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Mansouri H, Kemerli M, MacIver R, Amili O. Development of idealized human aortic models for in vitro and in silico hemodynamic studies. Front Cardiovasc Med 2024; 11:1358601. [PMID: 39161662 PMCID: PMC11330894 DOI: 10.3389/fcvm.2024.1358601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 06/25/2024] [Indexed: 08/21/2024] Open
Abstract
Background The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies. Objective This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings. Methods Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Results Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models. Conclusions The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.
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Affiliation(s)
- Hamid Mansouri
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
| | - Muaz Kemerli
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
- Department of Mechanical Engineering, Sakarya University, Sakarya, Turkey
| | - Robroy MacIver
- Children’s Heart Clinic, Children’s Hospitals and Clinics of Minnesota, Minneapolis, MN, United States
| | - Omid Amili
- Department of Mechanical, Industrial, and Manufacturing Engineering, University of Toledo, Toledo, OH, United States
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2
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Breitenstein-Attach A, Steitz M, Sun X, Hao Y, Kiekenap J, Emeis J, Tuladhar SR, Berger F, Schmitt B. In Vitro Comparison of a Closed and Semi-closed Leaflet Design for Adult and Pediatric Transcatheter Heart Valves. Ann Biomed Eng 2024; 52:2051-2064. [PMID: 38615078 PMCID: PMC11247063 DOI: 10.1007/s10439-024-03502-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 03/25/2024] [Indexed: 04/15/2024]
Abstract
Transcatheter heart valve replacements (TVR) are mostly designed in a closed position (c) with leaflets coaptating. However, recent literature suggests fabricating valves in semi-closed (sc) position to minimize pinwheeling. With about 100,000 children in need of a new pulmonary valve each year worldwide, this study evaluates both geometrical approaches in adult as well as pediatric size and condition. Three valves of each geometry were fabricated in adult (30 mm) and pediatric (15 mm) size, using porcine pericardium. To evaluate performance, the mean transvalvular pressure gradient (TPG), effective orifice area (EOA), and regurgitation fraction (RF) were determined in three different annulus geometries (circular, elliptic, and tilted). For both adult-sized valve geometries, the TPG (TPGC = 2.326 ± 0.115 mmHg; TPGSC = 1.848 ± 0.175 mmHg)* and EOA (EOAC = 3.69 ± 0.255 cm2; EOASC = 3.565 ± 0.025 cm2)* showed no significant difference. Yet the RF as well as its fluctuation was significantly higher for valves with the closed geometry (RFC = 12.657 ± 7.669 %; RFSC = 8.72 ± 0.977 %)*. Recordings showed that the increased backflow was caused by pinwheeling due to a surplus of tissue material. Hydrodynamic testing of pediatric TVRs verified the semi-closed geometry being favourable. Despite the RF (RFC = 7.721 ± 0.348 cm2; RFSC = 5.172 ± 0.679 cm2), these valves also showed an improved opening behaviour ((TPGC = 20.929 ± 0.497 cm2; TPGSC = 15.972 ± 1.158 cm2); (EOAC = 0.629 ± 0.017 cm2; EOASC = 0.731 ± 0.026 cm2)). Both adult and pediatric TVR with semi-closed geometry show better fluiddynamic functionality compared to valves with a closed design due to less pinwheeling. Besides improved short-term functionality, less pinwheeling potentially prevents early valve degeneration and improves durability. *Results are representatively shown for a circular annulus geometry.
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Affiliation(s)
- Alexander Breitenstein-Attach
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany.
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany.
- DZHK (German Centre for Cardiovascular Research), Potsdamer Str. 58, Berlin, Germany.
| | - Marvin Steitz
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Potsdamer Str. 58, Berlin, Germany
| | - Xiaolin Sun
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Potsdamer Str. 58, Berlin, Germany
| | - Yimeng Hao
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
| | - Jonathan Kiekenap
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
| | - Jasper Emeis
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
| | - Sugat Ratna Tuladhar
- Department for Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Straße 1, Hannover, Germany
| | - Felix Berger
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
| | - Boris Schmitt
- Department of Pediatric Cardiology and Congenital Heart Disease, German Heart Center Berlin (Charité), Augustenburger Platz 1, Berlin, Germany
- Department of Pediatric Cardiology and Congenital Heart Disease, Charité - University Medicine Berlin, Augustenburger Platz 1, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Potsdamer Str. 58, Berlin, Germany
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Macé LG, Fringand T, Cheylan I, Sabatier L, Meille L, Lenoir M, Favier J. Three-dimensional modelling of aortic leaflet coaptation and load-bearing surfaces: in silico design of aortic valve neocuspidizations. INTERDISCIPLINARY CARDIOVASCULAR AND THORACIC SURGERY 2024; 39:ivae108. [PMID: 38830038 PMCID: PMC11246164 DOI: 10.1093/icvts/ivae108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 04/30/2024] [Accepted: 05/30/2024] [Indexed: 06/05/2024]
Abstract
OBJECTIVES Three-dimensional (3D) modelling of aortic leaflets remains difficult due to insufficient resolution of medical imaging. We aimed to model the coaptation and load-bearing surfaces of the aortic leaflets and adapt this workflow to aid in the design of aortic valve neocuspidizations. METHODS Geometric morphometrics, using landmarks and semilandmarks, was applied to the geometric determinants of the aortic leaflets from computed tomography, followed by an isogeometric analysis using Non-Uniform Rational Basis Splines (NURBS). Ten aortic valve models were generated, measuring determinants of leaflet geometry defined as 3D NURBS curves, and leaflet coaptation and load-bearing surfaces were defined as 3D NURBS surfaces. Neocuspidizations were obtained by either shifting the upper central coaptation landmark towards the sinotubular junction or using parametric neo-landmarks placed on a centreline drawn between the centroid of the aortic root base and centroid of a circle circumscribing the 3 upper commissural landmarks. RESULTS The ratio of the leaflet free margin length to the geometric height was 1.83, whereas the ratio of the commissural coaptation height to the central coaptation height was 1.93. The median coaptation surface was 137 mm2 (IQR 58) and the median load-bearing surface was 203 mm2 (60) per leaflet. Neocuspidization multiplied the central coaptation height by 3.7 and the coaptation surfaces by 1.97 and 1.92 using the native coaptation axis and centroid coaptation axis, respectively. CONCLUSIONS Geometric morphometrics reliably defined the coaptation and load-bearing surfaces of aortic leaflets, enabling an experimental 3D design for the in silico neocuspidization of aortic valves.
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Affiliation(s)
- Loïc Georges Macé
- Department of Cardiac Surgery, La Timone Hospital, AP-HM, Aix Marseille Univ, Marseille, France
- Aix Marseille Univ, CNRS, Centrale Med, M2P2, Marseille, France
| | - Tom Fringand
- Aix Marseille Univ, CNRS, Centrale Med, M2P2, Marseille, France
| | | | | | - Laurent Meille
- Cardiovascular Department, Clinique Rhône Durance, Avignon, France
| | - Marien Lenoir
- Department of Cardiac Surgery, La Timone Hospital, AP-HM, Aix Marseille Univ, Marseille, France
- Aix Marseille Univ, CNRS, Centrale Med, M2P2, Marseille, France
| | - Julien Favier
- Aix Marseille Univ, CNRS, Centrale Med, M2P2, Marseille, France
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Bahadormanesh N, Tomka B, Abdelkhalek M, Khodaei S, Maftoon N, Keshavarz-Motamed Z. A Doppler-exclusive non-invasive computational diagnostic framework for personalized transcatheter aortic valve replacement. Sci Rep 2023; 13:8033. [PMID: 37198194 PMCID: PMC10192526 DOI: 10.1038/s41598-023-33511-6] [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: 10/21/2022] [Accepted: 04/13/2023] [Indexed: 05/19/2023] Open
Abstract
Given the associated risks with transcatheter aortic valve replacement (TAVR), it is crucial to determine how the implant will affect the valve dynamics and cardiac function, and if TAVR will improve or worsen the outcome of the patient. Effective treatment strategies, indeed, rely heavily on the complete understanding of the valve dynamics. We developed an innovative Doppler-exclusive non-invasive computational framework that can function as a diagnostic tool to assess valve dynamics in patients with aortic stenosis in both pre- and post-TAVR status. Clinical Doppler pressure was reduced by TAVR (52.2 ± 20.4 vs. 17.3 ± 13.8 [mmHg], p < 0.001), but it was not always accompanied by improvements in valve dynamics and left ventricle (LV) hemodynamics metrics. TAVR had no effect on LV workload in 4 patients, and LV workload post-TAVR significantly rose in 4 other patients. Despite the group level improvements in maximum LV pressure (166.4 ± 32.2 vs 131.4 ± 16.9 [mmHg], p < 0.05), only 5 of the 12 patients (41%) had a decrease in LV pressure. Moreover, TAVR did not always improve valve dynamics. TAVR did not necessarily result in a decrease (in 9 out of 12 patients investigated in this study) in major principal stress on the aortic valve leaflets which is one of the main contributors in valve degeneration and, consequently, failure of heart valves. Diastolic stresses increased significantly post-TAVR (34%, 109% and 81%, p < 0.001) for each left, right and non-coronary leaflets respectively. Moreover, we quantified the stiffness and material properties of aortic valve leaflets which correspond with the reduced calcified region average stiffness among leaflets (66%, 74% and 62%; p < 0.001; N = 12). Valve dynamics post-intervention should be quantified and monitored to ensure the improvement of patient conditions and prevent any further complications. Improper evaluation of biomechanical valve features pre-intervention as well as post-intervention may result in harmful effects post-TAVR in patients including paravalvular leaks, valve degeneration, failure of TAVR and heart failure.
