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Zhu Y, Yajima S, Park MH, Venkatesh A, Stark CJ, Tran NA, Walsh SK, Ethiraj S, Wilkerson RJ, Lin LE, Lee SH, Gates KY, Arthur JD, Baker SW, Mullis DM, Wu CA, Harima S, Pokhrel B, Resuello D, Bergamasco H, Wu MA, Baccouche BM, Pandya PK, Elde S, Wang H, Woo YJ. Large Animal Translational Validation of 3 Mitral Valve Repair Operations for Mitral Regurgitation Using a Mitral Valve Prolapse Model: A Comprehensive In Vivo Biomechanical Engineering Analysis. Circ Cardiovasc Interv 2024; 17:e013196. [PMID: 38626077 DOI: 10.1161/circinterventions.123.013196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 01/19/2024] [Indexed: 04/18/2024]
Abstract
BACKGROUND Various mitral repair techniques have been described. Though these repair techniques can be highly effective when performed correctly in suitable patients, limited quantitative biomechanical data are available. Validation and thorough biomechanical evaluation of these repair techniques from translational large animal in vivo studies in a standardized, translatable fashion are lacking. We sought to evaluate and validate biomechanical differences among different mitral repair techniques and further optimize repair operations using a large animal mitral valve prolapse model. METHODS Male Dorset sheep (n=20) had P2 chordae severed to create the mitral valve prolapse model. Fiber Bragg grating force sensors were implanted to measure chordal forces. Ten sheep underwent 3 randomized, paired mitral valve repair operations: neochord repair, nonresectional leaflet remodeling, and triangular resection. The other 10 sheep underwent neochord repair with 2, 4, and 6 neochordae. Data were collected at baseline, mitral valve prolapse, and after each repair. RESULTS All mitral repair techniques successfully eliminated regurgitation. Compared with mitral valve prolapse (0.54±0.18 N), repair using neochord (0.37±0.20 N; P=0.02) and remodeling techniques (0.30±0.15 N; P=0.001) reduced secondary chordae peak force. Neochord repair further decreased primary chordae peak force (0.21±0.14 N) to baseline levels (0.20±0.17 N; P=0.83), and was associated with lower primary chordae peak force compared with the remodeling (0.34±0.18 N; P=0.02) and triangular resectional techniques (0.36±0.27 N; P=0.03). Specifically, repair using 2 neochordae resulted in higher peak primary chordal forces (0.28±0.21 N) compared with those using 4 (0.22±0.16 N; P=0.02) or 6 neochordae (0.19±0.16 N; P=0.002). No difference in peak primary chordal forces was observed between 4 and 6 neochordae (P=0.05). Peak forces on the neochordae were the lowest using 6 neochordae (0.09±0.11 N) compared with those of 4 neochordae (0.15±0.14 N; P=0.01) and 2 neochordae (0.29±0.18 N; P=0.001). CONCLUSIONS Significant biomechanical differences were observed underlying different mitral repair techniques in a translational large animal model. Neochord repair was associated with the lowest primary chordae peak force compared to the remodeling and triangular resectional techniques. Additionally, neochord repair using at least 4 neochordae was associated with lower chordal forces on the primary chordae and the neochordae. This study provided key insights about mitral valve repair optimization and may further improve repair durability.
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Affiliation(s)
- Yuanjia Zhu
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
- Department of Bioengineering (Y.Z., Y.J.W.), Stanford University, CA
| | - Shin Yajima
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Matthew H Park
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
- Department of Mechanical Engineering (M.H.P., P.K.P.), Stanford University, CA
| | - Akshay Venkatesh
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Charles J Stark
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Nicholas A Tran
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Sabrina K Walsh
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Sidarth Ethiraj
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Robert J Wilkerson
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Luca E Lin
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Seung Hyun Lee
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Kate Y Gates
- Department of Comparative Medicine (K.Y.G., J.D.A., S.W.B.), Stanford University, CA
| | - Justin D Arthur
- Department of Comparative Medicine (K.Y.G., J.D.A., S.W.B.), Stanford University, CA
| | - Sam W Baker
- Department of Comparative Medicine (K.Y.G., J.D.A., S.W.B.), Stanford University, CA
| | - Danielle M Mullis
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Catherine A Wu
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Shun Harima
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Bipul Pokhrel
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Dominique Resuello
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Hunter Bergamasco
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Matthew A Wu
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Basil M Baccouche
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Pearly K Pandya
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
- Department of Mechanical Engineering (M.H.P., P.K.P.), Stanford University, CA
| | - Stefan Elde
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery (Y.Z., S.Y., M.H.P., A.V., C.J.S., N.A.T., S.K.W., S. Ethiraj, R.J.W., L.E.L., S.H.L., D.M.M., C.A.W., S.H., B.P., D.R., H.B., M.A.W., B.M.B., P.K.P., S. Elde, H.W., Y.J.W.), Stanford University, CA
- Department of Bioengineering (Y.Z., Y.J.W.), Stanford University, CA
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2
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Park MH, van Kampen A, Zhu Y, Melnitchouk S, Levine RA, Borger MA, Woo YJ. Neochordal Goldilocks: Analyzing the biomechanics of neochord length on papillary muscle forces suggests higher tolerance to shorter neochordae. J Thorac Cardiovasc Surg 2024; 167:e78-e89. [PMID: 37160219 DOI: 10.1016/j.jtcvs.2023.04.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/10/2023] [Accepted: 04/20/2023] [Indexed: 05/11/2023]
Abstract
OBJECTIVE Estimating neochord lengths during mitral valve repair is challenging, because approximation must be performed largely based on intuition and surgical experience. Little data exist on quantifying the effects of neochord length misestimation. We aimed to evaluate the impact of neochord length on papillary muscle forces and mitral valve hemodynamics, which is especially pertinent because increased forces have been linked to aberrant mitral valve biomechanics. METHODS Porcine mitral valves (n = 8) were mounted in an ex vivo heart simulator, and papillary muscles were fixed to high-resolution strain gauges while hemodynamic data were recorded. We used an adjustable system to modulate neochord lengths. Optimal length was qualitatively verified by a single experienced operator, and neochordae were randomly lengthened or shortened in 1-mm increments up to ±5 mm from the optimal length. RESULTS Optimal length neochordae resulted in the lowest peak composite papillary muscle forces (6.94 ± 0.29 N), significantly different from all lengths greater than ±1 mm. Both longer and shorter neochordae increased forces linearly according to difference from optimal length. Both peak papillary muscle forces and mitral regurgitation scaled more aggressively for longer versus shorter neochordae by factors of 1.6 and 6.9, respectively. CONCLUSIONS Leveraging precision ex vivo heart simulation, we found that millimeter-level neochord length differences can result in significant differences in papillary muscle forces and mitral regurgitation, thereby altering valvular biomechanics. Differences in lengthened versus shortened neochordae scaling of forces and mitral regurgitation may indicate different levels of biomechanical tolerance toward longer and shorter neochordae. Our findings highlight the need for more thorough biomechanical understanding of neochordal mitral valve repair.
