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Toma M, Singh-Gryzbon S, Frankini E, Wei Z(A, Yoganathan AP. Clinical Impact of Computational Heart Valve Models. MATERIALS (BASEL, SWITZERLAND) 2022; 15:3302. [PMID: 35591636 PMCID: PMC9101262 DOI: 10.3390/ma15093302] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 12/17/2022]
Abstract
This paper provides a review of engineering applications and computational methods used to analyze the dynamics of heart valve closures in healthy and diseased states. Computational methods are a cost-effective tool that can be used to evaluate the flow parameters of heart valves. Valve repair and replacement have long-term stability and biocompatibility issues, highlighting the need for a more robust method for resolving valvular disease. For example, while fluid-structure interaction analyses are still scarcely utilized to study aortic valves, computational fluid dynamics is used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress, and oscillatory shear index in the thoracic aorta. It has been analyzed that computational flow dynamic analyses can be integrated with other methods to create a superior, more compatible method of understanding risk and compatibility.
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Affiliation(s)
- Milan Toma
- Department of Osteopathic Manipulative Medicine, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, NY 11568, USA;
| | - Shelly Singh-Gryzbon
- Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (S.S.-G.); (A.P.Y.)
| | - Elisabeth Frankini
- Department of Osteopathic Manipulative Medicine, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, P.O. Box 8000, Old Westbury, NY 11568, USA;
| | - Zhenglun (Alan) Wei
- Department of Biomedical Engineering, Francis College of Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA;
| | - Ajit P. Yoganathan
- Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (S.S.-G.); (A.P.Y.)
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Al-Maslamani NA, Khilan AA, Horn HF. Design of a 3D printed, motorized, uniaxial cell stretcher for microscopic and biochemical analysis of mechanotransduction. Biol Open 2021; 10:bio057778. [PMID: 33563607 PMCID: PMC7888744 DOI: 10.1242/bio.057778] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/13/2021] [Indexed: 12/14/2022] Open
Abstract
Cells respond to mechanical cues from their environment through a process of mechanosensing and mechanotransduction. Cell stretching devices are important tools to study the molecular pathways responsible for cellular responses to mechanobiological processes. We describe the development and testing of a uniaxial cell stretcher that has applications for microscopic as well as biochemical analyses. By combining simple fabrication techniques with adjustable control parameters, the stretcher is designed to fit a variety of experimental needs. The stretcher can be used for static and cyclic stretching. As a proof of principle, we visualize stretch induced deformation of cell nuclei via incremental static stretch, and changes in IEX1 expression via cyclic stretching. This stretcher is easily modified to meet experimental needs, inexpensive to build, and should be readily accessible for most laboratories with access to 3D printing.
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Affiliation(s)
- Noor A Al-Maslamani
- Biological and Biomedical Sciences Division, College of Health and Life Sciences, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Abdulghani A Khilan
- Biological and Biomedical Sciences Division, College of Health and Life Sciences, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Henning F Horn
- Biological and Biomedical Sciences Division, College of Health and Life Sciences, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
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Shar JA, Keswani SG, Grande-Allen KJ, Sucosky P. Computational Assessment of Valvular Dysfunction in Discrete Subaortic Stenosis: A Parametric Study. Cardiovasc Eng Technol 2021; 12:559-575. [PMID: 33432514 DOI: 10.1007/s13239-020-00513-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 12/22/2020] [Indexed: 01/16/2023]
Abstract
PURPOSE Discrete subaortic stenosis (DSS) is a left-ventricular outflow tract (LVOT) obstruction caused by a membranous lesion. DSS is associated with steep aortoseptal angles (AoSAs) and is a risk factor for aortic regurgitation (AR). However, the etiology of AR secondary to DSS remains unknown. This study aimed at quantifying computationally the impact of AoSA steepening and DSS on aortic valve (AV) hemodynamics and AR. METHODS An LV geometry reconstructed from cine-MRI data was connected to an AV geometry to generate a unified 2D LV-AV model. Six geometrical variants were considered: unobstructed (CTRL) and DSS-obstructed LVOT (DSS), each reflecting three AoSA variations (110°, 120°, 130°). Fluid-structure interaction simulations were run to compute LVOT flow, AV leaflet dynamics, and regurgitant fraction (RF). RESULTS AoSA steepening and DSS generated vortex dynamics alterations and stenotic flow conditions. While the CTRL-110° model generated the highest degree of leaflet opening asymmetry, DSS preferentially altered superior leaflet kinematics, and caused leaflet-dependent alterations in systolic fluttering. LVOT steepening and DSS subjected the leaflets to increasing WSS overloads (up to 94% increase in temporal shear magnitude), while DSS also increased WSS bidirectionality on the inferior leaflet belly (+ 0.30-point in oscillatory shear index). Although AoSA steepening and DSS increased diastolic transvalvular backflow, regurgitant fractions (RF < 7%) remained below the threshold defining clinical mild AR. CONCLUSIONS The mechanical interactions between AV leaflets and LVOT steepening/DSS hemodynamic derangements do not cause AR. However, the leaflet WSS abnormalities predicted in those anatomies provide new support to a mechanobiological etiology of AR secondary to DSS.
