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Qin T, Mao W, Caballero A, Kamioka N, Lerakis S, Lain S, Elefteriades J, Liang L, Sun W. Patient-specific analysis of bicuspid aortic valve hemodynamics using a fully coupled fluid-structure interaction model. Comput Biol Med 2024; 172:108191. [PMID: 38457932 DOI: 10.1016/j.compbiomed.2024.108191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/10/2024] [Accepted: 02/18/2024] [Indexed: 03/10/2024]
Abstract
Bicuspid aortic valve (BAV), the most common congenital heart disease, is prone to develop significant valvular dysfunction and aortic wall abnormalities such as ascending aortic aneurysm. Growing evidence has suggested that abnormal BAV hemodynamics could contribute to disease progression. In order to investigate BAV hemodynamics, we performed 3D patient-specific fluid-structure interaction (FSI) simulations with fully coupled blood flow dynamics and valve motion throughout the cardiac cycle. Results showed that the hemodynamics during systole can be characterized by a systolic jet and two counter-rotating recirculation vortices. At peak systole, the jet was usually eccentric, with asymmetric recirculation vortices and helical flow motion in the ascending aorta. The flow structure at peak systole was quantified using the vorticity, flow rate reversal ratio and local normalized helicity (LNH) at four locations from the aortic root to the ascending aorta. The systolic jet was evaluated with the peak velocity, normalized flow displacement, and jet angle. It was found that peak velocity and normalized flow displacement (rather than jet angle) gave a strong correlation with the vorticity and LNH in the ascending aorta, which suggests that these two metrics could be used for clinical noninvasive evaluation of abnormal blood flow patterns in BAV patients.
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Affiliation(s)
- Tongran Qin
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Sutra Medical Inc, Lake Forest, CA, USA
| | - Wenbin Mao
- Mechanical Engineering, University of South Florida, FL, USA
| | - Andrés Caballero
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; PAI+ Research Group, Mechanical Engineering Department, Universidad Autónoma de Occidente, Cali, Colombia
| | | | - Stamatios Lerakis
- Emory University, School of Medicine, Atlanta, GA, USA; Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Santiago Lain
- PAI+ Research Group, Mechanical Engineering Department, Universidad Autónoma de Occidente, Cali, Colombia
| | - John Elefteriades
- Aortic Institute, School of Medicine, Yale University, New Haven, CT, USA
| | - Liang Liang
- Department of Computer Science, University of Miami, Coral Gables, FL, USA
| | - Wei Sun
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Sutra Medical Inc, Lake Forest, CA, USA.
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2
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Henry M, Fadnes S, Lovstakken L, Mawad W, Mertens L, Nyrnes SA. Flow Dynamics in Children With Bicuspid Aortic Valve: A Blood Speckle Tracking Study. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:2354-2360. [PMID: 37573177 DOI: 10.1016/j.ultrasmedbio.2023.07.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/27/2023] [Accepted: 07/16/2023] [Indexed: 08/14/2023]
Abstract
OBJECTIVE Bicuspid aortic valve (BAV) is associated with progressive aortic dilation. Although the etiology is complex, altered flow dynamics is thought to play an important role. Blood speckle tracking (BST) allows for visualization and quantification of complex flow, which could be useful in identifying patients at risk of root dilation and could aid in surgical planning. The aims of this study were to assess and quantify flow in the aortic root and left ventricle using BST in children with bicuspid aortic valves. METHODS AND RESULTS A total of 38 children <10 y of age were included (24 controls, 14 with BAV). Flow dynamics were examined using BST in the aortic root and left ventricle. Children with BAV had altered systolic flow patterns in the aortic root and higher aortic root average vorticity (25.9 [23.4-29.2] Hz vs. 17.8 [9.0-26.2] Hz, p < 0.05), vector complexity (0.17 [0.14-0.31] vs. 0.05 [0.02-0.13], p < 0.01) and rate of energy loss (7.9 [4.9-12.1] mW/m vs. 2.7 [1.2-7.4] mW/m, p = 0.01). Left ventricular average diastolic vorticity (20.9 ± 5.8 Hz vs. 11.4 ± 5.2 Hz, p < 0.01), kinetic energy (0.11 ± 0.05 J/m vs. 0.04 ± 0.02 J/m, p < 0.01), vector complexity (0.38 ± 0.1 vs. 0.23 ± 0.1, p < 0.01) and rate of energy loss (11.1 ± 4.8 mW/m vs. 2.7 ± 1.9 mW/m, p < 0.01) were higher in children with BAV. CONCLUSION Children with BAV exhibit altered flow dynamics in the aortic root and left ventricle in the absence of significant aortic root dilation. This may represent a substrate and potential predictor for future dilation and diastolic dysfunction.
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Affiliation(s)
| | - Solveig Fadnes
- Norwegian University of Science and Technology, Trondheim, Norway
| | - Lasse Lovstakken
- Norwegian University of Science and Technology, Trondheim, Norway
| | - Wadi Mawad
- McGill University Health Centre, Montreal, QC, Canada
| | - Luc Mertens
- Hospital for Sick Children, Toronto, ON, Canada
| | - Siri Ann Nyrnes
- Norwegian University of Science and Technology, Trondheim, Norway; Children's Clinic, St. Olav's University Hospital, Trondheim, Norway
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3
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Bulut HI, Arjomandi Rad A, Syrengela AA, Ttofi I, Djordjevic J, Kaur R, Keiralla A, Krasopoulos G. A Comprehensive Review of Management Strategies for Bicuspid Aortic Valve (BAV): Exploring Epidemiology, Aetiology, Aortopathy, and Interventions in Light of Recent Guidelines. J Cardiovasc Dev Dis 2023; 10:398. [PMID: 37754827 PMCID: PMC10531880 DOI: 10.3390/jcdd10090398] [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: 08/17/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/28/2023] Open
Abstract
OBJECTIVE bicuspid aortic valve (BAV) stands as the most prevalent congenital heart condition intricately linked to aortic pathologies encompassing aortic regurgitation (AR), aortic stenosis, aortic root dilation, and aortic dissection. The aetiology of BAV is notably intricate, involving a spectrum of genes and polymorphisms. Moreover, BAV lays the groundwork for an array of structural heart and aortic disorders, presenting varying degrees of severity. Establishing a tailored clinical approach amid this diverse range of BAV-related conditions is of utmost significance. In this comprehensive review, we delve into the epidemiology, aetiology, associated ailments, and clinical management of BAV, encompassing imaging to aortic surgery. Our exploration is guided by the perspectives of the aortic team, spanning six distinct guidelines. METHODS We conducted an exhaustive search across databases like PubMed, Ovid, Scopus, and Embase to extract relevant studies. Our review incorporates 84 references and integrates insights from six different guidelines to create a comprehensive clinical management section. RESULTS BAV presents complexities in its aetiology, with specific polymorphisms and gene disorders observed in groups with elevated BAV prevalence, contributing to increased susceptibility to other cardiovascular conditions. The altered hemodynamics inherent to BAV instigate adverse remodelling of the aorta and heart, thus fostering the development of epigenetically linked aortic and heart diseases. Employing TTE screening for first-degree relatives of BAV patients might be beneficial for disease tracking and enhancing clinical outcomes. While SAVR is the primary recommendation for indicated AVR in BAV, TAVR might be an option for certain patients endorsed by adept aortic teams. In addition, proficient teams can perform aortic valve repair for AR cases. Aortic surgery necessitates personalized evaluation, accounting for genetic makeup and risk factors. While the standard aortic replacement threshold stands at 55 mm, it may be tailored to 50 mm or even 45 mm based on patient-specific considerations. CONCLUSION This review reiterates the significance of considering the multifactorial nature of BAV as well as the need for further research to be carried out in the field.
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Affiliation(s)
- Halil Ibrahim Bulut
- Cerrahpasa School of Medicine, Istanbul University-Cerrahpasa, Istanbul 34098, Turkey;
| | | | | | - Iakovos Ttofi
- Department of Cardiothoracic Surgery, Oxford University Hospital NHS Foundation Trust, Oxford OX3 9DU, UK; (I.T.); (J.D.); (R.K.); (A.K.)
| | - Jasmina Djordjevic
- Department of Cardiothoracic Surgery, Oxford University Hospital NHS Foundation Trust, Oxford OX3 9DU, UK; (I.T.); (J.D.); (R.K.); (A.K.)
| | - Ramanjit Kaur
- Department of Cardiothoracic Surgery, Oxford University Hospital NHS Foundation Trust, Oxford OX3 9DU, UK; (I.T.); (J.D.); (R.K.); (A.K.)
| | - Amar Keiralla
- Department of Cardiothoracic Surgery, Oxford University Hospital NHS Foundation Trust, Oxford OX3 9DU, UK; (I.T.); (J.D.); (R.K.); (A.K.)
| | - George Krasopoulos
- Department of Cardiothoracic Surgery, Oxford University Hospital NHS Foundation Trust, Oxford OX3 9DU, UK; (I.T.); (J.D.); (R.K.); (A.K.)
