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Almaghrabi S, Michelena H, Jelenc M, Abeln KB, Ehrlich T, Schäfers HJ. Contemporary Valvular Mechanisms of Aortic Regurgitation in Tricuspid Aortic Valves: Importance in Repair Versus Replacement Strategy. J Am Heart Assoc 2024; 13:e032532. [PMID: 38686861 PMCID: PMC11179890 DOI: 10.1161/jaha.123.032532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 02/19/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND This study was performed to determine cusp causes of aortic regurgitation in patients with tricuspid aortic valves without significant aortic dilatation and define cusp pathologies amenable to surgical repair (aortic valve repair [AVr]) versus aortic valve replacement. METHODS AND RESULTS We retrospectively reviewed surgical reports of consecutive adults with tricuspid aortic valves undergoing surgery for clinically significant aortic regurgitation within a prospective registry from January 2005 to September 2019. Valvular mechanisms were determined by systematic in vivo intraoperative quantification methods. Of 516 patients, 287 (56%) underwent repair (AVr; mean±SD age, 59.9±12.4 years; 81% men) and 229 (44%) underwent replacement (aortic valve replacement; mean±SD age, 62.8±13.8 years [P=0.01 compared to AVr]; 67% men). A single valvular mechanism was present in 454 patients (88%), with cusp prolapse (46%), retraction (24%), and perforation (18%) being the most common. Prolapse involved the right cusp in 86% of cases and was more frequent in men (P<0.001). Two-dimensional transesophageal echocardiography accuracy for predicting mechanisms was 73% to 82% for the right cusp, 55% to 61% for the noncoronary cusp, and 0% for the left-coronary cusp. Cusp prolapse, younger age, and larger patient size were associated with successful AVr (all P<0.03), whereas retraction, perforation, older age, and concomitant mitral repair were associated with aortic valve replacement (all P<0.03). CONCLUSIONS Right cusp prolapse is the most frequent single valvular mechanism in patients with tricuspid aortic valve aortic regurgitation, followed by cusp retraction and perforation. The accuracy of 2-dimensional transesophageal echocardiography is limited for left and noncoronary cusp mechanistic assessment. Prolapse is associated with successful AVr, whereas retraction and perforation are associated with aortic valve replacement. With systematic intraoperative quantification methods and current surgical techniques, more than half of tricuspid aortic valve aortic regurgitation cases may be successfully repaired.
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Affiliation(s)
- Saifalislam Almaghrabi
- Department of Thoracic and Cardiovascular Surgery Saarland University Medical Center and Saarland University Homburg/Saar Germany
| | | | - Matija Jelenc
- Department of Cardiovascular Surgery University Medical Center Ljubljana Ljubljana Slovenia
| | - Karen B Abeln
- Department of Thoracic and Cardiovascular Surgery Saarland University Medical Center and Saarland University Homburg/Saar Germany
| | - Tristan Ehrlich
- Department of Thoracic and Cardiovascular Surgery Saarland University Medical Center and Saarland University Homburg/Saar Germany
| | - Hans-Joachim Schäfers
- Department of Thoracic and Cardiovascular Surgery Saarland University Medical Center and Saarland University Homburg/Saar Germany
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Kim Y, Pyo WK, Kim WK, Suh GY, Kang K, Lee SH. A parametric study regarding structural design of a bioprosthetic aortic valve by 3D fluid-structure interaction simulations. Heliyon 2024; 10:e27310. [PMID: 38509976 PMCID: PMC10951528 DOI: 10.1016/j.heliyon.2024.e27310] [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: 11/30/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/22/2024] Open
Abstract
Since the introduction of transcatheter aortic valve (AV) implantation as a viable option, surgical bioprosthetic AVs have recently started incorporating shorter struts considering future valve-in-valve procedures. However, the effect of leaflet coaptation geometry on the longevity of these valves remains unexplored. To address this gap, we performed a finite element analysis on bioprosthetic AVs with varying strut heights using a two-way fluid-structure interaction method. To establish a baseline, we used a standard height based on a rendered platform image of the CE PERIMOUNT Magna Ease valve from Edward Lifesciences in Irvine, CA. Bovine pericardium properties were assigned to the leaflets, while normal saline properties were used as the recirculating fluid in hemodynamic simulations. The physiological pressure profile of the cardiac cycle was applied between the aorta and left ventricle. We calculated blood flow velocity, effective orifice area (EOA), and mechanical stress on the leaflets. The results reveal that as the strut height increases, the stroke volume increases, leakage volume decreases, and EOA improves. Additionally, the maximum mechanical stress experienced by the leaflet decreases by 62% as the strut height increases to 1.2 times the standard height. This research highlights that a low-strut design in bioprosthetic AVs may negatively affect their durability, which can be useful in design of next-generation bioprosthetic AVs.
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Affiliation(s)
- Yongwoo Kim
- Department of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea
| | - Won Kyung Pyo
- Department of Thoracic Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Wan Kee Kim
- Department of Thoracic and Cariovascular Surgery, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Gyeonggi-do, Republic of Korea
| | - Ga-Young Suh
- Department of Biomedical Engineering, California State University, Long Beach, CA, USA
| | - Keonwook Kang
- Department of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea
| | - Seung Hyun Lee
- Department of Thoracic Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
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3
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Tang X, Wu C. A predictive surrogate model for hemodynamics and structural prediction in abdominal aorta for different physiological conditions. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 243:107931. [PMID: 37992570 DOI: 10.1016/j.cmpb.2023.107931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/12/2023] [Accepted: 11/14/2023] [Indexed: 11/24/2023]
Abstract
BACKGROUND AND OBJECTIVE This study investigates the application of a Predictive Surrogate Model (PSM) for the prediction of the fluid and solid variables in the abdominal aorta by integrating Proper Orthogonal Decomposition (POD) and Long Short-Term Memory (LSTM) techniques. METHODS The Fluid-Structure Interaction (FSI) solver, which serves as the Full-Order Model (FOM), can capture the blood hemodynamics and structural mechanics precisely for a variety of physiological states, namely the rest and exercise conditions. RESULTS Detailed analyses have been conducted on velocity components, pressure, Wall Shear Stress (WSS), and Oscillatory Shear Index (OSI) variables. Firstly, the reconstruction error has been derived based on a specific number of POD bases to assess the Reduced Order Model (ROM). Notably, the reconstruction error for velocity components in the rest condition is one order of magnitude higher than that in the exercise condition, yet both remained below 10%. This error for pressure is even more minimal, being less than 1%. CONCLUSIONS The PSM is evaluated against rest and exercise conditions, exhibiting promising results despite the inherent complexities of the physiological conditions. Despite the inherent complexities of phenomena in the aorta, the predictive model demonstrates consistent error magnitudes for velocity components and wall-related indices, while solid variables show slightly higher errors.
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Affiliation(s)
- Xuan Tang
- Department of Physical Education, Yunnan University, Kunming, Yunnan Province, 650000, China; Department of Physical Education, Jeonbuk National University, Jeonju, Jeollabuk, 54896, Korea
| | - ChaoJie Wu
- Department of Physical Education, Jeonbuk National University, Jeonju, Jeollabuk, 54896, Korea.
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4
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Tao L, Jingyuan Z, Hongjun Z, Yijing L, Yan X, Yu C. Research on fatigue optimization simulation of polymeric heart valve based on the iterative sub-regional thickened method. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3717. [PMID: 37160536 DOI: 10.1002/cnm.3717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/08/2023] [Accepted: 04/14/2023] [Indexed: 05/11/2023]
Abstract
Prosthetic polymeric heart valves (PHVs) have the potential to overcome the inherent material and design limitations of traditional valves in the treatment of valvular heart disease; however, their durability remains limited. Optimal design of the valve structure is necessary to improve their durability. This study aimed to enhance the fatigue resistance of PHVs by improving the stress distribution. Iterative subregional thickening of the leaflets was used, and the mechanical stress distribution and hemodynamics of these polymeric tri-leaflet valves were characterized using a fluid-structure interaction approach. Subregional thickening led to a reduction in stress concentration on the leaflet, with the effective orifice area still meeting ISO 5840-3 and the regurgitant volume achieving a similar value to those in previous studies. The maximum stress in the final iteration was reduced by 28% compared with that of the prototype. The proposed method shows potential for analyzing the stress distribution and hemodynamic performance of subregional thickened valves and can further improve the durability of PHVs.
