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Anterior Mitral Leaflet Curvature During the Cardiac Cycle in the Normal Ovine Heart

Background— The dynamic changes of anterior mitral leaflet (AML) curvature are of primary importance for optimal left ventricular filling and emptying but are incompletely characterized. Methods and Results— Sixteen radiopaque markers were sutured to the AML in 11 sheep, and 4-dimensional marker coordinates were acquired with biplane videofluoroscopy. A surface subdivision algorithm was applied to compute the curvature across the AML at midsystole and at maximal valve opening. Septal-lateral (SL) and commissure-commissure (CC) curvature profiles were calculated along the SL AML meridian (MSL)and CC AML meridian (MCC), respectively, with positive curvature being concave toward the left atrium. At midsystole, the MSL was concave near the mitral annulus, turned from concave to convex across the belly, and was convex along the free edge. At maximal valve opening, the MSL was flat near the annulus, turned from slightly concave to convex across the belly, and flattened toward the free edge. In contrast, the MCC was concave near both commissures and convex at the belly at midsystole but convex near both commissures and concave at the belly at maximal valve opening. Conclusions— While the SL curvature of the AML along the MSL is similar across the belly region at midsystole and early diastole, the CC curvature of the AML along the MCC flips, with the belly being convex to the left atrium at midsystole and concave at maximal valve opening. These curvature orientations suggest optimal left ventricular inflow and outflow shapes of the AML and should be preserved during catheter or surgical interventions.