1
|
Wilson SI, Ingram KE, Oh A, Moreno MR, Kassi M. The role of innovative modeling and imaging techniques in improving outcomes in patients with LVAD. Front Cardiovasc Med 2023; 10:1248300. [PMID: 37692033 PMCID: PMC10484111 DOI: 10.3389/fcvm.2023.1248300] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 08/10/2023] [Indexed: 09/12/2023] Open
Abstract
Heart failure remains a significant cause of mortality in the United States and around the world. While organ transplantation is acknowledged as the gold standard treatment for end stage heart failure, supply is limited, and many patients are treated with left ventricular assist devices (LVADs). LVADs extend and improve patients' lives, but they are not without their own complications, particularly the hemocompatibility related adverse events (HRAE) including stroke, bleeding and pump thrombosis. Mainstream imaging techniques currently in use to assess appropriate device function and troubleshoot complications, such as echocardiography and cardiac computed tomography, provide some insight but do not provide a holistic understanding of pump induced flow alterations that leads to HRAEs. In contrast, there are technologies restricted to the benchtop-such as computational fluid dynamics and mock circulatory loops paired with methods like particle image velocimetry-that can assess flow metrics but have not been optimized for clinical care. In this review, we outline the potential role and current limitations of converging available technologies to produce novel imaging techniques, and the potential utility in evaluating hemodynamic flow to determine whether LVAD patients may be at higher risk of HRAEs. This addition to diagnostic and monitoring capabilities could improve prevention and treatment of LVAD-induced complications in heart failure patients.
Collapse
Affiliation(s)
- Shannon I. Wilson
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
| | - Katelyn E. Ingram
- DeBakey Heart and Vascular- Heart Center Research, Houston Methodist Research Institute, Houston, TX, United States
| | - Albert Oh
- School of Engineering Medicine, Texas A&M University, Houston, TX, United States
| | - Michael R. Moreno
- J. Mike Walker ‘66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, United States
| | - Mahwash Kassi
- Cardiology, DeBakey Heart and Vascular, Houston Methodist Hospital, Houston, TX, United States
| |
Collapse
|
2
|
Lu Q, Nehrer JM, Li J, Jamiolkowski MA, Rinaldi JE, Malinauskas RA. Platelet and leukocyte count assay for thrombogenicity screening of biomaterials and medical devices: Evaluation and improvement of ASTM F2888 test standard. J Biomed Mater Res B Appl Biomater 2021; 109:2259-2267. [PMID: 34106517 DOI: 10.1002/jbm.b.34887] [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: 12/07/2020] [Revised: 04/14/2021] [Accepted: 05/28/2021] [Indexed: 11/09/2022]
Abstract
An appropriate preclinical thrombogenicity evaluation of a blood-contacting device is important to reduce thrombosis and thromboembolism risks to patients. The in vitro platelet and leukocyte count assay, as described in the ASTM F2888 test standard, aims to assess thrombogenic potentials of blood-contacting materials. The goals of this study were to evaluate whether this standardized test method can effectively differentiate materials with different thrombogenic potentials and to investigate the impact of anticoagulation conditions on test sensitivity. Using human blood with various anticoagulation conditions, we performed the platelet and leukocyte count assays on four biomaterials and three positive control materials. We found that the use of sodium citrate anticoagulation as stipulated in the 2013 version of the ASTM F2888 standard cannot differentiate materials with different thrombogenic potentials. The modification to use low-concentration heparin, either with recalcified citrated blood or with direct heparinization, substantially improved the test sensitivity and enabled the assay to distinguish platelet count reduction between the positive controls and commonly used biomaterials. Leukocyte count was shown to be a much less sensitive indicator than platelet count for thrombogenicity evaluations of biomaterials. The findings from this study have been incorporated in the recent 2019 version of the ASTM F2888 standard.
Collapse
Affiliation(s)
- Qijin Lu
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Joshua M Nehrer
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Jiaming Li
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Megan A Jamiolkowski
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Jean E Rinaldi
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| | - Richard A Malinauskas
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
| |
Collapse
|
3
|
Becsek B, Pietrasanta L, Obrist D. Turbulent Systolic Flow Downstream of a Bioprosthetic Aortic Valve: Velocity Spectra, Wall Shear Stresses, and Turbulent Dissipation Rates. Front Physiol 2020; 11:577188. [PMID: 33117194 PMCID: PMC7550765 DOI: 10.3389/fphys.2020.577188] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 08/25/2020] [Indexed: 12/02/2022] Open
Abstract
Every year, a quarter million patients receive prosthetic heart valves in aortic valve replacement therapy. Prosthetic heart valves are known to lead to turbulent blood flow. This turbulent flow field may have adverse effects on blood itself, on the aortic wall and on the valve performance. A detailed characterization of the turbulent flow downstream of a valve could yield better understanding of its effect on shear-induced thrombocyte activation, unphysiological wall shear stresses and hemodynamic valve performance. Therefore, computational simulations of the flow past a bioprosthetic heart valve were performed. The computational results were validated against experimental measurements of the turbulent flow field with tomographic particle image velocimetry. The turbulent flow was analyzed for disturbance amplitudes, dissipation rates and shear stress distributions. It was found that approximately 26% of the hydrodynamic resistance of the valve was due to turbulent dissipation and that this dissipation mainly took place in a region about one valve diameter downstream of the valve orifice. Farther downstream, the turbulent fluctuations became weaker which was also reflected in the turbulent velocity spectra of the flow field. Viscous shear stresses were found to be in the range of the critical level for blood platelet activation. The turbulent flow led to elevated shear stress levels along the wall of the ascending aorta with strongly fluctuating and chaotic wall shear stress patterns. Further, we identified leaflet fluttering at 40 Hz which was connected to repeated shedding of vortex rings that appeared to feed the turbulent flow downstream of the valve.