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Affiliation(s)
- Nikrouz Bahadormanesh
- Department of Mechanical Engineering, McMaster University, JHE-310, Hamilton, ON, L8S 4L7, Canada
| | - Benjamin Tomka
- Department of Mechanical Engineering, McMaster University, JHE-310, Hamilton, ON, L8S 4L7, Canada
| | | | - Seyedvahid Khodaei
- Department of Mechanical Engineering, McMaster University, JHE-310, Hamilton, ON, L8S 4L7, Canada
| | - Nima Maftoon
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada
- Centre for Bioengineering and Biotechnology, University of Waterloo, Waterloo, ON, Canada
| | - Zahra Keshavarz-Motamed
- Department of Mechanical Engineering, McMaster University, JHE-310, Hamilton, ON, L8S 4L7, Canada.
- School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada.
- School of Computational Science and Engineering, McMaster University, Hamilton, ON, Canada.
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Bahadormanesh N, Tomka B, Kadem M, Khodaei S, Keshavarz-Motamed Z. An ultrasound-exclusive non-invasive computational diagnostic framework for personalized cardiology of aortic valve stenosis. Med Image Anal 2023; 87:102795. [PMID: 37060702 DOI: 10.1016/j.media.2023.102795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/27/2023] [Accepted: 03/06/2023] [Indexed: 03/30/2023]
Abstract
Aortic stenosis (AS) is an acute and chronic cardiovascular disease and If left untreated, 50% of these patients will die within two years of developing symptoms. AS is characterized as the stiffening of the aortic valve leaflets which restricts their motion and prevents the proper opening under transvalvular pressure. Assessments of the valve dynamics, if available, would provide valuable information about the patient's state of cardiac deterioration as well as heart recovery and can have incredible impacts on patient care, planning interventions and making critical clinical decisions with life-threatening risks. Despite remarkable advancements in medical imaging, there are no clinical tools available to quantify valve dynamics invasively or noninvasively. In this study, we developed a highly innovative ultrasound-based non-invasive computational framework that can function as a diagnostic tool to assess valve dynamics (e.g. transient 3-D distribution of stress and displacement, 3-D deformed shape of leaflets, geometric orifice area and angular positions of leaflets) for patients with AS at no risk to the patients. Such a diagnostic tool considers the local valve dynamics and the global circulatory system to provide a platform for testing the intervention scenarios and evaluating their effects. We used clinical data of 12 patients with AS not only to validate the proposed framework but also to demonstrate its diagnostic abilities by providing novel analyses and interpretations of clinical data in both pre and post intervention states. We used transthoracic echocardiogram (TTE) data for the developments and transesophageal echocardiography (TEE) data for validation.
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Affiliation(s)
| | - Benjamin Tomka
- Department of Mechanical Engineering, McMaster University Hamilton, ON, Canada
| | - Mason Kadem
- School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada
| | - Seyedvahid Khodaei
- Department of Mechanical Engineering, McMaster University Hamilton, ON, Canada
| | - Zahra Keshavarz-Motamed
- Department of Mechanical Engineering, McMaster University Hamilton, ON, Canada; School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada; School of Computational Science and Engineering, McMaster University, Hamilton, ON, Canada.
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A parametric geometry model of the aortic valve for subject-specific blood flow simulations using a resistive approach. Biomech Model Mechanobiol 2023; 22:987-1002. [PMID: 36853513 PMCID: PMC10167200 DOI: 10.1007/s10237-023-01695-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 01/22/2023] [Indexed: 03/01/2023]
Abstract
Cardiac valves simulation is one of the most complex tasks in cardiovascular modeling. Fluid-structure interaction is not only highly computationally demanding but also requires knowledge of the mechanical properties of the tissue. Therefore, an alternative is to include valves as resistive flow obstacles, prescribing the geometry (and its possible changes) in a simple way, but, at the same time, with a geometry complex enough to reproduce both healthy and pathological configurations. In this work, we present a generalized parametric model of the aortic valve to obtain patient-specific geometries that can be included into blood flow simulations using a resistive immersed implicit surface (RIIS) approach. Numerical tests are presented for geometry generation and flow simulations in aortic stenosis patients whose parameters are extracted from ECG-gated CT images.
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7
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The study of the relationship between unicuspid aortic valve insufficiency and heart disease by fluid-structure interaction modeling. BIOMEDICAL ENGINEERING ADVANCES 2023. [DOI: 10.1016/j.bea.2023.100079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
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8
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Effects of Hysteresis on the Dynamic Deformation of Artificial Polymeric Heart Valve. PROSTHESIS 2022. [DOI: 10.3390/prosthesis4040042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The deformation behavior of an artificial heart valve was analyzed using the explicit dynamic finite element method. Time variations of the left ventricle and the aortic pressure were considered as the mechanical boundary conditions in order to reproduce the opening and closing movements of the valve under the full cardiac cycle. The valve was assumed to be made from a medical polymer and hence, a hyperelastic Mooney–Rivlin model was assigned as the material model. A simple formula of the damage mechanics was also introduced into the theoretical material model to express the hysteresis response under the unloading state. Effects of the hysteresis on the valve deformation were characterized by the delay of response and the enlargement of displacement. Most importantly, the elastic vibration observed in the pure elastic response under the full close state was dramatically reduced by the conversion of a part of elastic energy to the dissipated energy due to hysteresis.
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Johnson EL, Laurence DW, Xu F, Crisp CE, Mir A, Burkhart HM, Lee CH, Hsu MC. Parameterization, geometric modeling, and isogeometric analysis of tricuspid valves. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2021; 384:113960. [PMID: 34262232 PMCID: PMC8274564 DOI: 10.1016/j.cma.2021.113960] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Approximately 1.6 million patients in the United States are affected by tricuspid valve regurgitation, which occurs when the tricuspid valve does not close properly to prevent backward blood flow into the right atrium. Despite its critical role in proper cardiac function, the tricuspid valve has received limited research attention compared to the mitral and aortic valves on the left side of the heart. As a result, proper valvular function and the pathologies that may cause dysfunction remain poorly understood. To promote further investigations of the biomechanical behavior and response of the tricuspid valve, this work establishes a parameter-based approach that provides a template for tricuspid valve modeling and simulation. The proposed tricuspid valve parameterization presents a comprehensive description of the leaflets and the complex chordae tendineae for capturing the typical three-cusp structural deformation observed from medical data. This simulation framework develops a practical procedure for modeling tricuspid valves and offers a robust, flexible approach to analyze the performance and effectiveness of various valve configurations using isogeometric analysis. The proposed methods also establish a baseline to examine the tricuspid valve's structural deformation, perform future investigations of native valve configurations under healthy and disease conditions, and optimize prosthetic valve designs.
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Affiliation(s)
- Emily L. Johnson
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Devin W. Laurence
- School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Fei Xu
- Ansys Inc., 807 Las Cimas Parkway, Austin, Texas 78746, USA
| | - Caroline E. Crisp
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Harold M. Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Chung-Hao Lee
- School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Institute for Biomedical Engineering, Science and Technology (IBEST), The University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
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Zervides C, Nohra O, Hunduma G, Thomas NW, Samia R. 2006 to 2019 Story; percutaneously implantable aortic valve prototypes. J Cardiothorac Surg 2021; 16:223. [PMID: 34362403 PMCID: PMC8348870 DOI: 10.1186/s13019-021-01597-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/27/2021] [Indexed: 11/10/2022] Open
Abstract
Aims A review was conducted on the composition, advantages and limitations of available aortic valve prototypes to create an ideal valve for percutaneous implantation. Patients Patients with multiple comorbidities who cannot withstand the risks of open cardiac surgery. Methodology The search was performed using online databases and textbooks. Articles were excluded based on specific criterion. Results Ten prototypes created between 2006 and 2019 were found and reviewed. The prototypes had a set of advantages and limitations with their characteristics coinciding at times. Conclusions The ideal percutaneously implantable aortic valve should have minimum coaptation height, zero folds in the leaflets, minimum valve height, minimum leaflet flexion and three leaflets. It can be composed of biological or synthetic material, as long as it provides minimal risk of thrombosis. However, more studies are needed to ensure other ideal parameters.
