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Li N, Ferracane J, Andeen N, Lewis S, Woltjer R, Rugonyi S, Jahangiri Y, Uchida B, Farsad K, Kaufman JA, Al-Hakim R. Endovascular Venous Stenosis and Thrombosis Large Animal Model: angiographic, histological, and biomechanical characterization. J Vasc Interv Radiol 2021; 33:255-261.e2. [PMID: 34915165 DOI: 10.1016/j.jvir.2021.10.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/20/2021] [Accepted: 10/03/2021] [Indexed: 10/19/2022] Open
Abstract
PURPOSE Characterize an ovine endovascular radiofrequency ablation based venous stenosis and thrombosis model for studying venous biomechanics and response to intervention. MATERIALS AND METHODS Unilateral short-segment (n= 2) or long-segment (n = 6) iliac vein stenoses were created in eight adult sheep using an endovenous radiofrequency (RF) ablation technique. Angiographic assessment was performed at baseline, immediately after venous stenosis creation, and after 2-week (n = 6) or 3-month (n = 2) survival. Stenosed iliac veins and contralateral healthy controls were harvested for histological and biomechanical assessment. RESULTS At follow-up, the short-segment RF ablation group showed stable stenosis without occlusion. The long-segment group showed complete venous occlusion/thrombosis with formation of collateral veins. Stenosed veins showed significant wall thickening (0.28 mm vs 0.16 mm; p = 0.0175) and confluent collagen deposition compared to healthy controls. Subacute non-adherent thrombi were apparent at 2 weeks, which were replaced by fibrous luminal obliteration with channels of recanalization at 3 months. Stenosed veins demonstrated increased longitudinal stiffness (448.5 ± 5.4 kPa vs. 314.6 ± 1.5 kPa, p < 0.0001) and decreased circumferential stiffness (140.8 ± 2.6 kPa vs. 246.0 ± 1.6 kPa, p < 0.0001) compared to healthy controls. CONCLUSION Endovenous radiofrequency ablation is a reliable technique for creating venous stenosis and thrombosis in a large animal model with histological and biomechanical attributes similar to those seen in humans. This platform can facilitate understanding of venous biomechanics and testing of venous specific devices and interventions.
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Affiliation(s)
- Ningcheng Li
- Dotter Interventional Institute, Oregon Health & Science University
| | - Jack Ferracane
- School of Dentistry, Oregon Health & Science University; Biomaterials and Biomechanics, Oregon Health & Science University
| | | | - Steven Lewis
- School of Dentistry, Oregon Health & Science University; Biomaterials and Biomechanics, Oregon Health & Science University
| | | | - Sandra Rugonyi
- Biomedical Engineering, Oregon Health & Science University
| | - Younes Jahangiri
- Dotter Interventional Institute, Oregon Health & Science University
| | - Barry Uchida
- Dotter Interventional Institute, Oregon Health & Science University
| | - Khashayar Farsad
- Dotter Interventional Institute, Oregon Health & Science University
| | - John A Kaufman
- Dotter Interventional Institute, Oregon Health & Science University
| | - Ramsey Al-Hakim
- Dotter Interventional Institute, Oregon Health & Science University.
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Brass M, Kassab GS. Iliac Veins Are More Compressible Than Iliac Arteries: A New Method of Testing. J Biomech Eng 2019; 141:2738441. [DOI: 10.1115/1.4044227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Indexed: 12/17/2022]
Abstract
Incompressibility implies that a tissue preserves its volume regardless of the loading conditions. Although this assumption is well-established in arterial wall mechanics, it is assumed to apply for the venous wall without validation. The objective of this study is to test whether the incompressibility assumption holds for the venous wall. To investigate the vascular wall volume under different loading conditions, inflation-extension testing protocol was used in conjunction with intravascular ultrasound (IVUS) in both common iliac arteries (n = 6 swine) and common iliac veins (n = 9 dogs). Use of IVUS allows direct visualizations of lumen dimensions simultaneous with direct measurements of outer dimensions during loading. The arterial tissue was confirmed to preserve volume during various load conditions (p = 0.11) consistent with the literature, while the venous tissue was found to lose volume (about 35%) under loaded conditions (p < 0.05). Using a novel methodology, this study shows the incompressibility assumption does not hold for the venous wall especially at higher pressures, which suggests that there may be fluid loss through the vein wall during loading. This has important implications for coupling of fluid transport across the wall and biomechanics of the wall in healthy and diseased conditions.
