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Vogl B, Sularz A, Lilly S, Thourani VH, Lindman BR, Alkhouli M, Hatoum H. Effect of Blood Pressure Levels on Sinus Hemodynamics in Relation to Calcification After Bioprosthetic Aortic Valve Replacement. Ann Biomed Eng 2024; 52:888-897. [PMID: 38157105 DOI: 10.1007/s10439-023-03426-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
Coexisting hypertension and aortic stenosis are common. Some studies showed that elevated blood pressures may be associated with progression of calcific aortic valve disease (CAVD) while others showed no correlation. Flow dynamics in the sinuses of Valsalva are considered key factors in the progression of CAVD. While the relationship between hemodynamics and CAVD is not yet fully understood, it has been demonstrated that they are tightly correlated. This study aims to investigate the effect of changing systolic and diastolic blood pressures (SBP and DBP, respectively) on sinus hemodynamics in relation to potential initiation or progression of CAVD after aortic valve replacement (AVR). Evolut R, SAPIEN 3 and Magna valves were deployed in an aortic root under pulsatile conditions. Using particle image velocimetry, the hemodynamics in the sinus were assessed. The velocity, vorticity, circulation ( Γ ) and shear stress were calculated. This study shows that under elevated SBP and DBP, velocity, vorticity, and shear stress nearby the leaflets increased. Additionally, larger fluctuations of Γ and area under the curve throughout the cardiac cycle were observed. Elevated blood pressures are associated with higher velocity, vorticity, and shear stress near the leaflets which may initiate or accelerate pro-calcific changes in the prosthetic leaflets leading to bioprosthetic valve degeneration.
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Affiliation(s)
- Brennan Vogl
- Biomedical Engineering Department, Michigan Technological University, 1400 Townsend Dr, Houghton, MI, 49931, USA
| | - Agata Sularz
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Scott Lilly
- Department of Cardiovascular Medicine, The Ohio State University, Columbus, OH, USA
| | - Vinod H Thourani
- Department of Cardiovascular Surgery, Marcus Valve Center, Piedmont Heart Institute, Atlanta, GA, USA
| | - Brian R Lindman
- Division of Cardiovascular Medicine, Structural Heart and Valve Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mohamad Alkhouli
- 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, Center of Biocomputing and Digital Health and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA.
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Faza NN, Harb SC, Wang DD, van den Dorpel MMP, Van Mieghem N, Little SH. Physical and Computational Modeling for Transcatheter Structural Heart Interventions. JACC Cardiovasc Imaging 2024; 17:428-440. [PMID: 38569793 DOI: 10.1016/j.jcmg.2024.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 04/05/2024]
Abstract
Structural heart disease interventions rely heavily on preprocedural planning and simulation to improve procedural outcomes and predict and prevent potential procedural complications. Modeling technologies, namely 3-dimensional (3D) printing and computational modeling, are nowadays increasingly used to predict the interaction between cardiac anatomy and implantable devices. Such models play a role in patient education, operator training, procedural simulation, and appropriate device selection. However, current modeling is often limited by the replication of a single static configuration within a dynamic cardiac cycle. Recognizing that health systems may face technical and economic limitations to the creation of "in-house" 3D-printed models, structural heart teams are pivoting to the use of computational software for modeling purposes.
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Affiliation(s)
- Nadeen N Faza
- Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA
| | | | | | | | | | - Stephen H Little
- Houston Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA.
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Vogl BJ, Chavez-Ponce A, Wentworth A, Erie E, Yadav P, Thourani VH, Dasi LP, Lindman B, Alkhouli M, Hatoum H. Differential Impact of Blood Pressure Control Targets on Epicardial Coronary Flow After Transcatheter Aortic Valve Replacement. STRUCTURAL HEART : THE JOURNAL OF THE HEART TEAM 2024; 8:100230. [PMID: 38283570 PMCID: PMC10818148 DOI: 10.1016/j.shj.2023.100230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/31/2023] [Accepted: 09/27/2023] [Indexed: 01/30/2024]
Abstract
Background The cause for the association between increased cardiovascular mortality rates and lower blood pressure (BP) after aortic valve replacement (AVR) is unclear. This study aims to assess how the epicardial coronary flow (ECF) after AVR varies as BP levels are changed in the presence of a right coronary lesion. Methods The hemodynamics of a 3D printed aortic root model with a SAPIEN 3 26 deployed were evaluated in an in vitro left heart simulator under a range of varying systolic blood pressure (SBP) and diastolic blood pressure (DBP). ECF and the flow ratio index were calculated. Flow index value <0.8 was considered a threshold for ischemia. Results As SBP decreased, the average ECF decreased below the physiological coronary minimum at 120 mmHg. As DBP decreased, the average ECF was still maintained above the physiological minimum. The flow ratio index was >0.9 for SBP ≥130 mmHg. However, at an SBP of 120 mmHg, the flow ratio was 0.63 (p ≤ 0.0055). With decreasing DBP, no BP condition yielded a flow ratio index that was less than 0.91. Conclusions Reducing BP to the current recommended levels assigned for the general population after AVR in the presence of coronary artery disease may require reconsideration of levels and treatment priority. Additional studies are needed to fully understand the changes in ECF dynamics after AVR in the presence and absence of coronary artery disease.
