A METHOD TO ASSESS ENDOCARDIAL REGIONAL LONGITUDINAL CURVATURE OF THE LEFT-VENTRICLE

Knowledge of the instantaneous geometry of the left ventricular (LV) chamber is necessary to calculate LV function and wall stresses. We describe a method utilizing myocardial markers that does not rely on any a priori assumptions of global LV geometry. Five dogs underwent placement of 25 endocardial and 3 epicardial miniature LV markers. Six weeks later, the animals were studied during conscious closed-chest conditions. The three-dimensional coordinates of the LV markers were used to compute longitudinal fitted curves for LV walls and septum during steady-state conditions; endocardial radii of curvature (r(curv)) were then computed for each region at the midequatorial (r(curv)-eq) and apical levels. There was a uniform decrease in r(curv) in each LV wall during systole (compared with diastole, P < 0.01); at end systole, r(curv) was regionally heterogeneous between opposing walls, e.g., anterior and posterior r(curv)-eq values were 17.2 +/- 2.0 and 17.7 +/- 1.8 (SD) cm, respectively (P < 0.05). At end diastole, only septal-lateral r(curv)-eq was different (16.9 +/- 2.1 vs. 18.7 +/- 1.3 cm; P < 0.05). Normalization of r(curv) (to instantaneous LV volume) removed the systolic-diastolic differences, but a similar pattern of regional heterogeneity persisted. The data presented pertain to the LV endocardial surface, but the method described can be applied to the epicardial surface as well; this new method offers promise in assessing dynamic changes in longitudinal LV endocardial curvature.