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.