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Affiliation(s)
- Brennan J. Vogl
- Biomedical Engineering Department, Michigan Technological University, Houghton, Michigan, USA
| | | | - Adam Wentworth
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Eric Erie
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Pradeep Yadav
- Department of Cardiovascular Surgery, Marcus Valve Center, Piedmont Heart Institute, Atlanta, Georgia, USA
| | - Vinod H. Thourani
- Department of Cardiovascular Surgery, Marcus Valve Center, Piedmont Heart Institute, Atlanta, Georgia, USA
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Brian Lindman
- Division of Cardiovascular Medicine, Structural Heart and Valve Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mohamad Alkhouli
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Hoda Hatoum
- Biomedical Engineering Department, Michigan Technological University, Houghton, Michigan, USA
- Health Research Institute, Center of Biocomputing and Digital Health and Institute of Computing and Cybersystems, Michigan Technological University, Houghton, Michigan, USA
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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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Jonnagiri R, Sundström E, Gutmark E, Anderson S, Pednekar AS, Taylor MD, Tretter JT, Gutmark-Little I. Influence of aortic valve morphology on vortical structures and wall shear stress. Med Biol Eng Comput 2023; 61:1489-1506. [PMID: 36763231 DOI: 10.1007/s11517-023-02790-6] [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: 03/23/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023]
Abstract
The aim of this paper is to assess the association between valve morphology and vortical structures quantitatively and to highlight the influence of valve morphology/orientation on aorta's susceptibility to shear stress, both proximal and distal. Four-dimensional phase-contrast magnetic resonance imaging (4D PCMRI) data of 6 subjects, 3 with tricuspid aortic valve (TAV) and 3 with functionally bicuspid aortic values (BAV) with right-left coronary leaflet fusion, were processed and analyzed for vorticity and wall shear stress trends. Computational fluid dynamics (CFD) has been used with moving TAV and BAV valve designs in patient-specific aortae to compare with in vivo shear stress data. Vorticity from 4D PCMRI data about the aortic centerline demonstrated that TAVs had a higher number of vortical flow structures than BAVs at peak systole. Coalescing of flow structures was shown to be possible in the arch region of all subjects. Wall shear stress (WSS) distribution from CFD results at the aortic root is predominantly symmetric for TAVs but highly asymmetric for BAVs with the region opposite the raphe (fusion location of underdeveloped leaflets) being subjected to higher WSS. Asymmetry in the size and number of leaflets in BAVs and TAVs significantly influence vortical structures and WSS in the proximal aorta for all valve types and distal aorta for certain valve orientations of BAV. Analysis of vortical structures using 4D PCMRI data (on the left side) and wall shear stress data using CFD (on the right side).
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Affiliation(s)
- Raghuvir Jonnagiri
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH, 45221, USA.