Collapse
Affiliation(s)
- Barna Becsek
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Leonardo Pietrasanta
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| |
Collapse
|
4
|
Wium E, Jordaan CJ, Botes L, Smit FE. Alternative mechanical heart valves for the developing world. Asian Cardiovasc Thorac Ann 2019; 28:431-443. [PMID: 31752500 DOI: 10.1177/0218492319891255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Due to the prevalence of rheumatic heart disease in the developing world, mechanical heart valves in the younger patient population remain the prostheses of choice if repair is not feasible. Despite their durability, mechanical valves are burdened by coagulation and thromboembolism. Modern design tools can be utilized during the design process of mechanical valves, which allow a more systematic design approach and more detailed analysis of the blood flow through and around valves. These tools include computer-aided design, manufacturing, and engineering, such as computational fluid dynamics and finite element analysis, modern manufacturing techniques such as additive manufacturing, and sophisticated in-vitro and in-vivo tests. Following this systematic approach, a poppet valve was redesigned and the results demonstrate the benefits of the method. More organized flow patterns and fewer complex fluid structures were observed. The alternative trileaflet valve design has also been identified as a potential solution and, if a similar design approach is adopted, it could lead to the development of an improved mechanical heart valve in the future. It is imperative that researchers in developing countries continue their search for a mechanical heart valve with a reduced thromboembolic risk, requiring less or no anticoagulation.
Collapse
Affiliation(s)
- Elsmari Wium
- Robert WM Frater Cardiovascular Research Centre, Department of Cardiothoracic Surgery, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa.,Department of Mechanical and Mechatronic Engineering, Faculty of Engineering, Stellenbosch University, Stellenbosch, South Africa
| | - Christiaan Johannes Jordaan
- Robert WM Frater Cardiovascular Research Centre, Department of Cardiothoracic Surgery, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - Lezelle Botes
- Department of Health Sciences, Central University of Technology, Bloemfontein, South Africa
| | - Francis Edwin Smit
- Robert WM Frater Cardiovascular Research Centre, Department of Cardiothoracic Surgery, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| |
Collapse
|
5
|
Saidy NT, Wolf F, Bas O, Keijdener H, Hutmacher DW, Mela P, De-Juan-Pardo EM. Biologically Inspired Scaffolds for Heart Valve Tissue Engineering via Melt Electrowriting. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900873. [PMID: 31058444 DOI: 10.1002/smll.201900873] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 04/14/2019] [Indexed: 06/09/2023]
Abstract
Heart valves are characterized to be highly flexible yet tough, and exhibit complex deformation characteristics such as nonlinearity, anisotropy, and viscoelasticity, which are, at best, only partially recapitulated in scaffolds for heart valve tissue engineering (HVTE). These biomechanical features are dictated by the structural properties and microarchitecture of the major tissue constituents, in particular collagen fibers. In this study, the unique capabilities of melt electrowriting (MEW) are exploited to create functional scaffolds with highly controlled fibrous microarchitectures mimicking the wavy nature of the collagen fibers and their load-dependent recruitment. Scaffolds with precisely-defined serpentine architectures reproduce the J-shaped strain stiffening, anisotropic and viscoelastic behavior of native heart valve leaflets, as demonstrated by quasistatic and dynamic mechanical characterization. They also support the growth of human vascular smooth muscle cells seeded both directly or encapsulated in fibrin, and promote the deposition of valvular extracellular matrix components. Finally, proof-of-principle MEW trileaflet valves display excellent acute hydrodynamic performance under aortic physiological conditions in a custom-made flow loop. The convergence of MEW and a biomimetic design approach enables a new paradigm for the manufacturing of scaffolds with highly controlled microarchitectures, biocompatibility, and stringent nonlinear and anisotropic mechanical properties required for HVTE.
Collapse
Affiliation(s)
- Navid T Saidy
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Frederic Wolf
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Onur Bas
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- ARC ITTC in Additive Biomanufacturing, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
| | - Hans Keijdener
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Dietmar W Hutmacher
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- ARC ITTC in Additive Biomanufacturing, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- Institute for Advanced Study, Technische Universität München, D-85748, Garching, Germany
| | - Petra Mela
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
- Medical Materials and Medical Implant Design, Department of Mechanical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching,
| | - Elena M De-Juan-Pardo
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
| |
Collapse
|
6
|
Hedayat M, Borazjani I. Comparison of platelet activation through hinge vs bulk flow in bileaflet mechanical heart valves. J Biomech 2019; 83:280-290. [DOI: 10.1016/j.jbiomech.2018.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 11/12/2018] [Accepted: 12/03/2018] [Indexed: 10/27/2022]
|
7
|
Zbavitel J, Fialová S. A numerical study of hemodynamic effects on the bileaflet mechanical heart valve. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201921302103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The work is focused on calculating hemodynamically negative effects of a flow through bileaflet mechanical heart valves (BMHV). Open-source FOAM-extend and cfMesh libraries were used for numerical simulation, the leaflet movement was solved as a fluid-structure interaction. A real model of the Sorin Bicarbon heart valve was employed as the default geometry for the following shape improvement. The unsteady boundary conditions correspond to physiological data of a cardiac cycle. It is shown how the modification of the shape of the original valve geometry positively affected the size of backflow areas. Based on numerical results, a significant reduction of shear stress magnitude is shown. The outcome of a direct numerical simulation (DNS) of transient flow was compared with results of low-Reynolds URANS model k-ω SST. Despite the limits of the two-dimensional solution and Newtonian fluid model, the suitability of models frequently used in literature was reviewed. Use of URANS models can suppress the formation of some relevant vortex structures which may affect the BMHV’s dynamics. The results of this analysis can find use in optimizing the design of the mechanical valve that would cause less damage to the blood cells and lower risk of thrombus formation.