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Affiliation(s)
- Li Tao
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Zhou Jingyuan
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Zhou Hongjun
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Li Yijing
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Xiong Yan
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Chen Yu
- Department of Applied Mechanics, Sichuan University, Chengdu, China
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5
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Zhou J, Li Y, Li T, Tian X, Xiong Y, Chen Y. Analysis of the Effect of Thickness on the Performance of Polymeric Heart Valves. J Funct Biomater 2023; 14:309. [PMID: 37367273 DOI: 10.3390/jfb14060309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/17/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
Polymeric heart valves (PHVs) are a promising and more affordable alternative to mechanical heart valves (MHVs) and bioprosthetic heart valves (BHVs). Materials with good durability and biocompatibility used for PHVs have always been the research focus in the field of prosthetic heart valves for many years, and leaflet thickness is a major design parameter for PHVs. The study aims to discuss the relationship between material properties and valve thickness, provided that the basic functions of PHVs are qualified. The fluid-structure interaction (FSI) approach was employed to obtain a more reliable solution of the effective orifice area (EOA), regurgitant fraction (RF), and stress and strain distribution of the valves with different thicknesses under three materials: Carbothane PC-3585A, xSIBS and SIBS-CNTs. This study demonstrates that the smaller elastic modulus of Carbothane PC-3585A allowed for a thicker valve (>0.3 mm) to be produced, while for materials with an elastic modulus higher than that of xSIBS (2.8 MPa), a thickness less than 0.2 mm would be a good attempt to meet the RF standard. What is more, when the elastic modulus is higher than 23.9 MPa, the thickness of the PHV is recommended to be 0.l-0.15 mm. Reducing the RF is one of the directions of PHV optimization in the future. Reducing the thickness and improving other design parameters are reliable means to reduce the RF for materials with high and low elastic modulus, respectively.
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Affiliation(s)
- Jingyuan Zhou
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China
| | - Yijing Li
- College of Mechanical Engineering, Sichuan University, Chengdu 610065, China
| | - Tao Li
- College of Mechanical Engineering, Sichuan University, Chengdu 610065, China
| | - Xiaobao Tian
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China
| | - Yan Xiong
- College of Mechanical Engineering, Sichuan University, Chengdu 610065, China
| | - Yu Chen
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China
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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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7
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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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8
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Influence of Blood Compressibility on Pulse Wave Propagation Properties Based on Elastic Thin-Walled Tube Theory. PHYSICAL ACTIVITY AND HEALTH 2023. [DOI: 10.5334/paah.214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
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9
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Morany A, Lavon K, Gomez Bardon R, Kovarovic B, Hamdan A, Bluestein D, Haj-Ali R. Fluid-structure interaction modeling of compliant aortic valves using the lattice Boltzmann CFD and FEM methods. Biomech Model Mechanobiol 2023; 22:837-850. [PMID: 36763197 DOI: 10.1007/s10237-022-01684-0] [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: 08/07/2022] [Accepted: 12/28/2022] [Indexed: 02/11/2023]
Abstract
The lattice Boltzmann method (LBM) has been increasingly used as a stand-alone CFD solver in various biomechanical applications. This study proposes a new fluid-structure interaction (FSI) co-modeling framework for the hemodynamic-structural analysis of compliant aortic valves. Toward that goal, two commercial software packages are integrated using the lattice Boltzmann (LBM) and finite element (FE) methods. The suitability of the LBM-FE hemodynamic FSI is examined in modeling healthy tricuspid and bicuspid aortic valves (TAV and BAV), respectively. In addition, a multi-scale structural approach that has been employed explicitly recognizes the heterogeneous leaflet tissues and differentiates between the collagen fiber network (CFN) embedded within the elastin matrix of the leaflets. The CFN multi-scale tissue model is inspired by monitoring the distribution of the collagen in 15 porcine leaflets. Different simulations have been examined, and structural stresses and resulting hemodynamics are analyzed. We found that LBM-FE FSI approach can produce good predictions for the flow and structural behaviors of TAV and BAV and correlates well with those reported in the literature. The multi-scale heterogeneous CFN tissue structural model enhances our understanding of the mechanical roles of the CFN and the elastin matrix behaviors. The importance of LBM-FE FSI also emerges in its ability to resolve local hemodynamic and structural behaviors. In particular, the diastolic fluctuating velocity phenomenon near the leaflets is explicitly predicted, providing vital information on the flow transient nature. The full closure of the contacting leaflets in BAV is also demonstrated. Accordingly, good structural kinematics and deformations are captured for the entire cardiac cycle.
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Affiliation(s)
- Adi Morany
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Karin Lavon
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| | | | - Brandon Kovarovic
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Ashraf Hamdan
- Department of Cardiology, Rabin Medical Center, Petach Tikva, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Rami Haj-Ali
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel. .,Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
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Kaiser AD, Shad R, Hiesinger W, Marsden AL. A design-based model of the aortic valve for fluid-structure interaction. Biomech Model Mechanobiol 2021; 20:2413-2435. [PMID: 34549354 PMCID: PMC10752438 DOI: 10.1007/s10237-021-01516-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 08/22/2021] [Indexed: 11/27/2022]
Abstract
This paper presents a new method for modeling the mechanics of the aortic valve and simulates its interaction with blood. As much as possible, the model construction is based on first principles, but such that the model is consistent with experimental observations. We require that tension in the leaflets must support a pressure, then derive a system of partial differential equations governing its mechanical equilibrium. The solution to these differential equations is referred to as the predicted loaded configuration; it includes the loaded leaflet geometry, fiber orientations and tensions needed to support the prescribed load. From this configuration, we derive a reference configuration and constitutive law. In fluid-structure interaction simulations with the immersed boundary method, the model seals reliably under physiological pressures and opens freely over multiple cardiac cycles. Further, model closure is robust to extreme hypo- and hypertensive pressures. Then, exploiting the unique features of this model construction, we conduct experiments on reference configurations, constitutive laws and gross morphology. These experiments suggest the following conclusions: (1) The loaded geometry, tensions and tangent moduli primarily determine model function. (2) Alterations to the reference configuration have little effect if the predicted loaded configuration is identical. (3) The leaflets must have sufficiently nonlinear material response to function over a variety of pressures. (4) Valve performance is highly sensitive to free edge length and leaflet height. These conclusions suggest appropriate gross morphology and material properties for the design of prosthetic aortic valves. In future studies, our aortic valve modeling framework can be used with patient-specific models of vascular or cardiac flow.
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Affiliation(s)
- Alexander D Kaiser
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA.
- Stanford Cardiovascular Institute, Stanford, CA, USA.
| | - Rohan Shad
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - William Hiesinger
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Alison L Marsden
- Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
- Department of Pediatrics (Cardiology), Stanford University, Stanford, CA, USA
- Stanford Cardiovascular Institute, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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11
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Ge X, Liu Y, Tu S, Simakov S, Vassilevski Y, Liang F. Model-based analysis of the sensitivities and diagnostic implications of FFR and CFR under various pathological conditions. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3257. [PMID: 31487426 DOI: 10.1002/cnm.3257] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/28/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
Although fractional flow reserve (FFR) and coronary flow reserve (CFR) are both frequently used to assess the functional severity of coronary artery stenosis, discordant results of diagnosis between FFR and CFR in some patient cohorts have been reported. In the present study, a computational model was employed to quantify the impacts of various pathophysiological factors on FFR and CFR. In addition, a hyperemic myocardial ischemic index (HMIx) was proposed as a reference for comparing the diagnostic performances of FFR and CFR. Obtained results showed that CFR was more susceptible than FFR to the influence of many pathophysiological factors unrelated to coronary artery stenosis. In particular, the numerical study proved that increasing hyperemic coronary microvascular resistance significantly elevated FFR while reducing CFR despite fixed severity of coronary artery stenosis, whereas introducing aortic valve disease only caused a significant decrease in CFR with little influence on FFR. These results provided theoretical evidence for explaining some clinical observations, such as the increased risk of discordant diagnostic results between FFR and CFR in patients with increased hyperemic microvascular resistance, and significant increase in CFR after surgical relief of severe aortic valve disease. When evaluated with respect to the predictive value for hyperemic myocardial ischemia, the performance of FFR was found to be considerably compromised in the presence of severe coronary vasodilation dysfunction or aortic valve disease, whereas the relationship between CFR and HMIx remained relatively stable, suggesting that CFR may be a more reliable indicator of myocardial ischemia under complex pathophysiological conditions.