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4
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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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5
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Hou Q, Tao K, Du T, Wei H, Zhang H, Chen S, Pan Y, Qiao A. A computational analysis of potential aortic dilation induced by the hemodynamic effects of bicuspid aortic valve phenotypes. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 220:106811. [PMID: 35447428 DOI: 10.1016/j.cmpb.2022.106811] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 03/01/2022] [Accepted: 04/10/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND OBJECTIVES The bicuspid aortic valve (BAV) is a major risk factor for the progression of aortic dilation (AD) because of the induced abnormal blood flow environment in aorta. The differences in the development of AD induced by BAV phenotypes remains unclear. Therefore, the objective of this study was to assess the potential locations of AD induced by different phenotypes of BAV. The different effects of opening orifice area and leaflet orientation on ascending aortic hemodynamics in Type-1 BAV was investigated by means of numerical simulation. METHODS Finite element dynamic analysis was performed on tricuspid aortic valve (TAV) and BAV models to simulate the motion of the leaflets and obtain the geometrical characteristics of AV at peak systole as a reference, which were used for aortic models. Then, four sets of aortic fluid models were designed according to the leaflet fusion types [TAV; BAV (left-right-coronary cusp fusion, LR; right-non-coronary cusp fusion, RN; left-non-coronary cusp fusion, LN)], and the computational fluid dynamics method was applied to compare the hemodynamic differences within the aorta at peak systole. RESULTS The maximum opening area of BAV was significantly reduced, resulting in alterations in aortic hemodynamics compared with TAV. The velocity streamlines were essentially parallel to the aortic wall in TAV. The average pressure and wall shear stress in aorta tend to be stable. In contrary, the eccentricity of BAV orifice jet resulted in high-velocity flow directed toward the ascending aorta (AA) wall and aortic arch for LR and LN; RN features an asymmetrical velocity distribution toward the outer bend of the middle AA, and eccentric flow tends to impact the distal AA. As the flow angle is associated with distinct flow impingement locations, different degrees of WSS and pressure concentration occur along the aortic wall from the AA to the aortic arch in three BAV types. CONCLUSIONS The BAV morphotype affects the aortic hemodynamics, and the abnormal blood flow associated with BAV may play a role in AD. The different BAV phenotypes determine the direction of blood flow jet and change the expression of dilation. LR is likely to cause dilation of the tubular AA; RN results in dilation of the middle AA to proximal aortic arch; and LN causes an increased incidence of the tubular AA and the proximal aortic arch.
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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
| | - Keyi Tao
- 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
| | - Tianming Du
- 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.
| | - Hongge Wei
- 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
| | - Shiliang Chen
- 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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6
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Vogl BJ, Niemi NR, Griffiths LG, Alkhouli MA, Hatoum H. Impact of calcific aortic valve disease on valve mechanics. Biomech Model Mechanobiol 2021; 21:55-77. [PMID: 34687365 DOI: 10.1007/s10237-021-01527-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 10/07/2021] [Indexed: 10/20/2022]
Abstract
The aortic valve is a highly dynamic structure characterized by a transvalvular flow that is unsteady, pulsatile, and characterized by episodes of forward and reverse flow patterns. Calcific aortic valve disease (CAVD) resulting in compromised valve function and increased pressure overload on the ventricle potentially leading to heart failure if untreated, is the most predominant valve disease. CAVD is a multi-factorial disease involving molecular, tissue and mechanical interactions. In this review, we aim at recapitulating the biomechanical loads on the aortic valve, summarizing the current and most recent research in the field in vitro, in-silico, and in vivo, and offering a clinical perspective on current strategies adopted to mitigate or approach CAVD.
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Affiliation(s)
- Brennan J Vogl
- Biomedical Engineering Department, Michigan Technological University, 1400 Townsend Dr, Houghton, MI, 49931, USA
| | - Nicholas R Niemi
- Biomedical Engineering Department, Michigan Technological University, 1400 Townsend Dr, Houghton, MI, 49931, USA
| | - Leigh G Griffiths
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | | | - Hoda Hatoum
- Biomedical Engineering Department, Michigan Technological University, 1400 Townsend Dr, Houghton, MI, 49931, USA. .,Health Research Institute, Michigan Technological University, Houghton, MI, USA. .,Center of Biocomputing and Digital Health, Michigan Technological University, Houghton, MI, USA.
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7
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Yan W, Li J, Wang W, Wei L, Wang S. A Fluid-Structure Interaction Study of Different Bicuspid Aortic Valve Phenotypes Throughout the Cardiac Cycle. Front Physiol 2021; 12:716015. [PMID: 34381379 PMCID: PMC8350765 DOI: 10.3389/fphys.2021.716015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
The bicuspid aortic valve (BAV) is a congenital malformation of the aortic valve with a variety of structural features. The current research on BAV mainly focuses on the systolic phase, while ignoring the diastolic hemodynamic characteristics and valve mechanics. The purpose of this study is to compare the differences in hemodynamics and mechanical properties of BAV with different phenotypes throughout the cardiac cycle by means of numerical simulation. Based on physiological anatomy, we established an idealized tricuspid aortic valve (TAV) model and six phenotypes of BAV models (including Type 0 a-p, Type 0 lat, Type 1 L-R, Type 1 N-L, Type 1 R-N, and Type 2), and simulated the dynamic changes of the aortic valve during the cardiac cycle using the fluid-structure interaction method. The morphology of the leaflets, hemodynamic parameters, flow patterns, and strain were analyzed. Compared with TAV, the cardiac output and effective orifice area of different BAV phenotypes decreased certain degree, along with the peak velocity and mean pressure difference increased both. Among all BAV models, Type 2 exhibited the worst hemodynamic performance. During the systole, obvious asymmetric flow field was observed in BAV aorta, which was related to the orientation of BAV. Higher strain was generated in diastole for BAV models. The findings of this study suggests specific differences in the hemodynamic characteristics and valve mechanics of different BAV phenotypes, including different severity of stenosis, flow patterns, and leaflet strain, which may be critical for prediction of other subsequent aortic diseases and differential treatment strategy for certain BAV phenotype.
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Affiliation(s)
- Wentao Yan
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Jianming Li
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
| | - Wenshuo Wang
- Department of Vascular Surgery, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Lai Wei
- Department of Vascular Surgery, Zhongshan Hospital Affiliated to Fudan University, Shanghai, China
| | - Shengzhang Wang
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, China.,Institute of Biomedical Engineering Technology, Academy for Engineering and Technology, Fudan University, Shanghai, China
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8
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Park MH, Zhu Y, Imbrie-Moore AM, Wang H, Marin-Cuartas M, Paulsen MJ, Woo YJ. Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation. Front Cardiovasc Med 2021; 8:673689. [PMID: 34307492 PMCID: PMC8295480 DOI: 10.3389/fcvm.2021.673689] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
The field of heart valve biomechanics is a rapidly expanding, highly clinically relevant area of research. While most valvular pathologies are rooted in biomechanical changes, the technologies for studying these pathologies and identifying treatments have largely been limited. Nonetheless, significant advancements are underway to better understand the biomechanics of heart valves, pathologies, and interventional therapeutics, and these advancements have largely been driven by crucial in silico, ex vivo, and in vivo modeling technologies. These modalities represent cutting-edge abilities for generating novel insights regarding native, disease, and repair physiologies, and each has unique advantages and limitations for advancing study in this field. In particular, novel ex vivo modeling technologies represent an especially promising class of translatable research that leverages the advantages from both in silico and in vivo modeling to provide deep quantitative and qualitative insights on valvular biomechanics. The frontiers of this work are being discovered by innovative research groups that have used creative, interdisciplinary approaches toward recapitulating in vivo physiology, changing the landscape of clinical understanding and practice for cardiovascular surgery and medicine.
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Affiliation(s)
- Matthew H Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States.,Department of Bioengineering, Stanford University, Stanford, CA, United States
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9
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Kazik HB, Kandail HS, LaDisa JF, Lincoln J. Molecular and Mechanical Mechanisms of Calcification Pathology Induced by Bicuspid Aortic Valve Abnormalities. Front Cardiovasc Med 2021; 8:677977. [PMID: 34124206 PMCID: PMC8187581 DOI: 10.3389/fcvm.2021.677977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 04/29/2021] [Indexed: 11/13/2022] Open
Abstract
Bicuspid aortic valve (BAV) is a congenital defect affecting 1-2% of the general population that is distinguished from the normal tricuspid aortic valve (TAV) by the existence of two, rather than three, functional leaflets (or cusps). BAV presents in different morphologic phenotypes based on the configuration of cusp fusion. The most common phenotypes are Type 1 (containing one raphe), where fusion between right coronary and left coronary cusps (BAV R/L) is the most common configuration followed by fusion between right coronary and non-coronary cusps (BAV R/NC). While anatomically different, BAV R/L and BAV R/NC configurations are both associated with abnormal hemodynamic and biomechanical environments. The natural history of BAV has shown that it is not necessarily the primary structural malformation that enforces the need for treatment in young adults, but the secondary onset of premature calcification in ~50% of BAV patients, that can lead to aortic stenosis. While an underlying genetic basis is a major pathogenic contributor of the structural malformation, recent studies have implemented computational models, cardiac imaging studies, and bench-top methods to reveal BAV-associated hemodynamic and biomechanical alterations that likely contribute to secondary complications. Contributions to the field, however, lack support for a direct link between the external valvular environment and calcific aortic valve disease in the setting of BAV R/L and R/NC BAV. Here we review the literature of BAV hemodynamics and biomechanics and discuss its previously proposed contribution to calcification. We also offer means to improve upon previous studies in order to further characterize BAV and its secondary complications.