Collapse
|
8
|
Selmi M, Chiu WC, Chivukula VK, Melisurgo G, Beckman JA, Mahr C, Aliseda A, Votta E, Redaelli A, Slepian MJ, Bluestein D, Pappalardo F, Consolo F. Blood damage in Left Ventricular Assist Devices: Pump thrombosis or system thrombosis? Int J Artif Organs 2018; 42:113-124. [PMID: 30354870 DOI: 10.1177/0391398818806162] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction: Despite significant technical advancements in the design and manufacture of Left Ventricular Assist Devices, post-implant thrombotic and thromboembolic complications continue to affect long-term outcomes. Previous efforts, aimed at optimizing pump design as a means of reducing supraphysiologic shear stresses generated within the pump and associated prothrombotic shear-mediated platelet injury, have only partially altered the device hemocompatibility. Methods: We examined hemodynamic mechanisms that synergize with hypershear within the pump to contribute to the thrombogenic potential of the overall Left Ventricular Assist Device system. Results: Numerical simulations of blood flow in differing regions of the Left Ventricular Assist Device system, that is the diseased native left ventricle, the pump inflow cannula, the impeller, the outflow graft and the anastomosed downstream aorta, reveal that prothrombotic hemodynamic conditions might occur at these specific sites. Furthermore, we show that beyond hypershear, additional hemodynamic abnormalities exist within the pump, which may elicit platelet activation, such as recirculation zones and stagnant platelet trajectories. We also provide evidences that particular Left Ventricular Assist Device implantation configurations and specific post-implant patient management strategies, such as those allowing aortic valve opening, are more hemodynamically favorable and reduce the thrombotic risk. Conclusion: We extend the perspective of pump thrombosis secondary to the supraphysiologic shear stress environment of the pump to one of Left Ventricular Assist Device system thrombosis, raising the importance of comprehensive characterization of the different prothrombotic risk factors of the total system as the target to achieve enhanced hemocompatibility and improved clinical outcomes.
Collapse
Affiliation(s)
- Matteo Selmi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
- Department of Surgery, Division of Cardiac Surgery, Università di Verona, Verona, Italy
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | | | - Giulio Melisurgo
- Anesthesia and Cardiothoracic Intensive Care, San Raffaele Scientific Institute, Milano, Italy
| | | | - Claudius Mahr
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Emiliano Votta
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
| | - Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
- Departments of Medicine and Biomedical Engineering, The University of Arizona, Tucson, AZ, USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Federico Pappalardo
- Anesthesia and Cardiothoracic Intensive Care, San Raffaele Scientific Institute, Milano, Italy
- Advanced Heart Failure and Mechanical Circulatory Support Program, San Raffaele Scientific Institute, Milano, Italy
- Università Vita-Salute San Raffaele, Milano, Italy
| | - Filippo Consolo
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy
- Advanced Heart Failure and Mechanical Circulatory Support Program, San Raffaele Scientific Institute, Milano, Italy
- Università Vita-Salute San Raffaele, Milano, Italy
| |
Collapse
|
9
|
Dimasi A, Roka-Moiia Y, Consolo F, Rasponi M, Fiore GB, Slepian MJ, Redaelli A. Microfluidic flow-based platforms for induction and analysis of dynamic shear-mediated platelet activation-Initial validation versus the standardized hemodynamic shearing device. BIOMICROFLUIDICS 2018; 12:042208. [PMID: 29861819 PMCID: PMC5963949 DOI: 10.1063/1.5024500] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
A microfluidic flow-based platform (μFP), able to stimulate platelets via exposure of shear stress patterns pertinent to cardiovascular devices and prostheses, was compared to the Hemodynamic Shearing Device (HSD)-a state-of-the-art bench-top system for exposure of platelets to defined levels and patterns of shear. Platelets were exposed to time-varying shear stress patterns in the two systems; in detail, platelets were recirculated in the μFP or stimulated in the HSD to replicate comparable exposure time. Shear-mediated platelet activation was evaluated via (i) the platelet activity state assay, allowing the measurement of platelet-mediated thrombin generation and associated prothrombotic tendencies, (ii) scanning electron microscopy to evaluate morphological changes of sheared platelets, and (iii) flow cytometry for the determination of platelet phosphatidylserine exposure as a marker of shear activation. The results revealed good matching and comparability between the two systems, with similar trends of platelet activation, formation of microaggregates, and analogous trends of activation marker exposure for both the HSD and microfluidic-stimulated samples. These findings support future translation of the microfluidic platform as a Point-of-Care facsimile system for the diagnosis of thrombotic risk in patients implanted with cardiovascular devices.
