1
|
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] [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.
Collapse
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
| |
Collapse
|
2
|
Koda Y, Tsukube T, Hoshino M, Yagi N, Ishibashi-Ueda H, Okada K. Structural properties in ruptured mitral chordae tendineae measured by synchrotron-based X-ray phase computed tomography. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:995-1002. [PMID: 37594861 PMCID: PMC10481270 DOI: 10.1107/s1600577523005167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 06/09/2023] [Indexed: 08/20/2023]
Abstract
The link between the structural properties and the rupturing of chordae tendineae in the mitral valve complex is still unclear. Synchrotron-radiation-based X-ray phase computed tomography (SR-XPCT) imaging is an innovative way to quantitatively analyze three-dimensional morphology. XPCT has been employed in this study to evaluate the chordae tendineae from patients with mitral regurgitation and to analyze structural changes in the ruptured chordae tendineae in patients with this condition. Six ruptured mitral chordae tendineae were obtained during surgical repairs for mitral regurgitation and were fixed with formalin. In addition, 12 healthy chordae tendineae were obtained from autopsies. Employing XPCT (effective pixel size, 3.5 µm; density resolution, 1 mg cm-3), the density of the chordae tendineae in each sample was measured. The specimens were subsequently analyzed pathologically. The mean age was 70.2 ± 3.0 in the rupture group and 67.2 ± 14.1 years old in the control group (p = 0.4927). All scans of chorda tendineae with SR-XPCT were performed successfully. The mean densities were 1.029 ± 0.004 in the rupture group and 1.085 ± 0.015 g cm-3 in the control group (p < 0.0001). Density based on SR-XPCT in the ruptured mitral chordae tendineae was significantly lower compared with the healthy chorda tendinea. Histological examination revealed a change in the components of the connective tissues in ruptured chorda tendinea, in accordance with the low density measured by SR-XPCT. SR-XPCT made it possible to measure tissue density in mitral chordae tendineae. Low density in mitral chordae tendineae is associated with a greater fragility in ruptured mitral chordae tendineae.
Collapse
Affiliation(s)
- Yojiro Koda
- Department of Surgery, Division of Cardiovascular Surgery, Kobe University Hospital, Kobe, Japan
| | - Takuro Tsukube
- Department of Surgery, Division of Cardiovascular Surgery, Kobe University Hospital, Kobe, Japan
- Division of Cardiovascular Surgery, Japanese Red Cross Kobe Hospital, Kobe, Japan
| | - Masato Hoshino
- Scattering and Imaging Division, Japan Synchrotron Radiation Research Institute, Sayo, Japan
| | - Naoto Yagi
- Scattering and Imaging Division, Japan Synchrotron Radiation Research Institute, Sayo, Japan
| | | | - Kenji Okada
- Department of Surgery, Division of Cardiovascular Surgery, Kobe University Hospital, Kobe, Japan
| |
Collapse
|
3
|
Islamagič L, Tjørnild MJ, Carlson Hanse L, Nygaard JV, Hasenkam JM. Biomechanical comparison of porcine mitral leaflets with porcine small intestinal submucosa extracellular matrix. Proc Inst Mech Eng H 2023; 237:435-442. [PMID: 36882979 DOI: 10.1177/09544119231158248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Porcine small intestinal submucosa extracellular matrix (SIS-ECM) used for cardiac valve repair has shown conflicting clinical outcomes with respect to calcification and failure. This may be related to differences in biomechanical properties of the material compared with the host site. The aim of this study was to compare the biomechanical properties of porcine mitral valve leaflets with SIS-ECM. Fresh porcine anterior and posterior mitral leaflet samples were cut radially and circumferentially. Similarly, 2- and 4-layered SIS-ECM were cut in orthogonal directions: length and width. Samples were subjected to a uniaxial tensile test or a dynamic mechanical analysis. Results show that the load of the porcine anterior circumferential leaflet was 39.5 N (2.4-48.5 N), which was significantly higher compared with the 2-layered length SIS-ECM which was 7.5 N (7-7.9 N), and the 4- layered length SIS-ECM which was 7.5 N (7.1-8.1 N) (p < 0.001). The load of the posterior circumferential leaflet was 9.7 N (8.3-10.7 N), which is still significantly higher when compared with the two versions of SIS-ECM. The degree of anisotropy (i.e. the ratio between circumferential-radial and width-length properties) was higher for the anterior- (ratio: 19) and posterior leaflet (ratio: 6) than the 2-layered (ratio: 5.1) and 4-layered SIS-ECM (ratio: 1.9). Especially 2-layered SIS-ECM more closely resembles the posterior mitral leaflet than the anterior mitral leaflet tissue and would be more suitable as a repair material in this position. Additionally, the anisotropic properties of mitral leaflets and SIS-ECM underscore the importance of correct orientation of the implant to ensure optimal reconstruction.
Collapse
Affiliation(s)
- Lejla Islamagič
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Marcell Juan Tjørnild
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lisa Carlson Hanse
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jens Vinge Nygaard
- Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark
| | - John Michael Hasenkam
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| |
Collapse
|
4
|
Wang B, Sierad LN, Mercuri JJ, Simionescu A, Simionescu DT, Williams LN, Vela R, Bajona P, Peltz M, Ramaswamy S, Hong Y, Liao J. Structural and biomechanical characterizations of acellular porcine mitral valve scaffolds: anterior leaflets, posterior leaflets, and chordae tendineae. ENGINEERED REGENERATION 2022; 3:374-386. [PMID: 38362305 PMCID: PMC10869114 DOI: 10.1016/j.engreg.2022.08.003] [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] [Indexed: 11/15/2022] Open
Abstract
Mitral valve (MV) tissue engineering is still in its early stage, and one major challenge in MV tissue engineering is to identify appropriate scaffold materials. With the potential of acellular MV scaffolds being demonstrated recently, it is important to have a full understanding of the biomechanics of the native MV components and their acellular scaffolds. In this study, we have successfully characterized the structural and mechanical properties of porcine MV components, including anterior leaflet (AL), posterior leaflet (PL), strut chordae, and basal chordae, before and after decellularization. Quantitative DNA assay showed more than 90% reduction in DNA content, and Griffonia simplicifolia (GS) lectin immunohistochemistry confirmed the complete lack of porcine α-Gal antigen in the acellular MV components. In the acellular AL and PL, the atrialis, spongiosa, and fibrosa trilayered structure, along with its ECM constitutes, i.e., collagen fibers, elastin fibers, and portion of GAGs, were preserved. Nevertheless, the ECM of both AL and PL experienced a certain degree of disruption, exhibiting a less dense, porous ECM morphology. The overall anatomical morphology of the strut and basal chordae were also maintained after decellularization, with longitudinal morphology experiencing minimum disruption, but the cross-sectional morphology exhibiting evenly-distributed porous structure. In the acellular AL and PL, the nonlinear anisotropic biaxial mechanical behavior was overall preserved; however, uniaxial tensile tests showed that the removal of cellular content and the disruption of structural ECM did result in small decreases in maximum tensile modulus, tissue extensibility, failure stress, and failure strain for both MV leaflets and chordae.
Collapse
Affiliation(s)
- Bo Wang
- Joint Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI 53226, United States
| | - Leslie N. Sierad
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Jeremy J. Mercuri
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Agneta Simionescu
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Dan T. Simionescu
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States
| | - Lakiesha N. Williams
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, United States
| | - Ryan Vela
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Pietro Bajona
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
- Allegheny Health Network-Drexel University College of Medicine, Pittsburgh, PA 15212, United States
| | - Matthias Peltz
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States
| | - Sharan Ramaswamy
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, United States
| | - Yi Hong
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76010, United States
| | - Jun Liao
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX 76010, United States
| |
Collapse
|
5
|
Dumont KA, Dahl Aguilera HM, Persson R, Prot V, Escobar Kvitting JP, Urheim S. Mitral Annular Elasticity Determines Severity of Regurgitation in Barlow's Disease. J Am Soc Echocardiogr 2022; 35:1037-1046. [PMID: 35842077 DOI: 10.1016/j.echo.2022.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 11/24/2022]
Abstract
AIMS Barlow's disease (BD) with late systolic mitral regurgitation provides diagnostic and therapeutic challenges. The mechanisms of the regurgitation are still unclear. We hypothesized that the onset and the severity of late systolic regurgitation are determined by annulus dynamics and the mechanical stresses imposed by the left ventricle. METHODS AND RESULTS Ten patients with BD and mitral annulus disjunction (MAD) were compared with ten healthy controls. Resting blood pressure (BP) was measured and transthoracic three-dimensional (3D) echocardiography was analyzed using a holographic display that allows tracking and measurements of mitral annulus surface area (ASA) throughout the cardiac cycle. A novel annulus elastance index (dASA/dP) was calculated between aortic valve opening and onset of mitral regurgitation. Severity of MAD was quantified as the disjunction index (mm*degree). Leaflet coaptation area was calculated using a finite element model. Peak systolic ASA in controls and patients were 9.3±0.6 and 21.1±3.1 cm2, respectively (p<0.001). In patients ASA increased rapidly during LV ejection and onset of mitral regurgitation coincided closely with peak upslope of annulus area change (dASA/dt). The finite element model showed a close association between rapid annulus displacement and coaptation area deficit in BD. Systolic annulus elastance index (0.058±0.036 cm2/mmHg) correlated strongly with disjunction index (r=0.91, p<0.0001). Moreover, regurgitation volume showed a positive correlation with systolic BP (r=0.80, p<0.01) CONCLUSION: The present pilot study supports the hypothesis that annulus dilatation may accentuate mitral valve regurgitation in patients with Barlow's disease. A novel annulus elastance index may predict the severity of mitral valve regurgitation in selected patients.