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Affiliation(s)
- Hail B. Kazik
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, United States
| | | | - John F. LaDisa
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, United States
- Division of Cardiovascular Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
- Section of Pediatric Cardiology, The Herma Heart Institute, Children's Wisconsin, Milwaukee, WI, United States
| | - Joy Lincoln
- Section of Pediatric Cardiology, The Herma Heart Institute, Children's Wisconsin, Milwaukee, WI, United States
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
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10
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Iwata K, Sekine T, Tanaka I, Ando T, Orita E. Turbulent Kinetic Energy Is Different from Viscous Energy Loss. Radiographics 2020; 40:2142-2144. [PMID: 33136486 DOI: 10.1148/rg.2020200177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kotomi Iwata
- Department of Radiology, Nippon Medical School, Tokyo, Japan; Department of Radiology, Nippon Medical School Musashikosugi Hospital, 1-396 Kosugicho, Nakaharaku, Kawasaki, Kanagawa 211-8533, Japan (T.S.)
| | - Tetsuro Sekine
- Department of Radiology, Nippon Medical School, Tokyo, Japan; Department of Radiology, Nippon Medical School Musashikosugi Hospital, 1-396 Kosugicho, Nakaharaku, Kawasaki, Kanagawa 211-8533, Japan (T.S.)
| | - Izumi Tanaka
- Department of Radiology, Nippon Medical School, Tokyo, Japan; Department of Radiology, Nippon Medical School Musashikosugi Hospital, 1-396 Kosugicho, Nakaharaku, Kawasaki, Kanagawa 211-8533, Japan (T.S.)
| | - Takahiro Ando
- Department of Radiology, Nippon Medical School, Tokyo, Japan; Department of Radiology, Nippon Medical School Musashikosugi Hospital, 1-396 Kosugicho, Nakaharaku, Kawasaki, Kanagawa 211-8533, Japan (T.S.)
| | - Erika Orita
- Department of Radiology, Nippon Medical School, Tokyo, Japan; Department of Radiology, Nippon Medical School Musashikosugi Hospital, 1-396 Kosugicho, Nakaharaku, Kawasaki, Kanagawa 211-8533, Japan (T.S.)
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11
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Niccolini G, Manuello A, Capone A, Marongiu G, Dell'Osa AH, Fois A, Velluzzi F, Concu A. Possible Assessment of Calf Venous Pump Efficiency by Computational Fluid Dynamics Approach. Front Physiol 2020; 11:1003. [PMID: 33013438 PMCID: PMC7510250 DOI: 10.3389/fphys.2020.01003] [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: 11/24/2019] [Accepted: 07/23/2020] [Indexed: 11/24/2022] Open
Abstract
Three-dimensional simulations of peripheral, deep venous flow during muscular exercise in limbs of healthy subjects and in those with venous dysfunction were carried out by a computational fluid-dynamics (CFD) approach using the STAR CCM + platform. The aim was to assess the effects of valvular incompetence on the venous calf pump efficiency. The model idealizes the lower limb circulation by a single artery, a capillary bed represented by a porous region and a single vein. The focus is on a segment of the circuit which mimics a typical deep vein at the level of the calf muscle, such as the right posterior tibial vein. Valves are idealized as ball valves, and periodic muscle contractions are given by imposing time-dependent boundary conditions to the calf segment wall. Flow measurements were performed in two cross-sections downstream and upstream of the calf pump. Model results demonstrate a reduced venous return for incompetent valves during calf exercise. Two different degrees of valvular incompetence are considered, by restricting the motion of one or both valves. Model results showed that only the proximal valve is critical, with a 30% reduction of venous return during calf exercise in case of valvular incompetence: the net flow volume ejected by the calf in central direction was 0.14 mL per working cycle, against 0.2 mL for simulated healthy limbs. This finding appeared to be consistent with a 25% reduction of the calf ejection fraction, experimentally observed in chronic venous disease limbs compared with healthy limbs.
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Affiliation(s)
- Gianni Niccolini
- Department of Structural, Geotechnical and Building Engineering, Politecnico di Torino, Turin, Italy
| | - Andrea Manuello
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Antonio Capone
- Orthopedic Clinic, Department of Surgical Sciences, University of Cagliari, Cagliari, Italy
| | - Giuseppe Marongiu
- Orthopedic Clinic, Department of Surgical Sciences, University of Cagliari, Cagliari, Italy
| | - Antonio Hector Dell'Osa
- Instituto de Desarrollo Economico e Innovación, Universidad Nacional de Tierra del Fuego, Antartida e Islas del Atlantico Sur, Ushuaia, Argentina
| | - Andrea Fois
- Biosignal Acquisition System, Nomadyca Ltd., Kampala, Uganda
| | - Fernanda Velluzzi
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Alberto Concu
- 2C Technologies Ltd., Academic Spin-Off, University of Cagliari, Cagliari, Italy
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12
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Emendi M, Sturla F, Ghosh RP, Bianchi M, Piatti F, Pluchinotta FR, Giese D, Lombardi M, Redaelli A, Bluestein D. Patient-Specific Bicuspid Aortic Valve Biomechanics: A Magnetic Resonance Imaging Integrated Fluid-Structure Interaction Approach. Ann Biomed Eng 2020; 49:627-641. [PMID: 32804291 DOI: 10.1007/s10439-020-02571-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 07/14/2020] [Indexed: 12/15/2022]
Abstract
Congenital bicuspid aortic valve (BAV) consists of two fused cusps and represents a major risk factor for calcific valvular stenosis. Herein, a fully coupled fluid-structure interaction (FSI) BAV model was developed from patient-specific magnetic resonance imaging (MRI) and compared against in vivo 4-dimensional flow MRI (4D Flow). FSI simulation compared well with 4D Flow, confirming direction and magnitude of the flow jet impinging onto the aortic wall as well as location and extension of secondary flows and vortices developing at systole: the systolic flow jet originating from an elliptical 1.6 cm2 orifice reached a peak velocity of 252.2 cm/s, 0.6% lower than 4D Flow, progressively impinging on the ascending aorta convexity. The FSI model predicted a peak flow rate of 22.4 L/min, 6.7% higher than 4D Flow, and provided BAV leaflets mechanical and flow-induced shear stresses, not directly attainable from MRI. At systole, the ventricular side of the non-fused leaflet revealed the highest wall shear stress (WSS) average magnitude, up to 14.6 Pa along the free margin, with WSS progressively decreasing towards the belly. During diastole, the aortic side of the fused leaflet exhibited the highest diastolic maximum principal stress, up to 322 kPa within the attachment region. Systematic comparison with ground-truth non-invasive MRI can improve the computational model ability to reproduce native BAV hemodynamics and biomechanical response more realistically, and shed light on their role in BAV patients' risk for developing complications; this approach may further contribute to the validation of advanced FSI simulations designed to assess BAV biomechanics.
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Affiliation(s)
- Monica Emendi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.,Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Francesco Sturla
- 3D and Computer Simulation Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, Italy
| | - Ram P Ghosh
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Matteo Bianchi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Filippo Piatti
- 3D and Computer Simulation Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, Italy
| | - Francesca R Pluchinotta
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.,Multimodality Cardiac Imaging, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.,Department of Pediatric and Adult Congenital Heart Disease, IRCCS Policlinico San Donato, San Donato Milanese, Italy
| | | | - Massimo Lombardi
- Multimodality Cardiac Imaging, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
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13
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de Oliveira DMC, Abdullah N, Green NC, Espino DM. Biomechanical Assessment of Bicuspid Aortic Valve Phenotypes: A Fluid-Structure Interaction Modelling Approach. Cardiovasc Eng Technol 2020; 11:431-447. [PMID: 32519086 DOI: 10.1007/s13239-020-00469-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 06/04/2020] [Indexed: 12/11/2022]
Abstract
PURPOSE Bicuspid aortic valve (BAV) is a congenital heart malformation with phenotypic heterogeneity. There is no prior computational study that assesses the haemodynamic and valve mechanics associated with BAV type 2 against a healthy tricuspid aortic valve (TAV) and other BAV categories. METHODS A proof-of-concept study incorporating three-dimensional fluid-structure interaction (FSI) models with idealised geometries (one TAV and six BAVs, namely type 0 with lateral and anterior-posterior orientations, type 1 with R-L, N-R and N-L leaflet fusion and type 2) has been developed. Transient physiological boundary conditions have been applied and simulations were run using an Arbitrary Lagrangian-Eulerian formulation. RESULTS Our results showed the presence of abnormal haemodynamics in the aorta and abnormal valve mechanics: type 0 BAVs yielded the best haemodynamical and mechanical outcomes, but cusp stress distribution varied with valve orifice orientation, which can be linked to different cusp calcification location onset; type 1 BAVs gave rise to similar haemodynamics and valve mechanics, regardless of raphe position, but this position altered the location of abnormal haemodynamic features; finally, type 2 BAV constricted the majority of blood flow, exhibiting the most damaging haemodynamic and mechanical repercussions when compared to other BAV phenotypes. CONCLUSION The findings of this proof-of-concept work suggest that there are specific differences across haemodynamics and valve mechanics associated with BAV phenotypes, which may be critical to subsequent processes associated with their pathophysiology processes.