Collapse
Affiliation(s)
- Annalisa Dimasi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy
| | - Yana Roka-Moiia
- Department of Medicine and Biomedical Engineering, Sarver Heart Center, University of Arizona, 1501 N Campbell Ave, Tucson, Arizona 85724, USA
| | | | - Marco Rasponi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy
| | - Gianfranco B. Fiore
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy
| | - Marvin J Slepian
- Department of Medicine and Biomedical Engineering, Sarver Heart Center, University of Arizona, 1501 N Campbell Ave, Tucson, Arizona 85724, USA
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy
| |
Collapse
|
10
|
Sievers HH, Schubert K, Jamali A, Scharfschwerdt M. The influence of different inflow configurations on computational fluid dynamics in a novel three-leaflet mechanical heart valve prosthesis. Interact Cardiovasc Thorac Surg 2018; 27:475-480. [DOI: 10.1093/icvts/ivy086] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/22/2018] [Indexed: 01/08/2023] Open
Affiliation(s)
- Hans-Hinrich Sievers
- Department of Cardiac and Thoracic Vascular Surgery, University of Luebeck, Luebeck, Germany
| | - Kathrin Schubert
- Department of Cardiac and Thoracic Vascular Surgery, University of Luebeck, Luebeck, Germany
| | - Ashkan Jamali
- Department of Cardiac and Thoracic Vascular Surgery, University of Luebeck, Luebeck, Germany
| | - Michael Scharfschwerdt
- Department of Cardiac and Thoracic Vascular Surgery, University of Luebeck, Luebeck, Germany
| |
Collapse
|
11
|
Buck AKW, Goebel SG, Goodin MS, Wright NJ, Groszek JJ, Moyer J, Singh S, Bluestein D, Fissell WH, Roy S. Original article submission: Platelet stress accumulation analysis to predict thrombogenicity of an artificial kidney. J Biomech 2018; 69:26-33. [PMID: 29395231 DOI: 10.1016/j.jbiomech.2018.01.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/27/2017] [Accepted: 01/08/2018] [Indexed: 02/01/2023]
Abstract
An implantable artificial kidney using a hemofilter constructed from an array of silicon membranes to provide ultrafiltration requires a suitable blood flow path to ensure stable operation in vivo. Two types of flow paths distributing blood to the array of membranes were evaluated: parallel and serpentine. Computational fluid dynamics (CFD) simulations were used to guide the development of the blood flow paths. Pressure data from animal tests were used to obtain pulsatile flow conditions imposed in the transient simulations. A key consideration for stable operation in vivo is limiting platelet stress accumulation to avoid platelet activation and thrombus formation. Platelet stress exposure was evaluated by CFD particle tracking methods through the devices to provide distributions of platelet stress accumulation. The distributions of stress accumulation over the duration of a platelet lifetime for each device revealed that stress accumulation for the serpentine flow path exceeded levels expected to cause platelet activation while the accumulated stress for the parallel flow path was below expected activation levels.
Collapse
Affiliation(s)
- Amanda K W Buck
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | | | | | - Nathan J Wright
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Joseph J Groszek
- Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jarrett Moyer
- Department of Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Sukhveer Singh
- Department of Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - William H Fissell
- Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shuvo Roy
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
| |
Collapse
|
12
|
Méndez Rojano R, Mendez S, Nicoud F. Introducing the pro-coagulant contact system in the numerical assessment of device-related thrombosis. Biomech Model Mechanobiol 2018; 17:815-826. [PMID: 29302840 DOI: 10.1007/s10237-017-0994-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/14/2017] [Indexed: 11/28/2022]
Abstract
Thrombosis is a major concern in blood-coated medical devices. Contact activation, which is the initial part of the coagulation cascade in device-related thrombosis, is not considered in current thrombus formation models. In the present study, pro-coagulant reactions including the contact activation system are coupled with a fluid solver in order to evaluate the potential of the contact system to initiate thrombin production. The biochemical/fluid model is applied to a backward-facing step configuration, a flow configuration that frequently appears in medical devices. In contrast to the in vivo thrombosis models in which a specific thrombotic zone (injury region) is set a priori by the user to initiate the coagulation reaction, a reactive surface boundary condition is applied to the whole device wall. Simulation results show large thrombin concentration in regions related to recirculation zones without the need of an a priori knowledge of the thrombus location. The numerical results align well with the regions prone to thrombosis observed in experimental results reported in the literature. This approach could complement thrombus formation models that take into account platelet activity and thrombus growth to optimize a wide range of medical devices.
Collapse
Affiliation(s)
- Rodrigo Méndez Rojano
- Institut Montpelliérain Alexander Grothendieck, CNRS, Univ. Montpellier, 2 Place Eugène Bataillon, 34095, Montpellier Cedex 5, France.