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Affiliation(s)
- Xinyang Ge
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Youjun Liu
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Shengxian Tu
- Med-X Research Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Sergey Simakov
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700, Russia
- Institute for Personalized Medicine, Sechenov University, Moscow, 119991, Russia
| | - Yuri Vassilevski
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700, Russia
- Institute for Personalized Medicine, Sechenov University, Moscow, 119991, Russia
- Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, 119333, Russia
| | - Fuyou Liang
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai Jiao Tong University, Shanghai, 200240, China
- Institute for Personalized Medicine, Sechenov University, Moscow, 119991, Russia
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12
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Progressive Calcification in Bicuspid Valves: A Coupled Hemodynamics and Multiscale Structural Computations. Ann Biomed Eng 2021; 49:3310-3322. [PMID: 34708308 DOI: 10.1007/s10439-021-02877-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 10/13/2021] [Indexed: 10/20/2022]
Abstract
Bicuspid aortic valve (BAV) is the most common congenital heart disease. Calcific aortic valve disease (CAVD) accounts for the majority of aortic stenosis (AS) cases. Half of the patients diagnosed with AS have a BAV, which has an accelerated progression rate. This study aims to develop a computational modeling approach of both the calcification progression in BAV, and its biomechanical response incorporating fluid-structure interaction (FSI) simulations during the disease progression. The calcification is patient-specifically reconstructed from Micro-CT images of excised calcified BAV leaflets, and processed with a novel reverse calcification technique that predicts prior states of CAVD using a density-based criterion, resulting in a multilayered calcified structure. Four progressive multilayered calcified BAV models were generated: healthy, mild, moderate, and severe, and were modeled by FSI simulations during the full cardiac cycle. A valve apparatus model, composed of the excised calcified BAV leaflets, was tested in an in-vitro pulse duplicator, to validate the severe model. The healthy model was validated against echocardiography scans. Progressive AS was characterized by higher systolic jet flow velocities (2.08, 2.3, 3.37, and 3.85 m s-1), which induced intense vortices surrounding the jet, coupled with irregular recirculation backflow patterns that elevated viscous shear stresses on the leaflets. This study shed light on the fluid-structure mechanism that drives CAVD progression in BAV patients.
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Hou Q, Liu G, Liu N, Zhang H, Qu Z, Zhang H, Li H, Pan Y, Qiao A. Effect of Valve Height on the Opening and Closing Performance of the Aortic Valve Under Aortic Root Dilatation. Front Physiol 2021; 12:697502. [PMID: 34526908 PMCID: PMC8435789 DOI: 10.3389/fphys.2021.697502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/04/2021] [Indexed: 12/13/2022] Open
Abstract
Patients with aortic valve disease can suffer from valve insufficiency after valve repair surgery due to aortic root dilatation. The paper investigates the effect of valve height (Hv) on the aortic valve opening and closing in order to select the appropriate range of Hv for smoother blood flow through the aortic valve and valve closure completely in the case of continuous aortic root dilatation. A total of 20 parameterized three-dimensional models of the aortic root were constructed following clinical surgical guidance. Aortic annulus diameter (DAA) was separately set to 26, 27, 28, 29, and 30 mm to simulate aortic root dilatation. HV value was separately set to 13.5, 14, 14.5, and 15 mm to simulate aortic valve alterations in surgery. Time-varying pressure loads were applied to the valve, vessel wall of the ascending aorta, and left ventricle. Then, finite element analysis software was employed to simulate the movement and mechanics of the aortic root. The feasible design range of the valve size was evaluated using maximum stress, geometric orifice area (GOA), and leaflet contact force. The results show that the valve was incompletely closed when HV was 13.5 mm and DAA was 29 or 30 mm. The GOA of the valve was small when HV was 15 mm and DAA was 26 or 27 mm. The corresponding values of the other models were within the normal range. Compared with the model with an HV of 14 mm, the model with an HV of 14.5 mm could effectively reduce maximum stress and had relatively larger GOA and less change in contact force. As a result, valve height affects the performance of aortic valve opening and closing. Smaller HV is adapted to smaller DAA and vice versa. When HV is 14.5 mm, the valve is well adapted to the dilatation of the aortic root to enhance repair durability. Therefore, more attention should be paid to HV in surgical planning.
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Affiliation(s)
- Qianwen Hou
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Guimei Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Ning Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Honghui Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Zhuoran Qu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Hanbing Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Hui Li
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Youlian Pan
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Aike Qiao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China.,Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
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14
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The effect of fundamental curves on geometric orifice and coaptation areas of polymeric heart valves. J Mech Behav Biomed Mater 2020; 112:104039. [DOI: 10.1016/j.jmbbm.2020.104039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 08/04/2020] [Accepted: 08/12/2020] [Indexed: 12/29/2022]
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15
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Structural Responses of Integrated Parametric Aortic Valve in an Electro-Mechanical Full Heart Model. Ann Biomed Eng 2020; 49:441-454. [PMID: 32705423 DOI: 10.1007/s10439-020-02575-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 07/15/2020] [Indexed: 10/23/2022]
Abstract
The aortic valve (AV) is located between the left ventricle and the aorta and responsible for maintaining an outward unidirectional flow. Many AV hemodynamic and structural aspects of have been extensively studied, however, more sophisticated models are needed to better understand the AV biomechanical behavior. This study deals with integrating a new parametric AV structural model with the electro-mechanical Living Heart Human Model® (LHHM). The LHHM is a finite element model simulating human heart capable of realistic electro-mechanical simulations. Different geometric metrics of AV have been examined. New integrated structural AV model within the LHHM better predict local stresses during the cardiac cycle due to the realistic boundary condition derived from the LHHM. It was found that ellipticity index (EI), calculated as the ratio between the maximal (Max) and minimal (Min) aortic annulus (AA) diameters, well correlates with measured clinical data obtained from patients undergoing computed tomography (CT) while the annular perimeter (Perim) matches the same trend. This increases the confidence in the predicted kinematic behavior, leaflets coaptation, and the overall stresses. From the clinical aspect, the new proposed coupled and integrated AV modeling can serve as a platform for design and implementation of pre-transcatheter aortic valve replacement (TAVR) procedures.
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16
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Ehrlich T, de Kerchove L, Vojacek J, Boodhwani M, El-Hamamsy I, De Paulis R, Lansac E, Bavaria JE, El Khoury G, Schäfers HJ. State-of-the art bicuspid aortic valve repair in 2020. Prog Cardiovasc Dis 2020; 63:457-464. [PMID: 32380025 DOI: 10.1016/j.pcad.2020.04.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 04/13/2020] [Indexed: 02/07/2023]
Abstract
Patients with a bicuspid aortic valve (BAV) frequently require surgical intervention for aortic regurgitation (AR) and/or aneurysm. Valve-preserving surgery and repair of regurgitant BAVs have evolved into an increasingly used alternative to replacement. Anatomic predictors of possible repair failures have been identified and solutions developed. Using current techniques most non-calcified BAVs can be preserved or repaired. Excellent repair durability and freedom from valve-related complications can be achieved if all pathologic components of aortic valve and root including annular dilatation are corrected. Anatomic variations must be addressed using tailored approaches.
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Affiliation(s)
- Tristan Ehrlich
- Department of Thoracic and Cardiovascular Surgery, Saarland University Medical Center, Homburg/Saar, Germany
| | - Laurent de Kerchove
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain and Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Jan Vojacek
- Department of Cardiac Surgery, University Hospital Hradec K0ralove, Czech Republic
| | - Munir Boodhwani
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Canada
| | - Ismail El-Hamamsy
- Department of Cardiovascular Surgery, Mount Sinai Hospital, Icahn Scholl of Medicine at Mount Sinai, New York, USA
| | | | - Emmanuel Lansac
- Departement of Cardiac Surgery, Institut Mutualiste Montsouris, Paris, France
| | - Joseph E Bavaria
- Division of Cardiac Surgery, University of Pennsylvania, Philadelphia, United States of America
| | - Gebrine El Khoury
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain and Division of Cardiothoracic and Vascular Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Hans-Joachim Schäfers
- Department of Thoracic and Cardiovascular Surgery, Saarland University Medical Center, Homburg/Saar, Germany.