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Affiliation(s)
- Diana M C de Oliveira
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Nazirul Abdullah
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - Naomi C Green
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
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14
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Diagnostic and prognostic significance of cardiovascular vortex formation. J Cardiol 2019; 74:403-411. [DOI: 10.1016/j.jjcc.2019.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 05/07/2019] [Indexed: 12/16/2022]
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15
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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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16
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Dallard J, Labrosse MR, Sohmer B, Beller CJ, Boodhwani M. Investigation of raphe function in the bicuspid aortic valve and its influence on clinical criteria-A patient-specific finite element study. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3117. [PMID: 29905015 DOI: 10.1002/cnm.3117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/05/2018] [Indexed: 06/08/2023]
Abstract
The aortic valve is normally composed of 3 cusps. In one common lesion, 2 cusps are fused together. The conjoined area of the fused cusps is termed raphe. Occurring in 1% to 2% of the population, the bicuspid aortic valve (BAV) is the most common congenital cardiac malformation. The majority of BAV patients eventually require surgery. There is a lack in the literature regarding modeling of the raphe (geometry and material properties), its role and its influence on BAV function. The present study aims to propose improvements on these aspects. Three patient-specific finite element models of BAVs were created based on 3D trans-esophageal echocardiography measurements, and assuming age-dependent material properties. The raphe was initially given the same material properties as its underlying cusps. Two levels of validation were performed; one based on the anatomical validation of the pressurized geometry in diastole (involving 7 anatomical measures), as simulated starting from the unpressurized geometry, and the other based on a functional assessment using clinical measurements in both systole and diastole (involving 16 functional measures). The pathology was successfully reproduced in the FE models of all 3 patients. To further investigate the role of the raphe, 2 additional scenarios were considered; (1) the raphe was considered as almost rigid, (2) the raphe was totally removed. The results confirmed the interpretation of the raphe as added stiffness in the fused cusp's rotation with respect to the aortic wall, as well as added support for stress distribution from the fused cusps to the aortic wall.
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Affiliation(s)
- Jérémy Dallard
- Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, Canada
| | - Michel R Labrosse
- Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, Canada
| | - Benjamin Sohmer
- Division of Cardiac Anesthesiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Carsten J Beller
- Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany
| | - Munir Boodhwani
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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17
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Ha H, Kvitting JP, Dyverfeldt P, Ebbers T. Validation of pressure drop assessment using 4D flow MRI-based turbulence production in various shapes of aortic stenoses. Magn Reson Med 2018; 81:893-906. [PMID: 30252155 DOI: 10.1002/mrm.27437] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/08/2018] [Accepted: 06/08/2018] [Indexed: 11/08/2022]
Abstract
PURPOSE To validate pressure drop measurements using 4D flow MRI-based turbulence production in various shapes of stenotic stenoses. METHODS In vitro flow phantoms with seven different 3D-printed aortic valve geometries were constructed and scanned with 4D flow MRI with six-directional flow encoding (ICOSA6). The pressure drop through the valve was non-invasively predicted based on the simplified Bernoulli, the extended Bernoulli, the turbulence production, and the shear-scaling methods. Linear regression and agreement of the predictions with invasively measured pressure drop were analyzed. RESULTS All pressure drop predictions using 4D Flow MRI were linearly correlated to the true pressure drop but resulted in different regression slopes. The regression slope and 95% limits of agreement for the simplified Bernoulli method were 1.35 and 11.99 ± 21.72 mm Hg. The regression slope and 95% limits of agreement for the extended Bernoulli method were 1.02 and 0.74 ± 8.48 mm Hg. The regression slope and 95% limits of agreement for the turbulence production method were 0.89 and 0.96 ± 8.01 mm Hg. The shear-scaling method presented good correlation with an invasively measured pressure drop, but the regression slope varied between 0.36 and 1.00 depending on the shear-scaling coefficient. CONCLUSION The pressure drop assessment based on the turbulence production method agrees well with the extended Bernoulli method and invasively measured pressure drop in various shapes of the aortic valve. Turbulence-based pressure drop estimation can, as a complement to the conventional Bernoulli method, play a role in the assessment of valve diseases.
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Affiliation(s)
- Hojin Ha
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Republic of Korea.,Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
| | - John-Peder Kvitting
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.,Department of Cardiothoracic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Petter Dyverfeldt
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
| | - Tino Ebbers
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
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18
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Sinus Hemodynamics in Representative Stenotic Native Bicuspid and Tricuspid Aortic Valves: An In-Vitro Study. FLUIDS 2018. [DOI: 10.3390/fluids3030056] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
(1) The study’s objective is to assess sinus hemodynamics differences between stenotic native bicuspid aortic valve (BAV) and native tricuspid aortic valve (TrAV) sinuses in order to assess sinus flow shear and vorticity dynamics in these common pathological states of the aortic valve. (2) Representative patient-specific aortic roots with BAV and TrAV were selected, segmented, and 3D printed. The flow dynamics within the sinus were assessed in-vitro using particle image velocimetry in a left heart simulator at physiological pressure and flow conditions. Hemodynamic data calculations, vortex tracking, shear stress probability density functions and sinus washout calculations based on Lagrangian particle tracking were performed. (3) (a) At peak systole, velocity and vorticity in BAV reach 0.67 ± 0.02 m/s and 374 ± 5 s−1 versus 0.49 ± 0.03 m/s and 293 ± 3 s−1 in TrAV; (b) Aortic sinus vortex is slower to form but conserved in BAV sinus; (c) BAV shear stresses exceed those of TrAV (1.05 Pa versus 0.8 Pa); (d) Complete TrAV washout was achieved after 1.5 cycles while it was not for BAV. 4) In conclusion, sinus hemodynamics dependence on the different native aortic valve types and sinus morphologies was clearly highlighted in this study.
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19
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Hatoum H, Dollery J, Lilly SM, Crestanello J, Dasi LP. Impact of patient-specific morphologies on sinus flow stasis in transcatheter aortic valve replacement: An in vitro study. J Thorac Cardiovasc Surg 2018; 157:540-549. [PMID: 29980299 DOI: 10.1016/j.jtcvs.2018.05.086] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 10/14/2022]
Abstract
OBJECTIVE The goal of this study is to evaluate how sinus flow patterns after transcatheter aortic valve replacement in realistic representative patient roots vary. Sinus flow can affect transcatheter aortic valve operation and likely leaflet thrombosis occurrence due to stasis and poor washout. How the interaction between transcatheter aortic valve and representative patient aortic roots affects sinus hemodynamics is important to establish for future individualization of transcatheter aortic valve replacement therapy. METHODS Two representative patient aortic roots were selected, segmented and 3-dimensional printed followed by deployment of Medtronic CoreValve (Medtronic Inc, Irvine, Calif) and Edwards SAPIEN (Edwards Lifesciences, Irvine Calif) transcatheter aortic valves. Sinus hemodynamics were assessed in vitro using high spatio-temporal resolution particle-image-velocimetry. Detailed sinus vortex tracking, shear stress probability density functions, and sinus washout were evaluated and assessed as a function of valve type and representative patient morphology as independent case studies. RESULTS Peak velocity in the sinus with SAPIEN valve was approximately 3 times higher than with CoreValve for both models (0.30 ± 0.02 m/s and 0.34 ± 0.041 m/s vs 0.13 ± 0.01 m/s and 0.10 ± 0.02 m/s) (P < .01). Between representative patient models, vorticity magnitudes were significantly different (75 ± 1.1 s-1, 77 ± 3.2 s-1, 109 ± 2.3 s-1, and 250 ± 4.1 s-1) (P < .01) regardless of valve type. Sinus blood washout characteristic as a function of cardiac cycles was strongly both patient related and valve specific. Fluid dynamics favored shear stresses and washout characteristics due to a smaller sinus and sinotubular junction, further amplified by the SAPIEN valve. CONCLUSIONS Sinus flow dynamics are highly sensitive to aortic root characteristics and transcatheter aortic valve aortic root interaction. Differences in sinus-flow washout and stasis regions between representative patient models may be reflected in different risks of leaflet thrombosis or valve degeneration.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Jennifer Dollery
- Division of Cardiac Surgery, Department of Surgery, The Ohio State University, Columbus, Ohio
| | - Scott M Lilly
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, Ohio
| | - Juan Crestanello
- Division of Cardiac Surgery, Department of Surgery, The Ohio State University, Columbus, Ohio
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio; Division of Cardiac Surgery, Department of Surgery, The Ohio State University, Columbus, Ohio.
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20
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Motta SE, Fioretta ES, Dijkman PE, Lintas V, Behr L, Hoerstrup SP, Emmert MY. Development of an Off-the-Shelf Tissue-Engineered Sinus Valve for Transcatheter Pulmonary Valve Replacement: a Proof-of-Concept Study. J Cardiovasc Transl Res 2018; 11:182-191. [PMID: 29560553 DOI: 10.1007/s12265-018-9800-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 03/05/2018] [Indexed: 11/30/2022]
Abstract
Tissue-engineered heart valves with self-repair and regeneration properties may overcome the problem of long-term degeneration of currently used artificial prostheses. The aim of this study was the development and in vivo proof-of-concept of next-generation off-the-shelf tissue-engineered sinus valve (TESV) for transcatheter pulmonary valve replacement (TPVR). Transcatheter implantation of off-the-shelf TESVs was performed in a translational sheep model for up to 16 weeks. Transapical delivery of TESVs was successful and showed good acute and short-term performance (up to 8 weeks), which then worsened over time most likely due to a non-optimized in vitro valve design. Post-mortem analyses confirmed the remodelling potential of the TESVs, with host cell infiltration, polymer degradation, and collagen and elastin deposition. TESVs proved to be suitable as TPVR in a preclinical model, with encouraging short-term performance and remodelling potential. Future studies will enhance the clinical translation of such approach by improving the valve design to ensure long-term functionality.
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Affiliation(s)
- Sarah E Motta
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Emanuela S Fioretta
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Petra E Dijkman
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Valentina Lintas
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Luc Behr
- Institute Mutualiste Montsouris (IMMR), Paris, France
| | - Simon P Hoerstrup
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Wyss Translational Center Zurich, University and ETH Zurich, Zurich, Switzerland
| | - Maximilian Y Emmert
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland. .,Wyss Translational Center Zurich, University and ETH Zurich, Zurich, Switzerland. .,Heart Center Zurich, University Hospital Zurich, Zurich, Switzerland.