| | - Simon Mendez
- Institut Montpelliérain Alexander Grothendieck, CNRS, Univ. Montpellier, 2 Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
| | - Franck Nicoud
- Institut Montpelliérain Alexander Grothendieck, CNRS, Univ. Montpellier, 2 Place Eugène Bataillon, 34095, Montpellier Cedex 5, France
| |
Collapse
|
13
|
Hedayat M, Asgharzadeh H, Borazjani I. Platelet activation of mechanical versus bioprosthetic heart valves during systole. J Biomech 2017; 56:111-116. [DOI: 10.1016/j.jbiomech.2017.03.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 03/01/2017] [Accepted: 03/03/2017] [Indexed: 11/16/2022]
|
14
|
Bluestein D. Utilizing Computational Fluid Dynamics in Cardiovascular Engineering and Medicine-What You Need to Know. Its Translation to the Clinic/Bedside. Artif Organs 2017; 41:117-121. [PMID: 28181302 DOI: 10.1111/aor.12914] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8181, USA
| |
Collapse
|
15
|
Capoccia M. Mechanical Circulatory Support for Advanced Heart Failure: Are We about to Witness a New "Gold Standard"? J Cardiovasc Dev Dis 2016; 3:E35. [PMID: 29367578 PMCID: PMC5715724 DOI: 10.3390/jcdd3040035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 12/03/2016] [Accepted: 12/06/2016] [Indexed: 01/08/2023] Open
Abstract
The impact of left ventricular assist devices (LVADs) for the treatment of advanced heart failure has played a significant role as a bridge to transplant and more recently as a long-term solution for non-eligible candidates. Continuous flow left ventricular assist devices (CF-LVADs), based on axial and centrifugal design, are currently the most popular devices in view of their smaller size, increased reliability and higher durability compared to pulsatile flow left ventricular assist devices (PF-LVADs). The trend towards their use is increasing. Therefore, it has become mandatory to understand the physics and the mathematics behind their mode of operation for appropriate device selection and simulation set up. For this purpose, this review covers some of these aspects. Although very successful and technologically advanced, they have been associated with complications such as pump thrombosis, haemolysis, aortic regurgitation, gastro-intestinal bleeding and arterio-venous malformations. There is perception that the reduced arterial pulsatility may be responsible for these complications. A flow modulation control approach is currently being investigated in order to generate pulsatility in rotary blood pumps. Thrombus formation remains the most feared complication that can affect clinical outcome. The development of a preoperative strategy aimed at the reduction of complications and patient-device suitability may be appropriate. Patient-specific modelling based on 3D reconstruction from CT-scan combined with computational fluid dynamic studies is an attractive solution in order to identify potential areas of stagnation or challenging anatomy that could be addressed to achieve the desired outcome. The HeartMate II (axial) and the HeartWare HVAD (centrifugal) rotary blood pumps have been now used worldwide with proven outcome. The HeartMate III (centrifugal) is now emerging as the new promising device with encouraging preliminary results. There are now enough pumps on the market: it is time to focus on the complications in order to achieve the full potential and selling-point of this type of technology for the treatment of the increasing heart failure patient population.
Collapse
Affiliation(s)
- Massimo Capoccia
- Scottish National Advanced Heart Failure Service, Golden Jubilee National Hospital, Glasgow G81 4DY, UK.
- Biomedical Engineering, University of Strathclyde, Glasgow G4 0NW, UK.
| |
Collapse
|
16
|
Zhang P, Zhang N, Gao C, Zhang L, Gao Y, Deng Y, Bluestein D. Scalability Test of Multiscale Fluid-Platelet Model for Three Top Supercomputers. COMPUTER PHYSICS COMMUNICATIONS 2016; 204:132-140. [PMID: 27570250 PMCID: PMC4999248 DOI: 10.1016/j.cpc.2016.03.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have tested the scalability of three supercomputers: the Tianhe-2, Stampede and CS-Storm with multiscale fluid-platelet simulations, in which a highly-resolved and efficient numerical model for nanoscale biophysics of platelets in microscale viscous biofluids is considered. Three experiments involving varying problem sizes were performed: Exp-S: 680,718-particle single-platelet; Exp-M: 2,722,872-particle 4-platelet; and Exp-L: 10,891,488-particle 16-platelet. Our implementations of multiple time-stepping (MTS) algorithm improved the performance of single time-stepping (STS) in all experiments. Using MTS, our model achieved the following simulation rates: 12.5, 25.0, 35.5 μs/day for Exp-S and 9.09, 6.25, 14.29 μs/day for Exp-M on Tianhe-2, CS-Storm 16-K80 and Stampede K20. The best rate for Exp-L was 6.25 μs/day for Stampede. Utilizing current advanced HPC resources, the simulation rates achieved by our algorithms bring within reach performing complex multiscale simulations for solving vexing problems at the interface of biology and engineering, such as thrombosis in blood flow which combines millisecond-scale hematology with microscale blood flow at resolutions of micro-to-nanoscale cellular components of platelets. This study of testing the performance characteristics of supercomputers with advanced computational algorithms that offer optimal trade-off to achieve enhanced computational performance serves to demonstrate that such simulations are feasible with currently available HPC resources.
Collapse
Affiliation(s)
- Peng Zhang
- Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794-3600, United States
| | - Na Zhang
- Applied Mathematics Department, Stony Brook University, Stony Brook, NY 11794-8151, United States
| | - Chao Gao
- Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794-3600, United States
| | - Li Zhang
- Applied Mathematics Department, Stony Brook University, Stony Brook, NY 11794-8151, United States
| | - Yuxiang Gao
- Cluster Solution Department, Cray Inc., San Jose, CA 95112, United States
| | - Yuefan Deng
- Applied Mathematics Department, Stony Brook University, Stony Brook, NY 11794-8151, United States
| | - Danny Bluestein
- Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794-3600, United States
| |
Collapse
|
17
|
Microfluidic approaches for the assessment of blood cell trauma: a focus on thrombotic risk in mechanical circulatory support devices. Int J Artif Organs 2016; 39:184-93. [PMID: 27034318 DOI: 10.5301/ijao.5000485] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2016] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Mechanical circulatory support devices (MCSDs) are emerging as a valuable therapeutic option for the management of end-stage heart failure. However, although recipients are routinely administered with anti-thrombotic (AT) drugs, thrombosis persists as a severe post-implant complication. Conventional clinical assays and coagulation markers demonstrate partial ability in preventing the onset of thrombosis. Through years, different laboratory techniques have been proposed as potential tools for the evaluation of platelets' hemostatic response in MCSD recipients. Most rely on platelet aggregation tests; they are performed in static or low shear conditions, neglecting the prominent contribution of MCSD shear-induced mechanical load in enhancing platelet activation (PA). On the other hand, those tests able to account for shear-induced PA have limited possibility of effective clinical translation. AIMS AND METHODS Advances on this side have been addressed by microfluidic technology. Microfluidic devices have been developed for AT drug monitoring under flow, able to replicate physiological and/or constant shear flow conditions in vitro. In this paper, we present a newly developed microfluidic platform able to expose platelets to MCSD-specific dynamic shear stress patterns. We performed in vitro tests circulating human platelets in the microfluidic platform and quantifying the dynamics of PA by means of the Platelet Activity State (PAS) assay. RESULTS Our results prove the feasibility of using microfluidics for the diagnosis of MCSD-related thrombotic risk. This study paves the way for the development of a miniaturized point-of-care device for monitoring AT drug regimen. Such a system may have significant impact on limiting the incidence of thrombosis in MCSD recipients.
