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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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Park C, Singh M, Saeed MY, Nguyen CT, Roche ET. Biorobotic hybrid heart as a benchtop cardiac mitral valve simulator. DEVICE 2024; 2:100217. [PMID: 38312504 PMCID: PMC10836162 DOI: 10.1016/j.device.2023.100217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
In this work, we developed a high-fidelity beating heart simulator that provides accurate mitral valve pathophysiology. The benchtop platform is based on a biorobotic hybrid heart that combines preserved intracardiac tissue with soft robotic cardiac muscle providing dynamic left ventricular motion and precise anatomical features designed for testing intracardiac devices, particularly for mitral valve repair. The heart model is integrated into a mock circulatory loop, and the active myocardium drives fluid circulation producing physiological hemodynamics without an external pulsatile pump. Using biomimetic soft robotic technology, the heart can replicate both ventricular and septal wall motion, as well as intraventricular pressure-volume relationships. This enables the system to recreate the natural motion and function of the mitral valve, which allows us to demonstrate various surgical and interventional techniques. The biorobotic cardiovascular simulator allows for real-time hemodynamic data collection, direct visualization of the intracardiac procedure, and compatibility with clinical imaging modalities.
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Affiliation(s)
- Clara Park
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology; Cambridge, MA, USA 02139
- Department of Mechanical Engineering, Massachusetts Institute of Technology; Cambridge, MA, USA 02139
| | - Manisha Singh
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology; Cambridge, MA, USA 02139
| | - Mossab Y. Saeed
- Department of Cardiac Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA 02115
| | - Christopher T. Nguyen
- Cardiovascular Research Center, Massachusetts General Hospital; Charlestown, MA, USA 02114
- Cardiovascular Innovation Research Center, Heart Vascular Thoracic Institute, Cleveland Clinic; Cleveland, OH, USA 44195
- Imaging Sciences, Imaging Institute, Cleveland Clinic; Cleveland, OH, USA 44195
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic; Cleveland, OH, USA 44196
| | - Ellen T. Roche
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology; Cambridge, MA, USA 02139
- Department of Mechanical Engineering, Massachusetts Institute of Technology; Cambridge, MA, USA 02139
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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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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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Delling FN, Noseworthy PA, Adams DH, Basso C, Borger M, Bouatia-Naji N, Elmariah S, Evans F, Gerstenfeld E, Hung J, Le Tourneau T, Lewis J, Miller MA, Norris RA, Padala M, Perazzolo-Marra M, Shah DJ, Weinsaft JW, Enriquez-Sarano M, Levine RA. Research Opportunities in the Treatment of Mitral Valve Prolapse: JACC Expert Panel. J Am Coll Cardiol 2022; 80:2331-2347. [PMID: 36480975 PMCID: PMC9981237 DOI: 10.1016/j.jacc.2022.09.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/31/2022] [Accepted: 09/12/2022] [Indexed: 12/10/2022]
Abstract
In light of the adverse prognosis related to severe mitral regurgitation, heart failure, or sudden cardiac death in a subset of patients with mitral valve prolapse (MVP), identifying those at higher risk is key. For the first time in decades, researchers have the means to rapidly advance discovery in the field of MVP thanks to state-of-the-art imaging techniques, novel omics methodologies, and the potential for large-scale collaborations using web-based platforms. The National Heart, Lung, and Blood Institute recently initiated a webinar-based workshop to identify contemporary research opportunities in the treatment of MVP. This report summarizes 3 specific areas in the treatment of MVP that were the focus of the workshop: 1) improving management of degenerative mitral regurgitation and associated left ventricular systolic dysfunction; 2) preventing sudden cardiac death in MVP; and 3) understanding the mechanisms and progression of MVP through genetic studies and small and large animal models, with the potential of developing medical therapies.