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21
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Experimental Assessment of Flow Fields Associated with Heart Valve Prostheses Using Particle Image Velocimetry (PIV): Recommendations for Best Practices. Cardiovasc Eng Technol 2018. [DOI: 10.1007/s13239-018-0348-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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22
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In Vitro Validation of a Numerical Simulation of Leaflet Kinematics in a Polymeric Aortic Valve Under Physiological Conditions. Cardiovasc Eng Technol 2018; 9:42-52. [DOI: 10.1007/s13239-018-0340-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 01/05/2018] [Indexed: 10/18/2022]
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23
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Experimental Study of Right Ventricular Hemodynamics After Tricuspid Valve Replacement Therapies to Treat Tricuspid Regurgitation. Cardiovasc Eng Technol 2017; 8:401-418. [DOI: 10.1007/s13239-017-0328-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 08/21/2017] [Indexed: 10/19/2022]
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24
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Cao K, Sucosky P. Computational comparison of regional stress and deformation characteristics in tricuspid and bicuspid aortic valve leaflets. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e02798. [PMID: 27138991 DOI: 10.1002/cnm.2798] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 03/22/2016] [Accepted: 04/20/2016] [Indexed: 06/05/2023]
Abstract
The bicuspid aortic valve (BAV) is the most common congenital valvular defect and a major risk factor for secondary calcific aortic valve disease. While hemodynamics is presumed to be a potential contributor to this complication, the validation of this theory has been hampered by the limited knowledge of the mechanical stress abnormalities experienced by BAV leaflets and their dependence on the heterogeneous BAV fusion patterns. The objective of this study was to compare computationally the regional and temporal fluid wall shear stress (WSS) and structural deformation characteristics in tricuspid aortic valve (TAV), type-0, and type-I BAV leaflets. Arbitrary Lagrangian-Eulerian fluid-structure interaction models were designed to simulate the flow and leaflet dynamics in idealized TAV, type-0, and type-I BAV geometries subjected to physiologic transvalvular pressure. The regional leaflet mechanics was quantified in terms of temporal shear magnitude (TSM), oscillatory shear index (OSI), temporal shear gradient (TSG), and stretch. The simulations identified regions of WSS overloads and increased WSS bidirectionality (174% increase in temporal shear magnitude, 0.10 increase in OSI on type-0 leaflets) in BAV leaflets relative to TAV leaflets. BAV leaflets also experienced larger radial deformations than TAV leaflets (4% increase in type-0 BAV leaflets). Type-I BAV leaflets exhibited contrasted WSS environments marked by WSS overloads on the non-coronary leaflet and sub-physiologic WSS levels on the fused leaflet. This study provides important insights into the mechanical characteristics of BAV leaflets, which may further our understanding of the role played by hemodynamic forces in BAV disease. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- K Cao
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, 365 Fitzpatrick Hall, Notre Dame, IN, 46556, USA
| | - P Sucosky
- Department of Mechanical and Materials Engineering, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA
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25
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McNally A, Madan A, Sucosky P. Morphotype-Dependent Flow Characteristics in Bicuspid Aortic Valve Ascending Aortas: A Benchtop Particle Image Velocimetry Study. Front Physiol 2017; 8:44. [PMID: 28203207 PMCID: PMC5285369 DOI: 10.3389/fphys.2017.00044] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/17/2017] [Indexed: 12/11/2022] Open
Abstract
The bicuspid aortic valve (BAV) is a major risk factor for secondary aortopathy such as aortic dilation. The heterogeneous BAV morphotypes [left-right-coronary cusp fusion (LR), right-non-coronary cusp fusion (RN), and left-non-coronary cusp fusion (LN)] are associated with different dilation patterns, suggesting a role for hemodynamics in BAV aortopathogenesis. However, assessment of this theory is still hampered by the limited knowledge of the hemodynamic abnormalities generated by the distinct BAV morphotypes. The objective of this study was to compare experimentally the hemodynamics of a normal (i.e., non-dilated) ascending aorta (AA) subjected to tricuspid aortic valve (TAV), LR-BAV, RN-BAV, and NL-BAV flow. Tissue BAVs reconstructed from porcine TAVs were subjected to physiologic pulsatile flow conditions in a left-heart simulator featuring a realistic aortic root and compliant aorta. Phase-locked particle image velocimetry experiments were carried out to characterize the flow in the aortic root and in the tubular AA in terms of jet skewness and displacement, as well as mean velocity, viscous shear stress and Reynolds shear stress fields. While all three BAVs generated skewed and asymmetrical orifice jets (up to 1.7- and 4.0-fold increase in flow angle and displacement, respectively, relative to the TAV at the sinotubular junction), the RN-BAV jet was out of the plane of observation. The LR- and NL-BAV exhibited a 71% increase in peak-systolic orifice jet velocity relative to the TAV, suggesting an inherent degree of stenosis in BAVs. While these two BAV morphotypes subjected the convexity of the aortic wall to viscous shear stress overloads (1.7-fold increase in maximum peak-systolic viscous shear stress relative to the TAV-AA), the affected sites were morphotype-dependent (LR-BAV: proximal AA, NL-BAV: distal AA). Lastly, the LR- and NL-BAV generated high degrees of turbulence in the AA (up to 2.3-fold increase in peak-systolic Reynolds shear stress relative to the TAV) that were sustained from peak systole throughout the deceleration phase. This in vitro study reveals substantial flow abnormalities (increased jet skewness, asymmetry, jet velocity, turbulence, and shear stress overloads) in non-dilated BAV aortas, which differ from those observed in dilated aortas but still coincide with aortic wall regions prone to dilation.
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Affiliation(s)
- Andrew McNally
- Department of Aerospace and Mechanical Engineering, University of Notre Dame Notre Dame, IN, USA
| | - Ashish Madan
- Department of Mechanical and Materials Engineering, Wright State University Dayton, OH, USA
| | - Philippe Sucosky
- Department of Mechanical and Materials Engineering, Wright State University Dayton, OH, USA
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Toninato R, Salmon J, Susin FM, Ducci A, Burriesci G. Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves. J Biomech 2016; 49:2635-2643. [PMID: 27282961 PMCID: PMC5061069 DOI: 10.1016/j.jbiomech.2016.05.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 04/24/2016] [Accepted: 05/24/2016] [Indexed: 11/23/2022]
Abstract
PURPOSE The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature. METHODS An in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations. All tests were performed on a pulse duplicator, under physiological pressure and flow conditions. The fluid dynamics established in the various cases were analysed by means of 2D Particle Image Velocimetry, and related with the achieved hydrodynamic performance. RESULTS Each configuration is associated with substantially different flow dynamics, which significantly affects the valve performance. The configuration most closely replicating healthy native anatomy was characterised by the best hemodynamic performance, and any mismatch in size and position between the valve and the root produced substantial modification of the fluid dynamics downstream of the valve, hindering the hydrodynamic performance of the system. The worst conditions were observed for a configuration characterised by the total absence of the Valsalva sinuses. CONCLUSION This study provides an explanation for the different vortical structures described in the literature downstream of bioprosthetic valves, enlightening the experimental complications in valve testing. Most importantly, the results clearly identify the fluid mechanisms promoted by the Valsalva sinuses to enhance the ejection and closing phases, and this study exposes the importance of an optimal integration of the valve and root, to operate as a single system.
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Affiliation(s)
- Riccardo Toninato
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK; Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering - University of Padua, Italy
| | - Jacob Salmon
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK
| | - Francesca Maria Susin
- Cardiovascular Fluid Dynamics Laboratory HER, Department of Civil, Environmental and Architectural Engineering - University of Padua, Italy
| | - Andrea Ducci
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK
| | - Gaetano Burriesci
- UCL Cardiovascular Engineering Laboratory, UCL Mechanical Engineering, University College London, UK.
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Flow-Induced Damage to Blood Cells in Aortic Valve Stenosis. Ann Biomed Eng 2016; 44:2724-36. [PMID: 27048168 PMCID: PMC9924290 DOI: 10.1007/s10439-016-1577-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/23/2016] [Indexed: 12/11/2022]
Abstract
Valvular hemolysis and thrombosis are common complications associated with stenotic heart valves. This study aims to determine the extent to which hemodynamics induce such traumatic events. The viscous shear stress downstream of a severely calcified bioprosthetic valve was evaluated via in vitro 2D particle image velocimetry measurements. The blood cell membrane response to the measured stresses was then quantified using 3D immersed-boundary computational simulations. The shear stress level at the boundary layer of the jet flow formed downstream of the valve orifice was observed to reach a maximum of 1000-1700 dyn/cm(2), which was beyond the threshold values reported for platelet activation (100-1000 dyn/cm(2)) and within the range of thresholds reported for red blood cell (RBC) damage (1000-2000 dyn/cm(2)). Computational simulations demonstrated that the resultant tensions at the RBC membrane surface were unlikely to cause instant rupture, but likely to lead to membrane plastic failure. The resultant tensions at the platelet surface were also calculated and the potential damage was discussed. It was concluded that although shear-induced thrombotic trauma is very likely in stenotic heart valves, instant hemolysis is unlikely and the shear-induced damage to RBCs is mostly subhemolytic.