Collapse
|
18
|
Valerio L, Tran PL, Sheriff J, Brengle W, Ghosh R, Chiu WC, Redaelli A, Fiore GB, Pappalardo F, Bluestein D, Slepian MJ. Aspirin has limited ability to modulate shear-mediated platelet activation associated with elevated shear stress of ventricular assist devices. Thromb Res 2016; 140:110-117. [PMID: 26938158 DOI: 10.1016/j.thromres.2016.01.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 01/25/2016] [Accepted: 01/31/2016] [Indexed: 10/22/2022]
Abstract
Continuous flow ventricular assist devices (cfVADs) while effective in advanced heart failure, remain plagued by thrombosis related to abnormal flows and elevated shear stress. To limit cfVAD thrombosis, patients utilize complex anti-thrombotic regimens built upon a foundation of aspirin (ASA). While much data exists on ASA as a modulator of biochemically-mediated platelet activation, limited data exists as to the efficacy of ASA as a means of limiting shear-mediated platelet activation, particularly under elevated shear stress common within cfVADs. We investigated the ability of ASA (20, 25 and 125 μM) to limit shear-mediated platelet activation under conditions of: 1) constant shear stress (30 dynes/cm(2) and 70 dynes/cm(2)); 2) dynamic shear stress, and 3) initial high shear exposure (70 dynes/cm(2)) followed by low shear exposure - i.e. a platelet sensitization protocol, utilizing a hemodynamic shearing device providing uniform shear stress in vitro. The efficacy of ASA to limit platelet activation mediated via passage through a clinical cfVAD system (DeBakey Micromed) in vitro was also studied. ASA reduced platelet activation only under conditions of low shear stress (38% reduction compared to control, n=10, p<0.004), with minimal protection at higher shear stress and under dynamic conditions (n=10, p>0.5) with no limitation of platelet sensitization. ASA had limited ability (25.6% reduction in platelet activation rate) to modulate shear-mediated platelet activation induced via cfVAD passage. These findings, while performed under "deconstructed" non-clinical conditions by utilizing purified platelets alone in vitro, provide a potential contributory mechanistic explanation for the persistent thrombosis rates experienced clinically in cfVAD patients despite ASA therapy. An opportunity exists to develop enhanced pharmacologic strategies to limit shear-mediated platelet activation at elevated shear levels associated with mechanical circulatory support devices.
Collapse
Affiliation(s)
- Lorenzo Valerio
- Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy; Department of Cardiothoracic Anesthesia and Intensive Care, Istituto Scientifico San Raffaele, Milan, Italy.
| | - Phat L Tran
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - William Brengle
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Ram Ghosh
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Alberto Redaelli
- Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Gianfranco B Fiore
- Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Federico Pappalardo
- Department of Cardiothoracic Anesthesia and Intensive Care, Istituto Scientifico San Raffaele, Milan, Italy
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Marvin J Slepian
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA; Department of Medicine, Sarver Heart Center, University of Arizona, Tucson, AZ, USA; Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| |
Collapse
|
19
|
Jahandardoost M, Fradet G, Mohammadi H. Hemodynamic study of the elliptic St. Jude Medical valve: A computational study. Proc Inst Mech Eng H 2016; 230:85-96. [DOI: 10.1177/0954411915621341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Despite successful implantation of St. Jude Medical bileaflet mechanical heart valves, red blood cell lysis and thrombogenic complications associated with these types of valves are yet to be addressed. In our previous study, we proposed an elliptic housing where 10% ovality was applied to the housing of St. Jude Medical valves. Our preliminary results suggested that the overall hemodynamic performance of St. Jude Medical valves improved in both the closing and opening phases. In this study, we evaluated the hemodynamics around the leaflets in the opening phase using a more sophisticated computational platform, computational fluid dynamics. Results suggested both lower shear stress and wall shear stress values and an overall improved hemodynamic performance in the proposed design. This improvement is characterized by lower values of shear stress and wall shear stress in the regions downstream of the leaflets, lower pressure drop across the valve and smaller recirculation zones in the sinuses areas. The proposed design may open a new chapter in the concept of design and hemodynamic improvement of the next generation of mechanical heart valves.