Collapse
Affiliation(s)
- Karl-Andreas Dumont
- Department of Cardiothoracic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
| | - Hans Martin Dahl Aguilera
- Department of Structural Engineering, Faculty of Engineering Science, The Norwegian University of Science and Technology, Trondheim, Norway.
| | - Robert Persson
- Department of Heart Disease, Haukeland University Hospital, Bergen, Norway.
| | - Victorien Prot
- Department of Structural Engineering, Faculty of Engineering Science, The Norwegian University of Science and Technology, Trondheim, Norway.
| | | | - Stig Urheim
- Department of Heart Disease, Haukeland University Hospital, Bergen, Norway.
| |
Collapse
|
6
|
Vandemaele P, Vander Linden K, Deferm S, Jashari R, Rega F, Bertrand P, Vandervoort P, Vander Sloten J, Famaey N, Fehervary H. Alterations in Human Mitral Valve Mechanical Properties Secondary to Left Ventricular Remodeling: A Biaxial Mechanical Study. Front Cardiovasc Med 2022; 9:876006. [PMID: 35811738 PMCID: PMC9258718 DOI: 10.3389/fcvm.2022.876006] [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: 02/14/2022] [Accepted: 04/11/2022] [Indexed: 11/18/2022] Open
Abstract
Secondary mitral regurgitation occurs when a left ventricular problem causes leaking of the mitral valve. The altered left ventricular geometry changes the orientation of the subvalvular apparatus, thereby affecting the mechanical stress on the mitral valve. This in turn leads to active remodeling of the mitral valve, in order to compensate for the ventricular remodeling. In this study, a biomechanical analysis was performed on eight human mitral valves with secondary mitral regurgitation and ten healthy human mitral valves to better understand this pathophysiology and its effect on the mechanical properties of these tissues. Samples were obtained from the anterior and posterior leaflet and used for planar biaxial mechanical experiments. Uniaxial experiments were performed on four groups of mitral valve chords: anterior basal, anterior marginal, posterior basal and posterior marginal chords. The mechanical response of the mitral valve leaflets was fitted to the May-Newman and Yin constitutive model, whereas the material parameters of the third order Ogden model were determined for the chord samples. Next, stiffnesses calculated at low and high stress levels were statistically analyzed. Leaflet samples with secondary mitral regurgitation showed a small thickness increase and a change in anisotropy index compared to healthy control valves. Diseased leaflets were more compliant circumferentially and stiffer radially, resulting in anisotropic samples with the radial direction being stiffest. In addition, chord samples were slightly thicker and less stiff at high stress in secondary mitral regurgitation, when grouped per leaflet type and insertion region. These results confirm mechanical alterations due to the pathophysiological valvular changes caused by left ventricular remodeling. It is important that these changes in mechanical behavior are incorporated into computational models of the mitral valve.
Collapse
Affiliation(s)
- Paulien Vandemaele
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Klaas Vander Linden
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Sébastien Deferm
- Cardiology, Hospital Oost-Limburg, Genk, Belgium
- Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium
| | - Ramadan Jashari
- European Homograft Bank, Clinic Saint-Jean, Brussels, Belgium
| | - Filip Rega
- Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | | | - Pieter Vandervoort
- Cardiology, Hospital Oost-Limburg, Genk, Belgium
- Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium
| | - Jos Vander Sloten
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Nele Famaey
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- FIBEr, KU Leuven, Leuven, Belgium
| | - Heleen Fehervary
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
- FIBEr, KU Leuven, Leuven, Belgium
| |
Collapse
|
7
|
Adamo A, Bartolacci JG, Pedersen DD, Traina MG, Kim S, Pantano A, Ghersi G, Watkins SC, Wagner WR, Badylak SF, D'Amore A. Continuous Microfiber Wire Mandrel-Less Biofabrication for Soft Tissue Engineering Applications. Adv Healthc Mater 2022; 11:e2102613. [PMID: 35394654 DOI: 10.1002/adhm.202102613] [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: 11/30/2021] [Revised: 03/27/2022] [Indexed: 11/10/2022]
Abstract
Suture materials are the most common bioimplants in surgical and clinical practice, playing a crucial role in wound healing and tendon and ligament repair. Despite the assortment available on the market, sutures are still affected by significant disadvantages, including failure in mimicking the mechanical properties of the tissue, excessive fibrosis, and inflammation. This study introduces a mandrel-less electrodeposition apparatus to fabricate continuous microfiber wires of indefinite length. The mandrel-less biofabrication produces wires, potentially used as medical fibers, with different microfiber bundles, that imitate the hierarchical organization of native tissues, and tailored mechanical properties. Microfiber wire morphology and mechanical properties are characterized by scanning electron microscopy, digital image processing, and uniaxial tensile test. Wires are tested in vitro on monocyte/macrophage stimulation and in vivo on a rat surgical wound model. The wires produced by mandrel-less deposition show an increased M2 macrophage phenotype in vitro. The in vivo assessment demonstrates that microfiber wires, compared to the medical fibers currently used, reduce pro-inflammatory macrophage response and preserve their mechanical properties after 30 days of use. These results make this microfiber wire an ideal candidate as a suture material for soft tissue surgery, suggesting a crucial role of microarchitecture in more favorable host response.
Collapse
Affiliation(s)
- Arianna Adamo
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Ri. MED Foundation Palermo 90133 Italy
| | | | - Drake D. Pedersen
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Department of Bioengineering University of Pittsburgh Pittsburgh PA 15260 USA
| | - Marco G. Traina
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Department of Engineering University of Palermo Palermo 90133 Italy
| | - Seungil Kim
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
| | - Antonio Pantano
- Department of Engineering University of Palermo Palermo 90133 Italy
| | - Giulio Ghersi
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies Palermo 90123 Italy
| | - Simon C. Watkins
- Department of Cell Biology University of Pittsburgh School of Medicine Pittsburgh PA 15213 USA
| | - William R. Wagner
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Department of Bioengineering University of Pittsburgh Pittsburgh PA 15260 USA
- Department of Surgery School of Medicine University of Pittsburgh Pittsburgh PA 15260 USA
- Department of Chemical Engineering University of Pittsburgh Pittsburgh PA 15260 USA
| | - Stephen F. Badylak
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Department of Bioengineering University of Pittsburgh Pittsburgh PA 15260 USA
- Department of Surgery School of Medicine University of Pittsburgh Pittsburgh PA 15260 USA
| | - Antonio D'Amore
- McGowan Institute for Regenerative Medicine Pittsburgh PA 15219 USA
- Ri. MED Foundation Palermo 90133 Italy
- Department of Bioengineering University of Pittsburgh Pittsburgh PA 15260 USA
- Department of Surgery School of Medicine University of Pittsburgh Pittsburgh PA 15260 USA
- Clinical Translational Science Institute University of Pittsburgh Pittsburgh PA 15260 USA
| |
Collapse
|
8
|
Development of 3D Printed Mitral Valve Constructs for Transcatheter Device Modeling of Tissue and Device Deformation. Ann Biomed Eng 2022; 50:426-439. [PMID: 35220528 PMCID: PMC8917041 DOI: 10.1007/s10439-022-02927-y] [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: 08/23/2021] [Accepted: 02/06/2022] [Indexed: 11/29/2022]
Abstract
Transcatheter mitral valve repair (TMVR) therapies offer a minimally invasive alternative to surgical mitral valve (MV) repair for patients with prohibitive surgical risks. Pre-procedural planning and associated medical device modeling is primarily performed in silico, which does not account for the physical interactions between the implanted TMVR device and surrounding tissue and may result in poor outcomes. We developed 3D printed tissue mimics for modeling TMVR therapies. Structural properties of the mitral annuli, leaflets, and chordae were replicated from multi-material blends. Uniaxial tensile testing was performed on the resulting composites and their mechanical properties were compared to those of their target native components. Mimics of the MV annulus printed in homogeneous strips approximated the tangent moduli of the native mitral annulus at 2% and 6% strain. Mimics of the valve leaflets printed in layers of different stiffnesses approximated the force–strain and stress–strain behavior of native MV leaflets. Finally, mimics of the chordae printed as reinforced cylinders approximated the force–strain and stress–strain behavior of native chordae. We demonstrated that multi-material 3D printing is a viable approach to the development of tissue phantoms, and that printed patient-specific geometries can approximate the local deformation force which may act upon devices used for TMVR therapies.