| | - Elias Sundström
- Department of Engineering Mechanics, Royal Institute of Technology, 10044, Stockholm, Sweden
| | - Ephraim Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Shae Anderson
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Amol S Pednekar
- Division of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Michael D Taylor
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.,Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Justin T Tretter
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.,Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Iris Gutmark-Little
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45267, USA.,Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
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Hatoum H, Singh-Gryzbon S, Esmailie F, Ruile P, Neumann FJ, Blanke P, Thourani VH, Yoganathan AP, Dasi LP. Predictive Model for Thrombus Formation After Transcatheter Valve Replacement. Cardiovasc Eng Technol 2021; 12:576-588. [PMID: 34859378 PMCID: PMC11034843 DOI: 10.1007/s13239-021-00596-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 11/09/2021] [Indexed: 12/27/2022]
Abstract
PURPOSE Leaflet thrombosis is a significant adverse event after transcatheter aortic valve (TAV) replacement (TAVR). The purpose of our study was to present a semi-empirical, mathematical model that links patient-specific anatomic, valve, and flow parameters to predict likelihood of leaflet thrombosis. METHODS The two main energy sources of neo-sinus (NS) washout after TAVR include the jet flow downstream of the TAV and NS geometric change in volume due to the leaflets opening and closing. Both are highly dependent on patient anatomic and hemodynamic factors. As rotation of blood flow is prevalent in both the sinus of Valsalva and then the NS, we adopted the vorticity flux or circulation (Г) as a metric quantifying overall washout. Leaflet thrombus volumes were segmented based on hypo-attenuating leaflet thickening (HALT) in post-TAVR patient's gated computed tomography. Г was assessed using dimensional scaling as well as computational fluid dynamics (CFD) respectively and correlated to the thrombosis volumes using sensitivity and specificity analysis. RESULTS Г in the NS, that accounted for patient flow and anatomic conditions derived from scaling arguments significantly better predicted the occurrence of leaflet thrombus than CFD derived measures such as stasis volumes or wall shear stress. Given results from the six patient datasets considered herein, a threshold Г value of 28.0 yielded a sensitivity and specificity of 100% where patients with Gamma < 28 developed valve thrombosis. A 10% error in measurements of all variables can bring the sensitivity specificity down to 87%. CONCLUSION A predictive model relating likelihood of valve thrombosis using Г in the NS was developed with promising sensitivity and specificity. With further studies and improvements, this predictive technology may lead to alerting physicians on the risk for thrombus formation following TAVR.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Atlanta, GA, 30313, USA
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI, USA
| | - Shelly Singh-Gryzbon
- Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Atlanta, GA, 30313, USA
- Department of Chemical & Process Engineering, The University of the West Indies, St Augustine, Trinidad and Tobago
| | - Fateme Esmailie
- Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Atlanta, GA, 30313, USA
| | - Philipp Ruile
- Department of Cardiology and Angiology II, University Heart Center Freiburg-Bad Krozingen, Bad Krozingen, Germany
| | - Franz-Josef Neumann
- Department of Cardiology and Angiology II, University Heart Center Freiburg-Bad Krozingen, Bad Krozingen, Germany
| | - Philipp Blanke
- University of British Columbia and St. Paul's Hospital in Vancouver, Vancouver, Canada
| | - Vinod H Thourani
- Department of Cardiovascular Surgery, Marcus Heart Valve Center, Piedmont Heart Institute, Atlanta, GA, USA
| | - Ajit P Yoganathan
- Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Atlanta, GA, 30313, USA
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Atlanta, GA, 30313, USA.
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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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Integrating multi-fidelity blood flow data with reduced-order data assimilation. Comput Biol Med 2021; 135:104566. [PMID: 34157468 DOI: 10.1016/j.compbiomed.2021.104566] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/30/2021] [Accepted: 06/08/2021] [Indexed: 11/20/2022]
Abstract
High-fidelity patient-specific modeling of cardiovascular flows and hemodynamics is challenging. Direct blood flow measurement inside the body with in-vivo measurement modalities such as 4D flow magnetic resonance imaging (4D flow MRI) suffer from low resolution and acquisition noise. In-vitro experimental modeling and patient-specific computational fluid dynamics (CFD) models are subject to uncertainty in patient-specific boundary conditions and model parameters. Furthermore, collecting blood flow data in the near-wall region (e.g., wall shear stress) with experimental measurement modalities poses additional challenges. In this study, a computationally efficient data assimilation method called reduced-order modeling Kalman filter (ROM-KF) was proposed, which combined a sequential Kalman filter with reduced-order modeling using a linear model provided by dynamic mode decomposition (DMD). The goal of ROM-KF was to overcome low resolution and noise in experimental and uncertainty in CFD modeling of cardiovascular flows. The accuracy of the method was assessed with 1D Womersley flow, 2D idealized aneurysm, and 3D patient-specific cerebral aneurysm models. Synthetic experimental data were used to enable direct quantification of errors using benchmark datasets. The accuracy of ROM-KF in reconstructing near-wall hemodynamics was assessed by applying the method to problems where near-wall blood flow data were missing in the experimental dataset. The ROM-KF method provided blood flow data that were more accurate than the computational and synthetic experimental datasets and improved near-wall hemodynamics quantification.