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Affiliation(s)
- Margaret Brass
- Department of Biomedical Engineering, Indiana University Purdue University, Indianapolis, IN 46202
| | - Ghassan S. Kassab
- Department of Biomedical Engineering, California Medical Innovations Institute, San Diego, CA 92121 e-mail:
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Ramachandra AB, Humphrey JD, Marsden AL. Gradual loading ameliorates maladaptation in computational simulations of vein graft growth and remodelling. J R Soc Interface 2018; 14:rsif.2016.0995. [PMID: 28566510 DOI: 10.1098/rsif.2016.0995] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/28/2017] [Indexed: 12/21/2022] Open
Abstract
Vein graft failure is a prevalent problem in vascular surgeries, including bypass grafting and arteriovenous fistula procedures in which veins are subjected to severe changes in pressure and flow. Animal and clinical studies provide significant insight, but understanding the complex underlying coupled mechanisms can be advanced using computational models. Towards this end, we propose a new model of venous growth and remodelling (G&R) based on a constrained mixture theory. First, we identify constitutive relations and parameters that enable venous adaptations to moderate perturbations in haemodynamics. We then fix these relations and parameters, and subject the vein to a range of combined loads (pressure and flow), from moderate to severe, and identify plausible mechanisms of adaptation versus maladaptation. We also explore the beneficial effects of gradual increases in load on adaptation. A gradual change in flow over 3 days plus an initial step change in pressure results in fewer maladaptations compared with step changes in both flow and pressure, or even a gradual change in pressure and flow over 3 days. A gradual change in flow and pressure over 8 days also enabled a successful venous adaptation for loads as severe as the arterial loads. Optimization is used to accelerate parameter estimation and the proposed framework is general enough to provide a good starting point for parameter estimations in G&R simulations.
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Affiliation(s)
- Abhay B Ramachandra
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA.,Department of Pediatrics, Institute for Computational and Mathematical Engineering, Stanford, CA, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Alison L Marsden
- Department of Pediatrics, Institute for Computational and Mathematical Engineering, Stanford, CA, USA .,Department of Bioengineering, Stanford University, Stanford, CA, USA
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Biomechanical property and modelling of venous wall. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 133:56-75. [DOI: 10.1016/j.pbiomolbio.2017.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 11/18/2022]
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5
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Fennell VS, Martirosyan NL, Atwal GS, Kalani MYS, Ponce FA, Lemole GM, Dumont TM, Spetzler RF. Hemodynamics Associated With Intracerebral Arteriovenous Malformations: The Effects of Treatment Modalities. Neurosurgery 2017; 83:611-621. [DOI: 10.1093/neuros/nyx560] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 10/13/2017] [Indexed: 12/22/2022] Open
Abstract
Abstract
The understanding of the physiology of cerebral arteriovenous malformations (AVMs) continues to expand. Knowledge of the hemodynamics of blood flow associated with AVMs is also progressing as imaging and treatment modalities advance. The authors present a comprehensive literature review that reveals the physical hemodynamics of AVMs, and the effect that various treatment modalities have on AVM hemodynamics and the surrounding cortex and vasculature. The authors discuss feeding arteries, flow through the nidus, venous outflow, and the relative effects of radiosurgical monotherapy, endovascular embolization alone, and combined microsurgical treatments. The hemodynamics associated with intracranial AVMs is complex and likely changes over time with changes in the physical morphology and angioarchitecture of the lesions. Hemodynamic change may be even more of a factor as it pertains to the vast array of single and multimodal treatment options available. An understanding of AVM hemodynamics associated with differing treatment modalities can affect treatment strategies and should be considered for optimal clinical outcomes.