Collapse
|
9
|
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.
Collapse
|
10
|
Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study. Animals (Basel) 2021; 11:ani11061678. [PMID: 34199922 PMCID: PMC8230186 DOI: 10.3390/ani11061678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/26/2021] [Accepted: 05/30/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary The Chordae tendineae are part of the atrioventricular apparatus. They are mainly responsible for the mechanical functions of heart valves. Degenerative mitral valve disease is the most common heart disease in dogs and is responsible for about 75% of cases of heart failure. One of the complications of this disease is Chordae tendineae rupture. It is clinically relevant to better understand the biomechanical and structural properties of CT in order to begin further studies about biomarkers suggesting an episode of CT rupture. Such an episode leads to acute pulmonary oedema and worsens the clinical status of the patient. Information about the biomechanical and structural properties of healthy CT and CT affected by the degenerative process are essential in understanding how CT behave in an in vivo environment. Abstract The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and Chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of Chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of Chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.
Collapse
|
11
|
Marom G, Plitman Mayo R, Again N, Raanani E. Numerical Biomechanics Models of the Interaction Between a Novel Transcatheter Mitral Valve Device and the Subvalvular Apparatus. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2021; 16:327-333. [PMID: 33818178 PMCID: PMC8414811 DOI: 10.1177/1556984521999362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Objective Mitral valve regurgitation (MR) is a common valvular heart disease where
improper closing causes leakage. Currently, no transcatheter mitral valve
device is commercially available. Raanani (co-author) and colleagues have
previously proposed a unique rotational implantation, ensuring anchoring by
metallic arms that pull the chordae tendineae. This technique is now being
implemented in a novel device design. The aim of this study is to quantify
the rotational implantation effect on the mitral annulus kinematics and on
the stresses in the chordae and papillary muscles. Methods Finite element analysis of the rotational step of the implantation in a whole
heart model is employed to compare 5 arm designs with varying diameters
(25.9 mm to 32.4 mm) and rotation angles (up to 140°). The arm rotation that
grabs the chordae was modeled when the valve was in systolic
configuration. Results An increase in the rotation angle results in reduced mitral annulus
perimeters. Larger rotation angles led to higher chordae stresses with the
29.8 mm experiencing the maximum stresses. The calculated chordae stresses
suggest that arm diameter should be <27.8 mm and the rotation angle
<120°. Conclusions The upper limit of this diameter range is preferred in order to reduce the
stresses in the papillary muscles while grabbing more chords. The findings
of this study can help improving the design and performance of this unique
device and procedural technique.
Collapse
Affiliation(s)
- Gil Marom
- 26745 School of Mechanical Engineering, Tel Aviv University, Israel
| | | | - Nadav Again
- The Sheba Fund for Health Services and Research, Tel Hashomer, Israel
| | - Ehud Raanani
- 26744 Leviev Cardiothoracic and Vascular Center, Chaim Sheba Medical Center, Tel Hashomer, Israel
| |
Collapse
|
12
|
Constable M, Northeast R, Lawless BM, Burton HE, Gramigna V, Goh KL, Buchan KG, Espino DM. Mechanical testing of glutaraldehyde cross-linked mitral valves. Part two: Elastic and viscoelastic properties of chordae tendineae. Proc Inst Mech Eng H 2020; 235:291-299. [PMID: 33243079 DOI: 10.1177/0954411920975938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The aim of this study was to assess whether the mechanical properties of mitral valve chordae tendineae are sensitive to being cross-linked under load. A total 64 chordae were extracted from eight porcine hearts. Two chordae (posterior basal) from each heart were subjected to uniaxial ramp testing and six chordae (two strut, two anterior basal and two posterior basal) were subjected to dynamic mechanical analysis over frequencies between 0.5 and 10 Hz. Chordae were either cross-linked in tension or cross-linked in the absence of loading. Chordae cross-linked under load transitioned from high to low extension at a lower strain than cross-linked unloaded chordae (0.07 cf. 0.22), with greater pre-transitional (30.8 MPa cf. 5.78 MPa) and post-transitional (139 MPa cf. 74.1 MPa) moduli. The mean storage modulus of anterior strut chordae ranged from 48 to 54 MPa for cross-linked unloaded chordae, as compared to 53-61 MPa cross-linked loaded chordae. The mean loss modulus of anterior strut chordae ranged from 2.3 to 2.9 MPa for cross-linked unloaded chordae, as compared to 3.8-4.8 MPa cross-linked loaded chordae. The elastic and viscoelastic properties of chordae following glutaraldehyde cross-linking are dependent on the inclusion/exclusion of loading during the cross-linking process; with loading increasing the magnitude of the material properties measured.
Collapse
Affiliation(s)
- Matthew Constable
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Rhiannon Northeast
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Bernard M Lawless
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK.,Filament PD, Level 4 - Skypark 3, Skypark, Glasgow, UK
| | - Hanna E Burton
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| | - Vera Gramigna
- University of Magna Graecia, Catanzaro, Italy.,IBFM, National Research Council, Germaneto, Catanzaro, Italy
| | - Kheng Lim Goh
- Department of Mechanical Engineering, University of Newcastle, Singapore
| | - Keith G Buchan
- Department of Cardio-thoracic Surgery, Aberdeen Royal Infirmary, Forresterhill, Aberdeen, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, UK
| |
Collapse
|
13
|
Ramaraju H, Ul-Haque A, Verga AS, Bocks ML, Hollister SJ. Modulating nonlinear elastic behavior of biodegradable shape memory elastomer and small intestinal submucosa(SIS) composites for soft tissue repair. J Mech Behav Biomed Mater 2020; 110:103965. [PMID: 32957256 DOI: 10.1016/j.jmbbm.2020.103965] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/17/2020] [Accepted: 06/29/2020] [Indexed: 01/08/2023]
Abstract
Structural repair of soft tissue for regenerative therapies can be advanced by developing biocompatible and bioresorbable materials with mechanical properties similar to the tissue targeted for therapy. Developing new materials modeling soft tissue mechanics can mitigate many limitations of material based therapies, specifically concerning the mechanical stress and deformation the material imposes on surrounding tissue structures. However, many elastomeric materials used in soft tissue repair lack the ability to be delivered through minimally invasive surgical (MIS) or transcatheter routes and require open surgical approaches for placement and application. We have developed a biocompatible and fully biodegradable shape memory elastomer, poly-(glycerol dodecanedioate) (PGD), which fulfills the requirements for hyperelasticity and exhibits shape memory behavior to serve as a novel substrate material for regenerative therapy in minimally invasive clinical procedures. Our previous work demonstrated control over the tangent modulus at 12.5% compressive strain between 1 and 3 MPa by increasing the crosslinking density in the polymer. In order to improve control over a broader range of mechanical properties, nonlinear behavior, and toughness, we 1) varied PGD physical crosslink density, 2) incorporated sheets of porcine small intestinal submucosa (SIS, Cook Biotech, Inc.) with varying thickness, and 3) mixed lyophilized SIS particulates into PGD at different weight percentages. Tensile testing (ASTM D412a) revealed PGD containing SIS sheets of were stiffer than controls (p < 0.01). Incorporating lyophilized SIS particulates into PGD increased the strain to failure (p < 0.001) compared to PGD controls. Test specimens with 1 ply sheets had greater tear strength (ASTM D624c) compared to PGD tear specimens prepared control specimens (p < 0.001). However, incorporating SIS particulates decreased tear strength of PGD-SIS 0.5 wt% particulate composites (p < 0.01) compared to PGD controls. Incorporating 2 ply and 4 ply sheets and 0.5 wt% particulates into PGD decreased the fixity and recovery of composite materials compared to controls (p < 0.01). Nonlinear modeling of stress strain curves under uniaxial tension demonstrated tunability of PGD-SIS composite materials to model various nonlinear soft tissues. These findings support the use of shape memory PGD-SIS composite materials towards the design of implantable devices for a variety of soft tissue regeneration applications by minimally invasive surgery.
