. Following coronary occlusion, left ventricular end-diastolic area increased ( p < 0.0005), left ventricular end-systolic area increased ( p < 0.0005), and left ventricular area ejection fraction decreased (50 ± 2% to 30 ± 2%, p < 0.0005). The circumferential extent of regional wall motion overestimated the area at risk by 77% (226 ± 11 degrees vs 128 ± 7 degrees, p < 0.0005), whereas the circumferential extent of regional wall thickening corresponded to the area at risk (147 ± 9 degrees vs 128 ± 7 degrees, p = NS). In addition, the circumferential extent of regional wall motion overestimated regional wall thickening by 54% ( p < 0.0005). We conclude that regional wall thickening abnormality corresponds better to actual area at risk and that regional wall motion overestimates the extent of regional dysfunction. This overestimation most likely relates to the use of the centroid method of analysis which influences regional wall motion more than regional wall thickening.