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17
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Concepts of Bicuspid Aortic Valve Repair: A Review. Ann Thorac Surg 2020; 109:999-1006. [DOI: 10.1016/j.athoracsur.2019.09.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/16/2019] [Accepted: 09/03/2019] [Indexed: 12/27/2022]
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18
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Bettenhausen A, Hui DS. Commentary: Nature knows best. J Thorac Cardiovasc Surg 2020; 161:593-594. [PMID: 31926712 DOI: 10.1016/j.jtcvs.2019.10.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 10/25/2022]
Affiliation(s)
- Aaron Bettenhausen
- Department of Cardiothoracic Surgery, Long School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Tex
| | - Dawn S Hui
- Department of Cardiothoracic Surgery, Long School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Tex.
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19
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Gao B, Zhang Q, Chang Y. Hemodynamic effects of support modes of LVADs on the aortic valve. Med Biol Eng Comput 2019; 57:2657-2671. [PMID: 31707689 DOI: 10.1007/s11517-019-02058-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 11/02/2019] [Indexed: 12/11/2022]
Abstract
As the alternative treatment for heart failure, left ventricular assist devices (LVADs) have been widely applied to clinical practice. However, the effects of the support modes of LVADs on the biomechanical states of the aortic valve are still poorly understood. Hence, the present study investigates such effects and proposes a novel fluid-structure interaction (FSI) approach that combines the lattice Boltzmann method (LBM) and finite element (FE) method. Two support modes of LVADs, namely constant speed mode and constant flow mode, which have been widely applied to clinical practice, are also designed. Results demonstrate that the support modes of LVADs could significantly affect the biomechanical states of the aortic valve and the blood flow pattern of the ascending aorta. Compared with those in the constant flow mode, the leaflets in the constant speed mode could achieve better dynamic performance and lower stress during the systolic phase. The max radial displacement of the leaflets in the constant speed mode is at 8 mm, whereas that in the constant flow mode is at 0.8 mm. Furthermore, the outflow of LVADs directly impacts the aortic surfaces of the leaflets during the diastolic phase by increasing the level of wall shear stress of the leaflets. The leaflets in the constant speed mode receive less impact than those in the constant flow mode. The condition with such minimal impact is conducive to maintaining the normal structure of leaflets and benefits the reduction of the risk of valvular diseases. In sum, the support modes of LVADs exert a crucial effect on the biomechanical environment of the aortic valve. The constant speed mode is better than the constant flow mode in terms of providing a good hemodynamic environment for the aortic valve.
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Affiliation(s)
- Bin Gao
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China.
| | - Qi Zhang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Yu Chang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
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20
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Biomechanical modeling of transcatheter aortic valve replacement in a stenotic bicuspid aortic valve: deployments and paravalvular leakage. Med Biol Eng Comput 2019; 57:2129-2143. [PMID: 31372826 DOI: 10.1007/s11517-019-02012-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 07/08/2019] [Indexed: 12/17/2022]
Abstract
Calcific aortic valve disease (CAVD) is characterized by stiffened aortic valve leaflets. Bicuspid aortic valve (BAV) is the most common congenital heart disease. Transcatheter aortic valve replacement (TAVR) is a treatment approach for CAVD where a stent with mounted bioprosthetic valve is deployed on the stenotic valve. Performing TAVR in calcified BAV patients may be associated with post-procedural complications due to the BAV asymmetrical structure. This study aims to develop refined computational models simulating the deployments of Evolut R and PRO TAVR devices in a representative calcified BAV. The paravalvular leakage (PVL) was also calculated by computational fluid dynamics simulations. Computed tomography scan of severely stenotic BAV patient was acquired. The 3D calcium deposits were generated and embedded inside a parametric model of the BAV. Deployments of the Evolut R and PRO inside the calcified BAV were simulated in five bioprosthesis leaflet orientations. The hypothesis of asymmetric and elliptic stent deployment was confirmed. Positioning the bioprosthesis commissures aligned with the native commissures yielded the lowest PVL (15.7 vs. 29.5 mL/beat). The Evolut PRO reduced the PVL in half compared with the Evolut R (15.7 vs. 28.7 mL/beat). The proposed biomechanical computational model could optimize future TAVR treatment in BAV patients. Graphical abstract.
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21
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Lavon K, Halevi R, Marom G, Ben Zekry S, Hamdan A, Joachim Schäfers H, Raanani E, Haj-Ali R. Fluid-Structure Interaction Models of Bicuspid Aortic Valves: The Effects of Nonfused Cusp Angles. J Biomech Eng 2019; 140:2661744. [PMID: 29098290 DOI: 10.1115/1.4038329] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Indexed: 12/21/2022]
Abstract
Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5-2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the nonfused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance. Toward that goal, a parametric fluid-structure interaction (FSI) modeling approach of BAVs is presented. Four FSI models were generated with varying NFC angles between 120 deg and 180 deg. The FSI simulations were based on fully coupled structural and fluid dynamic solvers and corresponded to physiologic values, including the anisotropic hyper-elastic behavior of the tissue. The simulated angles led to different mechanical behavior, such as eccentric jet flow direction with a wider opening shape that was found for the smaller NFC angles, while a narrower opening orifice followed by increased jet flow velocity was observed for the larger NFC angles. Smaller NFC angles led to higher concentrated flow shear stress (FSS) on the NFC during peak systole, while higher maximal principal stresses were found in the raphe region during diastole. The proposed biomechanical models could explain the early failure of BAVs with decreased NFC angles, and suggests that a larger NFC angle is preferable in suture annuloplasty BAV repair surgery.
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Affiliation(s)
- Karin Lavon
- Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Rotem Halevi
- Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gil Marom
- Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794
| | - Sagit Ben Zekry
- Echocardiography Laboratory, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
| | - Ashraf Hamdan
- Department of Cardiology, Rabin Medical Center, Petach Tikva 4941492, Israel
| | - Hans Joachim Schäfers
- Department of Thoracic and Cardiovascular Surgery, University Hospitals of Saarland, Homburg 66421, Germany
| | - Ehud Raanani
- Department of Cardio-thoracic Surgery, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
| | - Rami Haj-Ali
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
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22
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Schäfers HJ. The 10 Commandments for Aortic Valve Repair. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2019; 14:188-198. [DOI: 10.1177/1556984519843909] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Hans-Joachim Schäfers
- Department of Thoracic and Cardiovascular Surgery, Saarland University Medical Center, Homburg/Saar, Germany
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23
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Wilson JT, Edgar LT, Prabhakar S, Horner M, van Loon R, Moore JE. A fully coupled fluid-structure interaction model of the secondary lymphatic valve. Comput Methods Biomech Biomed Engin 2018; 21:813-823. [DOI: 10.1080/10255842.2018.1521964] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- John T. Wilson
- Department of Bioengineering, Imperial College London, London, UK
| | - Lowell T. Edgar
- Department of Bioengineering, Imperial College London, London, UK
| | | | | | - Raoul van Loon
- Zienkiewicz Centre of Computational Engineering, College of Engineering, Swansea University, Swansea, UK
| | - James E. Moore
- Department of Bioengineering, Imperial College London, London, UK
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24
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Formato GM, Lo Rito M, Auricchio F, Frigiola A, Conti M. Aortic expansion induces lumen narrrowing in anomalous coronary arteries: a parametric structural finite element analysis. J Biomech Eng 2018; 140:2694849. [PMID: 30098160 DOI: 10.1115/1.4040941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Indexed: 01/05/2023]
Abstract
Anomalous aortic origin of coronary arteries (AAOCA) is a congenital disease that can lead to cardiac ischemia during intense physical activity. Although AAOCA is responsible for sudden cardiac death (SCD) among young athletes and soldiers, the mechanisms underlying the coronary occlusion during physical effort still have to be clarified. The present study investigates the correlation between geometric features of the anomaly and coronary lumen narrowing under aortic root dilatations. Idealized parametric computer-aided designed (CAD) models of the aortic root with anomalous and normal coronary are created and static finite element (FE) simulations of increasing aortic root expansions are carried out. Different coronary take-off angles and intramural penetrations are investigated to assess their role on coronary lumen narrowing. Results show that increasing aortic and coronary pressures lead to lumen expansions in normal coronaries, particularly in the proximal tract, while the expansion of anomalous coronary is impaired especially at the ostium. Concerning the geometric features of the anomaly, acute take-off angles cause elongated coronary ostia, with an eccentricity increasing with aortic expansion; the impact of intramural penetration of coronary on its luminal narrowing is limited. The present study provides a proof of concept of the biomechanical reasons underlying the lumen narrowing in AAOCA during aortic expansion, promoting the role of computational simulations as a tool to assess the mechanisms of this pathology.