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Affiliation(s)
- Constantinos Zervides
- University of Nicosia Medical School, University of Nicosia, 21 Ilia Papakyriakou, 2414, Engomi, Nicosia, Cyprus.
| | - Ornella Nohra
- University of Nicosia Medical School, University of Nicosia, 21 Ilia Papakyriakou, 2414, Engomi, Nicosia, Cyprus
| | - Gabriel Hunduma
- University of Nicosia Medical School, University of Nicosia, 21 Ilia Papakyriakou, 2414, Engomi, Nicosia, Cyprus
| | - Neil Wild Thomas
- University of Nicosia Medical School, University of Nicosia, 21 Ilia Papakyriakou, 2414, Engomi, Nicosia, Cyprus
| | - Ramy Samia
- University of Nicosia Medical School, University of Nicosia, 21 Ilia Papakyriakou, 2414, Engomi, Nicosia, Cyprus
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11
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Yan W, Li J, Wang W, Wei L, Wang S. A Fluid-Structure Interaction Study of Different Bicuspid Aortic Valve Phenotypes Throughout the Cardiac Cycle. Front Physiol 2021; 12:716015. [PMID: 34381379 PMCID: PMC8350765 DOI: 10.3389/fphys.2021.716015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
The bicuspid aortic valve (BAV) is a congenital malformation of the aortic valve with a variety of structural features. The current research on BAV mainly focuses on the systolic phase, while ignoring the diastolic hemodynamic characteristics and valve mechanics. The purpose of this study is to compare the differences in hemodynamics and mechanical properties of BAV with different phenotypes throughout the cardiac cycle by means of numerical simulation. Based on physiological anatomy, we established an idealized tricuspid aortic valve (TAV) model and six phenotypes of BAV models (including Type 0 a-p, Type 0 lat, Type 1 L-R, Type 1 N-L, Type 1 R-N, and Type 2), and simulated the dynamic changes of the aortic valve during the cardiac cycle using the fluid-structure interaction method. The morphology of the leaflets, hemodynamic parameters, flow patterns, and strain were analyzed. Compared with TAV, the cardiac output and effective orifice area of different BAV phenotypes decreased certain degree, along with the peak velocity and mean pressure difference increased both. Among all BAV models, Type 2 exhibited the worst hemodynamic performance. During the systole, obvious asymmetric flow field was observed in BAV aorta, which was related to the orientation of BAV. Higher strain was generated in diastole for BAV models. The findings of this study suggests specific differences in the hemodynamic characteristics and valve mechanics of different BAV phenotypes, including different severity of stenosis, flow patterns, and leaflet strain, which may be critical for prediction of other subsequent aortic diseases and differential treatment strategy for certain BAV phenotype.
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Affiliation(s)
- Wentao Yan
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Jianming Li
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Wenshuo Wang
- Department of Vascular Surgery, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Lai Wei
- Department of Vascular Surgery, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Shengzhang Wang
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
- Institute of Biomedical Engineering Technology, Academy for Engineering and Technology, Fudan University, Shanghai, China
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12
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Kerr MM, Gourlay T. Design and numerical simulation for the development of an expandable paediatric heart valve. Int J Artif Organs 2020; 44:518-524. [PMID: 33300423 PMCID: PMC8366171 DOI: 10.1177/0391398820977509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Current paediatric valve replacement options cannot compensate for somatic growth, leading to an obstruction of flow as the child outgrows the prosthesis. This often necessitates an increase in revision surgeries, leading to legacy issues into adulthood. An expandable valve concept was modelled with an inverse relationship between annulus size and height, to retain the leaflet geometry without requiring additional intervention. Parametric design modelling was used to define certain valve parameter aspect ratios in relation to the base radius, Rb, including commissural radius, Rc, valve height, H and coaptation height, x. Fluid-structure simulations were subsequently carried out using the Immersed Boundary method to radially compress down the fully expanded aortic valve whilst subjecting it to diastolic and systolic loading cycles. Leaflet radial displacements were analysed to determine if valve performance is likely to be compromised following compression. Work is ongoing to optimise valvular parameter design for the paediatric patient cohort.
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Affiliation(s)
- Monica M Kerr
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - Terence Gourlay
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
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13
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Hedayat M, Patel TR, Kim T, Belohlavek M, Hoffmann KR, Borazjani I. A hybrid echocardiography-CFD framework for ventricular flow simulations. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e03352. [PMID: 32419374 DOI: 10.1002/cnm.3352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 06/11/2023]
Abstract
Image-based CFD is a powerful tool to study cardiovascular flows while 2D echocardiography (echo) is the most widely used noninvasive imaging modality for the diagnosis of heart disease. Here, echo is combined with CFD, that is, an echo-CFD framework, to study ventricular flows. To achieve this, the previous 3D reconstruction from multiple 2D echo at standard cross sections is extended by: (a) reconstructing aortic and mitral valves from 2D echo and closing the left-ventricle (LV) geometry by approximating a superior wall; (b) incorporating the physiological assumption of the fixed apex as a reference (fixed) point in the 3D reconstruction; and (c) incorporating several smoothing algorithms to remove the nonphysical oscillations (ringing) near the basal section. The method is applied to echo from a baseline LV and one after inducing acute myocardial ischemia (AMI). The 3D reconstruction is validated by comparing it against a reference reconstruction from many echo sections while flow simulations are validated against the Doppler ultrasound velocity measurements. The sensitivity study shows that the choice of the smoothing algorithm does not change the flow pattern inside the LV. However, the presence of the mitral valve can significantly change the flow pattern during the diastole phase. In addition, the abnormal shape of a LV with AMI can drastically change the flow during diastole. Furthermore, the hemodynamic energy loss, as an indicator of the LV pumping performance, for different test cases is calculated, which shows a larger energy loss for a LV with AMI compared to the baseline one.
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Affiliation(s)
- Mohammadali Hedayat
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Tatsat R Patel
- Department of Mechanical and Aerospace Engineering, State University of New York at Buffalo, Buffalo, New York, USA
| | - Taeouk Kim
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Marek Belohlavek
- Department of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona, USA
| | - Kenneth R Hoffmann
- Department of Neurosurgery, University at Buffalo SUNY, Buffalo, New York, USA
| | - Iman Borazjani
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
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14
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Loureiro-Ga M, Veiga C, Fdez-Manin G, Jimenez VA, Calvo-Iglesias F, Iñiguez A. A biomechanical model of the pathological aortic valve: simulation of aortic stenosis. Comput Methods Biomech Biomed Engin 2020; 23:303-311. [PMID: 31996041 DOI: 10.1080/10255842.2020.1720001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aortic stenosis (AS) disease is a narrowing of the aortic valve (AV) opening which reduces blood flow from the heart causing several health complications. Although a lot of work has been done in AV simulations, most of the efforts have been conducted regarding healthy valves. In this article, a new three-dimensional patient-specific biomechanical model of the valve, based on a parametric formulation of the stenosis that permits the simulation of different degrees of pathology, is presented. The formulation is based on a double approach: the first one is done from the geometric point of view, reducing the effective ejection area of the AV by joining leaflets using a zipper effect to sew them; the second one, in terms of functionality, is based on the modification of AV tissue properties due to the effect of calcifications. Both healthy and stenotic valves were created using patient-specific data and results of the numerical simulation of the valve function are provided. Analysis of the results shows a variation in the first principal stress, geometric orifice area, and blood velocity which were validated against clinical data. Thus, the possibility to create a pipeline which allows the integration of patient-specific data from echocardiographic images and iFR studies to perform finite elements analysis is proved.
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Affiliation(s)
- Marcos Loureiro-Ga
- Applied Mathematics Department II - Telecommunications Engineering Faculty, Univeristiy of Vigo, Vigo, Spain.,Cardiology Department, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Cesar Veiga
- Cardiology Department, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Generosa Fdez-Manin
- Applied Mathematics Department II - Telecommunications Engineering Faculty, Univeristiy of Vigo, Vigo, Spain
| | - Victor Alfonso Jimenez
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
| | - Francisco Calvo-Iglesias
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
| | - Andres Iñiguez
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
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15
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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.
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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.
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Capoulade R, Teoh JG, Bartko PE, Teo E, Scholtz JE, Tastet L, Shen M, Mihos CG, Park YH, Garcia J, Larose E, Isselbacher EM, Sundt TM, MacGillivray TE, Melnitchouk S, Ghoshhajra BB, Pibarot P, Hung J. Relationship Between Proximal Aorta Morphology and Progression Rate of Aortic Stenosis. J Am Soc Echocardiogr 2018; 31:561-569.e1. [DOI: 10.1016/j.echo.2017.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Indexed: 10/18/2022]
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17
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Xu F, Morganti S, Zakerzadeh R, Kamensky D, Auricchio F, Reali A, Hughes TJ, Sacks MS, Hsu MC. A framework for designing patient-specific bioprosthetic heart valves using immersogeometric fluid-structure interaction analysis. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2938. [PMID: 29119728 PMCID: PMC5893448 DOI: 10.1002/cnm.2938] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 09/08/2017] [Accepted: 10/22/2017] [Indexed: 05/07/2023]
Abstract
Numerous studies have suggested that medical image derived computational mechanics models could be developed to reduce mortality and morbidity due to cardiovascular diseases by allowing for patient-specific surgical planning and customized medical device design. In this work, we present a novel framework for designing prosthetic heart valves using a parametric design platform and immersogeometric fluid-structure interaction (FSI) analysis. We parameterize the leaflet geometry using several key design parameters. This allows for generating various perturbations of the leaflet design for the patient-specific aortic root reconstructed from the medical image data. Each design is analyzed using our hybrid arbitrary Lagrangian-Eulerian/immersogeometric FSI methodology, which allows us to efficiently simulate the coupling of the deforming aortic root, the parametrically designed prosthetic valves, and the surrounding blood flow under physiological conditions. A parametric study is performed to investigate the influence of the geometry on heart valve performance, indicated by the effective orifice area and the coaptation area. Finally, the FSI simulation result of a design that balances effective orifice area and coaptation area reasonably well is compared with patient-specific phase contrast magnetic resonance imaging data to demonstrate the qualitative similarity of the flow patterns in the ascending aorta.
