Remodeling potential of the mitral valve following surgical repair

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DESCRIPTION (provided by applicant): After two decades of emphasis on valve replacement, cardiac surgeons have been gradually turning to mitral valve repair. MV repair, rather than replacement, maintains better ventricular mechanics and fewer complications, such as endocarditis, thromboembolism, and anticoagulant-related hemorrhage. Unfortunately, recent long term studies using more rigorous definitions of failure have identified less optimistic result for repair durability; bringing into question such aggressive surgical practice and suggesting that repair techniques though mature can be improved upon. In most cases, failures were a result of disruption at the leaflet, chordal, or annular suture lines. These failure modes suggest excessive tissue stress and the resulting strain induced tissue damage as an etiologic factor. Thus, there has been growing interest in developing more robust repair strategies for patients with IMR. Promising concepts include leaflet augmentation to restore leaflet mobility, and saddle shaped annuloplasty to restore normal annular shape. If designed correctly, leaflet augmentation techniques can alleviate chordal-leaflet tethering and reduce leaflet stress by promoting leaflet curvature and coaptation. Leaflet augmentation will also allow the placement of larger annuloplasty rings that should reduce annular-annuloplasty ring separation forces. We thus hypothesize that IMR repair techniques that reinstate normal annular geometry (size and shape) and restore mobile leaflet tissue will result in reduced annular and chordal force distribution compared with undersized flat annuloplasty alone. This in turn will lead to restoration of homeostatic normal tissue stress levels and MVIC biosynthetic responses, ultimately leading to improved repair durability.