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Affiliation(s)
- Francesca N Delling
- Department of Medicine (Cardiovascular Division), University of California-San Francisco, San Francisco, California, USA.
| | - Peter A Noseworthy
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - David H Adams
- Department of Cardiovascular Surgery, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Cristina Basso
- Cardiovascular Pathology, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy
| | | | | | - Sammy Elmariah
- Department of Medicine (Cardiovascular Division), University of California-San Francisco, San Francisco, California, USA; Department of Medicine, Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Frank Evans
- National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
| | - Edward Gerstenfeld
- Department of Medicine (Cardiovascular Division), University of California-San Francisco, San Francisco, California, USA
| | - Judy Hung
- Department of Medicine, Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Thierry Le Tourneau
- Nantes Université, CHU Nantes, CNRS, INSERM, l'Institut du Thorax, Nantes, France
| | - John Lewis
- Heart Valve Voice US, Washington, DC, USA
| | - Marc A Miller
- Helmsley Electrophysiology Center, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Russell A Norris
- Department of Regenerative Medicine and Cell Biology, Department of Neurosurgery, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Muralidhar Padala
- Department of Surgery (Cardiothoracic Surgery Division), Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Dipan J Shah
- Department of Cardiology, Houston Methodist, Weill Cornell Medical College, Houston, Texas, USA
| | | | | | - Robert A Levine
- Massachusetts General Hospital Cardiac Ultrasound Laboratory, Boston, Massachusetts, USA
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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: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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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Fernández L, Monzonís AM, El-Diasty MM, Álvarez-Lorenzo C, Concheiro Á, Fernández ÁL. Biomechanical characteristics of different methods of neo-chordal fixation to the papillary muscles. J Card Surg 2022; 37:4408-4415. [PMID: 36229983 PMCID: PMC10092600 DOI: 10.1111/jocs.17027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/15/2022] [Accepted: 09/03/2022] [Indexed: 01/06/2023]
Abstract
BACKGROUND AND AIM OF THE STUDY Several techniques have been described for neo-chordal fixation to the papillary muscles without any reported clinical differences. The objective of this study is to compare in vitro the biomechanical properties of four of these common techniques. METHODS We studied the biomechanical properties of expanded polytetrafluoroethylene neo-chordal fixation using four techniques: nonknotted simple stitch, nonknotted figure-of-eight stitch, knotted pledgeted mattress stitch, and knotted pledgeted stitch using commercially available prefabricated loops. Neo-chordae were submitted to a total of 20 traction-relaxation cycles with incremental loads of 1, 2, and 4 N. We calculated the elongation, the force-strain curve, elasticity, and the maximum tolerated load before neo-chordal failure. RESULTS The elongation of the neo-chordae was lowest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and he commercially prefabricated loops (p < .001). Conversely, the elastic modulus was highest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and the prefabricated loops (p < .001). The maximum tolerated load was similar with the simple stitch (28.87 N) and with the figure-of-eight stitch (31.39 N) but was significantly lower with the pledgeted mattress stitch (20.51 N) and with the prefabricated loops (7.78 N). CONCLUSION In vitro, neo-chordal fixation by nonknotted simple or nonknotted figure-of-eight stitches resulted in less compliance as opposed to the use of knotted pledgeted stitches. Fixation technique seemed to influence neo-chordal biomechanical properties, however, it did not seem to affect the strength of the suture when subjected to loads within physiological ranges.
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Affiliation(s)
- Luis Fernández
- Department of Applied Physics, School of Physics, University of Santiago de Compostela, Santiago, Spain
| | | | | | - Carmen Álvarez-Lorenzo
- Department of Pharmacology, Pharmacy, and Pharmaceutical Technology, University of Santiago de Compostela, Santiago, Spain
| | - Ángel Concheiro
- Department of Pharmacology, Pharmacy, and Pharmaceutical Technology, University of Santiago de Compostela, Santiago, Spain
| | - Ángel L Fernández
- Divison of Cardiac Surgery, Department of Surgery, University Hospital, University of Santiago de Compostela, Santiago, Spain
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11
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Park MH, Imbrie-Moore AM, Zhu Y, Sellke M, Marin-Cuartas M, Wilkerson R, Woo YJ. A Novel Accelerated Fatigue Testing System for Pulsatile Applications of Cardiac Devices Using Widely Translatable Cam and Linkage-Based Mechanisms. Med Eng Phys 2022; 109:103896. [DOI: 10.1016/j.medengphy.2022.103896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/02/2022] [Accepted: 09/21/2022] [Indexed: 10/14/2022]
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12
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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] [Key Words] [Grants] [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 Suture pull-out remains a significant mechanism of long-term neochordal repair failure, as demonstrated by clinical reports on recurrent mitral valve regurgitation and need for reoperation. The objective of this study was to provide a quantitative comparison of suture pull-out forces for various neochordal implantation locations. Methods Posterior leaflets were excised from fresh porcine mitral valves (n = 54) and fixed between two 3-dimensional-printed plates. Gore-Tex CV-5 sutures (WL Gore & Associates Inc) were placed with distances from the leading edge and widths between anchoring sutures with values of 2 mm, 6 mm, and 10 mm for a total of 9 groups (n = 6 per group). Mechanical testing was performed using a tensile testing machine to evaluate pull-out force of the suture through the mitral valve leaflet. Results Increasing the suture anchoring width improved failure strength significantly across all leading-edge distances (P < .001). Additionally, increasing the leading-edge distance from 2 mm to 6 mm increased suture pull-out forces significantly across all suture widths (P < .001). For 6-mm and 10-mm widths, increasing the leading-edge distance from 6 mm to 10 mm increased suture pull-out forces by an average of 3.58 ± 0.15 N; in comparison, for leading-edge distances of 6 mm and 10 mm, increasing the suture anchoring width from 6 mm to 10 mm improves the force by an average of 7.09 ± 0.44 N. Conclusions Increasing suture anchoring width and leading-edge distance improves the suture pull-out force through the mitral leaflet, which may optimize postrepair durability. The results suggest a comparative advantage to increasing suture anchoring width compared with leading-edge distance.
