Despite the refinement of surgical techniques and devices over the past two decades, the durability of mitral valve repair in the context of ischemic mitral regurgitation remains disappointing. Finite element modeling of the mitral valve has previously demonstrated that disruption of optimal annular and leaflet geometry dramatically increases peak leaflet stress. Furthermore, recent studies have shown that disruption of normal valvular-ventricular mechanics contributes to ischemic left ventricular remodeling as well as adverse valvular bioarchitechtural remodeling. Initial work in our laboratory has demonstrated that mitral annuloplasty utilizing a traditional planar ring fails to restore normal mitral annular and leaflet geometry in an ovine model of ischemic mitral regurgitation. We hypothesize that 1). as IMR develops progressive annular dilatation and flattening leads to increased leaflet and chordal stress, which is associated with contractile dysfunction of the LV basilar segments.2) Placement of a flat annuloplasty ring to treat IMR exacerbates these maladaptive stress patterns and further impairs basilar LV function. 3) Placement of a three-dimensionally appropriate (i.e. saddle-shaped) annuloplasty ring to treat IMR improves leaflet and chordal stress patterns and improves/preserves basilar LV function. To test our hypotheses, we will apply geometric and finite element modeling based on high-resolution echocardiographic imaging to a well-characterized ovine model of chronic ischemic mitral regurgitation undergoing mitral annuloplasty with either a traditional flat ring or a custom-built non-planar """"""""saddle"""""""" shaped ring.
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