Dongyang Xu1, Erin McBride1, Kanika Kalra1, Keawepono Wong1, Robert A Guyton2, Eric L Sarin3, Muralidhar Padala4. 1. Structural Heart Research & Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, Ga. 2. Structural Heart Research & Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, Ga; Division of Cardiothoracic Surgery, Department of Surgery, Emory University, Atlanta, Ga. 3. Structural Heart Research & Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, Ga; Department of Cardiothoracic Surgery, Inova Heart and Vascular Institute, Fairfax, Va. 4. Structural Heart Research & Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, Ga; Division of Cardiothoracic Surgery, Department of Surgery, Emory University, Atlanta, Ga. Electronic address: spadala@emory.edu.
Abstract
OBJECTIVE: Undersizing mitral annuloplasty (UMA) is a frequently used surgical repair technique to correct ischemic mitral regurgitation in patients with heart failure. In this study, we sought to test the hypothesis that downsizing the mitral annulus can adversely affect the shape and mechanics of the left ventricle inhibiting its functional recovery. METHODS: Eighteen farm swine that underwent an inferolateral myocardial infarction and developed ischemic mitral regurgitation of >2+ severity after 2 months were assigned as follows: 9 swine received an undersized mitral annuloplasty, 6 received papillary muscle approximation (PMA), and 3 animals did not receive any other intervention. Animals lived another 3 months and cardiac magnetic resonance imaging was performed before termination to assess ventricle mechanics and function. RESULTS: Ejection fraction was comparable between the 2 repair groups before surgery, but was significantly lower in UMA at 38.89% ± 7.91% versus 50.83% ± 9.04% in the PMA group (P = .0397). Animals receiving UMA had lower regional peak fractional shortening and reduced systolic and diastolic radial velocities compared with PMA and in some regions were lower than sham. Animals that underwent UMA had higher circumferential strain than sham, but lower than PMA. UMA animals have lower longitudinal strain compared to sham group and lower LV torsion than PMA. CONCLUSIONS: Undersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricle mechanics. Mitral valve repair strategies should focus not only on restoring valve competence, but preserving ventricle mechanics.
OBJECTIVE: Undersizing mitral annuloplasty (UMA) is a frequently used surgical repair technique to correct ischemic mitral regurgitation in patients with heart failure. In this study, we sought to test the hypothesis that downsizing the mitral annulus can adversely affect the shape and mechanics of the left ventricle inhibiting its functional recovery. METHODS: Eighteen farm swine that underwent an inferolateral myocardial infarction and developed ischemic mitral regurgitation of >2+ severity after 2 months were assigned as follows: 9 swine received an undersized mitral annuloplasty, 6 received papillary muscle approximation (PMA), and 3 animals did not receive any other intervention. Animals lived another 3 months and cardiac magnetic resonance imaging was performed before termination to assess ventricle mechanics and function. RESULTS: Ejection fraction was comparable between the 2 repair groups before surgery, but was significantly lower in UMA at 38.89% ± 7.91% versus 50.83% ± 9.04% in the PMA group (P = .0397). Animals receiving UMA had lower regional peak fractional shortening and reduced systolic and diastolic radial velocities compared with PMA and in some regions were lower than sham. Animals that underwent UMA had higher circumferential strain than sham, but lower than PMA. UMA animals have lower longitudinal strain compared to sham group and lower LV torsion than PMA. CONCLUSIONS: Undersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricle mechanics. Mitral valve repair strategies should focus not only on restoring valve competence, but preserving ventricle mechanics.
Authors: Matthew H Park; Yuanjia Zhu; Annabel M Imbrie-Moore; Hanjay Wang; Mateo Marin-Cuartas; Michael J Paulsen; Y Joseph Woo Journal: Front Cardiovasc Med Date: 2021-07-08