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Affiliation(s)
- Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Antonia van Kampen
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Mass; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Mass; University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif
| | - Serguei Melnitchouk
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Mass
| | - Robert A Levine
- Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Mass
| | - Michael A Borger
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Mass
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif.
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Zhu Y, Lee SH, Venkatesh A, Wu CA, Stark CJ, Ethiraj S, Lee JJ, Park MH, Yajima S, Woo YJ. Biomechanical engineering analysis of neochordae length's impact on chordal forces in mitral repair. Eur J Cardiothorac Surg 2024; 65:ezae008. [PMID: 38258541 DOI: 10.1093/ejcts/ezae008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 12/20/2023] [Accepted: 01/17/2024] [Indexed: 01/24/2024] Open
Abstract
OBJECTIVES Artificial neochordae implantation is commonly used for mitral valve (MV) repair. However, neochordae length estimation can be difficult to perform. The objective was to assess the impact of neochordae length changes on MV haemodynamics and neochordal forces. METHODS Porcine MVs (n = 6) were implanted in an ex vivo left heart simulator. MV prolapse (MVP) was generated by excising at least 2 native primary chordae supporting the P2 segments from each papillary muscle. Two neochordae anchored on each papillary muscle were placed with 1 tied to the native chord length (exact length) and the other tied with variable lengths from 2× to 0.5× of the native length (variable length). Haemodynamics, neochordal forces and echocardiography data were collected. RESULTS Neochord implantation repair successfully eliminated mitral regurgitation with repaired regurgitant fractions of approximately 4% regardless of neochord length (P < 0.01). Leaflet coaptation height also significantly improved to a minimum height of 1.3 cm compared with that of MVP (0.9 ± 0.4 cm, P < 0.05). Peak and average forces on exact length neochordae increased as variable length neochordae lengths increased. Peak and average forces on the variable length neochordae increased with shortened lengths. Overall, chordal forces appeared to vary more drastically in variable length neochordae compared with exact length neochordae. CONCLUSIONS MV regurgitation was eliminated with neochordal repair, regardless of the neochord length. However, chordal forces varied significantly with different neochord lengths, with a preferentially greater impact on the variable length neochord. Further validation studies may be performed before translating to clinical practices.
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Affiliation(s)
- Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Seung Hyun Lee
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Akshay Venkatesh
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Catherine A Wu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Charles J Stark
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Sidarth Ethiraj
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Justin J Lee
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Shin Yajima
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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Elde S, Woo YJ. Neochords: How long, how many, too many? JTCVS Tech 2023; 22:59-64. [PMID: 38152190 PMCID: PMC10750996 DOI: 10.1016/j.xjtc.2023.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/11/2023] [Accepted: 10/19/2023] [Indexed: 12/29/2023] Open
Affiliation(s)
- Stefan Elde
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, Calif
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, Calif
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, Calif
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, Calif
- Department of Bioengineering, Stanford University School of Medicine, Stanford, Calif
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Morimura H, Okamoto Y, Takada J, Tabata M, Iwasaki K. Repairable ex vivo model of functional and degenerative mitral regurgitation. Eur J Cardiothorac Surg 2023; 64:ezad371. [PMID: 37951590 PMCID: PMC10903162 DOI: 10.1093/ejcts/ezad371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/19/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023] Open
Abstract
OBJECTIVES Transcatheter mitral valve repair is an emerging alternative to the surgical repair. This technology requires preclinical studies to assess efficacy in mitigating mitral regurgitation (MR). However, ex vivo MR models are not established. We developed 2 novel repairable models, functional and degenerative, which can quantitatively assess regurgitation and effect of intervention. METHODS We used porcine mitral valves and a pulsatile flow circulation system. In the functional MR model, the annulus was immersed in 0.1% collagenase solution and dilated using 3D-printed dilators. To control the regurgitation grade, the sizes of the dilator and silicone sheet in which the valve was sutured to were adjusted. Chordae of P2 were severed in the degenerative model, and the number of severed chordae was adjusted to control the regurgitation grade. Models were repaired using the edge-to-edge or artificial chordae technique. RESULTS The mean regurgitant fraction of the moderate-severe functional and degenerative models were 47.9% [standard deviation (SD): 2.2%] and 58.5% (SD: 8.0%), which were significantly reduced to 28.7% (SD: 4.4%) (P < 0.001) and 26.0% (SD: 4.4%) (P < 0.001) after the valve repair procedures. Severe functional model had a mean regurgitant fraction of 59.4% (SD: 6.0%). CONCLUSIONS Both functional and degenerative models could produce sufficient MR levels that meet the interventional indication criteria. The repairable models are valuable in evaluating the efficacy of valve repair procedures and devices. The ability to control the amount of regurgitation enhances the versatility and reliability of these models. These reproducible models could expedite the development of novel devices.
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Affiliation(s)
- Hayato Morimura
- Cooperative Major in Advanced Biomedical Sciences, Joint Graduate School of Tokyo Women's Medical University and Waseda University, Waseda University, Tokyo, Japan
| | - Yusei Okamoto
- Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, Tokyo, Japan
| | - Jumpei Takada
- Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Minoru Tabata
- Department of Cardiovascular Surgery, Juntendo University, Tokyo, Japan
| | - Kiyotaka Iwasaki
- Cooperative Major in Advanced Biomedical Sciences, Joint Graduate School of Tokyo Women's Medical University and Waseda University, Waseda University, Tokyo, Japan
- Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, Tokyo, Japan
- Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
- Institute for Medical Regulatory Science, Waseda University, Tokyo, Japan
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Yajima S, Zhu Y, Stark CJ, Wilkerson RJ, Park MH, Stefan E, Woo YJ. Chordal force profile after neochordal repair of anterior mitral valve prolapse: An ex vivo study. JTCVS OPEN 2023; 15:164-172. [PMID: 37808060 PMCID: PMC10556825 DOI: 10.1016/j.xjon.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/17/2023] [Accepted: 04/17/2023] [Indexed: 10/10/2023]
Abstract
Objective This study aimed to biomechanically evaluate the force profiles on the anterior primary and secondary chordae after neochord repair for anterior valve prolapse with varied degrees of residual mitral regurgitation using an ex vivo heart simulator. Methods The experiment used 8 healthy porcine mitral valves. Chordal forces were measured using fiber Bragg grating sensors on primary and secondary chordae from A2 segments. The anterior valve prolapse model was generated by excising 2 primary chordae at the A2 segment. Neochord repair was performed with 2 pairs of neochords. Varying neochord lengths simulated postrepair residual mitral regurgitation with regurgitant fraction at >30% (moderate), 10% to 30% (mild), and <10% (perfect repair). Results Regurgitant fractions of baseline, moderate, mild, and perfect repair were 4.7% ± 0.8%, 35.8% ± 2.1%, 19.8% ± 2.0%, and 6.0% ± 0.7%, respectively (P < .001). Moderate had a greater peak force of the anterior primary chordae (0.43 ± 0.06 N) than those of baseline (0.19 ± 0.04 N; P = .011), mild (0.23 ± 0.05 N; P = .041), and perfect repair (0.21 ± 0.03 N; P = .006). In addition, moderate had a greater peak force of the anterior secondary chordae (1.67 ± 0.17 N) than those of baseline (0.64 ± 0.13 N; P = .003), mild (0.84 ± 0.24 N; P = .019), and perfect repair (0.68 ± 0.14 N; P = .001). No significant differences in peak and average forces on both primary and secondary anterior chordae were observed between the baseline and perfect repair as well as the mild and perfect repair. Conclusions Moderate residual mitral regurgitation after neochord repair was associated with increased anterior primary and secondary chordae forces in our ex vivo anterior valve prolapse model. This difference in chordal force profile may influence long-term repair durability, providing biomechanical evidence in support of obtaining minimal regurgitation when repairing mitral anterior valve prolapse.
