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Liu H, Sacks M, Simonian NT, Gorman J, Gorman R. Simulated Effects of Acute Left Ventricular Myocardial Infarction On Mitral Regurgitation in an Ovine Model. J Biomech Eng 2024:1-52. [PMID: 38652602 DOI: 10.1115/1.4065376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Development of patient specific models of LV-MV interactions in ischemic mitral regurgitation (IMR) are complicated by the substantial variability and complex etiologies, making it difficult to extract underlying mechanisms. We thus developed a detailed ovine LV-MV finite element model based for the normal and acute post-MI states. The ovine LV FEM model was first extended to incorporate a detailed MV leaflet sub-model with a functionally-equivalent CT structure. The resulting complete LV-MV model was first used to simulate the full cardiac cycle in the normal state to establish baseline responses. We then simulated regional acute infarctions of varying sizes in various known infarct anatomical locations by shutting down the local myocardial contractility, while remote regions were allowed to adjust their active contractile patterns to maintain the prescribed pressure-volume loop. Simulation results indicated that the posterobasal infarct induced the largest MV regurgitation orifice area, consistent with experimental observations. We incorporated previously reported MV leaflet pre-strains (Amini et al., Ann Biomed Eng. 2012 Jul;40(7):1455-67) in the simulations, which then resulted in excellent agreement. Extensional deformations of the posterior leaflets occurred in the posterobasal and laterobasal infarcts, while compressive deformations of anterior leaflets were observed in the anterobasal infarct. The present study is the first detailed LV-MV simulations to reveal the important role of ,V EAF;ET pre-strain For accurate model prediction, underscoring that proper accounting of residual strains is an essential part of accurate simulations of organ level function.
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Affiliation(s)
- Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Michael Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Natalie T Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Joseph Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, PA USA
| | - Robert Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, PA USA
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Liu H, Simonian NT, Pouch AM, Iaizzo PA, Gorman JH, Gorman RC, Sacks MS. A Computational Pipeline for Patient-Specific Prediction of the Postoperative Mitral Valve Functional State. J Biomech Eng 2023; 145:111002. [PMID: 37382900 PMCID: PMC10405284 DOI: 10.1115/1.4062849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 06/30/2023]
Abstract
While mitral valve (MV) repair remains the preferred clinical option for mitral regurgitation (MR) treatment, long-term outcomes remain suboptimal and difficult to predict. Furthermore, pre-operative optimization is complicated by the heterogeneity of MR presentations and the multiplicity of potential repair configurations. In the present work, we established a patient-specific MV computational pipeline based strictly on standard-of-care pre-operative imaging data to quantitatively predict the post-repair MV functional state. First, we established human mitral valve chordae tendinae (MVCT) geometric characteristics obtained from five CT-imaged excised human hearts. From these data, we developed a finite-element model of the full patient-specific MV apparatus that included MVCT papillary muscle origins obtained from both the in vitro study and the pre-operative three-dimensional echocardiography images. To functionally tune the patient-specific MV mechanical behavior, we simulated pre-operative MV closure and iteratively updated the leaflet and MVCT prestrains to minimize the mismatch between the simulated and target end-systolic geometries. Using the resultant fully calibrated MV model, we simulated undersized ring annuloplasty (URA) by defining the annular geometry directly from the ring geometry. In three human cases, the postoperative geometries were predicted to 1 mm of the target, and the MV leaflet strain fields demonstrated close agreement with noninvasive strain estimation technique targets. Interestingly, our model predicted increased posterior leaflet tethering after URA in two recurrent patients, which is the likely driver of long-term MV repair failure. In summary, the present pipeline was able to predict postoperative outcomes from pre-operative clinical data alone. This approach can thus lay the foundation for optimal tailored surgical planning for more durable repair, as well as development of mitral valve digital twins.