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Affiliation(s)
- Giovanni Maria Formato
- University of Pavia, Dept. of Civil Engineering and Architecture (DICAr), Pavia, Italy, 27100
| | - Mauro Lo Rito
- IRCCS Policlinico San Donato, Dept. of Congenital Cardiac Surgery, San Donato Milanese, Italy, 20097
| | - Ferdinando Auricchio
- University of Pavia, Dept. of Civil Engineering and Architecture (DICAr), Pavia, Italy, 27100
| | - Alessandro Frigiola
- IRCCS Policlinico San Donato, Dept. of Congenital Cardiac Surgery, San Donato Milanese, Italy, 20097
| | - Michele Conti
- University of Pavia, Dept. of Civil Engineering and Architecture (DICAr), Pavia, Italy, 27100
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25
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Sodhani D, Reese S, Aksenov A, Soğanci S, Jockenhövel S, Mela P, Stapleton SE. Fluid-structure interaction simulation of artificial textile reinforced aortic heart valve: Validation with an in-vitro test. J Biomech 2018; 78:52-69. [PMID: 30086860 DOI: 10.1016/j.jbiomech.2018.07.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 06/05/2018] [Accepted: 07/09/2018] [Indexed: 01/11/2023]
Abstract
Prosthetic heart valves deployed in the left heart (aortic and mitral) are subjected to harsh hemodynamical conditions. Most of the tissue engineered heart valves have been developed for the low pressure pulmonary position because of the difficulties in fabricating a mechanically strong valve, able to withstand the systemic circulation. This necessitates the use of reinforcing scaffolds, resulting in a tissue-engineered textile reinforced tubular aortic heart valve. Therefore, to better design these implants, material behaviour of the composite, valve kinematics and its hemodynamical response need to be evaluated. Experimental assessment can be immensely time consuming and expensive, paving way for numerical studies. In this work, the material properties obtained using the previously proposed multi-scale numerical method for textile composites was evaluated for its accuracy. An in silico immersed boundary (IB) fluid structure interaction (FSI) simulation emulating the in vitro experiment was set-up to evaluate and compare the geometric orifice area and flow rate for one beat cycle. Results from the in silico FSI simulation were found to be in good coherence with the in vitro test during the systolic phase, while mean deviation of approximately 9% was observed during the diastolic phase of a beat cycle. Merits and demerits of the in silico IB-FSI method for the presented case study has been discussed with the advantages outweighing the drawbacks, indicating the potential towards an effective use of this framework in the development and analysis of heart valves.
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Affiliation(s)
- Deepanshu Sodhani
- Institute of Applied Mechanics, RWTH Aachen University, Mies-van-der-Rohe-Str. 1, 52074 Aachen, Germany.
| | - Stefanie Reese
- Institute of Applied Mechanics, RWTH Aachen University, Mies-van-der-Rohe-Str. 1, 52074 Aachen, Germany
| | - Andrey Aksenov
- Capvidia NV, Research Park Haasrode, Technologielaan 3, B-3001 Leuven, Belgium
| | - Sinan Soğanci
- Capvidia NV, Research Park Haasrode, Technologielaan 3, B-3001 Leuven, Belgium
| | - Stefan Jockenhövel
- Institute of Applied Medical Engineering, Helmholtz Institute & ITA-Institut for Textiltechnik, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Petra Mela
- Institute of Applied Medical Engineering, Helmholtz Institute & ITA-Institut for Textiltechnik, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Scott E Stapleton
- Dept. of Mechanical Engineering, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA
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26
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Halevi R, Hamdan A, Marom G, Lavon K, Ben-Zekry S, Raanani E, Haj-Ali R. A New Growth Model for Aortic Valve Calcification. J Biomech Eng 2018; 140:2682794. [DOI: 10.1115/1.4040338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Indexed: 11/08/2022]
Abstract
Calcific aortic valve disease (CAVD) is a progressive disease in which minerals accumulate in the tissue of the aortic valve cusps, stiffening them and preventing valve opening and closing. The process of valve calcification was found to be similar to that of bone formation including cell differentiation to osteoblast-like cells. Studies have shown the contribution of high strains to calcification initiation and growth process acceleration. In this paper, a new strain-based calcification growth model is proposed. The model aims to explain the unique shape of the calcification and other disease characteristics. The calcification process was divided into two stages: Calcification initiation and calcification growth. The initiation locations were based on previously published findings and a reverse calcification technique (RCT), which uses computed tomography (CT) scans of patients to reveal the calcification initiation point. The calcification growth process was simulated by a finite element model of one aortic valve cusp loaded with cyclic loading. Similar to Wolff's law, describing bone response to stress, our model uses strains to drive calcification formation. The simulation grows calcification from its initiation point to its full typical stenotic shape. Study results showed that the model was able to reproduce the typical calcification growth pattern and shape, suggesting that strain is the main driving force behind calcification progression. The simulation also sheds light on other disease characteristics, such as calcification growth acceleration as the disease progresses, as well as sensitivity to hypertension.
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Affiliation(s)
- Rotem Halevi
- School of Mechanical Engineering, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Ashraf Hamdan
- Department of Cardiology, Rabin Medical Center, Petach Tikva 4941492, Israel
| | - Gil Marom
- School of Mechanical Engineering, Tel-Aviv University, Tel Aviv 69978, Israel
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794
| | - Karin Lavon
- School of Mechanical Engineering, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Sagit Ben-Zekry
- Echocardiography Laboratory, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
| | - Ehud Raanani
- Cardiothoracic Surgery Department, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
| | - Rami Haj-Ali
- School of Mechanical Engineering, The Nathan Cummings Chair in Mechanics, The Fleischman Faculty of Engineering, Tel-Aviv University, Tel Aviv 69978, Israel e-mail:
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27
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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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AVANZINI ANDREA. INFLUENCE OF LEAFLET’S MATRIX STIFFNESS AND FIBER ORIENTATION ON THE OPENING DYNAMICS OF A PROSTHETIC TRILEAFLET HEART VALVE. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417500968] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biological valves are employed for aortic valve substitution since a long time but there is a growing effort toward the development of new engineered tissues, in which the complex mechanical response of native leaflets is replicated using composite materials consisting of a soft matrix with embedded reinforcing fibers. The main goal of the present study is to investigate the influence that variations on fiber orientation and matrix stiffness may have on valve dynamics. To this aim, a fluid–structure interaction (FSI) model of a trileaflet valve was implemented in which the opening phase was simulated and leaflet matrix stiffness and fiber orientation were varied in the framework of an anisotropic hyperelastic strain energy function. Results show that both parameters may affect significantly transvalvular pressure gradient and effective orifice area (EOA). For the opening phase of the valve examined, less favorable flow conditions were found when preferred fiber orientation is circumferential, due to lower maximum EOA achievable. Such configuration in combination with stiffer matrix may result in significant degradation of valve performances. Overall fiber orientation can potentially be taylored to optimize valve dynamics, provided also structural aspects that may be prominent in the closure phase, are considered.
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Affiliation(s)
- ANDREA AVANZINI
- Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze, 38, I-25123, Brescia, Italy
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29
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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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30
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Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting. Med Biol Eng Comput 2017; 55:1519-1548. [DOI: 10.1007/s11517-017-1688-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/10/2017] [Indexed: 11/26/2022]
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31
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Fedele M, Faggiano E, Dedè L, Quarteroni A. A patient-specific aortic valve model based on moving resistive immersed implicit surfaces. Biomech Model Mechanobiol 2017; 16:1779-1803. [PMID: 28593469 DOI: 10.1007/s10237-017-0919-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 05/12/2017] [Indexed: 11/26/2022]
Abstract
In this paper, we propose a full computational framework to simulate the hemodynamics in the aorta including the valve. Closed and open valve surfaces, as well as the lumen aorta, are reconstructed directly from medical images using new ad hoc algorithms, allowing a patient-specific simulation. The fluid dynamics problem that accounts from the movement of the valve is solved by a new 3D-0D fluid-structure interaction model in which the valve surface is implicitly represented through level set functions, yielding, in the Navier-Stokes equations, a resistive penalization term enforcing the blood to adhere to the valve leaflets. The dynamics of the valve between its closed and open position is modeled using a reduced geometric 0D model. At the discrete level, a finite element formulation is used and the SUPG stabilization is extended to include the resistive term in the Navier-Stokes equations. Then, after time discretization, the 3D fluid and 0D valve models are coupled through a staggered approach. This computational framework, applied to a patient-specific geometry and data, allows to simulate the movement of the valve, the sharp pressure jump occurring across the leaflets, and the blood flow pattern inside the aorta.