Collapse
Affiliation(s)
- Harsha Ramaraju
- Georgia Institute of Technology, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, GA, USA.
| | - Anum Ul-Haque
- Georgia Institute of Technology, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, GA, USA
| | - Adam S Verga
- Georgia Institute of Technology, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, GA, USA
| | - Martin L Bocks
- Case Western Reserve University, School of Medicine, Cleveland, OH, USA
| | - Scott J Hollister
- Georgia Institute of Technology, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, GA, USA
| |
Collapse
|
14
|
Ferrari E, Gallo M, Wang C, Zhang L, Taramasso M, Maisano F, Pirelli L, Berdajs D, von Segesser LK. Three-dimensional printing in adult cardiovascular medicine for surgical and transcatheter procedural planning, teaching and technological innovation. Interact Cardiovasc Thorac Surg 2020; 30:203-214. [PMID: 31633170 DOI: 10.1093/icvts/ivz250] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/09/2019] [Accepted: 09/15/2019] [Indexed: 12/23/2022] Open
Abstract
Three-dimensional (3D)-printing technologies in cardiovascular surgery have provided a new way to tailor surgical and percutaneous treatments. Digital information from standard cardiac imaging is integrated into physical 3D models for an accurate spatial visualization of anatomical details. We reviewed the available literature and analysed the different printing technologies, the required procedural steps for 3D prototyping, the used cardiac imaging, the available materials and the clinical implications. We have highlighted different materials used to replicate aortic and mitral valves, vessels and myocardial properties. 3D printing allows a heuristic approach to investigate complex cardiovascular diseases, and it is a unique patient-specific technology providing enhanced understanding and tactile representation of cardiovascular anatomies for the procedural planning and decision-making process. 3D printing may also be used for medical education and surgical/transcatheter training. Communication between doctors and patients can also benefit from 3D models by improving the patient understanding of pathologies. Furthermore, medical device development and testing can be performed with rapid 3D prototyping. Additionally, widespread application of 3D printing in the cardiovascular field combined with tissue engineering will pave the way to 3D-bioprinted tissues for regenerative medicinal applications and 3D-printed organs.
Collapse
Affiliation(s)
- Enrico Ferrari
- Cardiovascular Surgery, Cardiocentro Ticino, Lugano, Switzerland
| | - Michele Gallo
- Cardiovascular Surgery, Cardiocentro Ticino, Lugano, Switzerland
| | | | - Lei Zhang
- Cardiovascular Surgery, Nanjing Jinling Hospital, Nanjing, China
| | | | - Francesco Maisano
- Cardiovascular Surgery, Zurich University Hospital, Zurich, Switzerland
| | - Luigi Pirelli
- Cardiothoracic Surgery, Lenox Hill Heart and Vascular Institute, New York, NY, USA
| | - Denis Berdajs
- Cardiovascular Surgery, Basel University Hospital, Basel, Switzerland
| | - Ludwig Karl von Segesser
- Department of Surgery, Cardiovascular Research Unit, Lausanne University Hospital, Lausanne, Switzerland
| |
Collapse
|
15
|
Ross CJ, Hsu MC, Baumwart R, Mir A, Burkhart HM, Holzapfel GA, Wu Y, Lee CH. Quantification of load-dependent changes in the collagen fiber architecture for the strut chordae tendineae-leaflet insertion of porcine atrioventricular heart valves. Biomech Model Mechanobiol 2020; 20:223-241. [PMID: 32809131 PMCID: PMC8008705 DOI: 10.1007/s10237-020-01379-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 08/08/2020] [Indexed: 10/23/2022]
Abstract
Atrioventricular heart valves (AHVs) regulate the unidirectional flow of blood through the heart by opening and closing of the leaflets, which are supported in their functions by the chordae tendineae (CT). The leaflets and CT are primarily composed of collagen fibers that act as the load-bearing component of the tissue microstructures. At the CT-leaflet insertion, the collagen fiber architecture is complex, and has been of increasing focus in the previous literature. However, these previous studies have not been able to quantify the load-dependent changes in the tissue's collagen fiber orientations and alignments. In the present study, we address this gap in knowledge by quantifying the changes in the collagen fiber architecture of the mitral and tricuspid valve's strut CT-leaflet insertions in response to the applied loads by using a unique approach, which combines polarized spatial frequency domain imaging with uniaxial mechanical testing. Additionally, we characterized these microstructural changes across the same specimen without the need for tissue fixatives. We observed increases in the collagen fiber alignments in the CT-leaflet insertion with increased loading, as described through the degree of optical anisotropy. Furthermore, we used a leaflet-CT-papillary muscle entity method during uniaxial testing to quantify the chordae tendineae mechanics, including the derivation of the Ogden-type constitutive modeling parameters. The results from this study provide a valuable insight into the load-dependent behaviors of the strut CT-leaflet insertion, offering a research avenue to better understand the relationship between tissue mechanics and the microstructure, which will contribute to a deeper understanding of AHV biomechanics.
Collapse
Affiliation(s)
- Colton J Ross
- Biomechanics and Biomaterial Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Ryan Baumwart
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
| | - Arshid Mir
- Department of Pediatric Cardiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Harold M Burkhart
- Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria.,Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Yi Wu
- Biomechanics and Biomaterial Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA
| | - Chung-Hao Lee
- Biomechanics and Biomaterial Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA. .,School of Aerospace and Mechanical Engineering, Affiliated Faculty, Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK, 73019, USA.
| |
Collapse
|
16
|
Leonés A, Lieblich M, Benavente R, Gonzalez JL, Peponi L. Potential Applications of Magnesium-Based Polymeric Nanocomposites Obtained by Electrospinning Technique. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1524. [PMID: 32759696 PMCID: PMC7466477 DOI: 10.3390/nano10081524] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/19/2022]
Abstract
In the last few decades, the development of new electrospun materials with different morphologies and advanced multifunctional properties are strongly consolidated. There are several reviews that describe the processing, use and characterization of electrospun nanocomposites, however, based on our knowledge, no review on electrospun nanocomposites reinforced with nanoparticles (NPs) based on magnesium, Mg-based NPs, are reported. Therefore, in the present review, we focus attention on the fabrication of these promising electrospun materials and their potential applications. Firstly, the electrospinning technique and its main processing window-parameters are described, as well as some post-processing methods used to obtain Mg-based materials. Then, the applications of Mg-based electrospun nanocomposites in different fields are pointed out, thus taking into account the current trend in developing inorganic-organic nanocomposites to gradually satisfy the challenges that the industry generates. Mg-based electrospun nanocomposites are becoming an attractive field of research for environmental remediation (waste-water cleaning and air filtration) as well as for novel technical textiles. However, the mayor application of Mg-based electrospun materials is in the biomedical field, as pointed out. Therefore, this review aims to clarify the tendency in using electrospinning technique and Mg-based nanoparticles to huge development at industrial level in the near future.
Collapse
Affiliation(s)
- Adrián Leonés
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain; (A.L.); (R.B.)
- Interdisciplinary Platform for “Sustainable Plastics towards a Circular Economy” (SUSPLAST-CSIC), 28006 Madrid, Spain
| | - Marcela Lieblich
- Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), 28040 Madrid, Spain; (M.L.); (J.L.G.)
| | - Rosario Benavente
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain; (A.L.); (R.B.)
| | - José Luis Gonzalez
- Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), 28040 Madrid, Spain; (M.L.); (J.L.G.)
- CIBER-BBN, 28040 Madrid, Spain
| | - Laura Peponi
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain; (A.L.); (R.B.)
- Interdisciplinary Platform for “Sustainable Plastics towards a Circular Economy” (SUSPLAST-CSIC), 28006 Madrid, Spain
| |
Collapse
|
17
|
Chen S, Sari CR, Gao H, Lei Y, Segers P, De Beule M, Wang G, Ma X. Mechanical and morphometric study of mitral valve chordae tendineae and related papillary muscle. J Mech Behav Biomed Mater 2020; 111:104011. [PMID: 32835989 DOI: 10.1016/j.jmbbm.2020.104011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 07/07/2020] [Accepted: 07/21/2020] [Indexed: 01/21/2023]
Abstract
The mitral valve (MV) apparatus is a complex mechanical structure including annulus, valve leaflets, papillary muscles (PMs) and connected chordae tendineae. Chordae anchor to the papillary muscles to help the valve open and close properly during one cardiac cycle. It is of paramount importance to understand the functional, mechanical, and microstructural properties of mitral valve chordae and connecting PMs. In particular, little is known about the biomechanical properties of the anterior and posterior papillary muscle and corresponding chords. In this work, we performed uniaxial and biaxial tensile tests on the anterolateral (APM) and posteromedial papillary muscle (PPM), and their respective corresponding chordae tendineae, chordaeAPM and chordaePPM, in porcine hearts. Histology was carried out to link the microstructure and macro-mechanical behavior of the chordae and PMs. Our results demonstrate that chordaePPM are less in number, but significantly longer and stiffer than chordaeAPM. These different biomechanical properties may be partially explained by the higher collagen core ratio and larger collagen fibril density of chordaePPM. No significant mechanical or microstructural differences were observed along the circumferential and longitudinal directions of APM and PPM samples. Data measured on chordae and PMs were further fitted with the Ogden and reduced Holzapfel - Ogden strain energy functions, respectively. This study presents the first comparative anatomical, mechanical, and structural dataset of porcine mitral valve chordae and related PMs. Results indicate that a PM based classification of chordae will need to be considered in the analysis of the MV function or planning a surgical treatment, which will also help developing more precise computational models of MV.