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Affiliation(s)
- Fei Xu
- Department of Mechanical Engineering, Iowa State University, 2025 Black Engineering, Ames, IA 50011, USA
| | - Simone Morganti
- Department of Electrical, Computer, and Biomedical Engineering, University of Pavia, via Ferrata 3, 27100, Pavia Italy
| | - Rana Zakerzadeh
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - David Kamensky
- Department of Structural Engineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0085 La Jolla, CA 92093, USA
| | - Ferdinando Auricchio
- Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 3, 27100, Pavia, Italy
| | - Alessandro Reali
- Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 3, 27100, Pavia, Italy
| | - Thomas J.R. Hughes
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - Michael S. Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th St, Stop C0200, Austin, TX 78712, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, 2025 Black Engineering, Ames, IA 50011, USA
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De Kerchove L, Momeni M, Aphram G, Watremez C, Bollen X, Jashari R, Boodhwani M, Astarci P, Noirhomme P, El Khoury G. Free margin length and coaptation surface area in normal tricuspid aortic valve: an anatomical study. Eur J Cardiothorac Surg 2017; 53:1040-1048. [DOI: 10.1093/ejcts/ezx456] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/05/2017] [Indexed: 11/14/2022] Open
Affiliation(s)
- Laurent De Kerchove
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
- Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Mona Momeni
- Division of Anesthesiology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Gaby Aphram
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
- Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Christine Watremez
- Division of Anesthesiology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Xavier Bollen
- Center for Research in Mechatronics (CEREM), Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Ramadan Jashari
- European Homograft Bank, St-Jean Hospital, Brussels, Belgium
| | - Munir Boodhwani
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Parla Astarci
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
- Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Philippe Noirhomme
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
- Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Gebrine El Khoury
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
- Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
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19
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Hurtado-Aguilar LG, Mulderrig S, Moreira R, Hatam N, Spillner J, Schmitz-Rode T, Jockenhoevel S, Mela P. Ultrasound for In Vitro, Noninvasive Real-Time Monitoring and Evaluation of Tissue-Engineered Heart Valves. Tissue Eng Part C Methods 2017; 22:974-981. [PMID: 27673356 DOI: 10.1089/ten.tec.2016.0300] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tissue-engineered heart valves are developed in bioreactors where biochemical and mechanical stimuli are provided for extracellular matrix formation. During this phase, the monitoring possibilities are limited by the need to maintain the sterility and integrity of the valve. Therefore, noninvasive and nondestructive techniques are required. As such, optical imaging is commonly used to verify valve's functionality in vitro. It provides important information (i.e., leaflet symmetry, geometric orifice area, and closing and opening times), which is, however, usually limited to a singular view along the central axis from the outflow side. In this study, we propose ultrasound as a monitoring method that, in contrast to established optical imaging, can assess the valve from different planes, scanning the whole three-dimensional geometry. We show the potential benefits associated with the application of ultrasound to bioreactors, in advancing heart valve tissue engineering from design to fabrication and in vitro maturation. Specifically, we demonstrate that additional information, otherwise unavailable, can be gained to evaluate the valve's functionality (e.g., coaptation length, and effective cusp height and shape). Furthermore, we show that Doppler techniques provide qualitative visualization and quantitative evaluation of the flow through the valve, in real time and throughout the whole in vitro fabrication phase.
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Affiliation(s)
- Luis G Hurtado-Aguilar
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany
| | - Shane Mulderrig
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany
| | - Ricardo Moreira
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany
| | - Nima Hatam
- 2 Department for Cardiothoracic and Vascular Surgery, University Hospital RWTH Aachen , Aachen, Germany
| | - Jan Spillner
- 2 Department for Cardiothoracic and Vascular Surgery, University Hospital RWTH Aachen , Aachen, Germany
| | - Thomas Schmitz-Rode
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany
| | - Stefan Jockenhoevel
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany .,3 Institute for Textile Engineering, RWTH Aachen University , Aachen, Germany
| | - Petra Mela
- 1 Department of Tissue Engineering and Textile Implants, AME-Helmholtz Institute for Biomedical Engineering, University Hospital RWTH Aachen , Aachen, Germany
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20
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Fallahiarezoudar E, Ahmadipourroudposht M, Yusof NM, Idris A, Ngadiman NHA. 3D Biofabrication of Thermoplastic Polyurethane (TPU)/Poly-l-lactic Acid (PLLA) Electrospun Nanofibers Containing Maghemite (γ-Fe₂O₃) for Tissue Engineering Aortic Heart Valve. Polymers (Basel) 2017; 9:E584. [PMID: 30965883 PMCID: PMC6418800 DOI: 10.3390/polym9110584] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/24/2017] [Accepted: 11/03/2017] [Indexed: 01/04/2023] Open
Abstract
Valvular dysfunction as the prominent reason of heart failure may causes morbidity and mortality around the world. The inability of human body to regenerate the defected heart valves necessitates the development of the artificial prosthesis to be replaced. Besides, the lack of capacity to grow, repair or remodel of an artificial valves and biological difficulty such as infection or inflammation make the development of tissue engineering heart valve (TEHV) concept. This research presented the use of compound of poly-l-lactic acid (PLLA), thermoplastic polyurethane (TPU) and maghemite nanoparticle (γ-Fe₂O₃) as the potential biomaterials to develop three-dimensional (3D) aortic heart valve scaffold. Electrospinning was used for fabricating the 3D scaffold. The steepest ascent followed by the response surface methodology was used to optimize the electrospinning parameters involved in terms of elastic modulus. The structural and porosity properties of fabricated scaffold were characterized using FE-SEM and liquid displacement technique, respectively. The 3D scaffold was then seeded with aortic smooth muscle cells (AOSMCs) and biological behavior in terms of cell attachment and proliferation during 34 days of incubation was characterized using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and confocal laser microscopy. Furthermore, the mechanical properties in terms of elastic modulus and stiffness were investigated after cell seeding through macro-indentation test. The analysis indicated the formation of ultrafine quality of nanofibers with diameter distribution of 178 ± 45 nm and 90.72% porosity. In terms of cell proliferation, the results exhibited desirable proliferation (109.32 ± 3.22% compared to the control) of cells over the 3D scaffold in 34 days of incubation. The elastic modulus and stiffness index after cell seeding were founded to be 22.78 ± 2.12 MPa and 1490.9 ± 12 Nmm², respectively. Overall, the fabricated 3D scaffold exhibits desirable structural, biological and mechanical properties and has the potential to be used in vivo.
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Affiliation(s)
- Ehsan Fallahiarezoudar
- Department of Materials, Manufacturing & Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
| | - Mohaddeseh Ahmadipourroudposht
- Department of Materials, Manufacturing & Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
| | - Noordin Mohd Yusof
- Department of Materials, Manufacturing & Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
| | - Ani Idris
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
| | - Nor Hasrul Akhmal Ngadiman
- Department of Materials, Manufacturing & Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia.
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21
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Zakerzadeh R, Hsu MC, Sacks MS. Computational methods for the aortic heart valve and its replacements. Expert Rev Med Devices 2017; 14:849-866. [PMID: 28980492 PMCID: PMC6542368 DOI: 10.1080/17434440.2017.1389274] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/04/2017] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Replacement with a prosthetic device remains a major treatment option for the patients suffering from heart valve disease, with prevalence growing resulting from an ageing population. While the most popular replacement heart valve continues to be the bioprosthetic heart valve (BHV), its durability remains limited. There is thus a continued need to develop a general understanding of the underlying mechanisms limiting BHV durability to facilitate development of a more durable prosthesis. In this regard, computational models can play a pivotal role as they can evaluate our understanding of the underlying mechanisms and be used to optimize designs that may not always be intuitive. Areas covered: This review covers recent progress in computational models for the simulation of BHV, with a focus on aortic valve (AV) replacement. Recent contributions in valve geometry, leaflet material models, novel methods for numerical simulation, and applications to BHV optimization are discussed. This information should serve not only to infer reliable and dependable BHV function, but also to establish guidelines and insight for the design of future prosthetic valves by analyzing the influence of design, hemodynamics and tissue mechanics. Expert commentary: The paradigm of predictive modeling of heart valve prosthesis are becoming a reality which can simultaneously improve clinical outcomes and reduce costs. It can also lead to patient-specific valve design.