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Parthasarathy J, Hatoum H, Flemister DC, Krull CM, Walter BA, Zhang W, Mery CM, Molossi S, Jadhav S, Dasi LP, Krishnamurthy R. Assessment of transfer of morphological characteristics of Anomalous Aortic Origin of a Coronary Artery from imaging to patient specific 3D Printed models: A feasibility study. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 201:105947. [PMID: 33535084 DOI: 10.1016/j.cmpb.2021.105947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVE This study aims to determine the accuracy of patient specific 3D printed models in capturing pathological anatomical characteristics derived from CT angiography (CTA) in children with anomalous aortic origin of a coronary artery (AAOCA). METHODS & MATERIALS Following institutional regulatory approval, a standardized protocol for CTA of AAOCA was utilized for imaging. Blood volume of the aorta and coronaries were segmented from the DICOM images. A total of 10 models from 8 AAOCA patients were created, including 2 post-operative models. Mechanical properties of Agilus30 a flexible photopolymer coated with a thin layer of parylene, polyurethane (PU) and silicone and native aortic tissue from a postmortem specimen were compared. AAOCA models with wall thicknesses of 2mm aorta and 1.5mm coronaries were 3D printed in Agilus30 and coated with PU. CT of the printed models was performed, and 3D virtual models were generated. Transfer of anatomical characteristics and geometric accuracy were compared between the patient model virtual models. RESULTS Dynamic modulus of Agilus30 at 2mm thickness was found to be close to native aortic tissue. Structured reporting of anatomical characteristics by imaging experts showed good concordance between patient and model CTA Comparative patient and virtual model measurements showed Pearson's correlation (r) of 0.9959 for aorta (n=70) and 0.9538 for coronaries (n=60) linear, and 0.9949 for aorta (n=30) and 0.9538 for coronaries (n=30) cross-sectional, dimensions. Surface contour map mean difference was 0.08 ± 0.29mm. CONCLUSIONS Geometrically accurate AAOCA models preserving morphological characteristics, essential for risk stratification and decision-making, can be 3D printed from a patient's CTA.
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Affiliation(s)
- Jayanthi Parthasarathy
- Department of Radiology, Nationwide Children's Hospital, The Ohio State University College of Medicine, 700 Children's Dr, E4A Columbus, Columbus, OH 43205, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Hoda Hatoum
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Dorma C Flemister
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Carly M Krull
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Benjamin A Walter
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Wei Zhang
- Department of Biostatistics & Data Science, University of Texas HSC, School of Public Health, Houston USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Carlos M Mery
- Texas Center for Pediatric and Congenital Heart Disease, University of Texas Dell Medical School / Dell Children's Medical Center, Austin, TX, USA
| | - Silvana Molossi
- Texas Center for Pediatric and Congenital Heart Disease, University of Texas Dell Medical School / Dell Children's Medical Center, Austin, TX, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Siddharth Jadhav
- Department of Radiology, Texas Children's Hospital, Baylor College of Medicine Houston, TX, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Rajesh Krishnamurthy
- Department of Radiology, Nationwide Children's Hospital, The Ohio State University College of Medicine, 700 Children's Dr, E4A Columbus, Columbus, OH 43205, USA; Department of Pediatrics, Section of Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
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Hatoum H, Krishnamurthy R, Parthasarathy J, Flemister DC, Krull CM, Walter BA, Mery CM, Molossi S, Dasi LP. Flow Dynamics in Anomalous Aortic Origin of a Coronary Artery in Children: Importance of the Intramural Segment. Semin Thorac Cardiovasc Surg 2020; 34:226-235. [PMID: 33242612 PMCID: PMC11062399 DOI: 10.1053/j.semtcvs.2020.11.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 11/17/2020] [Indexed: 01/02/2023]
Abstract
This study aims to assess the differences in pressure, fractional flow reserve (FFR) and coronary flow (with increasing pressure) of the proximal coronary artery in patients with anomalous aortic origin of a coronary artery with a confirmed ischemic event, without ischemic events, and before and after unroofing surgery, and compare to a patient with normal coronary arteries. Patient-specific flow models were 3D printed for 3 subjects with anomalous right coronary arteries with intramural course, 2 of them had documented ischemia, and compared with a patient with normal coronaries. The models were placed in the aortic position of a pulse duplicator and precise measurements to quantify FFR and coronary flow rate were performed from the aortic to the mediastinal segment of the anomalous right coronary artery. In an ischemic model, a gradual FFR drop (emulating that of pressure) was shown from the ostium location (∼1.0) to the distal intramural course (0.48). In nonischemic and normal patient models, FFR for all locations did not drop below 0.9. In a second ischemic model prior to repair, a drop to 0.44 was encountered at the intramural and mediastinal intersection, improving to 0.86 postrepair. There is a difference in instantaneous coronary flow rate with increasing aortic pressure in the ischemic models (slope 0.2846), compared to the postrepair and normal models (slope >0.53). These observations on patient models support a biomechanical basis for ischemia and potentially sudden cardiac death in aortic origin of a coronary artery, with a drop in pressure and FFR in the intramural segment, and a decrease in coronary flow rate with increasing aortic pressure, with both improving after corrective surgery.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia
| | - Rajesh Krishnamurthy
- Department of Radiology, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio..