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Affiliation(s)
- Shin Yajima
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Bioengineering, Stanford University, Stanford, Calif
| | - Charles J. Stark
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | | | - Matthew H. Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Elde Stefan
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Bioengineering, Stanford University, Stanford, Calif
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van Kampen A, Morningstar JE, Goudot G, Ingels N, Wenk JF, Nagata Y, Yaghoubian KM, Norris RA, Borger MA, Melnitchouk S, Levine RA, Jensen MO. Utilization of Engineering Advances for Detailed Biomechanical Characterization of the Mitral-Ventricular Relationship to Optimize Repair Strategies: A Comprehensive Review. Bioengineering (Basel) 2023; 10:601. [PMID: 37237671 PMCID: PMC10215167 DOI: 10.3390/bioengineering10050601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
The geometrical details and biomechanical relationships of the mitral valve-left ventricular apparatus are very complex and have posed as an area of research interest for decades. These characteristics play a major role in identifying and perfecting the optimal approaches to treat diseases of this system when the restoration of biomechanical and mechano-biological conditions becomes the main target. Over the years, engineering approaches have helped to revolutionize the field in this regard. Furthermore, advanced modelling modalities have contributed greatly to the development of novel devices and less invasive strategies. This article provides an overview and narrative of the evolution of mitral valve therapy with special focus on two diseases frequently encountered by cardiac surgeons and interventional cardiologists: ischemic and degenerative mitral regurgitation.
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Affiliation(s)
- Antonia van Kampen
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Leipzig Heart Centre, University Clinic of Cardiac Surgery, 02189 Leipzig, Germany
| | - Jordan E. Morningstar
- Department of Regenerative Medicine and Cell Biology, University of South Carolina, Charleston, SC 29425, USA
| | - Guillaume Goudot
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Neil Ingels
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40508, USA;
| | - Yasufumi Nagata
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Koushiar M. Yaghoubian
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Russell A. Norris
- Department of Regenerative Medicine and Cell Biology, University of South Carolina, Charleston, SC 29425, USA
| | - Michael A. Borger
- Leipzig Heart Centre, University Clinic of Cardiac Surgery, 02189 Leipzig, Germany
| | - Serguei Melnitchouk
- Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Robert A. Levine
- Cardiac Ultrasound Laboratory, Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Morten O. Jensen
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
- Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Park MH, Pandya PK, Zhu Y, Mullis DM, Wang H, Imbrie-Moore AM, Wilkerson R, Marin-Cuartas M, Woo YJ. A Novel Rheumatic Mitral Valve Disease Model with Ex Vivo Hemodynamic and Biomechanical Validation. Cardiovasc Eng Technol 2023; 14:129-140. [PMID: 35941509 PMCID: PMC9905378 DOI: 10.1007/s13239-022-00641-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 07/08/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE Rheumatic heart disease is a major cause of mitral valve (MV) dysfunction, particularly in disadvantaged areas and developing countries. There lacks a critical understanding of the disease biomechanics, and as such, the purpose of this study was to generate the first ex vivo porcine model of rheumatic MV disease by simulating the human pathophysiology and hemodynamics. METHODS Healthy porcine valves were altered with heat treatment, commissural suturing, and cyanoacrylate tissue coating, all of which approximate the pathology of leaflet stiffening and thickening as well as commissural fusion. Hemodynamic data, echocardiography, and high-speed videography were collected in a paired manner for control and model valves (n = 4) in an ex vivo left heart simulator. Valve leaflets were characterized in an Instron tensile testing machine to understand the mechanical changes of the model (n = 18). RESULTS The model showed significant differences indicative of rheumatic disease: increased regurgitant fractions (p < 0.001), reduced effective orifice areas (p < 0.001), augmented transmitral mean gradients (p < 0.001), and increased leaflet stiffness (p = 0.025). CONCLUSION This work represents the creation of the first ex vivo model of rheumatic MV disease, bearing close similarity to the human pathophysiology and hemodynamics, and it will be used to extensively study both established and new treatment techniques, benefitting the millions of affected victims.
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Affiliation(s)
- Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Pearly K Pandya
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Danielle M Mullis
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Robert Wilkerson
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA.
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
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Marin-Cuartas M, Zhu Y, Imbrie-Moore AM, Park MH, Wilkerson RJ, Leipzig M, Pandya PK, Paulsen MJ, Borger MA, Woo YJ. Biomechanical engineering analysis of an acute papillary muscle rupture disease model using an innovative 3D-printed left heart simulator. Interact Cardiovasc Thorac Surg 2022; 34:822-830. [PMID: 35022737 PMCID: PMC9153378 DOI: 10.1093/icvts/ivab373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/08/2021] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVES The severity of acute papillary muscle (PM) rupture varies according to the extent and site of the rupture. However, the haemodynamic effects of different rupture variations are still poorly understood. Using a novel ex vivo model, we sought to study acute PM rupture to improve clinical management. METHODS Using porcine mitral valves (n = 32) mounted within an ex vivo left heart simulator, PM rupture was simulated. The mitral valve was divided into quadrants for analysis according to the PM heads. Acute PM rupture was simulated by incrementally cutting from 1/3 to the total number of chordae arising from 1 PM head of interest. Haemodynamic parameters were measured. RESULTS Rupture >2/3 of the chordae from 1 given PM head or regurgitation fraction >60% led to markedly deteriorated haemodynamics. Rupture at the anterolateral PM had a stronger negative effect on haemodynamics than rupture at the posteromedial PM. Rupture occurring at the anterior head of the anterolateral PM led to more marked haemodynamic instability than rupture occurring at the other PM heads. CONCLUSIONS The haemodynamic effects of acute PM rupture vary considerably according to the site and extent of the rupture. Rupture of ≤2/3 of chordae from 1 PM head or rupture at the posteromedial PM lead to less marked haemodynamics effects, suggesting a higher likelihood of tolerating surgery. Rupture at the anterolateral PM, specifically the anterior head, rupture of >2/3 of chordae from 1 PM head or regurgitation fraction >60% led to marked haemodynamic instability, suggesting the potential benefit from bridging strategies prior to surgery.