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Affiliation(s)
- Rana Zakerzadeh
- Center for Cardiovascular Simulation Institute for Computational Engineering & Sciences Department of Biomedical Engineering The University of Texas at Austin, Austin, TX
| | - Ming-Chen Hsu
- Department of Mechanical Engineering Iowa State University, Ames, IA
| | - Michael S. Sacks
- Center for Cardiovascular Simulation Institute for Computational Engineering & Sciences Department of Biomedical Engineering The University of Texas at Austin, Austin, TX
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22
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Mohammadi H, Cartier R, Mongrain R. Fiber-reinforced computational model of the aortic root incorporating thoracic aorta and coronary structures. Biomech Model Mechanobiol 2017; 17:263-283. [PMID: 28929388 DOI: 10.1007/s10237-017-0959-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 08/31/2017] [Indexed: 01/03/2023]
Abstract
Cardiovascular diseases are still the leading causes of death in the developed world. The decline in the mortality associated with circulatory system diseases is accredited to development of new diagnostic and prognostic tools. It is well known that there is an inter relationship between the aortic valve impairment and pathologies of the aorta and coronary vessels. However, due to the limitations of the current tools, the possible link is not fully elucidated. Following our previous model of the aortic root including the coronaries, in this study, we have further developed the global aspect of the model by incorporating the anatomical structure of the thoracic aorta. This model is different from all the previous studies in the sense that inclusion of the coronary structures and thoracic aorta into the natural aortic valve introduces the notion of globality into the model enabling us to explore the possible link between the regional pathologies. The developed model was first validated using the available data in the literature under physiological conditions. Then, to provide a support for the possible association between the localized cardiovascular pathologies and global variations in hemodynamic conditions, we simulated the model for two pathological conditions including moderate and severe aortic valve stenoses. The findings revealed that malformations of the aortic valve are associated with development of low wall shear stress regions and helical blood flow in thoracic aorta that are considered major contributors to aortic pathologies.
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Affiliation(s)
- Hossein Mohammadi
- Mechanical Engineering Department, McGill University, Montreal, QC, H3A 0C3, Canada
| | - Raymond Cartier
- Department of Cardiovascular Surgery, Montreal Heart Institute, Montreal, QC, H1T 1C8, Canada
| | - Rosaire Mongrain
- Mechanical Engineering Department, McGill University, Montreal, QC, H3A 0C3, Canada.
- Department of Cardiovascular Surgery, Montreal Heart Institute, Montreal, QC, H1T 1C8, Canada.
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23
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A numerical study of the hemodynamic effect of the aortic valve on coronary flow. Biomech Model Mechanobiol 2017; 17:319-338. [DOI: 10.1007/s10237-017-0962-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 09/05/2017] [Indexed: 01/09/2023]
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24
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Model-Based Therapy Planning Allows Prediction of Haemodynamic Outcome after Aortic Valve Replacement. Sci Rep 2017; 7:9897. [PMID: 28851875 PMCID: PMC5575088 DOI: 10.1038/s41598-017-03693-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/26/2017] [Indexed: 11/13/2022] Open
Abstract
Optimizing treatment planning is essential for advances in patient care and outcomes. Precisely tailored therapy for each patient remains a yearned-for goal. Cardiovascular modelling has the potential to simulate and predict the functional response before the actual intervention is performed. The objective of this study was to proof the validity of model-based prediction of haemodynamic outcome after aortic valve replacement. In a prospective study design virtual (model-based) treatment of the valve and the surrounding vasculature were performed alongside the actual surgical procedure (control group). The resulting predictions of anatomic and haemodynamic outcome based on information from magnetic resonance imaging before the procedure were compared to post-operative imaging assessment of the surgical control group in ten patients. Predicted vs. post-operative peak velocities across the valve were comparable (2.97 ± 1.12 vs. 2.68 ± 0.67 m/s; p = 0.362). In wall shear stress (17.3 ± 12.3 Pa vs. 16.7 ± 16.84 Pa; p = 0.803) and secondary flow degree (0.44 ± 0.32 vs. 0.49 ± 0.23; p = 0.277) significant linear correlations (p < 0.001) were found between predicted and post-operative outcomes. Between groups blood flow patterns showed good agreement (helicity p = 0.852, vorticity p = 0.185, eccentricity p = 0.333). Model-based therapy planning is able to accurately predict post-operative haemodynamics after aortic valve replacement. These validated virtual treatment procedures open up promising opportunities for individually targeted interventions.
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Gu Z, Pan Y, Qiao A, Hu X, Dong N, Li X, Liu Y, Shang D. Numerical simulation of closure performance for neo-aortic valve for arterial switch operation. Biomed Eng Online 2016; 15:150. [PMID: 28155693 PMCID: PMC5260105 DOI: 10.1186/s12938-016-0264-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background Modeling neo-aortic valve for arterial switch surgical planning to simulate the neo-aortic valve closure performance. Methods We created five geometrical models of neo-aortic valve, namely model A, model B, model C, model D and model E with different size of sinotubular junction or sinus. The nodes at the ends of aorta and left ventricle duct fixed all the degrees of freedom. Transvalvular pressure of normal diastolic blood pressure of 54 mmHg was applied on the neo-aortic valve cusps. The neo-aortic valve closure performance was investigated by the parameters, such as stress of neo-aortic root, variation of neo-aortic valve ring as well as aortic valve cusps contact force in the cardiac diastole. Results The maximum stress of the five neo-aortic valves were 96.29, 98.34, 96.28, 98.26, and 90.60 kPa, respectively. Compared among five neo-aortic valve, aortic valve cusps contact forces were changed by 43.33, −10.00% enlarging or narrowing the sinotubular junction by 20% respectively based on the reference model A. The cusps contact forces were changed by 6.67, −23.33% with sinus diameter varying 1.2 times and 0.8 times respectively. Conclusions Comparing with stress of healthy adult subjects, the neo-aortic valve of infant creates lower stress. It is evident that enlarging or narrowing the sinotubular junction within a range of 20% can increase or decrease the maximum stress and aortic valve cusps contact force of neo-aortic valve.
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Affiliation(s)
- Zhaoyong Gu
- College of Life Science and Bio-Engineering, Beijing University of Technology, Pinleyuan, Chaoyang District, Beijing, China
| | - Youlian Pan
- College of Life Science and Bio-Engineering, Beijing University of Technology, Pinleyuan, Chaoyang District, Beijing, China.,College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Pinleyuan, Chaoyang District, Beijing, China
| | - Aike Qiao
- College of Life Science and Bio-Engineering, Beijing University of Technology, Pinleyuan, Chaoyang District, Beijing, China.
| | - Xingjian Hu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue, Qiaokou District, Wuhan, China
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue, Qiaokou District, Wuhan, China.
| | - Xiaofeng Li
- Center of Infant Heart, Beijing Anzhen Hospital, Capital Medical University, AnZhen Road, Chaoyang District, Beijing, China
| | - Yinglong Liu
- Center of Infant Heart, Beijing Anzhen Hospital, Capital Medical University, AnZhen Road, Chaoyang District, Beijing, China
| | - Deguang Shang
- College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Pinleyuan, Chaoyang District, Beijing, China
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26
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A Tri-Leaflet Nitinol Mesh Scaffold for Engineering Heart Valves. Ann Biomed Eng 2016; 45:413-426. [DOI: 10.1007/s10439-016-1778-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/09/2016] [Indexed: 01/03/2023]
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Serrani M, Brubert J, Stasiak J, De Gaetano F, Zaffora A, Costantino ML, Moggridge GD. A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis. J Biomech Eng 2016; 138:061001. [PMID: 27018454 DOI: 10.1115/1.4033178] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 11/08/2022]
Abstract
Styrene-based block copolymers are promising materials for the development of a polymeric heart valve prosthesis (PHV), and the mechanical properties of these polymers can be tuned via the manufacturing process, orienting the cylindrical domains to achieve material anisotropy. The aim of this work is the development of a computational tool for the optimization of the material microstructure in a new PHV intended for aortic valve replacement to enhance the mechanical performance of the device. An iterative procedure was implemented to orient the cylinders along the maximum principal stress direction of the leaflet. A numerical model of the leaflet was developed, and the polymer mechanical behavior was described by a hyperelastic anisotropic constitutive law. A custom routine was implemented to align the cylinders with the maximum principal stress direction in the leaflet for each iteration. The study was focused on valve closure, since during this phase the fibrous structure of the leaflets must bear the greatest load. The optimal microstructure obtained by our procedure is characterized by mainly circumferential orientation of the cylinders within the valve leaflet. An increase in the radial strain and a decrease in the circumferential strain due to the microstructure optimization were observed. Also, a decrease in the maximum value of the strain energy density was found in the case of optimized orientation; since the strain energy density is a widely used criterion to predict elastomer's lifetime, this result suggests a possible increase of the device durability if the polymer microstructure is optimized. The present method represents a valuable tool for the design of a new anisotropic PHV, allowing the investigation of different designs, materials, and loading conditions.