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Affiliation(s)
- Jason A Shar
- Department of Mechanical and Materials Engineering, Wright State University, Dayton, USA
| | - Sundeep G Keswani
- Division of Pediatric Surgery, Department of Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, USA
| | | | - Philippe Sucosky
- Department of Mechanical Engineering, Kennesaw State University, 840 Polytechnic Lane, Marietta, GA, 30060, USA.
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Swiatlowska P, Sanchez-Alonso JL, Mansfield C, Scaini D, Korchev Y, Novak P, Gorelik J. Short-term angiotensin II treatment regulates cardiac nanomechanics via microtubule modifications. NANOSCALE 2020; 12:16315-16329. [PMID: 32720664 DOI: 10.1039/d0nr02474k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mechanical properties of single myocytes contribute to the whole heart performance, but the measurement of mechanics in living cells at high resolution with minimal force interaction remains challenging. Angiotensin II (AngII) is a peptide hormone that regulates a number of physiological functions, including heart performance. It has also been shown to contribute to cell mechanics by inducing cell stiffening. Using non-contact high-resolution Scanning Ion Conductance Microscopy (SICM), we determine simultaneously cell topography and membrane transverse Young's modulus (YM) by a constant pressure application through a nanopipette. While applying pressure, the vertical position is recorded and a deformation map is generated from which YM can be calculated and corrected for the uneven geometry. High resolution of this method also allows studying specific membrane subdomains, such as Z-grooves and crests. We found that short-term AngII treatment reduces the transversal YM in isolated adult rat cardiomyocytes acting via an AT1 receptor. Blocking either a TGF-β1 receptor or Rho kinase abolishes this effect. Analysis of the cytoskeleton showed that AngII depletes microtubules by decreasing long-lived detyrosinated and acetylated microtubule populations. Interestingly, in the failing cardiomyocytes, which are stiffer than controls, the short-term AngII treatment also reduces the YM, thus normalizing the mechanical state of cells. This suggests that the short-term softening effect of AngII on cardiac cells is opposite to the well-characterized long-term hypertrophic effect. In conclusion, we generate a precise nanoscale indication map of location-specific transverse cortical YM within the cell and this can substantially advance our understanding of cellular mechanics in a physiological environment, for example in isolated cardiac myocytes.