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Affiliation(s)
- Vernard S Fennell
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Nikolay L Martirosyan
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
- Division of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona
| | - Gursant S Atwal
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - M Yashar S Kalani
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - Francisco A Ponce
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
| | - G Michael Lemole
- Division of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona
| | - Travis M Dumont
- Division of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona
| | - Robert F Spetzler
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona
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Fennell VS, Martirosyan NL, Atwal GS, Kalani MYS, Spetzler RF, Lemole GM, Dumont T. Effective Surgical Management of Competitive Venous Outflow Restriction After Radiosurgery for Cerebral AVMs: Report of 2 Cases. World Neurosurg 2016; 98:882.e1-882.e7. [PMID: 27838427 DOI: 10.1016/j.wneu.2016.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 10/31/2016] [Accepted: 11/01/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Intracranial arteriovenous malformations (AVMs) are complex pathologies. For patients who do not present with hemorrhage, treatment strategies are often predicated on reducing the risk of hemorrhage and minimizing morbidity. Outcomes vary according to the efficacy of treatment selected. Radiosurgical treatment of certain AVMs can result in incomplete obliteration and may also have only a minimal effect on the presenting nonhemorrhagic symptoms. CASE DESCRIPTIONS We present 2 cases of patients with AVMs who were initially treated with radiosurgery. Both patients' primary clinical symptoms were headaches, which persisted after radiosurgical treatment but abated after subsequent microsurgical resection with or without endovascular embolization. CONCLUSION Venous outflow obstruction is likely a sizable contributive factor in occipital AVMs among patients who present with headaches and symptoms of intracranial hypertension. Because these high-flow lesions may be suboptimally responsive to stereotactic radiosurgery, microsurgical resection, with or without adjunctive endovascular embolization, should be considered as an initial and definitive treatment strategy. Optimal outcomes may be achieved in patients with a visual deficit that is anatomically correlated to their AVMs.
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Affiliation(s)
- Vernard S Fennell
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Nikolay L Martirosyan
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA; Division of Neurosurgery, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
| | - Gursant S Atwal
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - M Yashar S Kalani
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Robert F Spetzler
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
| | - G Michael Lemole
- Division of Neurosurgery, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
| | - Travis Dumont
- Division of Neurosurgery, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
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Laurito T, Sueiras V, Fernandez N, Escobar LA, Martinez L, Andreopoulos F, Salman LH, Vazquez-Padron RI, Ziebarth NM. Assessment of micro-mechanical variations in experimental arteriovenous fistulae using atomic force microscopy. J Vasc Access 2016; 17:279-83. [PMID: 27032456 PMCID: PMC10949901 DOI: 10.5301/jva.5000514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/24/2015] [Indexed: 11/20/2022] Open
Abstract
PURPOSE This study presents a method to quantify micro-stiffness variations in experimental arteriovenous fistulae (AVF). METHODS AVF created by anastomosing the superficial epigastric vein to the femoral artery in Sprague-Dawley rats were allowed to remodel for 21 days before being harvested and preserved in culture medium. A custom atomic force microscope was used to measure microvascular stiffness (Young's modulus) in three areas of the AVF: the inflow artery, the juxta-anastomotic area, and the outflow vein. Morphometric measurements and collagen and elastin contents were also determined. RESULTS Atomic force microscopy indentation revealed an increased stiffness in the juxta-anastomotic area of the AVF compared to the outflow vein and inflow artery. The juxta-anastomotic area was also significantly stiffer than the contralateral vein. The lack of elasticity (higher Young's modulus) of the juxta-anastomotic region was associated with a thicker vascular wall that was rich in collagen but poor in elastin. CONCLUSIONS This study demonstrates for the first time the feasibility of using atomic force microscopy to measure local stiffness variations in experimental AVF. This technique could be instrumental in advancing our understanding of how micro-spatial organization of the AVF wall determines the overall biomechanical performance of this type of vascular access.