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da Costa FDA, Colatusso DDFF, da Costa ACBA, Balbi Filho EM, Cavicchioli VN, Lopes SAV, Ferreira ADDA, Collatusso C. Initial Surgical Experience with Aortic Valve Repair: Clinical and Echocardiographic Results. Braz J Cardiovasc Surg 2016; 31:183-90. [PMID: 27556321 PMCID: PMC5062723 DOI: 10.5935/1678-9741.20160027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/08/2016] [Indexed: 11/20/2022] Open
Abstract
Introduction Due to late complications associated with the use of conventional prosthetic
heart valves, several centers have advocated aortic valve repair and/or
valve sparing aortic root replacement for patients with aortic valve
insufficiency, in order to enhance late survival and minimize adverse
postoperative events. Methods From March/2012 thru March 2015, 37 patients consecutively underwent
conservative operations of the aortic valve and/or aortic root. Mean age was
48±16 years and 81% were males. The aortic valve was bicuspid in
54% and tricuspid in the remaining. All were operated with the aid of
intraoperative transesophageal echocardiography. Surgical techniques
consisted of replacing the aortic root with a Dacron graft whenever it was
dilated or aneurysmatic, using either the remodeling or the reimplantation
technique, besides correcting leaflet prolapse when present. Patients were
sequentially evaluated with clinical and echocardiographic studies and mean
follow-up time was 16±5 months. Results Thirty-day mortality was 2.7%. In addition there were two late deaths, with
late survival being 85% (CI 95% - 68%-95%) at two years. Two patients were
reoperated due to primary structural valve failure. Freedom from reoperation
or from primary structural valve failure was 90% (CI 95% - 66%-97%) and 91%
(CI 95% - 69%-97%) at 2 years, respectively. During clinical follow-up up to
3 years, there were no cases of thromboembolism, hemorrhage or
endocarditis. Conclusions Although this represents an initial series, these data demonstrates that
aortic valve repair and/or valve sparing aortic root surgery can be
performed with satisfactory immediate and short-term results.
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29
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Laadhari A, Quarteroni A. Numerical modeling of heart valves using resistive Eulerian surfaces. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02743. [PMID: 26255787 DOI: 10.1002/cnm.2743] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 05/22/2015] [Accepted: 08/04/2015] [Indexed: 06/04/2023]
Abstract
The goal of this work is the development and numerical implementation of a mathematical model describing the functioning of heart valves. To couple the pulsatile blood flow with a highly deformable thin structure (the valve's leaflets), a resistive Eulerian surfaces framework is adopted. A lumped-parameter model helps to couple the movement of the leaflets with the blood dynamics. A reduced circulation model describes the systemic hemodynamics and provides a physiological pressure profile at the downstream boundary of the valve. The resulting model is relatively simple to describe for a healthy valve and pathological heart valve functioning while featuring an affordable computational burden. Efficient time and spatial discretizations are considered and implemented. We address in detail the main features of the proposed method, and we report several numerical experiments for both two-dimensional and three-dimensional cases with the aim of illustrating its accuracy. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Aymen Laadhari
- Computer Vision Laboratory, Institut für Bildverarbeitung, Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology-ETHZ, CH-8092, Zürich, Switzerland
| | - Alfio Quarteroni
- Modeling and Scientific Computing, Mathematics Institute of Computational Science and Engineering (MATHICSE), École Polytechnique Fédérale de Lausanne-EPFL, CH-1015, Lausanne, Switzerland
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Duraiswamy N, Weaver JD, Ekrami Y, Retta SM, Wu C. A Parametric Computational Study of the Impact of Non-circular Configurations on Bioprosthetic Heart Valve Leaflet Deformations and Stresses: Possible Implications for Transcatheter Heart Valves. Cardiovasc Eng Technol 2016; 7:126-38. [PMID: 26864541 PMCID: PMC10406463 DOI: 10.1007/s13239-016-0259-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/02/2016] [Indexed: 11/26/2022]
Abstract
Although generally manufactured as circular devices with symmetric leaflets, transcatheter heart valves can become non-circular post-implantation, the impact of which on the long-term durability of the device is unclear. We investigated the effects of five non-circular (EllipMajor, EllipMinor, D-Shape, TriVertex, TriSides) annular configurations on valve leaflet stresses and valve leaflet deformations through finite element analysis. The highest in-plane principal stresses and strains were observed under an elliptical configuration with an aspect ratio of 1.25 where one of the commissures was on the minor axis of the ellipse. In this elliptical configuration (EllipMinor), the maximum principal stress increased 218% and the maximum principal strain increased 80% as compared with those in the circular configuration, and occurred along the free edge of the leaflet whose commissures were not on the minor axis (i.e., the "stretched" leaflet). The D-Shape configuration was similar to this elliptical configuration, with the degree to which the leaflets were stretched or sagging being less than the EllipMinor configuration. The TriVertex and TriSides configurations had similar leaflet deformation patterns in all three leaflets and similar to the Circular configuration. In the D-Shape, TriVertex, and TriSides configurations, the maximum principal stress was located near the commissures similar to the Circular configuration. In the EllipMinor and EllipMajor configurations, the maximum principal stress occurred near the center of the free edge of the "stretched" leaflets. These results further affirm recommendations by the International Standards Organization (ISO) that pre-clinical testing should consider non-circular configurations for transcatheter valve durability testing.
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Affiliation(s)
- Nandini Duraiswamy
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
| | - Jason D Weaver
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Yasamin Ekrami
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Stephen M Retta
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Changfu Wu
- Office of Device Evaluation (ODE)/Division of Cardiovascular Devices (DCD), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
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31
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PAN YOULIAN, QIAO AIKE, DONG NIANGUO. EFFECT OF THE POSITION OF THE CORONARY SINUS ORIFICE ON AORTIC LEAFLET COAPTATION. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414400090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background: The various components of the aortic root maintain a particular geometric relationship to guarantee unobstructed blood flow across the aortic valve and valve competence. Objective: To quantify the effect of the position of the coronary sinus orifice (CSO) on aortic leaflet coaptation. Methods: 2D and 3D finite element models of an aortic valve and root were constructed, with the CSO located on the bottom and middle of the sinuses. ADINA fluid-structure interaction solver was employed to perform computational simulation. Results: The mean sinus pressure with left and right CSO was 1.02E+4 Pa and 1.03E+4 Pa, respectively, and the average leaflet pressure with left and right CSO was 1.06E+4 Pa and 1.05E+4 Pa, respectively, for the model with CSO located in the middle and bottom of the sinus. The leaflet summit displacement differences of the CSO position on the bottom and middle between left and right coronary sinuses and none were 11.56, -107.57, 16.17 and -92.86 μm, respectively. Conclusions: The position of the CSO affects the pressure distribution of the aortic root. The local high pressure results in symmetrical deformation of the three leaflets, and decreases the risk of leaflet mismatch in coaptation.
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Affiliation(s)
- YOULIAN PAN
- College of Life Science and Bio-Engineering, Beijing University of Technology, Beijing 100124, P. R. China
| | - AIKE QIAO
- College of Life Science and Bio-Engineering, Beijing University of Technology, Beijing 100124, P. R. China
| | - NIANGUO DONG
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, P. R. China
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32
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Bioengineering Strategies for Polymeric Scaffold for Tissue Engineering an Aortic Heart Valve: An Update. Int J Artif Organs 2014; 37:651-67. [DOI: 10.5301/ijao.5000339] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2014] [Indexed: 12/17/2022]
Abstract
The occurrence of dysfunctional aortic valves is increasing every year, and current replacement heart valves, although having been shown to be clinically successful, are only short-term solutions and suffer from many agonizing long-term drawbacks. The tissue engineering of heart valves is recognized as one of the most promising answers for aortic valve disease therapy, but overcoming current shortcomings will require multidisciplinary efforts. The use of a polymeric scaffold to guide the growth of the tissue is the most common approach to generate a new tissue for an aortic heart valve. However, optimizing the design of the scaffold, in terms of biocompatibility, surface morphology for cell attachments and the correct rate of degradation is critical in creating a viable tissue-engineered aortic heart valve. This paper highlights the bioengineering strategies that need to be followed to construct a polymeric scaffold of sufficient mechanical integrity, with superior surface morphologies, that is capable of mimicking the valve dynamics in vivo. The current challenges and future directions of research for creating tissue-engineered aortic heart valves are also discussed.
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33
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Pan Y, Qiao A, Dong N. Fluid-structure interaction simulation of aortic valve closure with various sinotubular junction and sinus diameters. Ann Biomed Eng 2014; 43:1363-9. [PMID: 25224079 DOI: 10.1007/s10439-014-1120-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 09/10/2014] [Indexed: 12/22/2022]
Abstract
This study was designed to investigate the effect of sinotubular junction and sinus diameters on aortic valve closure to prevent the regurgitation of blood from the aorta into the left ventricle during ventricular diastole. The 2-dimensional geometry of a base aortic valve was reconstructed using the geometric constraints and modeling dimensions suggested by literature as the reference model A (aortic annulus diameter (DAA) = 26, diameters of sinotubular junction (DSTJ) = 26, sinus diameter (DS) = 40), and then the DSTJ and DS were modified to create five geometric models named as B (DSTJ = 31.2, DS = 40), C (DSTJ = 20.8, DS = 40), D (DSTJ = 26, DS = 48), E (DSTJ = 26, DS = 32) and F (DSTJ = 31.2, DS = 48) with different dimensions. Fluid structure interaction method was employed to simulate the movement and mechanics of aortic root. The performance of the aortic root was quantified in terms of blood flow velocity through aortic valve, annulus diameter as well as leaflet contact pressure. For comparison among A, B and C, the differences of annulus diameter and leaflet contact pressure do not exceed 5% with DSTJ increased by 1.2 times and decreased by 0.8 times. For comparison among A, D and E, annulus diameter was increased by 6.92% and decreased by 7.87%, and leaflet contact pressure was increased by 8.99% and decreased by 12.14% with DS increased by 1.2 times and decreased by 0.8 times. For comparison between A and F, annulus diameter was increased by 5.10%, and leaflet contact pressure was increased by 13.54% both with DSTJ and DS increased by 1.1 times. The results of leaflet contact pressure presented for all models were consistent with those of aortic annulus diameters. For the Ross operation involves replacing the diseased aortic valve, aortic valve closure function can be affected by various sinotubular junction and sinus diameter. Compared with the sinus diameters, sinotubular junction diameters have less effect on the performance of aortic valve closure, when the diameter difference is within a range of 20%. So surgical planning might give sinus diameter more consideration.
