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Dongyang Xu
BME PhD Defense Presentation
Date:2022-03-25
Time: 15:00 - 17:00 ET
Location / Meeting Link: https://zoom.us/j/6916395386?pwd=ZVM1RkQvNHNGL1htVStlL0wvWGR3QT09
Committee Members:
Muralidhar Padala, PhD (Advisor) Robert Guyton, MD John Oshinski, PhD Pavan Atluri, MD Sakya Tripathy, PhD Lakshmi Dasi, PhD
Title: Biomechanics of Annular and Sub-Annular Repairs for Functional Mitral Regurgitation
Abstract: Functional mitral regurgitation (FMR) is one of the most diagnosed comorbidities in heart failure (HF) patients. It has been shown to worsen prognosis, doubles mortality and increases HF hospitalization. The current standard treatment for FMR is known as undersizing mitral annuloplasty (UMA), in which a metallic ring-like structure is surgically sutured onto the mitral annulus to reduce its size so that the leaflets are brought back into coaptation. However, numerous studies have pointed out the clinically sub-optimal outcomes of UMA, illustrated by moderate to severe FMR reoccurrence and limited left ventricular (LV) functional recovery. Our preliminary work has shown that UMA, by drawing the posterior annulus forward, further restricts the motion of the posterior leaflet and makes anterior leaflet hyperextended, creating a “unicuspid” valve. Also, UMA deforms the LV basal myocardium into a curved structure that might impair its normal function. These observations have led us to hypothesize that UMA forces leaflet coaptation to correct FMR but unphysiologically alters the shape and biomechanics of both mitral valve (MV) and LV, which can potentially induce FMR reoccurrence and restrict LV reverse remodeling. In addition, we hypothesize that MV repair outcomes can be largely improved if such unphysiological biomechanics is reduced by changing the shape of traditional annuloplasty and/or performing sub-annular repairs. Therefore, this thesis consists of 4 specific aims: (Aim1) Investigate the impact of annuloplasty on MV hemodynamics, geometry, kinematics and chordal force distribution, (Aim2) Optimize traditional annuloplasty by modifying the shape of the ring and investigate its impact on MV function, (Aim 3) Investigate the impact of adding sub-annular repairs to annuloplasty on MV geometry, kinematics and chordal forces and (Aim 4) Investigate the impact of annular versus sub-annular repairs on LV regional biomechanics.