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Affiliation(s)
- Marco Fedele
- CMCS - MATHICSE - SB, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- CompMech Group, Department of Civil Engineering and Architecture, University of Pavia, Pavia, Italy
| | - Elena Faggiano
- CMCS - MATHICSE - SB, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
- CompMech Group, Department of Civil Engineering and Architecture, University of Pavia, Pavia, Italy.
| | - Luca Dedè
- CMCS - MATHICSE - SB, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy
| | - Alfio Quarteroni
- CMCS - MATHICSE - SB, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy
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32
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Luraghi G, Wu W, De Gaetano F, Rodriguez Matas JF, Moggridge GD, Serrani M, Stasiak J, Costantino ML, Migliavacca F. Evaluation of an aortic valve prosthesis: Fluid-structure interaction or structural simulation? J Biomech 2017; 58:45-51. [PMID: 28454910 PMCID: PMC5473331 DOI: 10.1016/j.jbiomech.2017.04.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 03/23/2017] [Accepted: 04/09/2017] [Indexed: 01/31/2023]
Abstract
Bio-inspired polymeric heart valves (PHVs) are excellent candidates to mimic the structural and the fluid dynamic features of the native valve. PHVs can be implanted as prosthetic alternative to currently clinically used mechanical and biological valves or as potential candidate for a minimally invasive treatment, like the transcatheter aortic valve implantation. Nevertheless, PHVs are not currently used for clinical applications due to their lack of reliability. In order to investigate the main features of this new class of prostheses, pulsatile tests in an in-house pulse duplicator were carried out and reproduced in silico with both structural Finite-Element (FE) and Fluid-Structure interaction (FSI) analyses. Valve kinematics and geometric orifice area (GOA) were evaluated to compare the in vitro and the in silico tests. Numerical results showed better similarity with experiments for the FSI than for the FE simulations. The maximum difference between experimental and FSI GOA at maximum opening time was only 5%, as compared to the 46.5% between experimental and structural FE GOA. The stress distribution on the valve leaflets clearly reflected the difference in valve kinematics. Higher stress values were found in the FSI simulations with respect to those obtained in the FE simulation. This study demonstrates that FSI simulations are more appropriate than FE simulations to describe the actual behaviour of PHVs as they can replicate the valve-fluid interaction while providing realistic fluid dynamic results.
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Affiliation(s)
- Giulia Luraghi
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Wei Wu
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Francesco De Gaetano
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Josè Felix Rodriguez Matas
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Geoff D Moggridge
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Marta Serrani
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Joanna Stasiak
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Maria Laura Costantino
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.
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33
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Mohammadi H, Cartier R, Mongrain R. The impact of the aortic valve impairment on the distant coronary arteries hemodynamics: a fluid-structure interaction study. Med Biol Eng Comput 2017; 55:1859-1872. [PMID: 28316038 DOI: 10.1007/s11517-017-1636-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 03/13/2017] [Indexed: 12/30/2022]
Abstract
Atherosclerosis is still the leading cause of death in the developed world. Although its initiation and progression is a complex multifactorial process, it is well known that blood flow-induced wall shear stress (WSS) is an important factor involved in early atherosclerotic plaque initiation. In recent clinical studies, it was established that the regional pathologies of the aortic valve can be involved in the formation of atherosclerotic plaques. However, the impact of hemodynamic effects is not yet fully elucidated for disease initiation and progression. In this study, our developed 3D global fluid-structure interaction model of the aortic root incorporating coronary arteries is used to investigate the possible interaction between coronary arteries and aortic valve pathologies. The coronary hemodynamics was examined and quantified for different degrees of aortic stenosis varying from nonexistent to severe. For the simulated healthy model, the calculated WSS varied between 0.41 and 1.34 Pa which is in the atheroprotective range. However, for moderate and severe aortic stenoses, wide regions of the coronary structures, especially the proximal sections around the first bifurcation, were exposed to lower values of WSS and therefore they were prone to atherosclerosis even in the case of healthy coronary arteries.
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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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34
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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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35
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Capelli C, Corsini C, Biscarini D, Ruffini F, Migliavacca F, Kocher A, Laufer G, Taylor AM, Schievano S, Andreas M, Burriesci G, Rath C. Pledget-Armed Sutures Affect the Haemodynamic Performance of Biologic Aortic Valve Substitutes: A Preliminary Experimental and Computational Study. Cardiovasc Eng Technol 2016; 8:17-29. [PMID: 27873180 PMCID: PMC5320018 DOI: 10.1007/s13239-016-0284-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 10/27/2016] [Indexed: 11/28/2022]
Abstract
Surgical aortic valve replacement is the most common procedure of choice for the treatment of severe aortic stenosis. Bioprosthetic valves are traditionally sewed-in the aortic root by means of pledget-armed sutures during open-heart surgery. Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow rapid implantation, therefore reducing the duration and invasiveness of the intervention. Different effects on the hemodynamics were clinically reported associated with the two technologies. The aim of this study was therefore to investigate whether the differences in hemodynamic performances are an effect of different anchoring systems. Two commercially available bio-prosthetic aortic valves, one sewed-in with pledget-armed sutures and one rapid-deployment, were thus tested in this study by means of a combined approach of experimental and computational tools. In vitro experiments were performed to evaluate the overall hydrodynamic performance under identical standard conditions; computational fluid dynamics analyses were set-up to explore local flow variations due to different design of the anchoring system. The results showed how the performance of cardiac valve substitutes is negatively affected by the presence of pledget-armed sutures. These are causing flow disturbances, which in turn increase the mean pressure gradient and decrease the effective orifice area. The combined approach of experiments and numerical simulations can be effectively used to quantify the detailed relationship between local fluid-dynamics and overall performances associated with different valve technologies.
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Affiliation(s)
- Claudio Capelli
- UCL Institute of Cardiovascular Science, and Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Guilford Street, London, WC1N 1EH, UK.
| | - Chiara Corsini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan, Italy
| | - Dario Biscarini
- UCL Institute of Cardiovascular Science, and Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Guilford Street, London, WC1N 1EH, UK.,Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan, Italy
| | - Francesco Ruffini
- UCL Institute of Cardiovascular Science, and Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Guilford Street, London, WC1N 1EH, UK.,Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan, Italy
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan, Italy
| | - Alfred Kocher
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Guenther Laufer
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Andrew M Taylor
- UCL Institute of Cardiovascular Science, and Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Guilford Street, London, WC1N 1EH, UK
| | - Silvia Schievano
- UCL Institute of Cardiovascular Science, and Great Ormond Street Hospital for Children, NHS Foundation Trust, 30 Guilford Street, London, WC1N 1EH, UK
| | - Martin Andreas
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Gaetano Burriesci
- Department of Mechanical Engineering, UCL, London, UK.,Fondazione Ri.MED, Bioengineering Group, Palermo, Italy
| | - Claus Rath
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria.,Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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36
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Fluid-Structure Interaction Study of Transcatheter Aortic Valve Dynamics Using Smoothed Particle Hydrodynamics. Cardiovasc Eng Technol 2016; 7:374-388. [PMID: 27844463 DOI: 10.1007/s13239-016-0285-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 11/04/2016] [Indexed: 10/20/2022]
Abstract
Computational modeling of heart valve dynamics incorporating both fluid dynamics and valve structural responses has been challenging. In this study, we developed a novel fully-coupled fluid-structure interaction (FSI) model using smoothed particle hydrodynamics (SPH). A previously developed nonlinear finite element (FE) model of transcatheter aortic valves (TAV) was utilized to couple with SPH to simulate valve leaflet dynamics throughout the entire cardiac cycle. Comparative simulations were performed to investigate the impact of using FE-only models vs. FSI models, as well as an isotropic vs. an anisotropic leaflet material model in TAV simulations. From the results, substantial differences in leaflet kinematics between FE-only and FSI models were observed, and the FSI model could capture the realistic leaflet dynamic deformation due to its more accurate spatial and temporal loading conditions imposed on the leaflets. The stress and the strain distributions were similar between the FE and FSI simulations. However, the peak stresses were different due to the water hammer effect induced by the fluid inertia in the FSI model during the closing phase, which led to 13-28% lower peak stresses in the FE-only model compared to that of the FSI model. The simulation results also indicated that tissue anisotropy had a minor impact on hemodynamics of the valve. However, a lower tissue stiffness in the radial direction of the leaflets could reduce the leaflet peak stress caused by the water hammer effect. It is hoped that the developed FSI models can serve as an effective tool to better assess valve dynamics and optimize next generation TAV designs.