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Affiliation(s)
- Youlian Pan
- College of Life Science and Bio-Engineering, Beijing University of Technology, Beijing, 100124, China
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34
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In vitro study of a standardized approach to aortic cusp extension. Int J Artif Organs 2014; 37:315-24. [PMID: 24811186 DOI: 10.5301/ijao.5000316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE Cusp extension technique (CET) is a reparative surgical procedure for restoring aortic valve function by suturing patches to the compromised native leaflets. Its outcomes are strongly dependent on the ability of the surgeon. We proposed and tested a novel approach on an in vitro model, aimed at standardizing and simplifying the surgical procedure. METHODS A set of standard pre-cut bovine pericardium patches, available in different sizes, was developed. The surgeon can choose the leaflet-specific patches to be implanted according to the patient anatomy, using a geometrical model of the aortic valve whose inputs are the measured intercommissural distances. The hemodynamic performance of this approach was evaluated on porcine aortic roots in a pulsatile mock loop. Hydrodynamic and kinematic evaluation of the samples was provided. RESULTS After CET, mean and maximum pressure drops were 3.1±1.3 mmHg and 25.4±5.0 mmHg respectively, and EOA was 3.8±0.8 cm. CONCLUSIONS Our approach to cusp extension proved to be reliable and effective in restoring valve functioning, without significantly altering the physiological kinematics. The use of pre-cut patches considerably simplified the surgery, increasing standardization and repeatability.
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Abstract
In the past two decades, major advances have been made in the clinical evaluation and treatment of valvular heart disease owing to the advent of noninvasive cardiac imaging modalities. In clinical practice, valvular disease evaluation is typically performed on two-dimensional (2D) images, even though most imaging modalities offer three-dimensional (3D) volumetric, time-resolved data. Such 3D data offer researchers the possibility to reconstruct the 3D geometry of heart valves at a patient-specific level. When these data are integrated with computational models, native heart valve biomechanical function can be investigated, and preoperative planning tools can be developed. In this review, we outline the advances in valve geometry reconstruction, tissue property modeling, and loading and boundary definitions for the purpose of realistic computational structural analysis of cardiac valve function and intervention.
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Affiliation(s)
- Wei Sun
- Tissue Mechanics Lab, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30313;
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36
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Morganti S, Valentini A, Favalli V, Serio A, Gambarin FI, Vella D, Mazzocchi L, Massetti M, Auricchio F, Arbustini E. Aortic root 3D parametric morphological model from 2D-echo images. Comput Biol Med 2013; 43:2196-204. [DOI: 10.1016/j.compbiomed.2013.09.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/18/2013] [Accepted: 09/21/2013] [Indexed: 10/26/2022]
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Straightening of curved pattern of collagen fibers under load controls aortic valve shape. J Biomech 2013; 47:341-6. [PMID: 24315286 DOI: 10.1016/j.jbiomech.2013.11.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/01/2013] [Accepted: 11/21/2013] [Indexed: 02/07/2023]
Abstract
The network of collagen fibers in the aortic valve leaflet is believed to play an important role in the strength and durability of the valve. However, in addition to its stress-bearing role, such a fiber network has the potential to produce functionally important shape changes in the closed valve under pressure load. We measured the average pattern of the collagen network in porcine aortic valve leaflets after staining for collagen. We then used finite element simulation to explore how this collagen pattern influences the shape of the closed valve. We observed a curved or bent pattern, with collagen fibers angled downward from the commissures toward the center of the leaflet to form a pattern that is concave toward the leaflet free edge. Simulations showed that these curved fiber trajectories straighten under pressure load, leading to functionally important changes in closed valve shape. Relative to a pattern of straight collagen fibers running parallel to the leaflet free edge, the concave pattern of curved fibers produces a closed valve with a 40% increase in central leaflet coaptation height and with decreased leaflet billow, resulting in a more physiological closed valve shape. Furthermore, simulations show that these changes in loaded leaflet shape reflect changes in leaflet curvature due to modulation of in-plane membrane stress resulting from straightening of the curved fibers. This effect appears to play an important role in normal valve function and may have important implications for the design of prosthetic and tissue engineered replacement valves.
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38
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Rankin JS, Bone MC, Fries PM, Aicher D, Schäfers HJ, Crooke PS. A refined hemispheric model of normal human aortic valve and root geometry. J Thorac Cardiovasc Surg 2013; 146:103-108.e1. [DOI: 10.1016/j.jtcvs.2012.06.043] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/12/2012] [Accepted: 06/15/2012] [Indexed: 11/25/2022]
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39
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Effects of valve geometry and tissue anisotropy on the radial stretch and coaptation area of tissue-engineered heart valves. J Biomech 2013; 46:1792-800. [DOI: 10.1016/j.jbiomech.2013.05.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 11/20/2022]
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40
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Kouhi E, Morsi YS. A parametric study on mathematical formulation and geometrical construction of a stentless aortic heart valve. J Artif Organs 2013; 16:425-42. [PMID: 23813273 DOI: 10.1007/s10047-013-0719-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 06/18/2013] [Indexed: 11/26/2022]
Abstract
This study presents a novel methodology for constructing an accurate geometrical model of a stentless aortic heart valve replacement (AVR). The main objective is to propose an optimized AVR model that can be used as an ideal scaffold for tissue engineering applications or a biocompatible prosthesis. Current techniques available for creating heart valve geometry, including leaflets, are very complicated and are not precise, due to the extensive use of various complicated parameters. This paper introduces an alternative design procedure that uses limited and effective numbers of controlling parameters to construct the whole valve including the sinus of valsalva. In doing so the hyperbolic curves for multithickness leaflets are used and a 3D elliptical formulation is incorporated for the surface geometry of the sinus of valsalva. Still, the feasibility and the precision of the mathematical method are established by performing standard deviation analysis on the constructed surfaces. The surface fitting residuals are found as low as error 0.2351 mm with standard deviation of 8.83e-5 over the commissural lines. Preliminary validation to the proposed AVR model performance is achieved by testing the generated AVR model under quasi static condition while obtaining the mesh independent setup. The numerical model showed a rapid response of the leaflets to the transvalvular pressure where adequate values of stress are measured over the commissural lines.
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Affiliation(s)
- Esfandyar Kouhi
- Biomechanics and Tissue Engineering Group, Faculty of Engineering & Industrial Sciences, Swinburne University of Technology, P.O Box 218, Hawthorn, VIC, 3122, Australia,
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Calleja A, Thavendiranathan P, Ionasec RI, Houle H, Liu S, Voigt I, Sai Sudhakar C, Crestanello J, Ryan T, Vannan MA. Automated Quantitative 3-Dimensional Modeling of the Aortic Valve and Root by 3-Dimensional Transesophageal Echocardiography in Normals, Aortic Regurgitation, and Aortic Stenosis. Circ Cardiovasc Imaging 2013; 6:99-108. [DOI: 10.1161/circimaging.112.976993] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background—
We tested the ability of a novel automated 3-dimensional (3D) algorithm to model and quantify the aortic root from 3D transesophageal echocardiography (TEE) and computed tomographic (CT) data.
Methods and Results—
We compared the quantitative parameters obtained by automated modeling from 3D TEE (n=20) and CT data (n=20) to those made by 2D TEE and targeted 2D from 3D TEE and CT in patients without valve disease (normals). We also compared the automated 3D TEE measurements in severe aortic stenosis (n=14), dilated root without aortic regurgitation (n=15), and dilated root with aortic regurgitation (n=20). The automated 3D TEE sagittal annular diameter was significantly greater than the 2D TEE measurements (
P
=0.004). This was also true for the 3D TEE and CT coronal annular diameters (
P
<0.01). The average 3D TEE and CT annular diameter was greater than both their respective 2D and 3D sagittal diameters (
P
<0.001). There was no significant difference in 2D and 3D measurements of the sinotubular junction and sinus of valsalva diameters (
P
>0.05) in normals, but these were significantly different (
P
<0.05) in abnormals. The 3 automated intercommissural distance and leaflet length and height did not show significant differences in the normals (
P
>0.05), but all 3 were significantly different compared with the abnormal group (
P
<0.05). The automated 3D annulus commissure coronary ostia distances in normals showed significant difference between 3D TEE and CT (
P
<0.05); also, these parameters by automated 3D TEE were significantly different in abnormal (
P
<0.05). Finally, the automated 3D measurements showed excellent reproducibility for all parameters.
