DYNAMIC MAGNETIC-RESONANCE-IMAGING ASSESSMENT OF THE EFFECT OF VENTRICULAR WALL CURVATURE ON REGIONAL FUNCTION IN HYPERTROPHIC CARDIOMYOPATHY

We hypothesized that contraction within the ventricular septum in hype rtrophic cardiomyopathy (HC) may be related to its abnormal morphology because ventricular wall stress is related to wall curvature by the L aplace equation, To test this, we studied 17 HC patients with various septal morphologies using dynamic magnetic resonance imaging technique s. Short- and long-axis curvatures of the basal septal and basal later al walls were determined on cine images as the reciprocal of the radiu s of the are best fit to the endocardial contour, which was negative i f the wall wets convex to the cavity of the left ventricle. Endocordia l and epicardial intramyocardial circumferential shortening (% circumf erential shortening) was measured in the septal and lateral walls on b asal short-axis myocardial tagging images. Septal walls were flatter i n the short-axis plane and more convex coward the jeff ventricular cav ity in the long-axis plane than lateral wells, as indicated by smaller short- and long-axis curvatures. Septal percent circumferential short ening was significantly lower then the lateral percent circumferential shortening, suggesting reduced septal contraction. Endocardial and ep icardial percent circumferential shortening showed significant positiv e correlations with wall curvatures, Multiple stepwise linear regressi on analysis revealed that both short- and long-axis curvatures signifi cantly contributed to percent circumferential shortening (r = 0.87 for endocardiol and r = 0.70 for epicardial, both p <0.0001). In conclusi on, wall curvature is related to wall function in HC; the more convex toward the left ventricular cavity the wall is, the less it contracts, Reduced contraction of the septum in HC may be partly due to its abno rmal curvature.