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Affiliation(s)
- Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Robert J Wilkerson
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Matthew Leipzig
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Pearly K Pandya
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Michael A Borger
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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Pandya PK, Wilkerson RJ, Imbrie-Moore AM, Zhu Y, Marin-Cuartas M, Park MH, Woo YJ. Quantitative Biomechanical Optimization of Neochordal Implantation Location on Mitral Leaflets during Valve Repair. JTCVS Tech 2022; 14:89-93. [PMID: 35967240 PMCID: PMC9366621 DOI: 10.1016/j.xjtc.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 04/01/2022] [Accepted: 05/10/2022] [Indexed: 11/01/2022] Open
Abstract
Objective Methods Results Conclusions
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11
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Zhu Y, Imbrie-Moore AM, Wilkerson RJ, Paulsen MJ, Park MH, Woo YJ. Ex vivo biomechanical analysis of flexible versus rigid annuloplasty rings in mitral valves using a novel annular dilation system. BMC Cardiovasc Disord 2022; 22:73. [PMID: 35219298 PMCID: PMC8882272 DOI: 10.1186/s12872-022-02515-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 02/07/2022] [Indexed: 12/04/2022] Open
Abstract
Background Mitral annuloplasty rings restore annular dimensions to increase leaflet coaptation, serving a fundamental component in mitral valve repair. However, biomechanical evaluations of annuloplasty rings are lacking. We aim to biomechanically analyze flexible and rigid annuloplasty rings using an ex vivo mitral annular dilation model. Methods Juvenile porcine mitral valves (n = 4) with intercommissural distance of 28 mm were dilated to intercommissural distances of 40 mm using a 3D-printed dilator and were sewn to an elastic mount. Fiber bragg grating sensors were anchored to native chordae to measure chordal forces. The valves were repaired using size 28 rigid and flexible annuloplasty rings in a random order. Hemodynamic data, echocardiography, and chordal force measurements were collected.
Results Mitral annular dilation resulted in decreased leaflet coaptation height and increased mitral regurgitation fraction. Both the flexible and rigid annuloplasty rings effectively increased leaflet coaptation height compared to that post dilation. Rigid ring annuloplasty repair significantly decreased the mitral regurgitation fraction. Flexible annuloplasty ring repair reduced the chordal rate of change of force (7.1 ± 4.4 N/s versus 8.6 ± 5.9 N/s, p = 0.02) and peak force (0.6 ± 0.5 N versus 0.7 ± 0.6 N, p = 0.01) compared to that from post dilation. Rigid annuloplasty ring repair was associated with higher chordal rate of change of force (9.8 ± 5.8 N/s, p = 0.0001) and peak force (0.7 ± 0.5 N, p = 0.01) compared to that after flexible ring annuloplasty repair. Conclusions Both rigid and flexible annuloplasty rings are effective in increasing mitral leaflet coaptation height. Although the rigid annuloplasty ring was associated with slightly higher chordal stress compared to that of the flexible annuloplasty ring, it was more effective in mitral regurgitation reduction. This study may help direct the design of an optimal annuloplasty ring to further improve patient outcomes.
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12
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Zhu Y, Imbrie-Moore AM, Paulsen MJ, Priromprintr B, Wang H, Lucian HJ, Farry JM, Woo YJ. Novel bicuspid aortic valve model with aortic regurgitation for hemodynamic status analysis using an ex vivo simulator. J Thorac Cardiovasc Surg 2022; 163:e161-e171. [PMID: 32747120 PMCID: PMC7769867 DOI: 10.1016/j.jtcvs.2020.06.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/11/2020] [Accepted: 06/15/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The objective was to design and evaluate a clinically relevant, novel ex vivo bicuspid aortic valve model that mimics the most common human phenotype with associated aortic regurgitation. METHODS Three bovine aortic valves were mounted asymmetrically in a previously validated 3-dimensional-printed left heart simulator. The non-right commissure and the non-left commissure were both shifted slightly toward the left-right commissure, and the left and right coronary cusps were sewn together. The left-right commissure was then detached and reimplanted 10 mm lower than its native height. Free margin shortening was used for valve repair. Hemodynamic status, high-speed videography, and echocardiography data were collected before and after the repair. RESULTS The bicuspid aortic valve model was successfully produced and repaired. High-speed videography confirmed prolapse of the fused cusp of the baseline bicuspid aortic valve models in diastole. Hemodynamic and pressure data confirmed accurate simulation of diseased conditions with aortic regurgitation and the subsequent repair. Regurgitant fraction postrepair was significantly reduced compared with that at baseline (14.5 ± 4.4% vs 28.6% ± 3.4%; P = .037). There was no change in peak velocity, peak gradient, or mean gradient across the valve pre- versus postrepair: 293.3 ± 18.3 cm/sec versus 325.3 ± 58.2 cm/sec (P = .29), 34.3 ± 4.2 mm Hg versus 43.3 ± 15.4 mm Hg (P = .30), and 11 ± 1 mm Hg versus 9.3 ± 2.5 mm Hg (P = .34), respectively. CONCLUSIONS An ex vivo bicuspid aortic valve model was designed that recapitulated the most common human phenotype with aortic regurgitation. These valves were successfully repaired, validating its potential for evaluating valve hemodynamics and optimizing surgical repair for bicuspid aortic valves.