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Affiliation(s)
- Pearly K. Pandya
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | | | - 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
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Matthew H. Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, 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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13
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Onohara D, Suresh KS, Silverman M, He Q, Kono T, Padala M. Image-Guided Targeted Mitral Valve Tethering with Chordal Encircling Snares as a Preclinical Model of Secondary Mitral Regurgitation. J Cardiovasc Transl Res 2022; 15:653-665. [PMID: 34618333 PMCID: PMC10797638 DOI: 10.1007/s12265-021-10177-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/23/2021] [Indexed: 10/20/2022]
Abstract
Development of transcatheter mitral valve interventions has ushered a significant need for large animal models of secondary mitral regurgitation. Though currently used heart failure models that chronically develop secondary mitral regurgitation are viable, the severity is lower than patients, the incubation time is long, and mortality is high. We sought to develop a swine model of acute secondary mitral regurgitation that uses image-guided placement of snares around the mitral chordae. Twenty-seven adult swine (n = 27) were assigned to secondary mitral regurgitation induced by valve tethering with image-guided chordal encircling snares (group 1, n = 7, tether MR (tMR)); secondary mitral regurgitation by percutaneous posterolateral myocardial infarction causing ventricular dysfunction and regurgitation (group 2, n = 6, functional MR (fMR)); and control animals (group 3, n = 14). Regurgitant fraction in tMR was 42.1 ± 14.2%, in fMR was 22 ± 9.6%, and in controls was 5.3 ± 3.8%. Mitral tenting height was 9.6 ± 1.3 mm in tMR, 10.1 ± 1.5 mm in fMR, and 5.8 ± 1.2 mm in controls. Chordal encircling tethers reproducibly induce clinically relevant levels of secondary mitral regurgitation, providing a new animal model for use in translational research.
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Affiliation(s)
- Daisuke Onohara
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA
- Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, GA, USA
| | - Kirthana Sreerangathama Suresh
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA
| | - Michael Silverman
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA
| | - Qi He
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA
| | - Takanori Kono
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA
| | - Muralidhar Padala
- Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center, Emory University Hospital Midtown, Atlanta, GA, USA.
- Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, GA, USA.