Collapse
Affiliation(s)
- Shengda Chen
- College of Bioengineering, Chongqing University, Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing, 400030, China; IBiTech - BioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium; Numerical Simulation Center, Microport, Shanghai, China
| | - Candra Ratna Sari
- College of Bioengineering, Chongqing University, Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing, 400030, China
| | - Hao Gao
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
| | - Yang Lei
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, China
| | - Patrick Segers
- IBiTech - BioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Matthieu De Beule
- IBiTech - BioMMeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium; FEops NV, Ghent, Belgium
| | - Guixue Wang
- College of Bioengineering, Chongqing University, Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing, 400030, China
| | - Xingshuang Ma
- College of Bioengineering, Chongqing University, Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing, 400030, China.
| |
Collapse
|
18
|
Laurence DW, Johnson EL, Hsu MC, Baumwart R, Mir A, Burkhart HM, Holzapfel GA, Wu Y, Lee CH. A pilot in silico modeling-based study of the pathological effects on the biomechanical function of tricuspid valves. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3346. [PMID: 32362054 PMCID: PMC8039906 DOI: 10.1002/cnm.3346] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/23/2020] [Accepted: 04/22/2020] [Indexed: 05/12/2023]
Abstract
Current clinical assessment of functional tricuspid valve regurgitation relies on metrics quantified from medical imaging modalities. Although these clinical methodologies are generally successful, the lack of detailed information about the mechanical environment of the valve presents inherent challenges for assessing tricuspid valve regurgitation. In the present study, we have developed a finite element-based in silico model of one porcine tricuspid valve (TV) geometry to investigate how various pathological conditions affect the overall biomechanical function of the TV. There were three primary observations from our results. Firstly, the results of the papillary muscle (PM) displacement study scenario indicated more pronounced changes in the TV biomechanical function. Secondly, compared to uniform annulus dilation, nonuniform dilation scenario induced more evident changes in the von Mises stresses (83.8-125.3 kPa vs 65.1-84.0 kPa) and the Green-Lagrange strains (0.52-0.58 vs 0.47-0.53) for the three TV leaflets. Finally, results from the pulmonary hypertension study scenario showed opposite trends compared to the PM displacement and annulus dilation scenarios. Furthermore, various chordae rupture scenarios were simulated, and the results showed that the chordae tendineae attached to the TV anterior and septal leaflets may be more critical to proper TV function. This in silico modeling-based study has provided a deeper insight into the tricuspid valve pathologies that may be useful, with moderate extensions, for guiding clinical decisions. NOVELTY STATEMENT: The novelties of the research are summarized below: A comprehensive in silico pilot study of how isolated functional tricuspid regurgitation pathologies and ruptured chordae tendineae would alter the tricuspid valve function; An extensive analysis of the tricuspid valve function, including mechanical quantities (eg, the von Mises stress and the Green-Lagrange strain) and clinically-relevant geometry metrics (eg, the tenting area and the coaptation height); and A developed computational modeling pipeline that can be extended to evaluate patient-specific tricuspid valve geometries and enhance the current clinical diagnosis and treatment of tricuspid regurgitation.
Collapse
Affiliation(s)
- Devin W. Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Emily L. Johnson
- Computational Fluid-Structure Interaction Laboratory, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | - Ming-Chen Hsu
- Computational Fluid-Structure Interaction Laboratory, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Harold M. Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2 8010 Graz, Austria
- Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
- Institute for Biomedical Engineering, Science, and Technology, The University of Oklahoma, Norman, OK 73019, USA
| |
Collapse
|
19
|
Kong F, Caballero A, McKay R, Sun W. Finite element analysis of MitraClip procedure on a patient-specific model with functional mitral regurgitation. J Biomech 2020; 104:109730. [DOI: 10.1016/j.jbiomech.2020.109730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 10/24/2022]
|
20
|
Ross CJ, Zheng J, Ma L, Wu Y, Lee CH. Mechanics and Microstructure of the Atrioventricular Heart Valve Chordae Tendineae: A Review. Bioengineering (Basel) 2020; 7:E25. [PMID: 32178262 PMCID: PMC7148526 DOI: 10.3390/bioengineering7010025] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 11/16/2022] Open
Abstract
The atrioventricular heart valves (AHVs) are responsible for directing unidirectional blood flow through the heart by properly opening and closing the valve leaflets, which are supported in their function by the chordae tendineae and the papillary muscles. Specifically, the chordae tendineae are critical to distributing forces during systolic closure from the leaflets to the papillary muscles, preventing leaflet prolapse and consequent regurgitation. Current therapies for chordae failure have issues of disease recurrence or suboptimal treatment outcomes. To improve those therapies, researchers have sought to better understand the mechanics and microstructure of the chordae tendineae of the AHVs. The intricate structures of the chordae tendineae have become of increasing interest in recent literature, and there are several key findings that have not been comprehensively summarized in one review. Therefore, in this review paper, we will provide a summary of the current state of biomechanical and microstructural characterizations of the chordae tendineae, and also discuss perspectives for future studies that will aid in a better understanding of the tissue mechanics-microstructure linking of the AHVs' chordae tendineae, and thereby improve the therapeutics for heart valve diseases caused by chordae failures.
Collapse
Affiliation(s)
- Colton J. Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA; (C.J.R.); (Y.W.)
| | - Junnan Zheng
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Zhejiang University, Hangzhou 310058, China; (J.Z.); (L.M.)
| | - Liang Ma
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Zhejiang University, Hangzhou 310058, China; (J.Z.); (L.M.)
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA; (C.J.R.); (Y.W.)
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA; (C.J.R.); (Y.W.)
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, OK 73019, USA
| |
Collapse
|
21
|
Ross CJ, Laurence DW, Hsu MC, Baumwart R, Zhao YD, Mir A, Burkhart HM, Holzapfel GA, Wu Y, Lee CH. Mechanics of Porcine Heart Valves' Strut Chordae Tendineae Investigated as a Leaflet-Chordae-Papillary Muscle Entity. Ann Biomed Eng 2020; 48:1463-1474. [PMID: 32006267 PMCID: PMC8048774 DOI: 10.1007/s10439-020-02464-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 01/23/2020] [Indexed: 11/28/2022]
Abstract
Proper blood flow through the atrioventricular heart valves (AHVs) relies on the holistic function of the valve and subvalvular structures, and a failure of any component can lead to life-threatening heart disease. A comprehension of the mechanical characteristics of healthy valvular components is necessary for the refinement of heart valve computational models. In previous studies, the chordae tendineae have been mechanically characterized as individual structures, usually in a clamping-based approach, which may not accurately reflect the in vivo chordal interactions with the leaflet insertion and papillary muscles. In this study, we performed uniaxial mechanical testing of strut chordae tendineae of the AHVs under a unique tine-based leaflet-chordae-papillary muscle testing to observe the chordae mechanics while preserving the subvalvular component interactions. Results of this study provided insight to the disparity of chordae tissue stress-stretch responses between the mitral valve (MV) and the tricuspid valve (TV) under their respective emulated physiological loading. Specifically, strut chordae tendineae of the MV anterior leaflet had peak stretches of 1.09-1.16, while peak stretches of 1.08-1.11 were found for the TV anterior leaflet strut chordae. Constitutive parameters were also derived for the chordae tissue specimens using an Ogden model, which is useful for AHV computational model refinement. Results of this study are beneficial to the eventual improvement of treatment methods for valvular disease.
Collapse
Affiliation(s)
- Colton J Ross
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK, 73019-3609, USA
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK, 73019-3609, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yan D Zhao
- Department of Biostatistics and Epidemiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Arshid Mir
- Department of Pediatric Cardiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Harold M Burkhart
- Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria.,Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK, 73019-3609, USA
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK, 73019-3609, USA. .,Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, OK, 73019, USA.
| |
Collapse
|
22
|
Lazicki TJ, Harvey JF, Rokkas CK, Tawil JN, Pagel PS. Dancing in the Dark: A Thin, Highly Mobile, Serpiginous Structure Rhythmically Protruding Into and Out of the Left Ventricular Outflow Tract. J Cardiothorac Vasc Anesth 2019; 34:1382-1384. [PMID: 31706851 DOI: 10.1053/j.jvca.2019.10.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Timothy J Lazicki
- Anesthesia Services, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI
| | - Julie F Harvey
- Anesthesia Services, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI
| | - Chris K Rokkas
- Cardiothoracic Surgery Services, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI
| | - Justin N Tawil
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI
| | - Paul S Pagel
- Anesthesia Services, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI.
| |
Collapse
|
23
|
Some Effects of Different Constitutive Laws on FSI Simulation for the Mitral Valve. Sci Rep 2019; 9:12753. [PMID: 31484963 PMCID: PMC6726639 DOI: 10.1038/s41598-019-49161-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/20/2019] [Indexed: 12/23/2022] Open
Abstract
In this paper, three different constitutive laws for mitral leaflets and two laws for chordae tendineae are selected to study their effects on mitral valve dynamics with fluid-structure interaction. We first fit these three mitral leaflet constitutive laws and two chordae tendineae laws with experimental data. The fluid-structure interaction is implemented in an immersed boundary framework with finite element extension for solid, that is the hybrid immersed boundary/finite element(IB/FE) method. We specifically compare the fluid-structure results of different constitutive laws since fluid-structure interaction is the physiological loading environment. This allows us to look at the peak jet velocity, the closure regurgitation volume, and the orifice area. Our numerical results show that different constitutive laws can affect mitral valve dynamics, such as the transvalvular flow rate, closure regurgitation and the orifice area, while the differences in fiber strain and stress are insignificant because all leaflet constitutive laws are fitted to the same set of experimental data. In addition, when an exponential constitutive law of chordae tendineae is used, a lower closure regurgitation flow is observed compared to that of a linear material model. In conclusion, combining numerical dynamic simulations and static experimental tests, we are able to identify suitable constitutive laws for dynamic behaviour of mitral leaflets and chordae under physiological conditions.