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37
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Soifer E, Weiss D, Marom G, Einav S. The effect of pathologic venous valve on neighboring valves: fluid-structure interactions modeling. Med Biol Eng Comput 2016; 55:991-999. [PMID: 27663560 DOI: 10.1007/s11517-016-1575-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/15/2016] [Indexed: 11/27/2022]
Abstract
Understanding the hemodynamics surrounding the venous valve environment is of a great importance for prosthetic valves design. The present study aims to evaluate the effect of leaflets' stiffening process on the venous valve hemodynamics, valve's failure on the next proximal valve hemodynamics and valve's failure in a secondary daughter vein on the healthy valve hemodynamics in the main vein when both of these valves are distal to a venous junction. Fully coupled, two-way fluid-structure interaction computational models were developed and employed. The sinus pocket region experiences the lowest fluid shear stress, and the base region of the sinus side of the leaflet experiences the highest tissue stress. The leaflets' stiffening increases the tissue stress the valve is experiencing in a very low fluid shear region. A similar effect occurs with the proximal healthy valve as a consequence of the distal valve's failure and with the mother vein valve as a consequence of daughter vein valve's failure. Understanding the described mechanisms may be helpful for elucidating the venous valve stiffness-function relationship in nature, the reasons for a retrograde development of reflux and the relationship between venous valves located near venous junctions, and for designing better prosthetic valves and for improving their positioning.
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Affiliation(s)
- Elina Soifer
- The Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel.
| | - Dar Weiss
- The Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Gil Marom
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Shmuel Einav
- The Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel.,Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
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38
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Dabiri Y, Ronsky J, Ali I, Basha A, Bhanji A, Narine K. Effects of Leaflet Design on Transvalvular Gradients of Bioprosthetic Heart Valves. Cardiovasc Eng Technol 2016; 7:363-373. [PMID: 27573761 DOI: 10.1007/s13239-016-0279-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/17/2016] [Indexed: 11/25/2022]
Abstract
Bioprosthetic aortic valves (BAVs) are becoming the prostheses of choice in heart valve replacement. The objective of this paper is to assess the effects of leaflet geometry on the mechanics and hemodynamics of BAVs in a fluid structure interaction model. The curvature and angle of leaflets were varied in 10 case studies whereby the following design parameters were altered: a circular arch, a line, and a parabola for the radial curvature, and a circular arch, a spline, and a parabola for the circumferential curvature. Six different leaflet angles (representative of the inclination of the leaflets toward the surrounding aortic wall) were analyzed. The 3-dimensional geometry of the models were created using SolidWorks, Pointwise was used for meshing, and Comsol Multiphysics was used for implicit finite element calculations. Realistic loading was enforced by considering the time-dependent strongly-coupled interaction between blood flow and leaflets. Higher mean pressure gradients as well as von Mises stresses were obtained with a parabolic or circular curvature for radial curvature or a parabolic or spline curvature for the circumferential curvature. A smaller leaflet angle was associated with a lower pressure gradient, and, a lower von Mises stress. The leaflet curvature and angle noticeably affected the speed of valve opening, and closing. When a parabola was used for circumferential or radial curvature, leaflets displacements were asymmetric, and they opened and closed more slowly. A circular circumferential leaflet curvature, a linear leaflet radial curvature, and leaflet inclination toward the surrounding aortic wall were associated with superior BAVs mechanics.
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Affiliation(s)
- Yaghoub Dabiri
- Libin Cardiovascular Institute of Alberta, Health Research Innovation Centre (HRIC), University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Janet Ronsky
- Schulich School of Engineering, University of Calgary, Calgary, Canada
| | - Imtiaz Ali
- Libin Cardiovascular Institute of Alberta, Health Research Innovation Centre (HRIC), University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Ameen Basha
- Cummings School of Medicine Health Sciences, University of Calgary, Calgary, Canada
| | - Alisha Bhanji
- Nanotechnology Engineering, University of Waterloo, Waterloo, Canada
| | - Kishan Narine
- Libin Cardiovascular Institute of Alberta, Health Research Innovation Centre (HRIC), University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada.
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39
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The Driving Mechanism for Unidirectional Blood Flow in the Tubular Embryonic Heart. Ann Biomed Eng 2016; 44:3069-3083. [DOI: 10.1007/s10439-016-1620-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 04/13/2016] [Indexed: 12/31/2022]
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40
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Flamini V, DeAnda A, Griffith BE. Immersed boundary-finite element model of fluid-structure interaction in the aortic root. THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS 2016; 30:139-164. [PMID: 26951951 PMCID: PMC4778980 DOI: 10.1007/s00162-015-0374-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
It has long been recognized that aortic root elasticity helps to ensure efficient aortic valve closure, but our understanding of the functional importance of the elasticity and geometry of the aortic root continues to e-volve as increasingly detailed in vivo imaging data become available. Herein, we describe a fluid-structure interaction model of the aortic root, including the aortic valve leaflets, the sinsuses of Valsalva, the aortic annulus, and the sinotubular junction, that employs a version of Peskin's immersed boundary (IB) method with a finite element (FE) description of the structural elasticity. As in earlier work, we use a fiber-based model of the valve leaflets, but this study extends earlier IB models of the aortic root by employing an incompressible hyperelastic model of the mechanics of the sinuses and ascending aorta using a constitutive law fit to experimental data from human aortic root tissue. In vivo pressure loading is accounted for by a backward displacement method that determines the unloaded configurations of the root model. Our model yields realistic cardiac output at physiological pressures, with low transvalvular pressure differences during forward flow, minimal regurgitation during valve closure, and realistic pressure loads when the valve is closed during diastole. Further, results from high-resolution computations indicate that although the detailed leaflet and root kinematics show some grid sensitivity, our IB model of the aortic root nonetheless produces essentially grid-converged flow rates and pressures at practical grid spacings for the high-Reynolds number flows of the aortic root. These results thereby clarify minimum grid resolutions required by such models when used as stand-alone models of the aortic valve as well as when used to provide models of the outflow valves in models of left ventricular fluid dynamics.
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Affiliation(s)
- Vittoria Flamini
- Department of Mechanical and Aerospace Engineering, New York University Tandon School of Engineering, Brooklyn, New York, USA
| | - Abe DeAnda
- Division of Cardiothoracic Surgery, Department of Surgery, University of Texas Medical Branch, Galveston, TX
| | - Boyce E Griffith
- Departments of Mathematics and Biomedical Engineering and McAllister Heart Institute, Phillips Hall, Campus Box 3250, University of North Carolina, Chapel Hill, North Carolina, USA, ,
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41
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Fluid-structure interaction modeling of calcific aortic valve disease using patient-specific three-dimensional calcification scans. Med Biol Eng Comput 2016; 54:1683-1694. [PMID: 26906280 DOI: 10.1007/s11517-016-1458-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/29/2016] [Indexed: 01/08/2023]
Abstract
Calcific aortic valve disease (CAVD) is characterized by calcification accumulation and thickening of the aortic valve cusps, leading to stenosis. The importance of fluid flow shear stress in the initiation and regulation of CAVD progression is well known and has been studied recently using fluid-structure interaction (FSI) models. While cusp calcifications are three-dimensional (3D) masses, previously published FSI models have represented them as either stiffened or thickened two-dimensional (2D) cusps. This study investigates the hemodynamic effect of these calcifications employing FSI models using 3D patient-specific calcification masses. A new reverse calcification technique (RCT) is used for modeling different stages of calcification growth based on the spatial distribution of calcification density. The RCT is applied to generate the 3D calcification deposits reconstructed from a patient-specific CT scans. Our results showed that consideration of 3D calcification deposits led to both higher fluid shear stresses and unique fluid shear stress distribution on the aortic side of the cusps that may have an impact on the calcification growth rate. However, the flow did not seem to affect the geometry of the calcification during the growth phase.