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Yousefi A, Bark DL, Dasi LP. Effect of Arched Leaflets and Stent Profile on the Hemodynamics of Tri-Leaflet Flexible Polymeric Heart Valves. Ann Biomed Eng 2016; 45:464-475. [PMID: 27307007 DOI: 10.1007/s10439-016-1674-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022]
Abstract
Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations. Three models were created with height to diameter ratio of 0.6, 0.7, and 0.88. The other three models were designed by altering arch height to stent diameter ratio, to be 0, 0.081, and 0.116. Particle image velocimetry experiments were conducted on each PHV to characterize velocity, vorticity, turbulent characteristics, effective orifice area, and regurgitant fraction. This study revealed that the presence of arches as well as higher stent profile reduced regurgitant flow down to 5%, while peak systole downstream velocity reduced to 58% and Reynolds Shear Stress values reduced 40%. Further, earlier reattachment of the forward flow jet was observed in PHVs with leaflet arches. These findings indicate that although both geometric factors help diminish the commissural gap during diastole, leaflet arches induce a larger jet opening, yielding to earlier flow reattachment and lower energy dissipation.
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Affiliation(s)
- Atieh Yousefi
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA
| | - David L Bark
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Lakshmi P Dasi
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA.
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Raghav V, Okafor I, Quach M, Dang L, Marquez S, Yoganathan AP. Long-Term Durability of Carpentier-Edwards Magna Ease Valve: A One Billion Cycle In Vitro Study. Ann Thorac Surg 2016; 101:1759-65. [PMID: 26806168 DOI: 10.1016/j.athoracsur.2015.10.069] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/24/2015] [Accepted: 10/26/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Durability and hemodynamic performance are top considerations in selecting a valve for valve replacement surgery. This study was conducted in order to evaluate the long-term mechanical durability and hydrodynamic performance of the Carpentier-Edwards PERIMOUNT Magna Ease Bioprostheses, through 1 billion cycles (equivalent to 25 years). METHODS In vitro valve hydrodynamic performance, durability, and quantitative flow visualization were conducted in accordance with ISO 5840:2005 heart valve standard. The study valves were subjected to accelerated valve cycling to an equivalent of 25 years of wear. Hydrodynamic evaluations at intervals of 100 million cycles (2.5 years) were performed on the study valves. New uncycled Magna Ease valves were used as hydrodynamic controls in this study. A quantitative assessment of the fluid motion downstream of the control and study valves was performed using particle image velocimetry. The results between the test and control valves were compared to assess valve performance after an equivalent of 25 years of wear. RESULTS All study valves met the ISO 5840 requirements for effective orifice area, 1.81 ± 0.06 cm(2) and 2.06 ± 0.17 cm(2), and regurgitant fraction, 1.11% ± 0.87% and 2.5% ± 2.34%, for the 21 mm and 23 mm study valves, respectively. The flow characterization of the control valves and the billion-cycle valves demonstrated that the valves exhibited similar flow characteristics. The velocity and shear stress fields were similar between the control and study valves. CONCLUSIONS The Magna Ease valves demonstrated excellent durability and hydrodynamic performance after an equivalent of 25 years of simulated in vitro wear. All study valves successfully endured 1 billion cycles of simulated wear, 5 times longer than the standard requirement for a tissue valve as stipulated in ISO 5840.
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Affiliation(s)
- Vrishank Raghav
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta
| | - Ikechukwu Okafor
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | | | - Lynn Dang
- Edwards Lifesciences, Irvine, California
| | | | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta; School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia.
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Midha PA, Raghav V, Condado JF, Arjunon S, Uceda DE, Lerakis S, Thourani VH, Babaliaros V, Yoganathan AP. How Can We Help a Patient With a Small Failing Bioprosthesis? JACC Cardiovasc Interv 2015; 8:2026-2033. [DOI: 10.1016/j.jcin.2015.08.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 10/22/2022]
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Kheradvar A, Groves EM, Falahatpisheh A, Mofrad MK, Hamed Alavi S, Tranquillo R, Dasi LP, Simmons CA, Jane Grande-Allen K, Goergen CJ, Baaijens F, Little SH, Canic S, Griffith B. Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies. Ann Biomed Eng 2015. [PMID: 26224522 DOI: 10.1007/s10439-015-1394-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In this final portion of an extensive review of heart valve engineering, we focus on the computational methods and experimental studies related to heart valves. The discussion begins with a thorough review of computational modeling and the governing equations of fluid and structural interaction. We then move onto multiscale and disease specific modeling. Finally, advanced methods related to in vitro testing of the heart valves are reviewed. This section of the review series is intended to illustrate application of computational methods and experimental studies and their interrelation for studying heart valves.
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Affiliation(s)
- Arash Kheradvar
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA. .,Department of Medicine, Division of Cardiology, University of California, Irvine School of Medicine, Irvine, CA, USA.
| | - Elliott M Groves
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA.,Department of Medicine, Division of Cardiology, University of California, Irvine School of Medicine, Irvine, CA, USA
| | - Ahmad Falahatpisheh
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA
| | - Mohammad K Mofrad
- Department of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA, USA
| | - S Hamed Alavi
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA
| | - Robert Tranquillo
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Lakshmi P Dasi
- Department of Mechanical Engineering, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Craig A Simmons
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada.,Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | | | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Frank Baaijens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Stephen H Little
- Houston Methodist DeBakey Heart & Vascular Center, Houston, TX, USA
| | - Suncica Canic
- Department of Mathematics, University of Houston, Houston, TX, USA
| | - Boyce Griffith
- Department of Mathematics, Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,McAllister Heart Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
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The effects of positioning of transcatheter aortic valves on fluid dynamics of the aortic root. ASAIO J 2015; 60:545-552. [PMID: 25010918 DOI: 10.1097/mat.0000000000000107] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Transcatheter aortic valve implantation is a novel treatment for severe aortic valve stenosis. Due to the recent use of this technology and the procedural variability, there is very little data that quantify the hemodynamic consequences of variations in valve placement. Changes in aortic wall stresses and fluid retention in the sinuses of Valsalva can have a significant effect on the clinical response a patient has to the procedure. By comprehensively characterizing complex flow in the sinuses of Valsalva using digital particle image velocimetry and an advanced heart-flow simulator, various positions of a deployed transcatheter valve with respect to a bioprosthetic aortic valve (valve-in-valve) were tested in vitro. Displacements of the transcatheter valve were axial and directed below the simulated native valve annulus. It was determined that for both blood residence time and aortic Reynolds stresses, it is optimal to have the annulus of the transcatheter valve deployed as close to the aortic valve annulus as possible.
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Influence of the aortic valve leaflets on the fluid-dynamics in aorta in presence of a normally functioning bicuspid valve. Biomech Model Mechanobiol 2015; 14:1349-61. [DOI: 10.1007/s10237-015-0679-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 04/22/2015] [Indexed: 01/28/2023]
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Jun BH, Saikrishnan N, Arjunon S, Yun BM, Yoganathan AP. Effect of hinge gap width of a St. Jude medical bileaflet mechanical heart valve on blood damage potential--an in vitro micro particle image velocimetry study. J Biomech Eng 2015; 136:091008. [PMID: 24976188 DOI: 10.1115/1.4027935] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 07/02/2014] [Indexed: 11/08/2022]
Abstract
The hinge regions of the bileaflet mechanical heart valve (BMHV) can cause blood element damage due to nonphysiological shear stress levels and regions of flow stasis. Recently, a micro particle image velocimetry (μPIV) system was developed to study whole flow fields within BMHV hinge regions with enhanced spatial resolution under steady leakage flow conditions. However, global velocity maps under pulsatile conditions are still necessary to fully understand the blood damage potential of these valves. The current study hypothesized that the hinge gap width will affect flow fields in the hinge region. Accordingly, the blood damage potential of three St. Jude Medical (SJM) BMHVs with different hinge gap widths was investigated under pulsatile flow conditions, using a μPIV system. The results demonstrated that the hinge gap width had a significant influence during the leakage flow phase in terms of washout and shear stress characteristics. During the leakage flow, the largest hinge gap generated the highest Reynolds shear stress (RSS) magnitudes (~1000 N/m²) among the three valves at the ventricular side of the hinge. At this location, all three valves indicated viscous shear stresses (VSS) greater than 30 N/m². The smallest hinge gap exhibited the lowest level of shear stress values, but had the poorest washout flow characteristics among the three valves, demonstrating propensity for flow stasis and associated activated platelet accumulation potential. The results from this study indicate that the hinge is a critical component of the BMHV design, which needs to be optimized to find the appropriate balance between reduction in fluid shear stresses and enhanced washout during leakage flow, to ensure minimal thrombotic complications.
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Cao K, Sucosky P. Effect of Bicuspid Aortic Valve Cusp Fusion on Aorta Wall Shear Stress: Preliminary Computational Assessment and Implication for Aortic Dilation. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/wjcd.2015.56016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Atkins SK, Sucosky P. Etiology of bicuspid aortic valve disease: Focus on hemodynamics. World J Cardiol 2014; 6:1227-1233. [PMID: 25548612 PMCID: PMC4278157 DOI: 10.4330/wjc.v6.i12.1227] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/08/2014] [Accepted: 12/01/2014] [Indexed: 02/06/2023] Open
Abstract
The bicuspid aortic valve (BAV) is the most common form of inheritable cardiac defect. Although this abnormality may still achieve normal valvular function, it is often associated with secondary valvular and aortic complications such as calcific aortic valve disease and aortic dilation. The clinical significance and economic burden of BAV disease justify the need for improved clinical guidelines and more robust therapeutic modalities, which address the root-cause of those pathologies. Unfortunately, the etiology of BAV valvulopathy and aortopathy is still a debated issue. While the BAV anatomy and its secondary complications have been linked historically to a common genetic root, recent advances in medical imaging have demonstrated the existence of altered hemodynamics near BAV leaflets prone to calcification and BAV aortic regions vulnerable to dilation. The abnormal mechanical stresses imposed by the BAV on its leaflets and on the aortic wall could be transduced into cell-mediated processes, leading ultimately to valvular calcification and aortic medial degeneration. Despite increasing evidence for this hemodynamic etiology, the demonstration of the involvement of mechanical abnormalities in the pathogenesis of BAV disease requires the investigation of causality between the blood flow environment imposed on the leaflets and the aortic wall and the local biology, which has been lacking to date. This editorial discusses the different hypothetical etiologies of BAV disease with a particular focus on the most recent advances in cardiovascular imaging, flow characterization techniques and tissue culture methodologies that have provided new evidence in support of the hemodynamic theory.