Collapse
|
24
|
Li K, Ogden RW, Holzapfel GA. A discrete fibre dispersion method for excluding fibres under compression in the modelling of fibrous tissues. J R Soc Interface 2019; 15:rsif.2017.0766. [PMID: 29386399 DOI: 10.1098/rsif.2017.0766] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/05/2018] [Indexed: 11/12/2022] Open
Abstract
Recently, micro-sphere-based methods derived from the angular integration approach have been used for excluding fibres under compression in the modelling of soft biological tissues. However, recent studies have revealed that many of the widely used numerical integration schemes over the unit sphere are inaccurate for large deformation problems even without excluding fibres under compression. Thus, in this study, we propose a discrete fibre dispersion model based on a systematic method for discretizing a unit hemisphere into a finite number of elementary areas, such as spherical triangles. Over each elementary area, we define a representative fibre direction and a discrete fibre density. Then, the strain energy of all the fibres distributed over each elementary area is approximated based on the deformation of the representative fibre direction weighted by the corresponding discrete fibre density. A summation of fibre contributions over all elementary areas then yields the resultant fibre strain energy. This treatment allows us to exclude fibres under compression in a discrete manner by evaluating the tension-compression status of the representative fibre directions only. We have implemented this model in a finite-element programme and illustrate it with three representative examples, including simple tension and simple shear of a unit cube, and non-homogeneous uniaxial extension of a rectangular strip. The results of all three examples are consistent and accurate compared with the previously developed continuous fibre dispersion model, and that is achieved with a substantial reduction of computational cost.
Collapse
Affiliation(s)
- Kewei Li
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16-II, 8010 Graz, Austria
| | - Ray W Ogden
- School of Mathematics and Statistics, University of Glasgow, University Place, Glasgow G12 8SQ, Scotland, UK
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16-II, 8010 Graz, Austria .,Faculty of Engineering Science and Technology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| |
Collapse
|
25
|
Lee CH, Laurence DW, Ross CJ, Kramer KE, Babu AR, Johnson EL, Hsu MC, Aggarwal A, Mir A, Burkhart HM, Towner RA, Baumwart R, Wu Y. Mechanics of the Tricuspid Valve-From Clinical Diagnosis/Treatment, In-Vivo and In-Vitro Investigations, to Patient-Specific Biomechanical Modeling. Bioengineering (Basel) 2019; 6:E47. [PMID: 31121881 PMCID: PMC6630695 DOI: 10.3390/bioengineering6020047] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 12/29/2022] Open
Abstract
Proper tricuspid valve (TV) function is essential to unidirectional blood flow through the right side of the heart. Alterations to the tricuspid valvular components, such as the TV annulus, may lead to functional tricuspid regurgitation (FTR), where the valve is unable to prevent undesired backflow of blood from the right ventricle into the right atrium during systole. Various treatment options are currently available for FTR; however, research for the tricuspid heart valve, functional tricuspid regurgitation, and the relevant treatment methodologies are limited due to the pervasive expectation among cardiac surgeons and cardiologists that FTR will naturally regress after repair of left-sided heart valve lesions. Recent studies have focused on (i) understanding the function of the TV and the initiation or progression of FTR using both in-vivo and in-vitro methods, (ii) quantifying the biomechanical properties of the tricuspid valve apparatus as well as its surrounding heart tissue, and (iii) performing computational modeling of the TV to provide new insight into its biomechanical and physiological function. This review paper focuses on these advances and summarizes recent research relevant to the TV within the scope of FTR. Moreover, this review also provides future perspectives and extensions critical to enhancing the current understanding of the functioning and remodeling tricuspid valve in both the healthy and pathophysiological states.
Collapse
Affiliation(s)
- Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, OK 73019, USA.
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Katherine E Kramer
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Anju R Babu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha 769008, India.
| | - Emily L Johnson
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ankush Aggarwal
- Glasgow Computational Engineering Centre, School of Engineering, University of Glasgow, Scotland G12 8LT, UK.
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Rheal A Towner
- Advance Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| |
Collapse
|
26
|
Grinberg D, Le MQ, Kwon YJ, Fernandez MA, Audigier D, Ganet F, Capsal JF, Obadia JF, Cottinet PJ. Mitral valve repair based on intraoperative objective measurement. Sci Rep 2019; 9:4677. [PMID: 30886234 PMCID: PMC6423320 DOI: 10.1038/s41598-019-41173-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/19/2019] [Indexed: 01/15/2023] Open
Abstract
In this paper, we propose a very innovative designed system that enables optimal length adjustment during transapical neochordae implantation for mitral valve repair, increasing accuracy and reproducibility of neochordae length adjustment. Also, such a new device allowed real-time measurement and recording of chordae tension, producing original physiological data. To the best of our knowledge, the tension of chordae had never been measured previously as precisely, especially in in vivo human clinical trials. Preliminary experimental data have been collected on 10 selected patients, giving us the opportunity to assess for the first time the tension applied on the chordae implanted in beating human hearts. The final goal of our measuring device is to provide reliable objective intraoperative data to improve the understanding of changes occurring after mitral valve repair (MVR). This novel measuring instrument may bring change in the paradigm of MVR by allowing repair with strong objective and quantitative, instead of qualitative anatomical analysis.
Collapse
Affiliation(s)
- Daniel Grinberg
- Department of adult cardiac surgery, Hopital cardiologique Louis Pradel - LYON medical school, 28, Avenue du Doyen Lépine, 69677 CEDEX, Bron, France. .,Université Lyon, INSA-Lyon, LGEF, EA682, F-69621, Villeurbanne, France. .,Department of cardiovascular surgery at Mount Sinai Hospital, Mount Sinai Health System, 1190 5th Avenue, 10029, New York City, NY, USA.
| | - Minh-Quyen Le
- Université Lyon, INSA-Lyon, LGEF, EA682, F-69621, Villeurbanne, France
| | - Young Joon Kwon
- Department of cardiovascular surgery at Mount Sinai Hospital, Mount Sinai Health System, 1190 5th Avenue, 10029, New York City, NY, USA
| | - Miguel A Fernandez
- French Institute for Research in Computer Science and Automation (INRIA), 2 Rue Simone IFF, 75012, Paris, France
| | - David Audigier
- Université Lyon, INSA-Lyon, LGEF, EA682, F-69621, Villeurbanne, France
| | - Florent Ganet
- Université Lyon, INSA-Lyon, LGEF, EA682, F-69621, Villeurbanne, France
| | | | - Jean François Obadia
- Department of adult cardiac surgery, Hopital cardiologique Louis Pradel - LYON medical school, 28, Avenue du Doyen Lépine, 69677 CEDEX, Bron, France
| | | |
Collapse
|
27
|
Fatemifar F, Feldman MD, Oglesby M, Han HC. Comparison of Biomechanical Properties and Microstructure of Trabeculae Carneae, Papillary Muscles, and Myocardium in the Human Heart. J Biomech Eng 2019; 141:021007. [PMID: 30418486 PMCID: PMC6298537 DOI: 10.1115/1.4041966] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 10/28/2018] [Indexed: 12/13/2022]
Abstract
Trabeculae carneae account for a significant portion of human ventricular mass, despite being considered embryologic remnants. Recent studies have found trabeculae hypertrophy and fibrosis in hypertrophied left ventricles with various pathological conditions. The objective of this study was to investigate the passive mechanical properties and microstructural characteristics of trabeculae carneae and papillary muscles compared to the myocardium in human hearts. Uniaxial tensile tests were performed on samples of trabeculae carneae and myocardium strips, while biaxial tensile tests were performed on samples of papillary muscles and myocardium sheets. The experimental data were fitted with a Fung-type strain energy function and material coefficients were determined. The secant moduli at given diastolic stress and strain levels were determined and compared among the tissues. Following the mechanical testing, histology examinations were performed to investigate the microstructural characteristics of the tissues. Our results demonstrated that the trabeculae carneae were significantly stiffer (Secant modulus SM2 = 80.06 ± 10.04 KPa) and had higher collagen content (16.10 ± 3.80%) than the myocardium (SM2 = 55.14 ± 20.49 KPa, collagen content = 10.06 ± 4.15%) in the left ventricle. The results of this study improve our understanding of the contribution of trabeculae carneae to left ventricular compliance and will be useful for building accurate computational models of the human heart.