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Mega M, Marom G, Halevi R, Hamdan A, Bluestein D, Haj-Ali R. Imaging analysis of collagen fiber networks in cusps of porcine aortic valves: effect of their local distribution and alignment on valve functionality. Comput Methods Biomech Biomed Engin 2015; 19:1002-8. [PMID: 26406926 DOI: 10.1080/10255842.2015.1088009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The cusps of native aortic valve (AV) are composed of collagen bundles embedded in soft tissue, creating a heterogenic tissue with asymmetric alignment in each cusp. This study compares native collagen fiber networks (CFNs) with a goal to better understand their influence on stress distribution and valve kinematics. Images of CFNs from five porcine tricuspid AVs are analyzed and fluid-structure interaction models are generated based on them. Although the valves had similar overall kinematics, the CFNs had distinctive influence on local mechanics. The regions with dilute CFN are more prone to damage since they are subjected to higher stress magnitudes.
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Affiliation(s)
- Mor Mega
- a School of Mechanical Engineering , Tel Aviv University , Tel Aviv , Israel
| | - Gil Marom
- b Department of Biomedical Engineering , Stony Brook University , Stony Brook , NY , USA
| | - Rotem Halevi
- a School of Mechanical Engineering , Tel Aviv University , Tel Aviv , Israel
| | - Ashraf Hamdan
- c Heart Institute, Chaim Sheba Medical Center , Tel Hashomer , Israel
| | - Danny Bluestein
- b Department of Biomedical Engineering , Stony Brook University , Stony Brook , NY , USA
| | - Rami Haj-Ali
- a School of Mechanical Engineering , Tel Aviv University , Tel Aviv , Israel
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Biomechanical evaluation of the pathophysiologic developmental mechanisms of mitral valve prolapse: effect of valvular morphologic alteration. Med Biol Eng Comput 2015; 54:799-809. [PMID: 26307201 DOI: 10.1007/s11517-015-1371-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 08/10/2015] [Indexed: 10/23/2022]
Abstract
Mitral valve prolapse (MVP) refers to an excessive billowing of the mitral valve (MV) leaflets across the mitral annular plane into the left atrium during the systolic portion of the cardiac cycle. The underlying mechanisms for the development of MVP and mitral regurgitation in association with MV tissue remodeling are still unclear. We performed computational MV simulations to investigate the pathophysiologic developmental mechanisms of MVP. A parametric MV geometry model was utilized for this study. Posterior leaflet enlargement and posterior chordal elongation models were created by adjusting the geometry of the posterior leaflet and chordae, respectively. Dynamic finite element simulations of MV function were performed over the complete cardiac cycle. Computational simulations demonstrated that enlarging posterior leaflet area increased large stress concentration in the posterior leaflets and chordae, and posterior chordal elongation decreased leaflet coaptation. When MVP was accompanied by both posterior leaflet enlargement and chordal elongation simultaneously, the posterior leaflet was exposed to extremely large prolapse with a substantial lack of leaflet coaptation. These data indicate that MVP development is closely related to tissue alterations of the leaflets and chordae. This biomechanical evaluation strategy can help us better understand the pathophysiologic developmental mechanisms of MVP.
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Wu W, Pott D, Mazza B, Sironi T, Dordoni E, Chiastra C, Petrini L, Pennati G, Dubini G, Steinseifer U, Sonntag S, Kuetting M, Migliavacca F. Fluid–Structure Interaction Model of a Percutaneous Aortic Valve: Comparison with an In Vitro Test and Feasibility Study in a Patient-Specific Case. Ann Biomed Eng 2015; 44:590-603. [DOI: 10.1007/s10439-015-1429-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/12/2015] [Indexed: 11/24/2022]
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Barannyk O, Oshkai P. The Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve. J Biomech Eng 2015; 137:051005. [DOI: 10.1115/1.4029747] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Indexed: 11/08/2022]
Abstract
In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases were classified into two clinical categories and were correlated with the corresponding changes in aortic root geometry while keeping the aortic base diameter fixed. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output, and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.
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Affiliation(s)
- Oleksandr Barannyk
- Mem. ASME Department of Mechanical Engineering, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Peter Oshkai
- Mem. ASME Department of Mechanical Engineering, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
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Halevi R, Hamdan A, Marom G, Mega M, Raanani E, Haj-Ali R. Progressive aortic valve calcification: Three-dimensional visualization and biomechanical analysis. J Biomech 2015; 48:489-97. [DOI: 10.1016/j.jbiomech.2014.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 10/24/2022]
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Marom G, Chiu WC, Slepian MJ, Bluestein D. Numerical model of total artificial heart hemodynamics and the effect of its size on stress accumulation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:5651-4. [PMID: 25571277 DOI: 10.1109/embc.2014.6944909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The total artificial heart (TAH) is a bi-ventricular mechanical circulatory support device that replaces the heart in patients with end-stage congestive heart failure. The device acts as blood pump via pneumatic activation of diaphragms altering the volume of the ventricular chambers. Flow in and out of the ventricles is controlled by mechanical heart valves. The aim of this study is to evaluate the flow regime in the TAH and to estimate the thrombogenic potential during systole. Toward that goal, three numerical models of TAHs of differing sizes, that include the deforming diaphragm and the blood flow from the left chamber to the aorta, are introduced. A multiphase model with injection of platelet particles is employed to calculate their trajectories. The shear stress accumulation in the three models are calculated along the platelets trajectories and their probability density functions, which represent the `thrombogenic footprint' of the device are compared. The calculated flow regime successfully captures the mitral regurgitation and the flows that open and close the aortic valve during systole. Physiological velocity magnitudes are found in all three models, with higher velocities and increased stress accumulation predicted for smaller devices.
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Jasinski MJ, Gocol R, Malinowski M, Hudziak D, Duraj P, Deja MA. Predictors of early and medium-term outcome of 200 consecutive aortic valve and root repairs. J Thorac Cardiovasc Surg 2015; 149:123-9. [DOI: 10.1016/j.jtcvs.2014.08.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/06/2014] [Accepted: 08/18/2014] [Indexed: 10/24/2022]
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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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Mazzitelli D, Stamm C, Rankin JS, Pfeiffer S, Fischlein T, Pirk J, Choi YH, Detter C, Kroll J, Beyersdorf F, Shrestha M, Schreiber C, Lange R. Leaflet reconstructive techniques for aortic valve repair. Ann Thorac Surg 2014; 98:2053-60. [PMID: 25468084 DOI: 10.1016/j.athoracsur.2014.06.052] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 05/30/2014] [Accepted: 06/09/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Refining leaflet reconstruction has become a primary issue in aortic valve repair. This descriptive analysis reviews leaflet pathology, repair techniques, and early results in a prospective regulatory trial of aortic valve repair. METHODS Sixty-five patients underwent valve repair for predominant moderate to severe aortic insufficiency (AI). The mean age was 63 ± 13 years, and 69% of the patients were male. Ascending aortic/root replacement was required in 62%. As a first step, ring annuloplasty was performed, and then leaflet repair included leaflet plication for prolapse, nodular unfolding, double pericardial patching of commissural defects or holes, complete pericardial leaflet replacement, leaflet extension, and Gore-Tex reinforcement. Leaflet techniques and causes of adverse outcomes were evaluated. RESULTS The follow-up time was 2-years maximal and 0.9 years mean, with a survival of 97%. Eighty percent of patients required repair of leaflet defects: leaflet prolapse (52/65-80%), ruptured commissures (6/65-9%), leaflet holes (4/65-6%), and nodular retraction (6/65-9%). The average preoperative AI grade of 2.9 ± 0.8 fell to 0.7 ± 0.7 (p < 0.0001). Three patients (4.6%) required interval valve replacement because of (1) suture untying, (2) iatrogenic leaflet tear, or (3) diphtheroid endocarditis. Five other patients experienced grade 2 or grade 3 AI: probable suture untying in 1 patient, ineffective leaflet extensions in 2 patients, and unsuccessful Gore-Tex reinforcements in 2 patients. Two patients with single pericardial leaflet replacements and all those with double pericardial reconstructions did well. CONCLUSIONS Leaflet defects are common in patients with moderate to severe AI. Leaflet plication, nodular unfolding, and double pericardial patching performed well. Gore-Tex and leaflet extension seemed less satisfactory. Standardization and experience with leaflet reconstruction will be important for optimizing the outcomes of aortic valve repair.
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Affiliation(s)
| | | | | | | | | | - Jan Pirk
- Institute for Clinical and Experimental Medicine, Prague, Czechoslovakia
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