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Seaman C, Akingba AG, Sucosky P. Steady flow hemodynamic and energy loss measurements in normal and simulated calcified tricuspid and bicuspid aortic valves. J Biomech Eng 2014; 136:1819200. [PMID: 24474392 DOI: 10.1115/1.4026575] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 01/27/2014] [Indexed: 01/01/2023]
Abstract
The bicuspid aortic valve (BAV), which forms with two leaflets instead of three as in the normal tricuspid aortic valve (TAV), is associated with a spectrum of secondary valvulopathies and aortopathies potentially triggered by hemodynamic abnormalities. While studies have demonstrated an intrinsic degree of stenosis and the existence of a skewed orifice jet in the BAV, the impact of those abnormalities on BAV hemodynamic performance and energy loss has not been examined. This steady-flow study presents the comparative in vitro assessment of the flow field and energy loss in a TAV and type-I BAV under normal and simulated calcified states. Particle-image velocimetry (PIV) measurements were performed to quantify velocity, vorticity, viscous, and Reynolds shear stress fields in normal and simulated calcified porcine TAV and BAV models at six flow rates spanning the systolic phase. The BAV model was created by suturing the two coronary leaflets of a porcine TAV. Calcification was simulated via deposition of glue beads in the base of the leaflets. Valvular performance was characterized in terms of geometric orifice area (GOA), pressure drop, effective orifice area (EOA), energy loss (EL), and energy loss index (ELI). The BAV generated an elliptical orifice and a jet skewed toward the noncoronary leaflet. In contrast, the TAV featured a circular orifice and a jet aligned along the valve long axis. While the BAV exhibited an intrinsic degree of stenosis (18% increase in maximum jet velocity and 7% decrease in EOA relative to the TAV at the maximum flow rate), it generated only a 3% increase in EL and its average ELI (2.10 cm2/m2) remained above the clinical threshold characterizing severe aortic stenosis. The presence of simulated calcific lesions normalized the alignment of the BAV jet and resulted in the loss of jet axisymmetry in the TAV. It also amplified the degree of stenosis in the TAV and BAV, as indicated by the 342% and 404% increase in EL, 70% and 51% reduction in ELI and 48% and 51% decrease in EOA, respectively, relative to the nontreated valve models at the maximum flow rate. This study indicates the ability of the BAV to function as a TAV despite its intrinsic degree of stenosis and suggests the weak dependence of pressure drop on orifice area in calcified valves.
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Characterization of a Bioprosthetic Bicuspid Venous Valve Hemodynamics: Implications for Mechanism of Valve Dynamics. Eur J Vasc Endovasc Surg 2014; 48:459-64. [DOI: 10.1016/j.ejvs.2014.06.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/07/2014] [Indexed: 11/24/2022]
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Bicuspid aortic valves are associated with increased wall and turbulence shear stress levels compared to trileaflet aortic valves. Biomech Model Mechanobiol 2014; 14:577-88. [DOI: 10.1007/s10237-014-0623-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 09/11/2014] [Indexed: 12/14/2022]
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Szeto K, Pastuszko P, del Álamo JC, Lasheras J, Nigam V. Bicuspid aortic valves experience increased strain as compared to tricuspid aortic valves. World J Pediatr Congenit Heart Surg 2014; 4:362-6. [PMID: 24327628 DOI: 10.1177/2150135113501901] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To determine whether the leaflets of bicuspid aortic valve (BAV) experience increased strain when compared to tricuspid aortic valve (TAV) leaflets. BACKGROUND The population at highest risk of aortic valve calcification (AVC) are individuals with BAVs. Currently, efforts to medically treat AVC are hampered by a limited understanding of the biomechanical forces involved in the molecular pathogenesis of AVC. METHODS Surgically created BAVs and control TAVs were placed into a left heart simulator. Strains were calculated by comparing the distances between points on the aortic valve (AoV) leaflet during various time points during a simulated cardiac cycle. RESULTS The fused leaflets of BAVs experience significantly more strain during systole when compared to TAVs. Specifically, BAVs experience 24% strain (P < .0001) in the radial direction, parallel to the direction of blood flow, as compared to TAVs. There was peak difference of 4% (P < .001) in the circumferential direction. DISCUSSION Based upon the data presented here, we are in the process of identifying how increased strain activates calcification-associated pathways in AoV cells. Future studies will examine whether these stretch responsive pathways can be blocked to inhibit calcification of BAVs.
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Affiliation(s)
- Kai Szeto
- Department of Pediatrics (Cardiology), University of California San Diego, La Jolla, CA, USA
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Barker AJ, van Ooij P, Bandi K, Garcia J, Albaghdadi M, McCarthy P, Bonow RO, Carr J, Collins J, Malaisrie SC, Markl M. Viscous energy loss in the presence of abnormal aortic flow. Magn Reson Med 2014; 72:620-8. [PMID: 24122967 PMCID: PMC4051863 DOI: 10.1002/mrm.24962] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/29/2013] [Accepted: 08/31/2013] [Indexed: 01/12/2023]
Abstract
PURPOSE To present a theoretical basis for noninvasively characterizing in vivo fluid-mechanical energy losses and to apply it in a pilot study of patients known to express abnormal aortic flow patterns. METHODS Four-dimensional flow MRI was used to characterize laminar viscous energy losses in the aorta of normal controls (n = 12, age = 37 ± 10 yr), patients with aortic dilation (n = 16, age = 52 ± 8 yr), and patients with aortic valve stenosis matched for age and aortic size (n = 14, age = 46 ± 15 yr), using a relationship between the three-dimensional velocity field and viscous energy dissipation. RESULTS Viscous energy loss was elevated significantly in the thoracic aorta in patients with dilated aorta (3.6 ± 1.3 mW, P = 0.024) and patients with aortic stenosis (14.3 ± 8.2 mW, P < 0.001) compared with healthy volunteers (2.3 ± 0.9 mW). The same pattern of significant differences was seen in the ascending aorta, where viscous energy losses in patients with dilated aortas (2.2 ± 1.1 mW, P = 0.021) and patients with aortic stenosis (10.9 ± 6.8 mW, P < 0.001) were elevated compared with healthy volunteers (1.2 ± 0.6 mW). CONCLUSION This technique provides a capability to quantify the contribution of abnormal laminar blood flow to increased ventricular afterload. In this pilot study, viscous energy loss in patient cohorts was significantly elevated and indicates that cardiac afterload is increased due to abnormal flow.
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Affiliation(s)
- Alex J Barker
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
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Moore B, Dasi LP. SPATIO-TEMPORAL COMPLEXITY OF THE AORTIC SINUS VORTEX. EXPERIMENTS IN FLUIDS 2014; 55:1770. [PMID: 25067881 PMCID: PMC4106046 DOI: 10.1007/s00348-014-1770-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The aortic sinus vortex is a classical flow structure of significant importance to aortic valve dynamics and the initiation and progression of calific aortic valve disease. We characterize the spatio-temporal characteristics of aortic sinus voxtex dynamics in relation to the viscosity of blood analog solution as well as heart rate. High resolution time-resolved (2KHz) particle image velocimetry was conducted to capture 2D particle streak videos and 2D instantaneous velocity and streamlines along the sinus midplane using a physiological but rigid aorta model fitted with a porcine bioprosthetic heart valve. Blood analog fluids used include a water-glycerin mixture and saline to elucidate the sensitivity of vortex dynamics to viscosity. Experiments were conducted to record 10 heart beats for each combination of blood analog and heart rate condition. Results show that the topological characteristics of the velocity field vary in time-scales as revealed using time bin averaged vectors and corresponding instantaneous streamlines. There exist small time-scale vortices and a large time-scale main vortex. A key flow structure observed is the counter vortex at the upstream end of the sinus adjacent to the base (lower half) of the leaflet. The spatio-temporal complexity of vortex dynamics is shown to be profoundly influenced by strong leaflet flutter during systole with a peak frequency of 200Hz and peak amplitude of 4 mm observed in the saline case. While fluid viscosity influences the length and time-scales as well as the introduction of leaflet flutter, heart rate influences the formation of counter vortex at the upstream end of the sinus. Higher heart rates are shown to reduce the strength of the counter vortex that can greatly influence the directionality and strength of shear stresses along the base of the leaflet. This study demonstrates the impact of heart rate and blood analog viscosity on aortic sinus hemodynamics.