Collapse
Affiliation(s)
- Fatemeh Fatemifar
- Department of Mechanical Engineering,
University of Texas at San Antonio,
San Antonio, TX 78249
| | - Marc D. Feldman
- Department of Medicine,
University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229
| | - Meagan Oglesby
- Department of Medicine,
University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229
| | - Hai-Chao Han
- Department of Mechanical Engineering,
University of Texas at San Antonio,
San Antonio, TX 78249
e-mail:
| |
Collapse
|
28
|
Comparative mechanical, morphological, and microstructural characterization of porcine mitral and tricuspid leaflets and chordae tendineae. Acta Biomater 2019; 85:241-252. [PMID: 30579963 DOI: 10.1016/j.actbio.2018.12.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 11/30/2018] [Accepted: 12/19/2018] [Indexed: 11/23/2022]
Abstract
BACKGROUND Healthy function of tricuspid valve (TV) structures is essential to avoid tricuspid regurgitation (TR) and may significantly improve disease prognosis. Mitral valve (MV) structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Therefore, clinical decisions and finite element (FE) simulations often rely heavily on MV data for TV applications, despite fundamentally different mechanical and physiological environments. METHOD/RESULTS To bridge this gap, we performed a rigorous mechanical, morphological, and microstructural characterization of the MV and TV leaflets and chordae in a porcine model. Planar biaxial testing, uniaxial testing, second harmonic generation imaging and Verhoeff Van Gieson staining were performed. Morphological parameters, tissue moduli, extensibility, and anisotropy were quantified and compared. No major differences in leaflet mechanics or structure were found between TV and MV; chordal mechanics, morphology, and structure were found to compensate for anatomical and physiological loading differences between the valves. No differences in chordal mechanics were observed by insertion point within a leaflet; the septal tricuspid leaflet (STL) and posterior mitral leaflet (PML) did not have distinguishable strut chords, and the STL had the shortest chords. Within a valve, chords from septally-located leaflets were more extensible. MV chords were stiffer. CONCLUSIONS This study presents the first rigorous comparative mechanical and structural dataset of MV and TV structures. Valve type and anatomical location may be stronger predictors of chordal mechanics. Chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications. STATEMENT OF SIGNIFICANCE A better understanding of the tricuspid valve (TV) and its associated structures is important for making advancements towards the repair of tricuspid regurgitation. Mitral valve structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Clinical decisions and computational simulations often rely heavily on MV data for TV applications, despite fundamentally different environments. We therefore performed a rigorous mechanical, morphological, and microstructural characterization of atrioventricular leaflets and chordae tendineae in a porcine model. Finding that valve type and anatomical location may be strong predictors of chordal mechanics, chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications.
Collapse
|
29
|
Boyle JJ, Soepriatna A, Damen F, Rowe RA, Pless RB, Kovacs A, Goergen CJ, Thomopoulos S, Genin GM. Regularization-Free Strain Mapping in Three Dimensions, With Application to Cardiac Ultrasound. J Biomech Eng 2019; 141:2705368. [PMID: 30267039 PMCID: PMC6298532 DOI: 10.1115/1.4041576] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 09/21/2018] [Indexed: 12/17/2022]
Abstract
Quantifying dynamic strain fields from time-resolved volumetric medical imaging and microscopy stacks is a pressing need for radiology and mechanobiology. A critical limitation of all existing techniques is regularization: because these volumetric images are inherently noisy, the current strain mapping techniques must impose either displacement regularization and smoothing that sacrifices spatial resolution, or material property assumptions that presuppose a material model, as in hyperelastic warping. Here, we present, validate, and apply the first three-dimensional (3D) method for estimating mechanical strain directly from raw 3D image stacks without either regularization or assumptions about material behavior. We apply the method to high-frequency ultrasound images of mouse hearts to diagnose myocardial infarction. We also apply the method to present the first ever in vivo quantification of elevated strain fields in the heart wall associated with the insertion of the chordae tendinae. The method shows promise for broad application to dynamic medical imaging modalities, including high-frequency ultrasound, tagged magnetic resonance imaging, and confocal fluorescence microscopy.
Collapse
Affiliation(s)
- John J. Boyle
- Department of Biomedical Engineering,
Washington University in St. Louis,
St. Louis, MO 63130;
Department of Orthopaedic Surgery,Columbia University,
Black Building 1406, 650 W 168 Street,
New York, NY 10032
e-mail:
| | - Arvin Soepriatna
- Weldon School of Biomedical Engineering,
Purdue University,
206 S. Martin Jischke Drive, Room 3025,
West Lafayette, IN 47907
e-mail:
| | - Frederick Damen
- Weldon School of Biomedical Engineering,
Purdue University,
206 S. Martin Jischke Drive, Room 3025,
West Lafayette, IN 47907
e-mail:
| | - Roger A. Rowe
- Department of Mechanical Engineering and
Materials Science,
Washington University in St. Louis,
Jolley Hall, CB 1185, 1 Brookings Drive,
St. Louis, MO 63130
e-mail:
| | - Robert B. Pless
- Department of Computer Science,
George Washington University,
800 22nd Street NW Room 4000,
Washington, DC 20052
e-mail:
| | - Attila Kovacs
- Department of Internal Medicine,
Cardiovascular Division,
Washington University School of Medicine,
660 S. Euclid Avenue, CB 8086,
St. Louis, MO 63110
e-mail:
| | - Craig J. Goergen
- Mem. ASME
Weldon School of Biomedical Engineering,
Purdue University,
206 S. Martin Jischke Drive, Room 3025,
West Lafayette, IN 47907
e-mail:
| | - Stavros Thomopoulos
- Mem. ASMEDepartment of Orthopaedic Surgery,
Columbia University,
New York, NY 10032;
Department of Biomedical Engineering,Columbia University,
Black Building 1408, 650 W 168 Street,
New York, NY 10032
e-mail:
| | - Guy M. Genin
- Fellow ASME
Department of Biomedical Engineering,
Washington University in St. Louis,
St. Louis, MO 63130;
Department of Mechanical Engineering and
Materials Science,
Washington University in St. Louis,
St. Louis, MO 63130;
NSF Science and Technology Center
for Engineering Mechanobiology,
Washington University in St. Louis,
Green Hall, CB 1099, 1 Brookings Drive,
St. Louis, MO 63130
e-mail:
| |
Collapse
|
30
|
Caballero A, Mao W, McKay R, Primiano C, Hashim S, Sun W. New insights into mitral heart valve prolapse after chordae rupture through fluid-structure interaction computational modeling. Sci Rep 2018; 8:17306. [PMID: 30470812 PMCID: PMC6251907 DOI: 10.1038/s41598-018-35555-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 11/07/2018] [Indexed: 12/19/2022] Open
Abstract
Mitral valve (MV) dynamics depends on a force balance across the mitral leaflets, the chordae tendineae, the mitral annulus, the papillary muscles and the adjacent ventricular wall. Chordae rupture disrupts the link between the MV and the left ventricle (LV), causing mitral regurgitation (MR), the most common valvular disease. In this study, a fluid-structure interaction (FSI) modeling framework is implemented to investigate the impact of chordae rupture on the left heart (LH) dynamics and severity of MR. A control and seven chordae rupture LH models were developed to simulate a pathological process in which minimal chordae rupture precedes more extensive chordae rupture. Different non-eccentric and eccentric regurgitant jets were identified during systole. Cardiac efficiency was evaluated by the ratio of external stroke work. MV structural results showed that basal/strut chordae were the major load-bearing chordae. An increased number of ruptured chordae resulted in reduced basal/strut tension, but increased marginal/intermediate load. Chordae rupture in a specific scallop did not necessarily involve an increase in the stress of the entire prolapsed leaflet. This work represents a further step towards patient-specific modeling of pathological LH dynamics, and has the potential to improve our understanding of the biomechanical mechanisms and treatment of primary MR.
Collapse
Affiliation(s)
- Andrés Caballero
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Wenbin Mao
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Raymond McKay
- Cardiology and Cardiac Surgery, The Hartford Hospital, Hartford, Connecticut, USA
| | - Charles Primiano
- Cardiology and Cardiac Surgery, The Hartford Hospital, Hartford, Connecticut, USA
| | - Sabet Hashim
- Cardiology and Cardiac Surgery, The Hartford Hospital, Hartford, Connecticut, USA
| | - Wei Sun
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
| |
Collapse
|
31
|
Liang J, Smith KD, Lu H, Seale TW, Gan RZ. Mechanical properties of the Papio anubis tympanic membrane: Change significantly from infancy to adulthood. Hear Res 2018; 370:143-154. [PMID: 30388572 DOI: 10.1016/j.heares.2018.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 10/05/2018] [Accepted: 10/14/2018] [Indexed: 11/16/2022]
Abstract
Mechanical properties of the tympanic membrane (TM) are important for studying the transfer function of the auditory system. However, nearly all reported human data are limited to adults because of the unavailability of temporal bones from children. In this study, we used the baboon (Papio anubis), a genetically close human relative, as a model to address the occurrence of age-dependent changes of the human TM. Forty-five baboon TMs were characterized in five age groups: <1 year, 1 to <2 years, 2 to <3 years, 3 to <5, and >5 years of age, comparable to human ages ranging from newborn to adult. The elastic properties of the baboon TMs were characterized by a micro-fringe projection technique. Volume displacement of the TM under quasi-static pressure was first determined from its micro-fringe pattern. Subsequently, these displacement values were used in a finite element model to derive mechanical properties. The Young's modulus of the baboon TM exhibited a modest decrease from 29.1 MPa to 26.0 MPa over the age groups. The average Young's modulus was ∼1.4 times higher than that of the adult human TM. This is the first time that age-related TM mechanical properties of high primate are reported. These new findings may help to explore the potential value of the baboon as a new primate model for future age-related hearing research on the normal and diseased ear.