| | - Jayanthi Parthasarathy
- Department of Radiology, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio
| | - Dorma C Flemister
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Carly M Krull
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Benjamin A Walter
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Carlos M Mery
- Texas Center for Pediatric and Congenital Heart Disease, University of Texas Dell Medical School / Dell Children's Medical Center, Austin, Texas
| | - Silvana Molossi
- Section of Pediatric Cardiology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia..
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Hatoum H, Maureira P, Lilly S, Dasi LP. Impact of Leaflet Laceration on Transcatheter Aortic Valve-in-Valve Washout: BASILICA to Solve Neosinus and Sinus Stasis. JACC Cardiovasc Interv 2020; 12:1229-1237. [PMID: 31272669 DOI: 10.1016/j.jcin.2019.04.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/26/2019] [Accepted: 04/09/2019] [Indexed: 11/17/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate any potential leaflet washout benefits after bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction during TAVR (BASILICA) in transcatheter valve-in-valve (ViV) in the context of leaflet thrombosis. BACKGROUND Leaflet thrombosis after transcatheter aortic valve replacement is secondary to flow stasis in both the sinus and neosinus. Strategies to improve washout and ameliorate neosinus and sinus flow velocities may have the potential to mitigate the occurrence of clinical and subclinical leaflet thrombosis. METHODS A 23-mm Edwards SAPIEN 3 and a 26-mm Medtronic Evolut were deployed in a 23-mm transparent surgical aortic valve model before and after leaflet laceration. The valves were placed in the aortic position of a pulse duplicator flow loop. Particle image velocimetry was performed to quantify sinus flow hemodynamic status. A tracing fluorescent dye was injected to evaluate the number of cycles to washout in both regions of interest. RESULTS The leaflet laceration procedure led to an increase in the velocities in the sinus and the neosinus by 50% for Evolut ViV and 61.9% for SAPIEN 3 ViV. In addition, leaflet laceration led to a reduction in overall cycles to washout in the neosinus by at least 56% with the Evolut and 54.5% with the SAPIEN 3 and in the sinus by at least 16.7% with the Evolut and 60.8% with the SAPIEN. CONCLUSIONS Leaflet laceration using a BASILICA-type approach may hold the potential to mitigate neosinus and sinus flow stasis. Controlled in vivo trials are necessary to establish the potential benefit of BASILICA to reduce the occurrence of leaflet thrombosis.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Pablo Maureira
- Department of Cardiovascular Surgery, CHU de Nancy, Nancy, France
| | - Scott Lilly
- Division of Cardiovascular Medicine, The Ohio State University, Columbus, Ohio
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio.