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Affiliation(s)
- Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA,Department of Bioengineering, Stanford University, Stanford, CA
| | - Annabel M. Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA,Department of Mechanical Engineering, Stanford University, Stanford, CA
| | | | - Bryant Priromprintr
- Department of Pediatrics, Division of Pediatric Cardiology, Stanford University, Stanford, CA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
| | - Haley J. Lucian
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
| | - Justin M. Farry
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA,Department of Bioengineering, Stanford University, Stanford, CA
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13
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Gleason TG, Aranki S. Commentary: Valvular mimicry in simulation-espice, adspice, prospice. J Thorac Cardiovasc Surg 2022; 163:e174-e176. [PMID: 32859417 PMCID: PMC9119723 DOI: 10.1016/j.jtcvs.2020.07.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 07/19/2020] [Accepted: 07/21/2020] [Indexed: 11/26/2022]
Affiliation(s)
- Thomas G Gleason
- Division of Cardiac Surgery, Brigham & Women's Hospital and Harvard Medical School, Boston, Mass.
| | - Sari Aranki
- Division of Cardiac Surgery, Brigham & Women's Hospital and Harvard Medical School, Boston, Mass
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Biomechanical engineering comparison of four leaflet repair techniques for mitral regurgitation using a novel 3-dimensional-printed left heart simulator. JTCVS Tech 2022; 10:244-251. [PMID: 34977730 PMCID: PMC8691825 DOI: 10.1016/j.xjtc.2021.09.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 09/24/2021] [Indexed: 01/05/2023] Open
Abstract
Objective Mitral valve repair is the gold standard treatment for degenerative mitral regurgitation; however, a multitude of repair techniques exist with little quantitative data comparing these approaches. Using a novel ex vivo model, we sought to evaluate biomechanical differences between repair techniques. Methods Using porcine mitral valves mounted within a custom 3-dimensional-printed left heart simulator, we induced mitral regurgitation using an isolated P2 prolapse model by cutting primary chordae. Next, we repaired the valves in series using the edge-to-edge technique, neochordoplasty, nonresectional remodeling, and classic leaflet resection. Hemodynamic data and chordae forces were measured and analyzed using an incomplete counterbalanced repeated measures design with the healthy pre-prolapse valve as a control. Results With the exception of the edge-to-edge technique, all repair methods effectively corrected mitral regurgitation, returning regurgitant fraction to baseline levels (baseline 11.9% ± 3.7%, edge-to-edge 22.5% ± 6.9%, nonresectional remodeling 12.3% ± 3.0%, neochordal 13.4% ± 4.8%, resection 14.7% ± 5.5%, P < 0.01). Forces on the primary chordae were minimized using the neochordal and nonresectional techniques whereas the edge-to-edge and resectional techniques resulted in significantly elevated primary forces. Secondary chordae forces also followed this pattern, with edge-to-edge repair generating significantly higher secondary forces and leaflet resection trending higher than the nonresectional and neochord repairs. Conclusions Although multiple methods of degenerative mitral valve repair are used clinically, their biomechanical properties vary significantly. Nonresectional techniques, including leaflet remodeling and neochordal techniques, appear to result in lower chordal forces in this ex vivo technical engineering model.
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Sadri V, Kohli K, Jimenez JH, Cranford WS, Berry AR, Grinberg D, Chitwood WR, Yoganathan AP. Impact of Anchor Location on Mitral Neo-chordae Forces: An In Vitro Study. Ann Thorac Surg 2021; 113:1378-1384. [PMID: 34958769 DOI: 10.1016/j.athoracsur.2021.10.072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 08/30/2021] [Accepted: 10/25/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE This study examined changes in force distribution between the neo-chordae corresponding to different ventricular anchor locations. DESCRIPTION Seven porcine mitral valves were mounted in a left heart simulator. Neo-chordae (ePTFE) originated from either a simulated left ventricular apex, papillary muscle base, or papillary muscle tip location. The neo-chordae were attached at three sites along the P2 leaflet segment (P2Lateral, P2Center, P2Medial). Mitral regurgitation was induced by cutting posterior leaflet P2 marginal chordae. The forces on each neo-chord required to restore normal mitral valve coaptation were quantified for different ventricular anchoring origins and leaflet insertion sites. EVALUATION The results showed that under both normotensive and hypertensive conditions, the force exerted was much higher at P2Center than either the P2Lateral or P2Medial, independent of ventricular anchor location. Also, forces on both the P2Lateral and P2Medial were not statistically different. CONCLUSIONS Artificial neo-chordae treatment for all anchoring locations was effective in correcting induced mitral regurgitation. The P2 central neo-chordae had a significantly higher force than both lateral neo-chords under all conditions.
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Affiliation(s)
- Vahid Sadri
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Keshav Kohli
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Jorge H Jimenez
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - William S Cranford
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Abigail R Berry
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | | | | | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University.
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Morningstar JE, Gensemer C, Moore R, Fulmer D, Beck TC, Wang C, Moore K, Guo L, Sieg F, Nagata Y, Bertrand P, Spampinato RA, Glover J, Poelzing S, Gourdie RG, Watts K, Richardson WJ, Levine RA, Borger MA, Norris RA. Mitral Valve Prolapse Induces Regionalized Myocardial Fibrosis. J Am Heart Assoc 2021; 10:e022332. [PMID: 34873924 PMCID: PMC9075228 DOI: 10.1161/jaha.121.022332] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/13/2021] [Indexed: 02/06/2023]
Abstract
Background Mitral valve prolapse (MVP) is one of the most common forms of cardiac valve disease and affects 2% to 3% of the population. Previous imaging reports have indicated that myocardial fibrosis is common in MVP and described its association with sudden cardiac death. These data combined with evidence for postrepair ventricular dysfunction in surgical patients with MVP support a link between fibrosis and MVP. Methods and Results We performed histopathologic analysis of left ventricular (LV) biopsies from peripapillary regions, inferobasal LV wall and apex on surgical patients with MVP, as well as in a mouse model of human MVP (Dzip1S14R/+). Tension-dependent molecular pathways were subsequently assessed using both computational modeling and cyclical stretch of primary human cardiac fibroblasts in vitro. Histopathology of LV biopsies revealed regionalized fibrosis in the peripapillary myocardium that correlated with increased macrophages and myofibroblasts. The MVP mouse model exhibited similar regional increases in collagen deposition that progress over time. As observed in the patient biopsies, increased macrophages and myofibroblasts were observed in fibrotic areas within the murine heart. Computational modeling revealed tension-dependent profibrotic cellular and molecular responses consistent with fibrosis locations related to valve-induced stress. These simulations also identified mechanosensing primary cilia as involved in profibrotic pathways, which was validated in vitro and in human biopsies. Finally, in vitro stretching of primary human cardiac fibroblasts showed that stretch directly activates profibrotic pathways and increases extracellular matrix protein production. Conclusions The presence of prominent regional LV fibrosis in patients and mice with MVP supports a relationship between MVP and progressive damaging effects on LV structure before overt alterations in cardiac function. The regionalized molecular and cellular changes suggest a reactive response of the papillary and inferobasal myocardium to increased chordal tension from a prolapsing valve. These studies raise the question whether surgical intervention on patients with MVP should occur earlier than indicated by current guidelines to prevent advanced LV fibrosis and potentially reduce residual risk of LV dysfunction and sudden cardiac death.