Collapse
Affiliation(s)
- Junfeng Liang
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA; Dept. of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Kyle D Smith
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA
| | - Hongbing Lu
- Dept. of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Thomas W Seale
- Dept. of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Rong Z Gan
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA.
| |
Collapse
|
32
|
Grinberg D, Cottinet PJ, Thivolet S, Audigier D, Capsal JF, Le MQ, Obadia JF. Measuring chordae tension during transapical neochordae implantation: Toward understanding objective consequences of mitral valve repair. J Thorac Cardiovasc Surg 2018; 158:746-755. [PMID: 30454983 DOI: 10.1016/j.jtcvs.2018.10.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/17/2018] [Accepted: 10/02/2018] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Complex structure of mitral valve and its central position in the heart limit assessment of mitral function to standardized calculated parameters assessed using medical imaging (echocardiography). Novel techniques, which allow mitral valve repair (MVr) in a beating heart, offer the opportunity for innovative objective assessment in physiologic and pathologic conditions. We report, to our knowledge, the first data of real-time chordal tension measurement during a transapical neochordae implantation. METHODS Seven patients with severe degenerative mitral regurgitation due to posterior prolapse underwent transapical MVr using the NeoChord DS 1000 (NeoChord Inc, Minneapolis, Minn). During prolapse correction, the tension applied on the neochordae was measured in addition to hemodynamic and echocardiographic parameters. RESULTS The traction applied on 1 chorda sustaining the P2 segment was measured at between 0.7 and 0.9 N, and oscillated with respiration. When several neochordae were set in tension, this initial tension was spread homogeneously on each chorda (mean sum of the amplitude of tension 0.98 ± 0.08 N). To achieve an optimal echocardiographic correction, a complementary synchronous traction on all chordae was required. During this adjustment, the sum of the tension decreased (mean 12 ± 2%; P = .018), suggesting that when normal physiology was restored, the valvular apparatus was in a low-stress state. This method allowed us to apply a precise and reproducible technique, leading to a good procedural success rate with a low morbidity and mortality rate. CONCLUSIONS The tension applied on chordae during transapical implantation of neochordae for degenerative mitral regurgitation can be measured, providing original data about the objective consequences of MVr on the mitral apparatus.
Collapse
Affiliation(s)
- Daniel Grinberg
- Department of Adult Cardiac Surgery, Hôpital cardiologique Louis Pradel, Lyon Medical School, Bron, France; Univ Lyon, INSA-Lyon, LGEF (Lab of electrical engineering and ferroelectricity), Villeurbanne, France; Department of Cardiovascular Surgery, Mount Sinai Hospital, New York, NY.
| | - Pierre-Jean Cottinet
- Univ Lyon, INSA-Lyon, LGEF (Lab of electrical engineering and ferroelectricity), Villeurbanne, France
| | - Sophie Thivolet
- Department of Adult Cardiac Surgery, Hôpital cardiologique Louis Pradel, Lyon Medical School, Bron, France
| | - David Audigier
- Univ Lyon, INSA-Lyon, LGEF (Lab of electrical engineering and ferroelectricity), Villeurbanne, France
| | - Jean-Fabien Capsal
- Univ Lyon, INSA-Lyon, LGEF (Lab of electrical engineering and ferroelectricity), Villeurbanne, France
| | - Minh-Quyen Le
- Univ Lyon, INSA-Lyon, LGEF (Lab of electrical engineering and ferroelectricity), Villeurbanne, France
| | - Jean-François Obadia
- Department of Adult Cardiac Surgery, Hôpital cardiologique Louis Pradel, Lyon Medical School, Bron, France
| |
Collapse
|
33
|
Madukauwa-David ID, Pierce EL, Sulejmani F, Pataky J, Sun W, Yoganathan AP. Suture dehiscence and collagen content in the human mitral and tricuspid annuli. Biomech Model Mechanobiol 2018; 18:291-299. [PMID: 30288649 DOI: 10.1007/s10237-018-1082-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 09/24/2018] [Indexed: 11/29/2022]
Abstract
Postoperative suture dehiscence is an important mode of short-term mitral and tricuspid valve (MV, TV) repair failure. We sought to evaluate suture pullout forces and collagen density in human atrioventricular valves for a better understanding of the comparative physiology between the valves and the underlying mechanobiological basis for suture retention. Mitral and tricuspid annuli were each excised from hearts from human donors age 60-79 with no history of heart disease (n = 6). Anchor sutures were vertically pulled until tearing through the tissue. Suture pullout force (FP) was measured as the maximum force at dehiscence. Subsequently, tissue samples from each tested suture position were evaluated for collagen content using a standard hydroxyproline assay. Among all mitral positions, no significant differences were detected among positions or regions with mean FP values falling between 6.9 ± 2.6 N (posterior region) and 10.3 ± 4.7 N (anterior region). Among all tricuspid positions, the maximum FP and minimum FP were 24.0 ± 9.2 N (trigonal region) and 4.5 ± 2.6 N (anterior region). Although for the MV, a given sample's collagen content had no correlation to its corresponding FP, the same relationship was significant for the TV. Further, the TV exhibited comparable FP to the MV overall, despite a nearly 40% reduction in collagen content. These findings suggest that sutures placed in the trigonal region of the TV have higher pullout force than those placed along other segments of the annuli. Furthermore, there are likely differences in collagen orientation between the mitral and tricuspid annuli, such that collagen content strongly impacts FP in one, but not the other.
Collapse
Affiliation(s)
| | - Eric L Pierce
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Suite 200, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Fatiesa Sulejmani
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Suite 200, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Joshua Pataky
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Suite 200, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Wei Sun
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Suite 200, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Suite 200, 387 Technology Circle, Atlanta, GA, 30313-2412, USA.
| |
Collapse
|
34
|
Pham T, Kong F, Martin C, Wang Q, Primiano C, McKay R, Elefteriades J, Sun W. Finite Element Analysis of Patient-Specific Mitral Valve with Mitral Regurgitation. Cardiovasc Eng Technol 2017; 8:3-16. [PMID: 28070866 DOI: 10.1007/s13239-016-0291-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/29/2016] [Indexed: 12/30/2022]
Abstract
Functional mitral regurgitation (FMR) is a significant complication of left ventricular dysfunction and strongly associated with a poor prognosis. In this study, we developed a patient-specific finite element (FE) model of the mitral apparatus in a FMR patient which included: both leaflets with thickness, annulus, chordae tendineae, and chordae insertions on the leaflets and origins on the papillary muscles. The FE model incorporated human age- and gender-matched anisotropic hyperelastic material properties, and MV closure at systole was simulated. The model was validated by comparing the FE results from valve closure simulation with the in vivo geometry of the MV at systole. It was found that the FE model could not replicate the in vivo MV geometry without the application of tethering pre-tension force in the chordae at diastole. Upon applying the pre-tension force and performing model optimization by adjusting the chordal length, position, and leaflet length, a good agreement between the FE model and the in vivo model was established. Not only were the chordal forces high at both diastole and systole, but the tethering force on the anterior papillary muscle was higher than that of the posterior papillary muscle, which resulted in an asymmetrical gap with a larger orifice area at the anterolateral commissure resulting in MR. The analyses further show that high peak stress and strain were found at the chordal insertions where large chordal tethering forces were found. This study shows that the pre-tension tethering force plays an important role in accurately simulating the MV dynamics in this FMR patient, particularly in quantifying the degree of leaflet coaptation and stress distribution. Due to the complexity of the disease, the patient-specific computational modeling procedure of FMR patients presented should be further evaluated using a large patient cohort. However, this study provides useful insights into the MV biomechanics of a FMR patient, and could serve as a tool to assist in pre-operative planning for MV repair or replacement surgical or interventional procedures.
Collapse
Affiliation(s)
- Thuy Pham
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Fanwei Kong
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Caitlin Martin
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | - Qian Wang
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA
| | | | - Raymond McKay
- Cardiology Department of Hartford Hospital, Hartford, CT, USA
| | | | - Wei Sun
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA.
| |
Collapse
|