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Affiliation(s)
- Tyler Laurito
- Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA
| | - Vivian Sueiras
- Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA
| | - Natasha Fernandez
- DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Luis A. Escobar
- DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Laisel Martinez
- DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Fotios Andreopoulos
- Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA
- DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Loay H. Salman
- Section of Interventional Nephrology, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Roberto I. Vazquez-Padron
- DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA
| | - Noël M. Ziebarth
- Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA
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Tabbara M, Duque JC, Martinez L, Escobar LA, Wu W, Pan Y, Fernandez N, Velazquez OC, Jaimes EA, Salman LH, Vazquez-Padron RI. Pre-existing and Postoperative Intimal Hyperplasia and Arteriovenous Fistula Outcomes. Am J Kidney Dis 2016; 68:455-64. [PMID: 27012909 DOI: 10.1053/j.ajkd.2016.02.044] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 02/07/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND The contribution of intimal hyperplasia (IH) to arteriovenous fistula (AVF) failure is uncertain. This observational study assessed the relationship between pre-existing, postoperative, and change in IH over time and AVF outcomes. STUDY DESIGN Prospective cohort study with longitudinal assessment of IH at the time of AVF creation (pre-existing) and transposition (postoperative). Patients were followed up for up to 3.3 years. SETTING & PARTICIPANTS 96 patients from a single center who underwent AVF surgery initially planned as a 2-stage procedure. Veins and AVF samples were collected from 66 and 86 patients, respectively. Matched-pair tissues were available from 56 of these patients. PREDICTORS Pre-existing, postoperative, and change in IH over time. OUTCOMES Anatomic maturation failure was defined as an AVF that never reached a diameter > 6mm. Primary unassisted patency was defined as the time elapsed from the second-stage surgery to the first intervention. MEASUREMENTS Maximal intimal thickness in veins and AVFs and change in intimal thickness over time. RESULTS Pre-existing IH (>0.05mm) was present in 98% of patients. In this group, the median intimal thickness increased 4.40-fold (IQR, 2.17- to 4.94-fold) between AVF creation and transposition. However, this change was not associated with pre-existing thickness (r(2)=0.002; P=0.7). Ten of 96 (10%) AVFs never achieved maturation, whereas 70% of vascular accesses remained patent at the end of the observational period. Postoperative IH was not associated with anatomic maturation failure using univariate logistic regression. Pre-existing, postoperative, and change in IH over time had no effects on primary unassisted patency. LIMITATIONS The small number of patients from whom longitudinal tissue samples were available and low incidence of anatomic maturation failure, which decreased the statistical power to find associations between end points and IH. CONCLUSIONS Pre-existing, postoperative, and change in IH over time were not associated with 2-stage AVF outcomes.
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Affiliation(s)
- Marwan Tabbara
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Juan C Duque
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Laisel Martinez
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Luis A Escobar
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Wensong Wu
- Department of Mathematics and Statistics, Florida International University, Miami, FL
| | - Yue Pan
- Department of Epidemiology and Public Health, University of Miami, Coral Gables, FL
| | - Natasha Fernandez
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Omaida C Velazquez
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Edgar A Jaimes
- Renal Service, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Loay H Salman
- Section of Interventional Nephrology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL
| | - Roberto I Vazquez-Padron
- DeWitt Daughtry Family Department of Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL.
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Veselý J, Horný L, Chlup H, Adámek T, Krajíček M, Žitný R. Constitutive modeling of human saphenous veins at overloading pressures. J Mech Behav Biomed Mater 2015; 45:101-8. [DOI: 10.1016/j.jmbbm.2015.01.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 01/21/2015] [Accepted: 01/29/2015] [Indexed: 12/25/2022]
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10
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Ramachandra AB, Sankaran S, Humphrey JD, Marsden AL. Computational simulation of the adaptive capacity of vein grafts in response to increased pressure. J Biomech Eng 2015; 137:1934919. [PMID: 25376151 PMCID: PMC4321118 DOI: 10.1115/1.4029021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 10/17/2014] [Indexed: 12/12/2022]
Abstract
Vein maladaptation, leading to poor long-term patency, is a serious clinical problem in patients receiving coronary artery bypass grafts (CABGs) or undergoing related clinical procedures that subject veins to elevated blood flow and pressure. We propose a computational model of venous adaptation to altered pressure based on a constrained mixture theory of growth and remodeling (G&R). We identify constitutive parameters that optimally match biaxial data from a mouse vena cava, then numerically subject the vein to altered pressure conditions and quantify the extent of adaptation for a biologically reasonable set of bounds for G&R parameters. We identify conditions under which a vein graft can adapt optimally and explore physiological constraints that lead to maladaptation. Finally, we test the hypothesis that a gradual, rather than a step, change in pressure will reduce maladaptation. Optimization is used to accelerate parameter identification and numerically evaluate hypotheses of vein remodeling.
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Affiliation(s)
- Abhay B. Ramachandra
- Department of Mechanical andAerospace Engineering,University of California San Diego,9500 Gilman Drive,La Jolla, CA 92093
| | - Sethuraman Sankaran
- Senior Computational Scientist HeartFlow, Inc.,1400 Seaport Blvd., Building B,Redwood City, CA 94063
| | - Jay D. Humphrey
- Department of Biomedical Engineering,Yale University,55 Prospect Street,New Haven, CT 06520
| | - Alison L. Marsden
- Department of Mechanicaland Aerospace Engineering,University of California San Diego,9500 Gilman Drive,La Jolla, CA 92093e-mail:
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