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Affiliation(s)
| | | | - Reece Moore
- Medical University of South CarolinaCharlestonSC
| | - Diana Fulmer
- Medical University of South CarolinaCharlestonSC
| | | | | | - Kelsey Moore
- Medical University of South CarolinaCharlestonSC
| | - Lilong Guo
- Medical University of South CarolinaCharlestonSC
| | - Franz Sieg
- Leipzig Heart InstituteUniversity of LeipzigGermany
| | - Yasufumi Nagata
- Cardiac Ultrasound LaboratoryCardiology DivisionMassachusetts General HospitalBostonMA
| | - Philippe Bertrand
- Cardiac Ultrasound LaboratoryCardiology DivisionMassachusetts General HospitalBostonMA
| | | | | | - Stephen Poelzing
- Center for Heart and Reparative Medicine ResearchFralin Biomedical Research InstituteVirginia TechRoanokeVA
| | - Robert G. Gourdie
- Center for Heart and Reparative Medicine ResearchFralin Biomedical Research InstituteVirginia TechRoanokeVA
| | - Kelsey Watts
- Biomedical Data Science and Informatics ProgramDepartment of BioengineeringClemson UniversityClemsonSC
| | - William J. Richardson
- Biomedical Data Science and Informatics ProgramDepartment of BioengineeringClemson UniversityClemsonSC
| | - Robert A. Levine
- Cardiac Ultrasound LaboratoryCardiology DivisionMassachusetts General HospitalBostonMA
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Ali-Ghosh H, Barlow CW. Commentary: Biomechanical differences after mitral valve repair: Is it time to use the science? JTCVS Tech 2021; 10:252-253. [PMID: 34984385 PMCID: PMC8691929 DOI: 10.1016/j.xjtc.2021.10.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/11/2021] [Accepted: 10/21/2021] [Indexed: 11/18/2022] Open
Affiliation(s)
- Hani Ali-Ghosh
- Department of Cardiothoracic Surgery, University Hospital Southampton, Southampton, United Kingdom
| | - Clifford William Barlow
- Department of Cardiothoracic Surgery, University Hospital Southampton, Southampton, United Kingdom
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18
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DeCampli WM. Commentary: Neochord integrity: More than just initial breaking strength. JTCVS OPEN 2021; 8:276-277. [PMID: 36004200 PMCID: PMC9390560 DOI: 10.1016/j.xjon.2021.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 11/26/2022]
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19
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Imbrie-Moore AM, Zhu Y, Bandy-Vizcaino T, Park MH, Wilkerson RJ, Woo YJ. Ex Vivo Model of Ischemic Mitral Regurgitation and Analysis of Adjunctive Papillary Muscle Repair. Ann Biomed Eng 2021; 49:3412-3424. [PMID: 34734363 DOI: 10.1007/s10439-021-02879-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 10/15/2021] [Indexed: 01/24/2023]
Abstract
Ischemic mitral regurgitation (IMR) is particularly challenging to repair with lasting durability due to the complex valvular and subvalvular pathologies resulting from left ventricular dysfunction. Ex vivo simulation is uniquely suited to quantitatively analyze the repair biomechanics, but advancements are needed to model the nuanced IMR disease state. Here we present a novel IMR model featuring a dilation device with precise dilatation control that preserves annular elasticity to enable accurate ex vivo analysis of surgical repair. Coupled with augmented papillary muscle head positioning, the enhanced heart simulator system successfully modeled IMR pre- and post-surgical intervention and enabled the analysis of adjunctive subvalvular papillary muscle repair to alleviate regurgitation recurrence. The model resulted in an increase in regurgitant fraction: 11.6 ± 1.7% to 36.1 ± 4.4% (p < 0.001). Adjunctive papillary muscle head fusion was analyzed relative to a simple restrictive ring annuloplasty repair and, while both repairs successfully eliminated regurgitation initially, the addition of the adjunctive subvalvular repair reduced regurgitation recurrence: 30.4 ± 5.7% vs. 12.5 ± 2.6% (p = 0.002). Ultimately, this system demonstrates the success of adjunctive papillary muscle head fusion in repairing IMR as well as provides a platform to optimize surgical techniques for increased repair durability.
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Affiliation(s)
- Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA.,Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | | | - Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA.,Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Robert J Wilkerson
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA. .,Department of Bioengineering, Stanford University, Stanford, CA, USA.
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20
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Park MH, Zhu Y, Imbrie-Moore AM, Wang H, Marin-Cuartas M, Paulsen MJ, Woo YJ. Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation. Front Cardiovasc Med 2021; 8:673689. [PMID: 34307492 PMCID: PMC8295480 DOI: 10.3389/fcvm.2021.673689] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
The field of heart valve biomechanics is a rapidly expanding, highly clinically relevant area of research. While most valvular pathologies are rooted in biomechanical changes, the technologies for studying these pathologies and identifying treatments have largely been limited. Nonetheless, significant advancements are underway to better understand the biomechanics of heart valves, pathologies, and interventional therapeutics, and these advancements have largely been driven by crucial in silico, ex vivo, and in vivo modeling technologies. These modalities represent cutting-edge abilities for generating novel insights regarding native, disease, and repair physiologies, and each has unique advantages and limitations for advancing study in this field. In particular, novel ex vivo modeling technologies represent an especially promising class of translatable research that leverages the advantages from both in silico and in vivo modeling to provide deep quantitative and qualitative insights on valvular biomechanics. The frontiers of this work are being discovered by innovative research groups that have used creative, interdisciplinary approaches toward recapitulating in vivo physiology, changing the landscape of clinical understanding and practice for cardiovascular surgery and medicine.
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Affiliation(s)
- Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Bioengineering, Stanford University, Stanford, CA, United States
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21
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Imbrie-Moore AM, Park MH, Paulsen MJ, Sellke M, Kulkami R, Wang H, Zhu Y, Farry JM, Bourdillon AT, Callinan C, Lucian HJ, Hironaka CE, Deschamps D, Joseph Woo Y. Biomimetic six-axis robots replicate human cardiac papillary muscle motion: pioneering the next generation of biomechanical heart simulator technology. J R Soc Interface 2020; 17:20200614. [PMID: 33259750 DOI: 10.1098/rsif.2020.0614] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Papillary muscles serve as attachment points for chordae tendineae which anchor and position mitral valve leaflets for proper coaptation. As the ventricle contracts, the papillary muscles translate and rotate, impacting chordae and leaflet kinematics; this motion can be significantly affected in a diseased heart. In ex vivo heart simulation, an explanted valve is subjected to physiologic conditions and can be adapted to mimic a disease state, thus providing a valuable tool to quantitatively analyse biomechanics and optimize surgical valve repair. However, without the inclusion of papillary muscle motion, current simulators are limited in their ability to accurately replicate cardiac biomechanics. We developed and implemented image-guided papillary muscle (IPM) robots to mimic the precise motion of papillary muscles. The IPM robotic system was designed with six degrees of freedom to fully capture the native motion. Mathematical analysis was used to avoid singularity conditions, and a supercomputing cluster enabled the calculation of the system's reachable workspace. The IPM robots were implemented in our heart simulator with motion prescribed by high-resolution human computed tomography images, revealing that papillary muscle motion significantly impacts the chordae force profile. Our IPM robotic system represents a significant advancement for ex vivo simulation, enabling more reliable cardiac simulations and repair optimizations.
