Quantitative Force Measurements to Optimize Valve Repair for Ischemic MR

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DESCRIPTION (provided by applicant): Ischemic mitral regurgitation (IMR) occurs when a structurally normal mitral valve (MV) is rendered incompetent as a result of myocardial infarction induced left ventricular remodeling. IMR effects between 1.6 to 2.8 million Americans. Mitral valve repair with undersized flat ring annuloplasty has become the preferred treatment. However, recent studies have demonstrated this approach is associated with a failure rate of 30% within 6 months of surgery. Most failures result from progressive leaflet tethering and annuloplasty ring dehiscence which implicates annular and chordal stress distribution as a mechanism. These suboptimal stress profiles are due, in part, to the fact that undersized annuloplasty likely accentuates the LV remodeling process by further impairing basal LV geometry and function. The inadequacy of undersized annuloplasty results from its failure to fulfill two of Carpentier's fundamental requirements for successful mitral valve repair: it does no reestablish normal annular geometry nor does it adequately restore leaflet mobility. Preliminary work has demonstrated the promise of saddle-shaped annuloplasty and leaflet augmentation in improving IMR repair. However, there are currently no data to support a consensus as to the optimal repair technique for IMR. Therefore, we have designed the specific aims of this project to test the hypothesis that IMR repair techniques that normalize annular geometry and restore leaflet mobility will result in more durable repairs by promoting better basal LV function, less exacerbation of LV remodeling and reduced annular and chordal stress distribution. Our innovative approach to this critical clinical problem leverages our group's unique combination of surgical and engineering expertise. Using both in vivo and in vitro models of IMR in combination with novel imaging and force transducer technology, we will assess the effect annuloplasty shape and leaflet tissue augmentation on valvular force distribution. Such an experimental approach allows for the preclinical optimization of a mitral valve repair procedures for IMR so only the most promising techniques need to be tested in patients.