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Hatoum H, Girault E, Heim F, Dasi LP. In-vitro characterization of self-expandable textile transcatheter aortic valves. J Mech Behav Biomed Mater 2020; 103:103559. [PMID: 31786509 PMCID: PMC11107174 DOI: 10.1016/j.jmbbm.2019.103559] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/10/2019] [Accepted: 11/25/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVE This study aims at assessing the global dynamic behavior, closing energy and turbulence characteristics of self-expandable textile (inclined and straight yarn) transcatheter aortic valves (TAV) versus bioprosthetic TAVs. METHODS Two self-expandable textile TAVs one with inclined yarn textile and another with straight yarn textile leaflets were assessed in a pulse duplicator and compared with a self-expandable commercial bioprosthetic TAV under physiological pressure and flow. Particle Image Velocimetry and high-speed imaging were performed. Effective orifice areas (EOA), leakage fractions (LF), Pinwheeling indices (PI), closing energy (E), viscous shear stresses (VSS) and Reynolds shear stresses (RSS) were calculated. RESULTS (a) EOAs and LFs were 2.27 ± 0.03 cm2, 31.7 ± 0.6%; 2.25 ± 0.08 cm2, 26.6 ± 0.7%; and 1.63 ± 0.01 cm2, 29.1 ± 1.25% for inclined textile, bioprosthetic and straight textile TAV respectively (p < 0.0001). (b) Following same order, PIs were significantly different going from 1.16 ± 0.21%, 8.48 ± 0.8% and 8.865 ± 0.58% with the exception of CoreValve and straight yarn valve (p = 0.37); (c) E is lowest for straight textile TAV (0.0024 ± 0.0017 J), followed by bioprosthetic valve (0.00259 ± 0.0011 J) and then 45° Oriented Yarn Valve (0.00334 ± 0.03 J) (d) At peak systole, the highest RSS distribution was with the Straight textile TAV reaching up to 330Pa. The bioprosthetic TAV shows the smallest range with RSS reaching around 230Pa and the inclined textile TAV up to 280Pa. VSS limits were comparable among the 3 valves ranging between 5.2Pa and 5.7Pa. CONCLUSION Hemodynamic similarities were found between the textile self-expandable valves and the bioprosthetic valve. This study constitutes another step towards showing the potential that textile valves have to become an alternative for the biological ones.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Elise Girault
- Laboratoire de Physique et Mécanique Textiles, Université de Haute Alsace, Mulhouse, France
| | - Frederic Heim
- Laboratoire de Physique et Mécanique Textiles, Université de Haute Alsace, Mulhouse, France
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States.
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Loureiro-Ga M, Veiga C, Fdez-Manin G, Jimenez VA, Calvo-Iglesias F, Iñiguez A. A biomechanical model of the pathological aortic valve: simulation of aortic stenosis. Comput Methods Biomech Biomed Engin 2020; 23:303-311. [PMID: 31996041 DOI: 10.1080/10255842.2020.1720001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aortic stenosis (AS) disease is a narrowing of the aortic valve (AV) opening which reduces blood flow from the heart causing several health complications. Although a lot of work has been done in AV simulations, most of the efforts have been conducted regarding healthy valves. In this article, a new three-dimensional patient-specific biomechanical model of the valve, based on a parametric formulation of the stenosis that permits the simulation of different degrees of pathology, is presented. The formulation is based on a double approach: the first one is done from the geometric point of view, reducing the effective ejection area of the AV by joining leaflets using a zipper effect to sew them; the second one, in terms of functionality, is based on the modification of AV tissue properties due to the effect of calcifications. Both healthy and stenotic valves were created using patient-specific data and results of the numerical simulation of the valve function are provided. Analysis of the results shows a variation in the first principal stress, geometric orifice area, and blood velocity which were validated against clinical data. Thus, the possibility to create a pipeline which allows the integration of patient-specific data from echocardiographic images and iFR studies to perform finite elements analysis is proved.