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Affiliation(s)
- Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.,Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.,Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Mark Sellke
- Department of Mathematics, Stanford University, Stanford, CA, USA
| | - Rohun Kulkami
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Justin M Farry
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | | | - Christine Callinan
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.,Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Haley J Lucian
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Camille E Hironaka
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Daniela Deschamps
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
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22
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Imbrie-Moore AM, Zhu Y, Park MH, Paulsen MJ, Wang H, Woo YJ. Artificial papillary muscle device for off-pump transapical mitral valve repair. J Thorac Cardiovasc Surg 2020; 164:e133-e141. [PMID: 33451843 DOI: 10.1016/j.jtcvs.2020.11.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/14/2020] [Accepted: 11/19/2020] [Indexed: 01/31/2023]
Abstract
OBJECTIVE New transapical minimally invasive artificial chordae implantation devices are a promising alternative to traditional open-heart repair, with the potential for decreased postoperative morbidity and reduced recovery time. However, these devices can place increased stress on the artificial chordae. We designed an artificial papillary muscle to alleviate artificial chordae stresses and thus increase repair durability. METHODS The artificial papillary muscle device is a narrow elastic column with an inner core that can be implanted during the minimally invasive transapical procedure via the same ventricular incision site. The device was 3-dimensionally printed in biocompatible silicone for this study. To test efficacy, porcine mitral valves (n = 6) were mounted in a heart simulator, and isolated regurgitation was induced. Each valve was repaired with a polytetrafluoroethylene suture with apical anchoring followed by artificial papillary muscle anchoring. In each case, a high-resolution Fiber Bragg Grating sensor recorded forces on the suture. RESULTS Hemodynamic data confirmed that both repairs-with and without the artificial papillary muscle device-were successful in eliminating mitral regurgitation. Both the peak artificial chordae force and the rate of change of force at the onset of systole were significantly lower with the device compared with apical anchoring without the device (P < .001 and P < .001, respectively). CONCLUSIONS Our novel artificial papillary muscle could integrate with minimally invasive repairs to shorten the artificial chordae and behave as an elastic damper, thus reducing sharp increases in force. With our device, we have the potential to improve the durability of off-pump transapical mitral valve repair procedures.
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Affiliation(s)
- Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif
| | - Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif.
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23
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Paulsen MJ, Imbrie-Moore AM, Baiocchi M, Wang H, Hironaka CE, Lucian HJ, Farry JM, Thakore AD, Zhu Y, Ma M, MacArthur JW, Woo YJ. Comprehensive Ex Vivo Comparison of 5 Clinically Used Conduit Configurations for Valve-Sparing Aortic Root Replacement Using a 3-Dimensional-Printed Heart Simulator. Circulation 2020; 142:1361-1373. [PMID: 33017215 PMCID: PMC7531510 DOI: 10.1161/circulationaha.120.046612] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Supplemental Digital Content is available in the text. Background: Many graft configurations are clinically used for valve-sparing aortic root replacement, some specifically focused on recapitulating neosinus geometry. However, the specific impact of such neosinuses on valvular and root biomechanics and the potential influence on long-term durability are unknown. Methods: Using a custom 3-dimenstional–printed heart simulator with porcine aortic roots (n=5), the anticommissural plication, Stanford modification, straight graft (SG), Uni-Graft, and Valsalva graft configurations were tested in series using an incomplete counterbalanced measures design, with the native root as a control, to mitigate ordering effects. Hemodynamic and videometric data were analyzed using linear models with conduit as the fixed effect of interest and valve as a fixed nuisance effect with post hoc pairwise testing using Tukey’s correction. Results: Hemodynamics were clinically similar between grafts and control aortic roots. Regurgitant fraction varied between grafts, with SG and Uni-Graft groups having the lowest regurgitant fractions and anticommissural plication having the highest. Root distensibility was significantly lower in SG versus both control roots and all other grafts aside from the Stanford modification (P≤0.01 for each). All grafts except SG had significantly higher cusp opening velocities versus native roots (P<0.01 for each). Relative cusp opening forces were similar between SG, Uni-Graft, and control groups, whereas anticommissural plication, Stanford modification, and Valsalva grafts had significantly higher opening forces versus controls (P<0.01). Cusp closing velocities were similar between native roots and the SG group, and were significantly lower than observed in the other conduits (P≤0.01 for each). Only SG and Uni-Graft groups experienced relative cusp closing forces approaching that of the native root, whereas relative forces were >5-fold higher in the anticommissural plication, Stanford modification, and Valsalva graft groups. Conclusions: In this ex vivo modeling system, clinically used valve-sparing aortic root replacement conduit configurations have comparable hemodynamics but differ in biomechanical performance, with the straight graft most closely recapitulating native aortic root biomechanics.
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Affiliation(s)
- Michael J Paulsen
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Mechanical Engineering (A.M.I.M.), Stanford University, CA
| | - Michael Baiocchi
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Health Research and Policy (M.B.), Stanford University, CA
| | - Hanjay Wang
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Camille E Hironaka
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Haley J Lucian
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Justin M Farry
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Akshara D Thakore
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Michael Ma
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - John W MacArthur
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery (M.J.P., A.M.I.-M., M.B., H.W., C.E.H., H.J.L., J.M.F., A.D.T., Y.Z., M.M., J.W.M., Y.J.W.), Stanford University, CA.,Department of Bioengineering (Y.J.W.), Stanford University, CA
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24
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A Novel Aortic Regurgitation Model from Cusp Prolapse with Hemodynamic Validation Using an Ex Vivo Left Heart Simulator. J Cardiovasc Transl Res 2020; 14:283-289. [PMID: 32495264 DOI: 10.1007/s12265-020-10038-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/20/2020] [Indexed: 02/07/2023]
Abstract
Although ex vivo simulation is a valuable tool for surgical optimization, a disease model that mimics human aortic regurgitation (AR) from cusp prolapse is needed to accurately examine valve biomechanics. To simulate AR, four porcine aortic valves were explanted, and the commissure between the two largest leaflets was detached and re-implanted 5 mm lower to induce cusp prolapse. Four additional valves were tested in their native state as controls. All valves were tested in a heart simulator while hemodynamics, high-speed videography, and echocardiography data were collected. Our AR model successfully reproduced cusp prolapse with significant increase in regurgitant volume compared with that of the controls (23.2 ± 8.9 versus 2.8 ± 1.6 ml, p = 0.017). Hemodynamics data confirmed the simulation of physiologic disease conditions. Echocardiography and color flow mapping demonstrated the presence of mild to moderate eccentric regurgitation in our AR model. This novel AR model has enormous potential in the evaluation of valve biomechanics and surgical repair techniques. Graphical Abstract.
