Andrew W. Siefert
Cardiovascular Mechanics, Heart Valve Mechanics, Ischemic Mitral Regurgitation, Heart Valve Repair, Cardiovascular Imaging
2009 M.S. Mechanical Engineering Michigan State University 2007 B.S. Mechanical Engineering, Michigan State University
Chronic Ischemic Mitral Regurgitation (IMR) can be defined as Mitral Regurgitation (MR) occurring as a result of chronic myocardial ischemia in the absence of any structural damage to the mitral valve. IMR results from post infarction Left Ventricular (LV) remodeling with subsequent papillary muscle displacement, annular dilatation, leaflet tethering, and malcopatation. In the United States, IMR is a large clinical burden with an estimated prevalence of 1.6 to 2.8 million patients. In the past decade, poor survival, low rates of reverse LV remodeling, and recurrent severe IMR have been observed in 10-15% of IMR patients who presented with a severely distended LV and undergo restrictive mitral annuloplasty (RMA). In these patients, the severely or progressively displacing PMs hinder RMA’s ability to sustain coaptation and urges the use of adjunct procedures to directly address subvalvular tethering. Moreover, a growing number of cases suffer from annuloplasty ring dehiscence, which with progressive leaflet tethering, can be exacerbated by undersized mitral annuloplasty. Although several strategies have proposed to improve outcomes by restoring normal valve function, repair durability has been a difficult end point to assess experimentally. To this end, we believe the reduction of forces that can contribute to repair failure is a reasonable surrogate endpoint for repair durability. The central hypothesis of this study is: Determining the forces that exist at the annular and subvalvular levels under normal, chronic IMR, and repair conditions will allow for the design of more durable repairs aimed to reduce chordal-leaflet tethering and annuloplasty ring dehiscence. Measurement and comparison of these forces may aid clinicians in the selection of more robust repair strategies in the management of IMR patients. Furthermore, the reduction of these forces may give allowance for the progressive nature of IMR and retard the recurrence of mitral regurgitation.