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Affiliation(s)
- Marcos Loureiro-Ga
- Applied Mathematics Department II - Telecommunications Engineering Faculty, Univeristiy of Vigo, Vigo, Spain.,Cardiology Department, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Cesar Veiga
- Cardiology Department, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Generosa Fdez-Manin
- Applied Mathematics Department II - Telecommunications Engineering Faculty, Univeristiy of Vigo, Vigo, Spain
| | - Victor Alfonso Jimenez
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
| | - Francisco Calvo-Iglesias
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
| | - Andres Iñiguez
- Cardiology Department, Complexo Hospitalario Universitario de Vigo (CHUVI), Alvaro Cunqueiro Hospital, SERGAS, Vigo, Spain
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Heitkemper M, Hatoum H, Dasi LP. In vitro hemodynamic assessment of a novel polymeric transcatheter aortic valve. J Mech Behav Biomed Mater 2019; 98:163-171. [PMID: 31238208 DOI: 10.1016/j.jmbbm.2019.06.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 06/06/2019] [Accepted: 06/17/2019] [Indexed: 01/12/2023]
Abstract
Transcatheter aortic valve replacement (TAVR) is a life-saving alternative to surgical intervention. However, the identification of features associated with poor outcomes, including residual paravalvular leakage (PVL), leaflet calcification, and subclinical leaflet thrombosis, are cause to be concerned about valve durablilty (Mylotte and Piazza, 2015a, 2015b; Dasi et al., 2017; Makkar et al., 2015; Kheradvar et al., 2015a). The aim of this study is to optimize the potential of a hyaluronan (HA) enhanced polymeric transcatheter aortic valve (HA-TAV) that has promised to reduce blood damage causing-turbulent flow while maintaining durability. HA-enhanced linear low-density polyethylene (LLDPE) leaflets were sutured to novel cobalt chromium stents, size 26 mm balloon expandable stents. Hemodynamic performance was assessed in a left heart simulator under physiological pressure and flow conditions and compared to a 26 mm Medtronic Evolut and 26 mm Edwards SAPIEN 3. High-speed imaging and particle image velocimetry (PIV) were performed. The HA-TAV demonstrated an effective orifice area (EOA) within one standard deviation of the leading valve, SAPIEN 3.The regurgitant fraction (RF) of the HA-TAV (11.23 ± 0.55%) is decreased in comparison the Evolut (15.74 ± 0.73%) and slightly higher than the SAPIEN 3 (10.92 ± 0.11%), which is considered trace regurgitation according to valve standards. A decreased number of higher principal Reynolds shear stresses were shown for the HA-TAV at each cardiac phase. The HA-TAV is directly comparable and in some cases superior to the leading commercially available prosthetic heart valves in in-vitro hemodynamic testing.
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Affiliation(s)
- Megan Heitkemper
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA; Department of Mechanical Engineering, The Ohio State University, Columbus, OH, USA
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.
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Hatoum H, Maureira P, Dasi LP. A turbulence in vitro assessment of On-X and St Jude Medical prostheses. J Thorac Cardiovasc Surg 2019; 159:88-97. [PMID: 30905419 PMCID: PMC6703975 DOI: 10.1016/j.jtcvs.2019.02.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/17/2019] [Accepted: 02/09/2019] [Indexed: 02/08/2023]
Abstract
OBJECTIVE The objective of this study was to investigate and compare the hemodynamic and turbulence characteristics upon implantation of St Jude Medical (SJM) (St Jude Medical, St Paul, Minn) and On-X (On-X Life Technologies, Kennesaw, Ga) bileaflet mechanical valves. Both valves are considered highly successful bileaflet mechanical valves characterized by good clinical outcomes despite their numerous design differences. Although thromboembolism remains the main disadvantage of bileaflet mechanical valves, On-X valves have been shown to need less anticoagulation therapy. METHODS Hemodynamic assessment of a 23-mm On-X bileaflet mechanical valve and a 23-mm bileaflet SJM valve implanted in an aortic root was performed under pulsatile physiologic conditions. Time-resolved and phase-locked particle-image-velocimetry images and high-speed imaging data were acquired. Pressure gradients, effective orifice areas, dimensionless area index, leaflet position tracking, velocity, and principal Reynolds shear stress were calculated. RESULTS Pressure gradient for the On-X valve was 4.15 ± 0.099 mm Hg versus 4.75 ± 0.048 mm Hg for SJM (P < .001). Effective orifice area for the On-X valve was 2.61 ± 0.045 cm2 versus 2.36 ± 0.022 cm2 for SJM (P < .001). Area index was higher with SJM (0.87 ± 0.008) than with On-X (0.73 ± 0.013) (P < .001). On-X showed fluctuating leaflet behavior during systole, whereas SJM leaflets were stable. At peak systole, the maximal velocity with On-X was 1.86 m/s versus 2.33 m/s with SJM. Reynolds shear stress was higher with On-X compared with SJM at peak systole (95 vs 72 Pa). Higher velocity fluctuation was noted with the On-X valve. CONCLUSIONS This study shows that despite the design differences that characterize the On-X valve, the hemodynamic and turbulence parameters were not necessarily improved compared with SJM.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Pablo Maureira
- Department of Cardiovascular Surgery, CHU de Nancy, Nancy, France
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio.