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Affiliation(s)
- Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712-1229
| | - Natalie T. Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712-1229
| | - Alison M. Pouch
- Departments of Radiology and Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Paul A. Iaizzo
- Visible Heart Laboratories, Department of Surgery, University of Minnesota, Minneapolis, MN 55455
| | - Joseph H. Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Smilow Center for Translational Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert C. Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Smilow Center for Translational Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712-1229
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Simonian NT, Liu H, Vakamudi S, Pirwitz MJ, Pouch AM, Gorman JH, Gorman RC, Sacks MS. Patient-Specific Quantitative In-Vivo Assessment of Human Mitral Valve Leaflet Strain Before and After MitraClip Repair. Cardiovasc Eng Technol 2023; 14:677-693. [PMID: 37670097 DOI: 10.1007/s13239-023-00680-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
PURPOSE Mitral regurgitation (MR) is a highly prevalent and deadly cardiac disease characterized by improper mitral valve (MV) leaflet coaptation. Among the plethora of available treatment strategies, the MitraClip is an especially safe option, but optimizing its long-term efficacy remains an urgent challenge. METHODS We applied our noninvasive image-based strain computation pipeline [1] to intraoperative transesophageal echocardiography datasets taken from ten patients undergoing MitraClip repair, spanning a range of MR etiologies and MitraClip configurations. We then analyzed MV leaflet strains before and after MitraClip implementation to develop a better understanding of (1) the pre-operative state of human regurgitant MV, and (2) the MitraClip's impact on the MV leaflet deformations. RESULTS The MV pre-operative strain fields were highly variable, underscoring both the heterogeneity of the MR in the patient population and the need for patient-specific treatment approaches. Similarly, there were no consistent overall post-operative strain patterns, although the average A2 segment radial strain difference between pre- and post-operative states was consistently positive. In contrast, the post-operative strain fields were better correlated to their respective pre-operative strain fields than to the inter-patient post-operative strain fields. This quantitative result implies that the patient specific pre-operative state of the MV guides its post-operative deformation, which suggests that the post-operative state can be predicted using pre-operative data-derived modelling alone. CONCLUSIONS The pre-operative MV leaflet strain patterns varied considerably across the range of MR disease states and after MitraClip repair. Despite large inter-patient heterogeneity, the post-operative deformation appears principally dictated by the pre-operative deformation state. This novel finding suggests that though the variation in MR functional state and MitraClip-induced deformation were substantial, the post-operative state can be predicted from the pre-operative data alone. This study suggests that, with use of larger patient cohort and corresponding long-term outcomes, quantitative predictive factors of MitraClip durability can be identified.
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Affiliation(s)
- Natalie T Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA
| | - Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA
| | - Sneha Vakamudi
- Ascension Texas Cardiovascular & Division of Cardiology, Department of Internal Medicine, Dell Medical School, University of Texas, Austin, TX, USA
| | - Mark J Pirwitz
- Ascension Texas Cardiovascular & Division of Cardiology, Department of Internal Medicine, Dell Medical School, University of Texas, Austin, TX, USA
| | - Alison M Pouch
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Smilow Center for Translational Research, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin , 201 East 24th St., Stop C0200, Austin, TX, 78712-1229, USA.
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Simonian NT, Liu H, Pouch AM, Gorman JH, Gorman RC, Sacks MS. Quantitative in vivo assessment of human mitral valve coaptation area after undersized ring annuloplasty repair for ischemic mitral regurgitation. JTCVS Tech 2022; 16:49-59. [PMID: 36510522 PMCID: PMC9735426 DOI: 10.1016/j.xjtc.2022.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/29/2022] [Accepted: 09/13/2022] [Indexed: 11/08/2022] Open
Abstract
Objectives Long-term outcomes of mitral valve repair procedures to correct ischemic mitral regurgitation remain unpredictable, due to an incomplete understanding of the disease process and the inability to reliably quantify the coaptation zone using echocardiography. Our objective was to quantify patient-specific mitral valve coaptation behavior from clinical echocardiographic images obtained before and after repair to assess coaptation restoration and its relationship with long-term repair durability. Methods To circumvent the limitations of clinical imaging, we applied a simulation-based shape-matching technique that allowed high-fidelity reconstructions of the complete mitral valve in the systolic configuration. We then applied this method to an extant database of human regurgitant mitral valves before and after undersized ring annuloplasty to quantify the effect of the repair on mitral valve coaptation geometry. Results Our method was able to successfully resolve the coaptation zone into distinct contacting and redundant regions. Results indicated that in patients whose regurgitation recurred 6 months postrepair, both the contacting and redundant regions were larger immediately postrepair compared with patients with no recurrence (P < .05), even when normalized to account for generally larger recurrent valves. Conclusions Although increasing leaflet coaptation area is an intuitively obvious way to improve long-term repair durability, this study has implied that this may not be a reliable target for mitral valve repair. This study underscores the importance of a rigorous understanding of the consequences of repair techniques on mitral valve behavior, as well as a patient-specific approach to ischemic mitral regurgitation treatment within the context of mitral valve and left ventricle function.
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Key Words
- CMF, chordal mimicking force
- ED, end-diastolic
- ES, end-systolic
- FE, finite element
- IMR, ischemic mitral regurgitation
- LV, left ventricle
- MR, mitral regurgitation
- MV, mitral valve
- MVTa, mitral valve tenting area
- URA, undersized ring annuloplasty
- mitral valve imaging
- mitral valve mechanics
- mitral valve regurgitation
- mitral valve repair
- myocardial infarction
- rt-3DE, real-time 3-dimensional echocardiography
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Affiliation(s)
- Natalie T. Simonian
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, Tex
| | - Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, Tex
| | - Alison M. Pouch
- Departments of Radiology and Bioengineering, University of Pennsylvania, Philadelphia, Pa
| | - Joseph H. Gorman
- Department of Surgery, Smilow Center for Translational Research, Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Robert C. Gorman
- Department of Surgery, Smilow Center for Translational Research, Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, Austin, Tex,Address for reprints: Michael S. Sacks, PhD, Department of Biomedical Engineering, The Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712-1229.
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