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14
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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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15
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May the Force Be With You. Ann Thorac Surg 2022; 113:1384-1385. [PMID: 34973188 DOI: 10.1016/j.athoracsur.2021.11.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 11/29/2021] [Indexed: 11/23/2022]
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16
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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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17
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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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18
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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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Park MH, Marin-Cuartas M, Imbrie-Moore AM, Wilkerson RJ, Pandya PK, Zhu Y, Wang H, Borger MA, Woo YJ. Biomechanical Analysis of Neochordal Repair Error from Diastolic Phase Inversion of Static Left Ventricular Pressurization. JTCVS Tech 2022; 12:54-64. [PMID: 35403058 PMCID: PMC8987390 DOI: 10.1016/j.xjtc.2022.01.009] [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: 07/27/2021] [Accepted: 01/12/2022] [Indexed: 11/30/2022] Open
Abstract
Objective Neochordal implantation is a common form of surgical mitral valve (MV) repair. However, neochord length is assessed using static left ventricular pressurization, leading surgeons to evaluate leaflet coaptation and valve competency when the left ventricle is dilating instead of contracting physiologically, referred to as diastolic phase inversion (DPI). We hypothesize that the difference in papillary muscle (PM) positioning between DPI and physiologic systole results in miscalculated neochord lengths, which might affect repair performance. Methods Porcine MVs (n = 6) were mounted in an ex vivo heart simulator and PMs were affixed to robots that accurately simulate PM motion. Baseline hemodynamic and chordal strain data were collected, after which P2 chordae were severed to simulate posterior leaflet prolapse from chordal rupture and subsequent mitral regurgitation. Neochord implantation was performed in the physiologic and DPI static configurations. Results Although both repairs successfully reduced mitral regurgitation, the DPI repair resulted in longer neochordae (2.19 ± 0.4 mm; P < .01). Furthermore, the hemodynamic performance was reduced for the DPI repair resulting in higher leakage volume (P = .01) and regurgitant fraction (P < .01). Peak chordal forces were reduced in the physiologic repair (0.57 ± 0.11 N) versus the DPI repair (0.68 ± 0.12 N; P < .01). Conclusions By leveraging advanced ex vivo technologies, we were able to quantify the effects of static pressurization on neochordal length determination. Our findings suggest that this post-repair assessment might slightly overestimate the neochordal length and that additional marginal shortening of neochordae might positively affect MV repair performance and durability by reducing load on surrounding native chordae.
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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
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Annabel M. Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | | | - Pearly K. Pandya
- 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
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Michael A. Borger
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Bioengineering, Stanford University, Stanford, Calif
- Address for reprints: Y. Joseph Woo, MD, Department of Cardiothoracic Surgery, Department of Bioengineering, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA 94305-5407.
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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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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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23
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Zurbuchen A, Pfenniger A, Omari S, Reichlin T, Vogel R, Haeberlin A. A Robot Mimicking Heart Motions: An Ex-Vivo Test Approach for Cardiac Devices. Cardiovasc Eng Technol 2021; 13:207-218. [PMID: 34409579 PMCID: PMC9114091 DOI: 10.1007/s13239-021-00566-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 07/12/2021] [Indexed: 11/25/2022]
Abstract
Purpose The pre-clinical testing of cardiovascular implants gains increasing attention due to the complexity of novel implants and new medical device regulations. It often relies on large animal experiments that are afflicted with ethical and methodical challenges. Thus, a method for simulating physiological heart motions is desired but lacking so far. Methods We developed a robotic platform that allows simulating the trajectory of any point of the heart (one at a time) in six degrees of freedom. It uses heart motion trajectories acquired from cardiac magnetic resonance imaging or accelero-meter data. The rotations of the six motors are calculated based on the input trajectory. A closed-loop controller drives the platform and a graphical user interface monitors the functioning and accuracy of the robot using encoder data. Results The robotic platform can mimic physiological heart motions from large animals and humans. It offers a spherical work envelope with a radius of 29 mm, maximum acceleration of 20 m/s2 and maximum deflection of ±19° along all axes. The absolute mean positioning error in x-, y- and z-direction is 0.21 ±0.06, 0.31 ±0.11 and 0.17 ±0.12 mm, respectively. The absolute mean orientation error around x-, y- and z-axis (roll, pitch and yaw) is 0.24 ±0.18°, 0.23 ±0.13° and 0.18 ±0.18°, respectively. Conclusion The novel robotic approach allows reproducing heart motions with high accuracy and repeatability. This may benefit the device development process and allows re-using previously acquired heart motion data repeatedly, thus avoiding animal trials. Supplementary Information The online version contains supplementary material available at 10.1007/s13239-021-00566-3.
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Affiliation(s)
- Adrian Zurbuchen
- Department of Cardiology, Bern University Hospital, University of Bern, Freiburgstrassse 3, 3010, Bern, Switzerland.
- sitem Center for Translational Medicine and Biomedical Entrepreneurship, University of Bern, Bern, Switzerland.
- ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland.
| | - Aloïs Pfenniger
- ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland
- Sonceboz SA, Sonceboz, Switzerland
| | - Sammy Omari
- Department of Cardiology, Bern University Hospital, University of Bern, Freiburgstrassse 3, 3010, Bern, Switzerland
- ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland
- Lyft Inc., San Francisco, CA, USA
| | - Tobias Reichlin
- Department of Cardiology, Bern University Hospital, University of Bern, Freiburgstrassse 3, 3010, Bern, Switzerland
| | - Rolf Vogel
- Department of Cardiology, Bürgerspital Solothurn, Solothurn, Switzerland
| | - Andreas Haeberlin
- Department of Cardiology, Bern University Hospital, University of Bern, Freiburgstrassse 3, 3010, Bern, Switzerland.
- sitem Center for Translational Medicine and Biomedical Entrepreneurship, University of Bern, Bern, Switzerland.
- ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland.
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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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25
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Paulsen MJ, Imbrie-Moore AM, Wang H, Bae JH, Hironaka CE, Farry JM, Lucian HJ, Thakore AD, MacArthur JW, Cutkosky MR, Woo YJ. Mitral chordae tendineae force profile characterization using a posterior ventricular anchoring neochordal repair model for mitral regurgitation in a three-dimensional-printed ex vivo left heart simulator. Eur J Cardiothorac Surg 2021; 57:535-544. [PMID: 31638697 PMCID: PMC7954270 DOI: 10.1093/ejcts/ezz258] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/19/2019] [Accepted: 08/26/2019] [Indexed: 12/13/2022] Open
Abstract
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OBJECTIVES Posterior ventricular anchoring neochordal (PVAN) repair is a non-resectional technique for correcting mitral regurgitation (MR) due to posterior leaflet prolapse, utilizing a single suture anchored in the myocardium behind the leaflet. This technique has demonstrated clinical efficacy, although a theoretical limitation is stability of the anchoring suture. We hypothesize that the PVAN suture positions the leaflet for coaptation, after which forces are distributed evenly with low repair suture forces. METHODS Porcine mitral valves were mounted in a 3-dimensional-printed heart simulator and chordal forces, haemodynamics and echocardiography were collected at baseline, after inducing MR by severing chordae, and after PVAN repair. Repair suture forces were measured with a force-sensing post positioned to mimic in vivo suture placement. Forces required to pull the myocardial suture free were also determined. RESULTS Relative primary and secondary chordae forces on both leaflets were elevated during prolapse (P < 0.05). PVAN repair eliminated MR in all valves and normalized chordae forces to baseline levels on anterior primary (0.37 ± 0.23 to 0.22 ± 0.09 N, P < 0.05), posterior primary (0.62 ± 0.37 to 0.14 ± 0.05 N, P = 0.001), anterior secondary (1.48 ± 0.52 to 0.85 ± 0.43 N, P < 0.001) and posterior secondary chordae (1.42 ± 0.69 to 0.59 ± 0.17 N, P = 0.005). Repair suture forces were minimal, even compared to normal primary chordae forces (0.08 ± 0.04 vs 0.19 ± 0.08 N, P = 0.002), and were 90 times smaller than maximum forces tolerated by the myocardium (0.08 ± 0.04 vs 6.9 ± 1.3 N, P < 0.001). DISCUSSION PVAN repair eliminates MR by positioning the posterior leaflet for coaptation, distributing forces throughout the valve. Given extremely low measured forces, the strength of the repair suture and the myocardium is not a limitation.
