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Park MH, van Kampen A, Melnitchouk S, Wilkerson RJ, Nagata Y, Zhu Y, Wang H, Pandya PK, Morningstar JE, Borger MA, Levine RA, Woo YJ. Native and Post-Repair Residual Mitral Valve Prolapse Increases Forces Exerted on the Papillary Muscles: A Possible Mechanism for Localized Fibrosis? Circ Cardiovasc Interv 2022; 15:e011928. [PMID: 36538583 PMCID: PMC9782735 DOI: 10.1161/circinterventions.122.011928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 10/24/2022] [Indexed: 12/25/2022]
Abstract
BACKGROUND Recent studies have linked mitral valve prolapse to localized myocardial fibrosis, ventricular arrhythmia, and even sudden cardiac death independent of mitral regurgitation or hemodynamic dysfunction. The primary mechanistic theory is rooted in increased papillary muscle traction and forces due to prolapse, yet no biomechanical evidence exists showing increased forces. Our objective was to evaluate the biomechanical relationship between prolapse and papillary muscle forces, leveraging advances in ex vivo modeling and technologies. We hypothesized that mitral valve prolapse with limited hemodynamic dysfunction leads to significantly higher papillary muscle forces, which could be a possible trigger for cellular and electrophysiological changes in the papillary muscles and adjacent myocardium. METHODS We developed an ex vivo papillary muscle force transduction and novel neochord length adjustment system capable of modeling targeted prolapse. Using 3 unique ovine models of mitral valve prolapse (bileaflet or posterior leaflet prolapse), we directly measured hemodynamics and forces, comparing physiologic and prolapsing valves. RESULTS We found that bileaflet prolapse significantly increases papillary muscle forces by 5% to 15% compared with an optimally coapting valve, which are correlated with statistically significant decreases in coaptation length. Moreover, we observed significant changes in the force profiles for prolapsing valves when compared with normal controls. CONCLUSIONS We discovered that bileaflet prolapse with the absence of hemodynamic dysfunction results in significantly elevated forces and altered dynamics on the papillary muscles. Our work suggests that the sole reduction of mitral regurgitation without addressing reduced coaptation lengths and thus increased leaflet surface area exposed to ventricular pressure gradients (ie, billowing leaflets) is insufficient for an optimal repair.
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Affiliation(s)
- Matthew H. Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
- Department of Mechanical Engineering, Stanford University, Stanford, CA
| | - Antonia van Kampen
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Serguei Melnitchouk
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Yasufumi Nagata
- Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
- Department of Bioengineering, Stanford University, Stanford, CA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
| | - Pearly K. Pandya
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
- Department of Mechanical Engineering, Stanford University, Stanford, CA
| | - Jordan E. Morningstar
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC
| | - Michael A. Borger
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Robert A. Levine
- Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
- Department of Bioengineering, Stanford University, Stanford, CA
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