Collapse
Affiliation(s)
- Mehdi Jahandardoost
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, The University of British Columbia, Okanagan Campus, Kelowna, BC, Canada
| | - Guy Fradet
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, The University of British Columbia, Okanagan Campus, Kelowna, BC, Canada
- Department of Surgery, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Hadi Mohammadi
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, The University of British Columbia, Okanagan Campus, Kelowna, BC, Canada
- Department of Surgery, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
- Biomedical Engineering Graduate Program, Faculty of Applied Science, The University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
20
|
Consolo F, Valerio L, Brizzola S, Rota P, Marazzato G, Vincoli V, Reggiani S, Redaelli A, Fiore G. On the Use of the Platelet Activity State Assay for the In Vitro Quantification of Platelet Activation in Blood Recirculating Devices for Extracorporeal Circulation. Artif Organs 2016; 40:971-980. [DOI: 10.1111/aor.12672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Filippo Consolo
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | - Lorenzo Valerio
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | - Stefano Brizzola
- Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare, Facoltà di Medicina Veterinaria; Università di Milano; Milano Italy
| | - Paolo Rota
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | - Giulia Marazzato
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | - Valentina Vincoli
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | | | - Alberto Redaelli
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| | - Gianfranco Fiore
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
| |
Collapse
|
21
|
Dimasi A, Rasponi M, Sheriff J, Chiu WC, Bluestein D, Tran PL, Slepian MJ, Redaelli A. Microfluidic emulation of mechanical circulatory support device shear-mediated platelet activation. Biomed Microdevices 2015; 17:117. [PMID: 26578003 PMCID: PMC4855287 DOI: 10.1007/s10544-015-0015-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Thrombosis of ventricular assist devices (VADs) compromises their performance, with associated risks of systemic embolization, stroke, pump stop and possible death. Anti-thrombotic (AT) drugs, utilized to limit thrombosis, are largely dosed empirically, with limited testing of their efficacy. Further, such testing, if performed, typically examines efficacy under static conditions, which is not reflective of actual shear-mediated flow. Here we adopted our previously developed Device Thrombogenicity Emulation methodology to design microfluidic platforms able to emulate representative shear stress profiles of mechanical circulatory support (MCS) devices. Our long-term goal is to utilize these systems for point-of-care (POC) personalized testing of AT efficacy under specific, individual shear profiles. First, we designed different types of microfluidic channels able to replicate sample shear stress patterns observed in MCS devices. Second, we explored the flexibility of microfluidic technology in generating dynamic shear stress profiles by modulating the geometrical features of the channels. Finally, we designed microfluidic channel systems able to emulate the shear stress profiles of two commercial VADs. From CFD analyses, the VAD-emulating microfluidic systems were able to replicate the main characteristics of the shear stress waveforms of the macroscale VADs (i.e., shear stress peaks and duration). Our results establish the basis for development of a lab-on-chip POC system able to perform device-specific and patient-specific platelet activation state assays.
Collapse
Affiliation(s)
- Annalisa Dimasi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, 20133, Italy
| | - Marco Rasponi
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, 20133, Italy
| | - Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8151, USA
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8151, USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8151, USA
| | - Phat L Tran
- Department of Medicine and Biomedical Engineering, Sarver Heart Center, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA
| | - Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8151, USA.
- Department of Medicine and Biomedical Engineering, Sarver Heart Center, University of Arizona, 1501 North Campbell Avenue, Tucson, AZ, 85724, USA.
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, 20133, Italy
| |
Collapse
|
22
|
Sheriff J, Tran PL, Hutchinson M, DeCook T, Slepian MJ, Bluestein D, Jesty J. Repetitive Hypershear Activates and Sensitizes Platelets in a Dose-Dependent Manner. Artif Organs 2015; 40:586-95. [PMID: 26527361 DOI: 10.1111/aor.12602] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Implantation of mechanical circulatory support (MCS) devices-ventricular assist devices and the total artificial heart-has emerged as a vital therapy for advanced and end-stage heart failure. Unfortunately, MCS patients face the requirement of life-long antiplatelet and anticoagulant therapy to combat thrombotic complications resulting from the dynamic and supraphysiologic shear stress conditions associated with such devices, whose effect on platelet activation is poorly understood. We developed a syringe-capillary viscometer-the "platelet hammer"-that repeatedly exposed platelets to average shear stresses up to 1000 dyne/cm(2) for as short as 25 ms. Platelet activation state was measured using a modified prothrombinase assay, with morphological changes analyzed using scanning electron microscopy. We observed an increase in platelet activation state and post-high shear platelet activation rate, or sensitization, with an increase in stress accumulation (SA), the product of shear stress and exposure time. A significant increase in platelet activation state was observed beyond an SA of 1500 dyne-s/cm(2) , with a marked increase in pseudopod length visible beyond an SA of 1000 dyne-s/cm(2) . Utility of the platelet hammer extends to studies of other shear-dependent pathologies, and may assist development of approaches to enhance the safety and effectiveness of MCS devices and objective antithrombotic pharmacotherapy management.