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Hatoum H, Dasi LP. Spatiotemporal Complexity of the Aortic Sinus Vortex as a Function of Leaflet Calcification. Ann Biomed Eng 2019; 47:1116-1128. [PMID: 30710186 DOI: 10.1007/s10439-019-02224-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/28/2019] [Indexed: 01/25/2023]
Abstract
Several studies have shown the variation of aortic sinus structures' hemodynamics with different flow and geometric characteristics. They have also correlated aortic sinus hemodynamics with the progression and evolution of calcific aortic valve disease (CAVD). This study aims at visualizing aortic sinus fluid structure variations as functions of different leaflet calcification degrees and assessing their potential relationship with CAVD. A degenerated 23 mm Carpentier-Edwards Perimount Magna valve extracted from a redo-surgery patient was implanted in an aortic root model and tested in a pulse duplicator left heart simulator. The valve has 3 leaflets with 3 different levels of calcium distribution: mild, moderate and severe. High-speed imaging and particle image velocimetry were performed to assess sinus vortices, leaflet tip position and velocity along with shear stress. Results have shown that (a) aortic sinus vortices initiation, entrapment and evolution varied with different calcified leaflet exposure; (b) higher velocities in the sinus were calculated with the mildly calcified leaflet compared to the moderately and severely calcified ones; (c) during systole, the mildly calcified leaflet sinus case shows the most spread-out and higher ranges of shear stress probabilities and highest magnitudes going from (- 1.5 to + 1.8 Pa) compared with (- 1.0 to + 1.0 Pa) for moderately and severely calcified leaflets. The higher the calcification degree the lower the shear stress range and likelihoods of having higher shear stress. This holds in diastole as well. This study shows the impact of calcification on the aortic sinus flow structures.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, 473 W 12th Ave, Columbus, OH, 43210, USA
| | - Lakshmi Prasad Dasi
- Department of Biomedical Engineering, The Ohio State University, 473 W 12th Ave, Columbus, OH, 43210, USA. .,Division of Cardiac Surgery, The Ohio State University, Columbus, OH, USA.
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Hatoum H, Dasi LP. Reduction of Pressure Gradient and Turbulence Using Vortex Generators in Prosthetic Heart Valves. Ann Biomed Eng 2018; 47:85-96. [PMID: 30209706 DOI: 10.1007/s10439-018-02128-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 09/10/2018] [Indexed: 11/30/2022]
Abstract
Blood damage and platelet activation are inherent problems with present day bi-leaflet mechanical heart valve designs. Passive flow control through different arrangements of vortex generators (VG) as means of improving pressure gradients and reducing turbulence are investigated. Rectangular VG arrays were mounted on the downstream surfaces of a 23 mm 3D printed mechanical valve. The effect of VGs on the resulting flow structures were assessed under pulsatile physiological flow conditions where high resolution particle image velocimetry measurement was performed. The co-rotating VGs showed lower Reynolds shear stresses and improved pressure gradients (PG) compared with the counter-rotating ones and the no-VG control one (that showed higher turbulence). RSS was found 38.13 ± 0.89, 12.95 ± 0.32, 15.75 ± 0.71, 24.54 ± 0.84 and 16.33 ± 0.58 Pa for the control, co-rotating VGs, 8 counter-rotating VGs, 4 far-spaced VGs and 4 closely-spaced VGs, respectively. PG of 10.45 ± 0.94 mmHg was obtained with co-rotating VGs and the difference was significant compared with the other configurations (control 14.88 ± 0.4 mmHg; 8 counter-rotating VGs 13.76 ± 0.51 mmHg; 4 far-spaced VGs 13.84 ± 0.09 mmHg; and 4 closely-spaced VGs 15.37 ± 0.16 mmHg). Co-rotating VGs for this application induce a more delayed flow separation and a more homogenized and streamlined transition of flow compared with the counter-rotating VGs. Passive flow control techniques deployed on BHMVs is potentially beneficial as significant control of flow at small length scales without inducing large-scale design modifications of the valve.
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Affiliation(s)
- Hoda Hatoum
- Department of Biomedical Engineering, The Ohio State University, 473W 12th Ave., Columbus, OH, 43210, USA
| | - Lakshmi P Dasi
- Department of Biomedical Engineering, The Ohio State University, 473W 12th Ave., Columbus, OH, 43210, USA.
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