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Affiliation(s)
- Brandon Moore
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523-1374
| | - Lakshmi Prasad Dasi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523-1374
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Gunning PS, Saikrishnan N, McNamara LM, Yoganathan AP. An in vitro evaluation of the impact of eccentric deployment on transcatheter aortic valve hemodynamics. Ann Biomed Eng 2014; 42:1195-206. [PMID: 24719050 DOI: 10.1007/s10439-014-1008-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
Patients with aortic stenosis present with calcium deposits on the native aortic valve, which can result in non-concentric expansion of Transcatheter Aortic Valve Replacement (TAVR) stents. The objective of this study is to evaluate whether eccentric deployment of TAVRs lead to turbulent blood flow and blood cell damage. Particle Image Velocimetry was used to quantitatively characterize fluid velocity fields, shear stress and turbulent kinetic energy downstream of TAVRs deployed in circular and eccentric orifices representative of deployed TAVRs in vivo. Effective orifice area (EOA) and mean transvalvular pressure gradient (TVG) values did not differ substantially in circular and eccentric deployed valves, with only a minor decrease in EOA observed in the eccentric valve (2.0 cm(2) for circular, 1.9 cm(2) for eccentric). Eccentric deployed TAVR lead to asymmetric systolic jet formation, with increased shear stresses (circular = 97 N/m(2) vs. eccentric = 119 N/m(2)) and regions of turbulence intensity (circular = 180 N/m(2) vs. eccentric = 230 N/m(2)) downstream that was not present in the circular deployed TAVR. The results of this study indicate that eccentric deployment of TAVRs can lead to altered flow characteristics and may potentially increase the hemolytic potential of the valve, which were not captured through hemodynamic evaluation alone.
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Affiliation(s)
- Paul S Gunning
- Biomechanics Research Centre, Department of Biomedical Engineering, National University of Ireland Galway, Galway, Ireland
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Atkins SK, Cao K, Rajamannan NM, Sucosky P. Bicuspid aortic valve hemodynamics induces abnormal medial remodeling in the convexity of porcine ascending aortas. Biomech Model Mechanobiol 2014; 13:1209-25. [PMID: 24599392 DOI: 10.1007/s10237-014-0567-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 02/24/2014] [Indexed: 12/21/2022]
Abstract
The type-I bicuspid aortic valve (BAV), which differs from the normal tricuspid aortic valve (TAV) most commonly by left-right coronary cusp fusion, is frequently associated with secondary aortopathies. While BAV aortic dilation has been linked to a genetic predisposition, hemodynamics has emerged as a potential alternate etiology. However, the link between BAV hemodynamics and aortic medial degeneration has not been established. The objective of this study was to compare the regional wall shear stresses (WSS) in a TAV and BAV ascending aorta (AA) and to isolate ex vivo their respective impact on aortic wall remodeling. The WSS environments generated in the convex region of a TAV and BAV AA were predicted through fluid-structure interaction (FSI) simulations in an aorta model subjected to both valvular flows. Remodeling of porcine aortic tissue exposed to TAV and BAV AA WSS for 48 h in a cone-and-plate bioreactor was investigated via immunostaining, immunoblotting and zymography. FSI simulations revealed the existence of larger and more unidirectional WSS in the BAV than in the TAV AA convexity. Exposure of normal aortic tissue to BAV AA WSS resulted in increased MMP-2 and MMP-9 expressions and MMP-2 activity but similar fibrillin-1 content and microfibril organization relative to the TAV AA WSS treatment. This study confirms the sensitivity of aortic tissue to WSS abnormalities and demonstrates the susceptibility of BAV hemodynamic stresses to focally mediate aortic medial degradation. The results provide compelling support to the important role of hemodynamics in BAV secondary aortopathy.
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Affiliation(s)
- Samantha K Atkins
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA
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Girdauskas E, Disha K, Borger MA, Kuntze T. Long-term prognosis of ascending aortic aneurysm after aortic valve replacement for bicuspid versus tricuspid aortic valve stenosis. J Thorac Cardiovasc Surg 2014; 147:276-82. [DOI: 10.1016/j.jtcvs.2012.11.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/05/2012] [Accepted: 11/06/2012] [Indexed: 11/16/2022]
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46
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Girdauskas E, Disha K, Borger MA, Kuntze T. Risk of proximal aortic dissection in patients with bicuspid aortic valve: how to address this controversy? Interact Cardiovasc Thorac Surg 2013; 18:355-9. [PMID: 24336701 DOI: 10.1093/icvts/ivt518] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The risk of acute aortic events in patients with bicuspid aortic valve (BAV) disease is a controversial issue. The real risk of aortic dissection in patients with BAV disease is unknown. An indirect assessment of this risk, however, could be gained with a more detailed understanding of the pathogenesis of BAV aortopathy. There are two major issues that should be clarified before one addresses the question of aortic dissection risk in BAV patients. The first issue, when analysing the data from previous BAV cohorts, is to determine what stage of BAV disease was present in the described patient population. In particular, was the risk of aortic dissection in BAV patients determined before or after aortic valve replacement (AVR) surgery? The second issue to consider is the functional state of the pathological valve within the observed population. In particular, did patients predominantly suffer from BAV stenosis or BAV insufficiency? Unfortunately, the vast majority of published reports do not separate between the different BAV phenotypes, thereby complicating interpretation of the results. Considering these two important clinical variables (i.e. the stage of BAV disease and the functional phenotype), we herein aim to explain the inconsistency of the published data with regard to the risk of aortic dissection in patients with BAV disease.
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Affiliation(s)
- Evaldas Girdauskas
- Department of Cardiac Surgery, Central Hospital Bad Berka, Bad Berka, Germany
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Numerical model of the aortic root and valve: Optimization of graft size and sinotubular junction to annulus ratio. J Thorac Cardiovasc Surg 2013; 146:1227-31. [DOI: 10.1016/j.jtcvs.2013.01.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 12/10/2012] [Accepted: 01/14/2013] [Indexed: 10/27/2022]
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Jun BH, Saikrishnan N, Yoganathan AP. Micro particle image velocimetry measurements of steady diastolic leakage flow in the hinge of a St. Jude Medical® regent™ mechanical heart valve. Ann Biomed Eng 2013; 42:526-40. [PMID: 24085344 DOI: 10.1007/s10439-013-0919-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 09/24/2013] [Indexed: 11/24/2022]
Abstract
A number of clinical, in vitro and computational studies have shown the potential for thromboembolic complications in bileaflet mechanical heart valves (BMHV), primarily due to the complex and unsteady flows in the valve hinges. These studies have focused on quantitative and qualitative parameters such as velocity magnitude, turbulent shear stresses, vortex formation, and platelet activation to identify potential for blood damage. However, experimental characterization of the whole flow fields within the valve hinges has not yet been conducted. This information can be utilized to investigate instantaneous damage to blood elements and also to validate numerical studies focusing on the hinge's complex fluid dynamics. The objective of this study was therefore to develop a high-resolution imaging system to characterize the flow fields and global velocity maps in a BMHV hinge. In this study, the steady leakage hinge flow fields representing the diastolic phase during the cardiac cycle in a 23 mm St. Jude Medical regent BMHV in the aortic position were characterized using a two-dimensional micro particle image velocimetry system. Diastolic flow was simulated by imposing a static pressure head on the aortic side. Under these conditions, a reverse flow jet from the aortic to the ventricular side was observed with velocities in the range of 1.47-3.24 m/s, whereas low flow regions were observed on the ventricular side of the hinge with viscous shear stress magnitude up to 60 N/m². High velocities and viscous shearing may be associated with platelet activation and hemolysis, while low flow zones can cause thrombosis due to increased residence time in the hinge. Overall, this study provides a high spatial resolution experimental technique to map the fluid velocity in the BMHV hinge, which can be extended to investigate micron-scale flow domains in various prosthetic devices under different hemodynamic conditions.
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Affiliation(s)
- Brian H Jun
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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Saikrishnan N, Yap CH, Lerakis S, Kumar G, Yoganathan AP. Revisiting the Gorlin equation for aortic stenosis — Is it correctly used in clinical practice? Int J Cardiol 2013; 168:2881-3. [DOI: 10.1016/j.ijcard.2013.03.125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/24/2013] [Accepted: 03/29/2013] [Indexed: 11/30/2022]
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50
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Gould ST, Srigunapalan S, Simmons CA, Anseth KS. Hemodynamic and cellular response feedback in calcific aortic valve disease. Circ Res 2013; 113:186-97. [PMID: 23833293 DOI: 10.1161/circresaha.112.300154] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This review highlights aspects of calcific aortic valve disease that encompass the entire range of aortic valve disease progression from initial cellular changes to aortic valve sclerosis and stenosis, which can be initiated by changes in blood flow (hemodynamics) and pressure across the aortic valve. Appropriate hemodynamics is important for normal valve function and maintenance, but pathological blood velocities and pressure can have profound consequences at the macroscopic to microscopic scales. At the macroscopic scale, hemodynamic forces impart shear stresses on the surface of the valve leaflets and cause deformation of the leaflet tissue. As discussed in this review, these macroscale forces are transduced to the microscale, where they influence the functions of the valvular endothelial cells that line the leaflet surface and the valvular interstitial cells that populate the valve extracellular matrix. For example, pathological changes in blood flow-induced shear stress can cause dysfunction, impairing their homeostatic functions, and pathological stretching of valve tissue caused by elevated transvalvular pressure can activate valvular interstitial cells and latent paracrine signaling cytokines (eg, transforming growth factor-β1) to promote maladaptive tissue remodeling. Collectively, these coordinated and complex interactions adversely impact bulk valve tissue properties, feeding back to further deteriorate valve function and propagate valve cell pathological responses. Here, we review the role of hemodynamic forces in calcific aortic valve disease initiation and progression, with focus on cellular responses and how they feed back to exacerbate aortic valve dysfunction.
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Affiliation(s)
- Sarah T Gould
- Department of Chemical and Biological Engineering, The Biofrontiers Institute, University of Colorado, Boulder, CO 80303, USA
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