Non-Planar Shape of the Mitral Annulus Reduces Systolic Strain on the Posterior Leaflet by Increasing Leaflet Curvature

The mitral valve annulus is a dynamic structure that changes in its shape during the cardiac cycle. It changes from a flat shape during diastole to a non-planar saddle shape during systole, which has been confirmed in animals and humans using various techniques. However a teleologic reason for nature’s selection of this shape and its role in mitral valve mechanics are poorly understood. Recent studies from our laboratory indicate that mitral annular saddle optimizes the force distribution on the valve components that could potentially affect valve function and mechanics. The objective of this study is to provide a quantitative and mechanistic insight into the synergy between the non-planar mitral annular shape and posterior leaflet mechanics. The posterior leaflet was specifically selected as most mitral valve surgeries require placement of suture lines in this region, which fail in more than 40% of the patients due to high strains in this region.