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Affiliation(s)
- Pamela Swiatlowska
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Jose L Sanchez-Alonso
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Catherine Mansfield
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | - Denis Scaini
- Department of Medicine, Imperial College London, London, UK and International School for Advanced Studies, Trieste, Italy
| | - Yuri Korchev
- Department of Medicine, Imperial College London, London, UK and Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Pavel Novak
- Department of Medicine, Imperial College London, London, UK and National University of Science and Technology, MISiS, Leninskiy prospect 4, Moscow, 119991, Russia
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
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Liu J, Cornelius K, Graham M, Leonard T, Tipton A, Yorde A, Sucosky P. Design and Computational Validation of a Novel Bioreactor for Conditioning Vascular Tissue to Time-Varying Multidirectional Fluid Shear Stress. Cardiovasc Eng Technol 2019; 10:531-542. [PMID: 31309526 DOI: 10.1007/s13239-019-00426-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/04/2019] [Indexed: 12/31/2022]
Abstract
PURPOSE The cardiovascular endothelium experiences pulsatile and multidirectional fluid wall shear stress (WSS). While the effects of non-physiologic WSS magnitude and pulsatility on cardiovascular function have been studied extensively, the impact of directional abnormalities remains unknown due to the challenge to replicate this characteristic in vitro. To address this gap, this study aimed at designing a bioreactor capable of subjecting cardiovascular tissue to time-varying WSS magnitude and directionality. METHODS The device consisted of a modified cone-and-plate bioreactor. The cone rotation generates a fluid flow subjecting tissue to desired WSS magnitude, while WSS directionality is achieved by altering the alignment of the tissue relative to the flow at each instant of time. Computational fluid dynamics was used to verify the device ability to replicate the native WSS of the proximal aorta. Cone and tissue mount velocities were determined using an iterative optimization procedure. RESULTS Using conditions derived from cone-and-plate theory, the initial simulations yielded root-mean-square errors of 22.8 and 8.4% in WSS magnitude and angle, respectively, between the predicted and the target signals over one cycle, relative to the time-averaged target values. The conditions obtained after two optimization iterations reduced those errors to 3.5 and 0.5%, respectively, and generated 0.2% and 0.01% difference in time-averaged WSS magnitude and angle, respectively, relative to the target waveforms. CONCLUSIONS A bioreactor capable of generating simultaneously desired time-varying WSS magnitude and directionality was designed and validated computationally. The ability to subject tissue to in vivo-like WSS will provide new insights into cardiovascular mechanobiology and disease.
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Affiliation(s)
- Janet Liu
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Kurtis Cornelius
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Mathew Graham
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Tremayne Leonard
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Austin Tipton
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Abram Yorde
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA
| | - Philippe Sucosky
- Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA.
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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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Cao K, Atkins SK, McNally A, Liu J, Sucosky P. Simulations of morphotype-dependent hemodynamics in non-dilated bicuspid aortic valve aortas. J Biomech 2016; 50:63-70. [PMID: 27855987 DOI: 10.1016/j.jbiomech.2016.11.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/02/2016] [Indexed: 11/24/2022]
Abstract
Bicuspid aortic valves (BAVs) generate flow abnormalities that may promote aortopathy. While positive helix fraction (PHF) index, flow angle (θ), flow displacement (d) and wall shear stress (WSS) exhibit abnormalities in dilated BAV aortas, it is unclear whether those anomalies stem from the abnormal valve anatomy or the dilated aorta. Therefore, the objective of this study was to quantify the early impact of different BAV morphotypes on aorta hemodynamics prior to dilation. Fluid-structure interaction models were designed to quantify standard peak-systolic flow metrics and temporal WSS characteristics in a realistic non-dilated aorta connected to functional tricuspid aortic valve (TAV) and type-I BAVs. While BAVs generated increased helicity (PHF>0.68) in the middle ascending aorta (AA), larger systolic flow skewness (θ>11.2°) and displacement (d>6.8mm) relative to the TAV (PHF=0.51; θ<5.5°; d<3.3mm), no distinct pattern was observed between morphotypes. In contrast, WSS magnitude and directionality abnormalities were BAV morphotype- and site-dependent. Type-I BAVs subjected the AA convexity to peak-systolic WSS overloads (up to 1014% difference vs. TAV). While all BAVs increased WSS unidirectionality on the proximal AA relative to the TAV, the most significant abnormality was achieved by the BAV with left-right-coronary cusp fusion on the wall convexity (up to 0.26 decrease in oscillatory shear index vs. TAV). The results indicate the existence of strong hemodynamic abnormalities in non-dilated type-I BAV AAs, their colocalization with sites vulnerable to dilation and the superior specificity of WSS metrics over global hemodynamic metrics to the valve anatomy.
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Affiliation(s)
- Kai Cao
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Samantha K Atkins
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Andrew McNally
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Janet Liu
- 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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