Conclusions—
Automated quantitative 3D modeling of the aortic root from 3D TEE or CT data is technically feasible and provides unique data that may aid surgical and transcatheter interventions.
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Affiliation(s)
- Anna Calleja
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Paaladinesh Thavendiranathan
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Razvan Ioan Ionasec
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Helene Houle
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Shizhen Liu
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Ingmar Voigt
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Chittoor Sai Sudhakar
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Juan Crestanello
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Thomas Ryan
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
| | - Mani A. Vannan
- From The Department of Medicine, Division of Cardiology (A.C., P.T., M.A.V., S.L., T.R.), Department of Surgery, Division of Cardiothoracic Surgery (C.S.S., J.C.), The Ohio State University, Columbus, OH; Siemens Healthcare, Ultrasound Division, Mountain View, CA (H.H.); and Siemens Corporate Research, Princeton, NJ (R.I., I.V)
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42
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Haj-Ali R, Marom G, Ben Zekry S, Rosenfeld M, Raanani E. A general three-dimensional parametric geometry of the native aortic valve and root for biomechanical modeling. J Biomech 2012; 45:2392-7. [PMID: 22854206 DOI: 10.1016/j.jbiomech.2012.07.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 06/12/2012] [Accepted: 07/02/2012] [Indexed: 10/28/2022]
Abstract
The complex three-dimensional (3D) geometry of the native tricuspid aortic valve (AV) is represented by select parametric curves allowing for a general construction and representation of the 3D-AV structure including the cusps, commissures and sinuses. The proposed general mathematical description is performed by using three independent parametric curves, two for the cusp and one for the sinuses. These curves are used to generate different surfaces that form the structure of the AV. Additional dependent curves are also generated and utilized in this process, such as the joint curve between the cusps and the sinuses. The model's feasibility to generate patient-specific parametric geometry is examined against 3D-transesophageal echocardiogram (3D-TEE) measurements from a non-pathological AV. Computational finite-element (FE) mesh can then be easily constructed from these surfaces. Examples are given for constructing several 3D-AV geometries by estimating the needed parameters from echocardiographic measurements. The average distance (error) between the calculated geometry and the 3D-TEE measurements was only 0.78±0.63mm. The proposed general 3D parametric method is very effective in quantitatively representing a wide range of native AV structures, with and without pathology. It can also facilitate a methodical quantitative investigation over the effect of pathology and mechanical loading on these major AV parameters.
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Affiliation(s)
- Rami Haj-Ali
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.
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43
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Auricchio F, Conti M, Ferrara A, Morganti S, Reali A. Patient-specific simulation of a stentless aortic valve implant: the impact of fibres on leaflet performance. Comput Methods Biomech Biomed Engin 2012; 17:277-85. [DOI: 10.1080/10255842.2012.681645] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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44
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VAN ASWEGEN KHJ, SMUTS AN, SCHEFFER C, WEICH HSVH, DOUBELL AF. INVESTIGATION OF LEAFLET GEOMETRY IN A PERCUTANEOUS AORTIC VALVE WITH THE USE OF FLUID-STRUCTURE INTERACTION SIMULATION. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519411004538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prosthetic aortic valves have been used for the replacement of dysfunctional native aortic valves in humans for more than fifty years. Current prosthetic valves have significant limitations and the development of improved aortic valve prostheses remains an important research focus area. This paper investigates one of the newer additions to the family of replacement valves, namely the stented percutaneous valve. An important design aspect of stented percutaneous valves, is the configuration of the leaflet's attachment to the surrounding stent. There are essentially two possible configurations: The first method is attaching the leaflets in a straight configuration, and the second method is to attach the leaflets in a curved configuration. Finite element models of both configurations were created, and the behavior of these configurations was then studied using a fluid-structure interaction (FSI) simulation. The FSI simulation was validated by means of comparing simulation results to actual measurements from a pulse duplicator using prototype valves of both configurations. The FSI results showed no significant difference between the valves' opening and closing behaviors. The von Mises stress distributions proved to be the largest differentiating and decisive factor between the two valves. The FSI simulations did however show that the leaflets that are attached in the straight configuration form folds that resembles that of the curved configuration as well as the native valve, but to a larger scale. The effect that these folds might have on valve tissue fatigue leaves room for future investigation.
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Affiliation(s)
- K. H. J. VAN ASWEGEN
- Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - A. N. SMUTS
- Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - C. SCHEFFER
- Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - H. S. VH. WEICH
- Cardiology Unit, Tygerberg Hospital and Stellenbosch University, Private Bag X1, Tygerberg 7505, South Africa
| | - A. F. DOUBELL
- Cardiology Unit, Tygerberg Hospital and Stellenbosch University, Private Bag X1, Tygerberg 7505, South Africa
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45
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Hammer PE, Chen PC, del Nido PJ, Howe RD. Computational model of aortic valve surgical repair using grafted pericardium. J Biomech 2012; 45:1199-204. [PMID: 22341628 DOI: 10.1016/j.jbiomech.2012.01.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 12/16/2011] [Accepted: 01/30/2012] [Indexed: 10/28/2022]
Abstract
Aortic valve reconstruction using leaflet grafts made from autologous pericardium is an effective surgical treatment for some forms of aortic regurgitation. Despite favorable outcomes in the hands of skilled surgeons, the procedure is underutilized because of the difficulty of sizing grafts to effectively seal with the native leaflets. Difficulty is largely due to the complex geometry and function of the valve and the lower distensibility of the graft material relative to native leaflet tissue. We used a structural finite element model to explore how a pericardial leaflet graft of various sizes interacts with two native leaflets when the valve is closed and loaded. Native leaflets and pericardium are described by anisotropic, hyperelastic constitutive laws, and we model all three leaflets explicitly and resolve leaflet contact in order to simulate repair strategies that are asymmetrical with respect to valve geometry and leaflet properties. We ran simulations with pericardial leaflet grafts of various widths (increase of 0%, 7%, 14%, 21% and 27%) and heights (increase of 0%, 13%, 27% and 40%) relative to the native leaflets. Effectiveness of valve closure was quantified based on the overlap between coapting leaflets. Results showed that graft width and height must both be increased to achieve proper valve closure, and that a graft 21% wider and 27% higher than the native leaflet creates a seal similar to a valve with three normal leaflets. Experimental validation in excised porcine aortas (n=9) corroborates the results of simulations.
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Affiliation(s)
- Peter E Hammer
- Department of Cardiac Surgery, Children's Hospital, Boston, MA, USA.
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46
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Valve-sparing aortic root repair without down-sizing of the annulus. J Thorac Cardiovasc Surg 2012; 143:294-302. [DOI: 10.1016/j.jtcvs.2011.10.056] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 09/22/2011] [Accepted: 10/21/2011] [Indexed: 11/22/2022]
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47
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A computational tool to support pre-operative planning of stentless aortic valve implant. Med Eng Phys 2011; 33:1183-92. [DOI: 10.1016/j.medengphy.2011.05.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 05/09/2011] [Accepted: 05/11/2011] [Indexed: 11/23/2022]
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48
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Izzat MB. Calibrated cusp sizers to facilitate aortic valve repair: development and clinical application. Interact Cardiovasc Thorac Surg 2011; 14:133-7. [PMID: 22159260 DOI: 10.1093/icvts/ivr082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Based on the natural mathematical relationships between the components of the human tri-leaflet aortic valve, new calibrated cusp sizers were developed in order to facilitate aortic valve assessment in the operating room and enhance the chance for a perfect restoration of aortic valve competence. These sizers were used clinically to guide the implementation of established aortic valve repair techniques in 10 consecutive patients with severe aortic valve regurgitation. Valve repair was successful in all cases, and at a median follow-up was 5.5 months, aortic valve function remained stable, with aortic regurgitation ≤1+ in every patient and no significant gradient across the aortic valves. This preliminary clinical experience indicates that the calibrated cusp sizers can provide reliable insight into the mechanism of aortic valve insufficiency, and can guide aortic valve repair techniques successfully. We hope that the simplicity and reproducibility of this method would assist in its dissemination and further increase the percentage of aortic valves that are repaired when compared with current practice.
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49
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Totaro P, Morganti S, Auricchio F, Viganò M. Computer-based analysis to optimize prosthesis sizing during aortic valve surgery. Int J Cardiol 2011; 151:253-4. [PMID: 21724273 DOI: 10.1016/j.ijcard.2011.06.079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Accepted: 06/14/2011] [Indexed: 11/30/2022]
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50
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A New Simple and Objective Method for Graft Sizing in Valve-Sparing Root Replacement Using the Reimplantation Technique. Ann Thorac Surg 2011; 92:749-51. [DOI: 10.1016/j.athoracsur.2011.03.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/24/2011] [Accepted: 03/08/2011] [Indexed: 11/23/2022]
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