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Affiliation(s)
- Michael J Paulsen
- Department of Cardiothoracic Surgery, 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
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Jung Hwa Bae
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Camille E Hironaka
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Justin M Farry
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Haley J Lucian
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Akshara D Thakore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - John W MacArthur
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Mark R Cutkosky
- 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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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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27
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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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28
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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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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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30
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Wan S, Liu J. Commentary: Strength at the cutting edge. JTCVS Tech 2020; 2:58-59. [PMID: 34317752 PMCID: PMC8298826 DOI: 10.1016/j.xjtc.2020.02.008] [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: 01/19/2020] [Revised: 01/19/2020] [Accepted: 02/02/2020] [Indexed: 11/22/2022] Open
Affiliation(s)
- Song Wan
- Division of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
- Address for reprints: Song Wan, MD, FRCS, Division of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
| | - Jun Liu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
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31
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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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Paulsen MJ, Bae JH, Imbrie-Moore AM, Wang H, Hironaka CE, Farry JM, Lucian H, Thakore AD, Cutkosky MR, Joseph Woo Y. Development and Ex Vivo Validation of Novel Force-Sensing Neochordae for Measuring Chordae Tendineae Tension in the Mitral Valve Apparatus Using Optical Fibers With Embedded Bragg Gratings. J Biomech Eng 2020; 142:014501. [PMID: 31253992 PMCID: PMC7104756 DOI: 10.1115/1.4044142] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 05/23/2019] [Indexed: 11/17/2022]
Abstract
Few technologies exist that can provide quantitative data on forces within the mitral valve apparatus. Marker-based strain measurements can be performed, but chordal geometry and restricted optical access are limitations. Foil-based strain sensors have been described and work well, but the sensor footprint limits the number of chordae that can be measured. We instead utilized fiber Bragg grating (FBG) sensors-optical strain gauges made of 125 μm diameter silica fibers-to overcome some limitations of previous methods of measuring chordae tendineae forces. Using FBG sensors, we created a force-sensing neochord (FSN) that mimics the natural shape and movement of native chordae. FBG sensors reflect a specific wavelength of light depending on the spatial period of gratings. When force is applied, the gratings move relative to one another, shifting the wavelength of reflected light. This shift is directly proportional to force applied. The FBG sensors were housed in a protective sheath fashioned from a 0.025 in. flat coil, and attached to the chordae using polytetrafluoroethylene suture. The function of the force-sensing neochordae was validated in a three-dimensional (3D)-printed left heart simulator, which demonstrated that FBG sensors provide highly sensitive force measurements of mitral valve chordae at a temporal resolution of 1000 Hz. As ventricular pressures increased, such as in hypertension, chordae forces also increased. Overall, FBG sensors are a viable, durable, and high-fidelity sensing technology that can be effectively used to measure mitral valve chordae forces and overcome some limitations of other such technologies.
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Affiliation(s)
- Michael J. Paulsen
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Jung Hwa Bae
- Department of Mechanical Engineering, Stanford
University, Stanford, CA 94305
| | - Annabel M. Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305; Department
of Mechanical Engineering, Stanford University,
Stanford, CA 94305
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Camille E. Hironaka
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Justin M. Farry
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Haley Lucian
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Akshara D. Thakore
- Department of Cardiothoracic Surgery, Stanford
University, Stanford, CA 94305
| | - Mark R. Cutkosky
- Department of Mechanical Engineering, Stanford
University, Stanford, CA 94305
| | - Y. Joseph Woo
- Norman E. Shumway Professor and Chair Department of Cardiothoracic
Surgery, Stanford University, Stanford, CA
94305; Department of Bioengineering, Stanford
University, Stanford, CA 94305
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Kaiser AD, McQueen DM, Peskin CS. Modeling the mitral valve. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3240. [PMID: 31330567 DOI: 10.1002/cnm.3240] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/18/2019] [Accepted: 07/14/2019] [Indexed: 06/10/2023]
Abstract
This work is concerned with modeling and simulation of the mitral valve, one of the four valves in the human heart. The valve is composed of leaflets, the free edges of which are supported by a system of chordae, which themselves are anchored to the papillary muscles inside the left ventricle. First, we examine valve anatomy and present the results of original dissections. These display the gross anatomy and information on fiber structure of the mitral valve. Next, we build a model valve following a design-based methodology, meaning that we derive the model geometry and the forces that are needed to support a given load and construct the model accordingly. We incorporate information from the dissections to specify the fiber topology of this model. We assume the valve achieves mechanical equilibrium while supporting a static pressure load. The solution to the resulting differential equations determines the pressurized configuration of the valve model. To complete the model, we then specify a constitutive law based on a stress-strain relation consistent with experimental data that achieves the necessary forces computed in previous steps. Finally, using the immersed boundary method, we simulate the model valve in fluid in a computer test chamber. The model opens easily and closes without leak when driven by physiological pressures over multiple beats. Further, its closure is robust to driving pressures that lack atrial systole or are much lower or higher than normal.
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Affiliation(s)
- Alexander D Kaiser
- Department of Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, New York
| | - David M McQueen
- Department of Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, New York
| | - Charles S Peskin
- Department of Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, New York
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Invited Commentary. Ann Thorac Surg 2019; 108:97-98. [DOI: 10.1016/j.athoracsur.2019.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/03/2019] [Indexed: 11/19/2022]
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