[Quantitation of regional left ventricular wall motion by curvature: two-dimensional echocardiographic analysis]

Echocardiographically abnormal regional configuration of the left ventricle is one of the clues in detecting asynergy of the left ventricular wall. For the quantitative assessment, regional left ventricular configuration was expressed quantitatively using a new index, relative curvature. To obtain the end-systolic curvature, end-systolic echocardiograms were digitized and divided into eight segments. Then end-systolic curvature was determined as the reciprocal of the circumradius of a triangle determined by three consecutive dividing points. Relative curvature was defined as the product of end-systolic curvature multiplied by end-diastolic circumference. To assess the accuracy of quantitative analysis of regional left ventricular wall motion by relative curvature, short-axis images of the left ventricle at the level of the chordae tendineae were analyzed in 20 patients with myocardial infarction and 20 normal subjects by three different indices: segmental area change using a fixed reference system, segmental wall thickness change, and relative curvature. Groups of 10 patients with anteroseptal infarction, 10 patients with inferoposterior infarction, and 10 normal subjects could be differentiated from each other by these three indices. With the 95 per cent confidence intervals obtained from 10 other normal subjects, asynergic segments were detected objectively. By segmental area change, the sensitivity was 100 per cent and the specificity was 90 per cent on the anterior wall; the sensitivity was 90 per cent and the specificity was 95 per cent on the posterior wall. By segmental wall thickness change, the sensitivity was 70 per cent and the specificity was 75 per cent on the anterior wall; and those were 80 per cent and 90 per cent, respectively, on the posterior wall. By relative curvature, the sensitivity was 100 per cent and the specificity was 85 per cent on the anterior wall; and those were 90 per cent and 90 per cent, respectively, on the posterior wall. It was concluded that left ventricular regional contraction could be assessed quantitatively by relative curvature which quantitatively expresses regional left ventricular configuration. This index is independent of any reference systems, so it is expected to be used for quantitative analysis of regional wall motion, even though the cardiac motion within the thorax is not disregarded.