The Journal of Thoracic and Cardiovascular Surgery
Adult: Mitral ValveUndersizing mitral annuloplasty alters left ventricular mechanics in a swine model of ischemic mitral regurgitation
Graphical abstract
Top row, Schematic representation of experimental design of this study. Bottom row, Key findings from this study that demonstrate the deleterious effect of undersizing mitral annuloplasty on left ventricle mechanics compared with papillary muscle approximation alone.
Section snippets
Experimental Design and Animal Use
The experimental design is summarized in Figure 2. Use of animals in this research was necessary, and the surgical procedures and medications to manage postoperative pain were reviewed and approved by the designated Institutional Animal Care and Use Committee at Emory University. The studies were performed in accordance to the National Institutes of Health guidelines for use of animals in research. Yorkshire farm swine (female or castrated male) were acquired from US Department of
Procedural Parameters and Outcomes
Of 29 animals that underwent a myocardial infarction, 18 were used in this study. Details of animal exclusion, deaths, and those lost during follow-up are included in Appendix E1 and Figure E3.
Valve and Ventricle Function
MR fraction was 24.5% ± 0.4% in the study population before surgery. At 3 months after surgery when cardiac magnetic resonance imaging was performed, neither of the repaired groups had any MR, whereas MR severity persisted in the sham group. In the UMA group, the mitral annular septal–lateral diameter was
Discussion
Data from this chronic heart failure model12 demonstrate that both UMA and PMA are effective in correcting IMR acutely and there is no recurrence of IMR within the 3-month follow-up duration. The unexpected finding is that despite correcting IMR completely in both repairs, LV function was significantly better in the animals that received PMA than those that received an annuloplasty ring. In the PMA group, ejection fraction was not only improved at 3 months compared with the preoperative
Conclusions
Undersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricular mechanics and torsion. Such perturbations to ventricular mechanics may inhibit reverse remodeling achieved after MR correction. Subannular repair with PMA, which did not perturb ventricular mechanics, yielded equal reduction in valvular competence and significant improvement in ventricular function after the repair. Altogether, mitral valve repair strategies may
References (25)
- et al.
Improvement following correction of secondary mitral regurgitation in end-stage cardiomyopathy with mitral annuloplasty
Am J Cardiol
(1996) - et al.
Impact of mitral valve annuloplasty on mortality risk in patients with mitral regurgitation and left ventricular systolic dysfunction
J Am Coll Cardiol
(2005) - et al.
Elimination of ischemic mitral regurgitation does not alter long-term left ventricular remodeling in the ovine model
Ann Thorac Surg
(2010) - et al.
Repair of ischemic mitral regurgitation does not increase mortality or improve long-term survival in patients undergoing coronary artery revascularization: a propensity analysis
Ann Thorac Surg
(2004) - et al.
Do annuloplasty rings designed to treat ischemic/functional mitral regurgitation alter left-ventricular dimensions in the acutely ischemic ovine heart?
J Thorac Cardiovasc Surg
(2019) Fiber orientation and ejection fraction in the human left ventricle
Biophys J
(1969)- et al.
Papillary muscle approximation versus restrictive annuloplasty alone for severe ischemic mitral regurgitation
J Am Coll Cardiol
(2016) - et al.
Anterior leaflet augmentation for ischemic mitral regurgitation
Ann Thorac Surg
(2004) - et al.
Restrictive mitral annuloplasty cures ischemic mitral regurgitation and heart failure
Ann Thorac Surg
(2008) - et al.
Preoperative left ventricular dimensions predict reverse remodeling following restrictive mitral annuloplasty in ischemic mitral regurgitation
Eur J Cardiothorac Surg
(2005)
Two-year outcomes of surgical treatment of moderate ischemic mitral regurgitation
N Engl J Med
Transcatheter mitral-valve repair in patients with heart failure
N Engl J Med
Cited by (7)
Commentary: More R-E-S-P-E-C-T for the mitral subvalvular apparatus
2022, Journal of Thoracic and Cardiovascular SurgeryCommentary: Ischemic mitral regurgitation: From annular restriction to papillary approximation, is it time to reconsider the lost technique?
2022, Journal of Thoracic and Cardiovascular SurgeryCommentary: The over and under on ischemic mitral regurgitation repair
2022, Journal of Thoracic and Cardiovascular SurgeryCommentary: Functional Mitral Stenosis After Undersizing Mitral Annuloplasty for Ischemic Mitral Regurgitation: Ignoring the Elephant in the Room
2022, Seminars in Thoracic and Cardiovascular SurgeryComputational Modeling of the Subject-Specific Effects of Annuloplasty Ring Sizing on the Mitral Valve to Repair Functional Mitral Regurgitation
2023, Annals of Biomedical EngineeringHeart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation
2021, Frontiers in Cardiovascular Medicine
Partially supported by grants 1R01HL135145, 1R01HL133667, and 1R01HL140325 from the National Institutes of Health, grant 14SDG20380081 from the American Heart Association, and infrastructure funding from the Carlyle Fraser Heart Center at Emory University Hospital Midtown to Dr Padala.