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25
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Wang H, Paulsen MJ, Imbrie-Moore AM, Tada Y, Bergamasco H, Baker SW, Shudo Y, Ma M, Woo YJ. In Vivo Validation of Restored Chordal Biomechanics After Mitral Ring Annuloplasty in a Rare Ovine Case of Natural Chronic Functional Mitral Regurgitation. J Cardiovasc Dev Dis 2020; 7:jcdd7020017. [PMID: 32429298 PMCID: PMC7344614 DOI: 10.3390/jcdd7020017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 01/11/2023] Open
Abstract
Mitral valve chordae tendineae forces are elevated in the setting of mitral regurgitation (MR). Ring annuloplasty is an essential component of surgical repair for MR, but whether chordal forces are reduced after mitral annuloplasty has never been validated in vivo. Here, we present an extremely rare ovine case of natural, severe chronic functional MR, in which we used force-sensing fiber Bragg grating neochordae to directly measure chordal forces in the baseline setting of severe MR, as well as after successful mitral ring annuloplasty repair. Overall, our report is the first to confirm in vivo that mitral ring annuloplasty reduces elevated chordae tendineae forces associated with chronic functional MR.
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Affiliation(s)
- Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA;
| | - Michael J. Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
| | - Annabel M. Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yuko Tada
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA;
- Department of Cardiovascular Medicine, Stanford University, Stanford, CA 94305, USA
| | - Hunter Bergamasco
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
| | - Sam W. Baker
- Department of Comparative Medicine, Stanford University, Stanford, CA 94305, USA;
| | - Yasuhiro Shudo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA;
| | - Michael Ma
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305, USA; (H.W.); (M.J.P.); (A.M.I.-M.); (H.B.); (Y.S.); (M.M.)
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA;
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Correspondence: ; Tel.: +1-650-725-3828
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26
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Merkle-Storms J, Liakopoulos OJ. Commentary: Mitral valve repair using adjustable posterior leaflet neochords. JTCVS Tech 2020; 2:56-57. [PMID: 34317751 PMCID: PMC8298850 DOI: 10.1016/j.xjtc.2020.01.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 12/13/2019] [Accepted: 01/02/2020] [Indexed: 12/03/2022] Open
Affiliation(s)
- Julia Merkle-Storms
- Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany
| | - Oliver J Liakopoulos
- Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany
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27
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Imbrie-Moore AM, Paulsen MJ, Zhu Y, Wang H, Lucian HJ, Farry JM, MacArthur JW, Ma M, Woo YJ. A novel cross-species model of Barlow's disease to biomechanically analyze repair techniques in an ex vivo left heart simulator. J Thorac Cardiovasc Surg 2020; 161:1776-1783. [PMID: 32249088 DOI: 10.1016/j.jtcvs.2020.01.086] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/17/2019] [Accepted: 01/02/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Barlow's disease remains challenging to repair, given the complex valvular morphology and lack of quantitative data to compare techniques. Although there have been recent strides in ex vivo evaluation of cardiac mechanics, to our knowledge, there is no disease model that accurately simulates the morphology and pathophysiology of Barlow's disease. The purpose of this study was to design such a model. METHODS To simulate Barlow's disease, a cross-species ex vivo model was developed. Bovine mitral valves (n = 4) were sewn into a porcine annulus mount to create excess leaflet tissue and elongated chordae. A heart simulator generated physiologic conditions while hemodynamic data, high-speed videography, and chordal force measurements were collected. The regurgitant valves were repaired using nonresectional repair techniques such as neochord placement. RESULTS The model successfully imitated the complexities of Barlow's disease, including redundant, billowing bileaflet tissues with notable regurgitation. After repair, hemodynamic data confirmed reduction of mitral leakage volume (25.9 ± 2.9 vs 2.1 ± 1.8 mL, P < .001) and strain gauge analysis revealed lower primary chordae forces (0.51 ± 0.17 vs 0.10 ± 0.05 N, P < .001). In addition, the maximum rate of change of force was significantly lower postrepair for both primary (30.80 ± 11.38 vs 8.59 ± 4.83 N/s, P < .001) and secondary chordae (33.52 ± 10.59 vs 19.07 ± 7.00 N/s, P = .006). CONCLUSIONS This study provides insight into the biomechanics of Barlow's disease, including sharply fluctuating force profiles experienced by elongated chordae prerepair, as well as restoration of primary chordae forces postrepair. Our disease model facilitates further in-depth analyses to optimize the repair of Barlow's disease.
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Affiliation(s)
- Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Haley J Lucian
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Justin M Farry
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - John W MacArthur
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Michael Ma
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif; Department of Bioengineering, Stanford University, Stanford, Calif.
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A novel 3D-Printed preferential posterior mitral annular dilation device delineates regurgitation onset threshold in an ex vivo heart simulator. Med Eng Phys 2020; 77:10-18. [PMID: 32008935 DOI: 10.1016/j.medengphy.2020.01.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/21/2019] [Accepted: 01/12/2020] [Indexed: 12/17/2022]
Abstract
Mitral regurgitation (MR) due to annular dilation occurs in a variety of mitral valve diseases and is observed in many patients with heart failure due to mitral regurgitation. To understand the biomechanics of MR and ultimately design an optimized annuloplasty ring, a representative disease model with asymmetric dilation of the mitral annulus is needed. This work shows the design and implementation of a 3D-printed valve dilation device to preferentially dilate the posterior mitral valve annulus. Porcine mitral valves (n = 3) were sewn into the device and mounted within a left heart simulator that generates physiologic pressures and flows through the valves, while chordal forces were measured. The valves were incrementally dilated, inducing MR, while hemodynamic and force data were collected. Flow analysis demonstrated that MR increased linearly with respect to percent annular dilation when dilation was greater than a 25.6% dilation threshold (p < 0.01). Pre-threshold, dilation did not cause significant increases in regurgitant fraction. Forces on the chordae tendineae increased as dilation increased prior to the identified threshold (p < 0.01); post-threshold, the MR resulted in highly variable forces. Ultimately, this novel dilation device can be used to more accurately model a wide range of MR disease states and their corresponding repair techniques using ex vivo experimentation. In particular, this annular dilation device provides the means to investigate the design and optimization of novel annuloplasty rings.
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