Collapse
Affiliation(s)
- Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Phat L Tran
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Marcus Hutchinson
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Tracy DeCook
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.,Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA.,Department of Medicine, Sarver Heart Center, University of Arizona, Tucson, AZ, USA
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Jolyon Jesty
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| |
Collapse
|
23
|
Min Yun B, Aidun CK, Yoganathan AP. Blood damage through a bileaflet mechanical heart valve: a quantitative computational study using a multiscale suspension flow solver. J Biomech Eng 2015; 136:101009. [PMID: 25070372 DOI: 10.1115/1.4028105] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 07/30/2014] [Indexed: 11/08/2022]
Abstract
Bileaflet mechanical heart valves (BMHVs) are among the most popular prostheses to replace defective native valves. However, complex flow phenomena caused by the prosthesis are thought to induce serious thromboembolic complications. This study aims at employing a novel multiscale numerical method that models realistic sized suspended platelets for assessing blood damage potential in flow through BMHVs. A previously validated lattice-Boltzmann method (LBM) is used to simulate pulsatile flow through a 23 mm St. Jude Medical (SJM) Regent™ valve in the aortic position at very high spatiotemporal resolution with the presence of thousands of suspended platelets. Platelet damage is modeled for both the systolic and diastolic phases of the cardiac cycle. No platelets exceed activation thresholds for any of the simulations. Platelet damage is determined to be particularly high for suspended elements trapped in recirculation zones, which suggests a shift of focus in blood damage studies away from instantaneous flow fields and toward high flow mixing regions. In the diastolic phase, leakage flow through the b-datum gap is shown to cause highest damage to platelets. This multiscale numerical method may be used as a generic solver for evaluating blood damage in other cardiovascular flows and devices.
Collapse
|
24
|
Piatti F, Sturla F, Marom G, Sheriff J, Claiborne TE, Slepian MJ, Redaelli A, Bluestein D. Hemodynamic and thrombogenic analysis of a trileaflet polymeric valve using a fluid-structure interaction approach. J Biomech 2015; 48:3641-9. [PMID: 26329461 DOI: 10.1016/j.jbiomech.2015.08.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 08/07/2015] [Accepted: 08/11/2015] [Indexed: 11/24/2022]
Abstract
Surgical valve replacement in patients with severe calcific aortic valve disease using either bioprosthetic or mechanical heart valves is still limited by structural valve deterioration for the former and thrombosis risk mandating anticoagulant therapy for the latter. Prosthetic polymeric heart valves have the potential to overcome the inherent material and design limitations of these valves, but their development is still ongoing. The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach. The FSI model replicated experimental conditions of the valve as tested in a left heart simulator. Hemodynamic parameters (transvalvular pressure gradient, flow rate, maximum velocity, and effective orifice area) were compared to assess the validity of the FSI model. The thrombogenic footprint of the polymeric valve was evaluated using a Lagrangian approach to calculate the stress accumulation (SA) values along multiple platelet trajectories and their statistical distribution. In the commissural regions, platelets were exposed to the highest SA values because of highest stress levels combined with local reverse flow patterns and vortices. Stress-loading waveforms from representative trajectories in regions of interest were emulated in our hemodynamic shearing device (HSD). Platelet activity was measured using our platelet activation state (PAS) assay and the results confirmed the higher thrombogenic potential of the commissural hotspots. In conclusion, the proposed method provides an in depth analysis of the hemodynamic and thrombogenic performance of the polymer valve prototype and identifies locations for further design optimization.
Collapse
Affiliation(s)
- Filippo Piatti
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Francesco Sturla
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Gil Marom
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Thomas E Claiborne
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA; Sarver Heart Center, University of Arizona, Tucson, AZ, USA
| | - Alberto Redaelli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
| |
Collapse
|
25
|
Chiu WC, Girdhar G, Xenos M, Alemu Y, Soares JS, Einav S, Slepian M, Bluestein D. Thromboresistance comparison of the HeartMate II ventricular assist device with the device thrombogenicity emulation- optimized HeartAssist 5 VAD. J Biomech Eng 2014; 136:021014. [PMID: 24337144 DOI: 10.1115/1.4026254] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Indexed: 11/08/2022]
Abstract
Approximately 7.5 × 106 patients in the US currently suffer from end-stage heart failure. The FDA has recently approved the designations of the Thoratec HeartMate II ventricular assist device (VAD) for both bridge-to-transplant and destination therapy (DT) due to its mechanical durability and improved hemodynamics. However, incidence of pump thrombosis and thromboembolic events remains high, and the life-long complex pharmacological regimens are mandatory in its VAD recipients. We have previously successfully applied our device thrombogenicity emulation (DTE) methodology for optimizing device thromboresistance to the Micromed Debakey VAD, and demonstrated that optimizing device features implicated in exposing blood to elevated shear stresses and exposure times significantly reduces shear-induced platelet activation and significantly improves the device thromboresistance. In the present study, we compared the thrombogenicity of the FDA-approved HeartMate II VAD with the DTE-optimized Debakey VAD (now labeled HeartAssist 5). With quantitative probability density functions of the stress accumulation along large number of platelet trajectories within each device which were extracted from numerical flow simulations in each device, and through measurements of platelet activation rates in recirculation flow loops, we specifically show that: (a) Platelets flowing through the HeartAssist 5 are exposed to significantly lower stress accumulation that lead to platelet activation than the HeartMate II, especially at the impeller-shroud gap regions (b) Thrombus formation patterns observed in the HeartMate II are absent in the HeartAssist 5 (c) Platelet activation rates (PAR) measured in vitro with the VADs mounted in recirculation flow-loops show a 2.5-fold significantly higher PAR value for the HeartMate II. This head to head thrombogenic performance comparative study of the two VADs, one optimized with the DTE methodology and one FDA-approved, demonstrates the efficacy of the DTE methodology for drastically reducing the device thrombogenic potential, validating the need for a robust in silico/in vitro optimization methodology for improving cardiovascular devices thromboresistance.
Collapse
|
26
|
Kheradvar A, Groves EM, Goergen CJ, Alavi SH, Tranquillo R, Simmons CA, Dasi LP, Grande-Allen KJ, Mofrad MRK, Falahatpisheh A, Griffith B, Baaijens F, Little SH, Canic S. Emerging Trends in Heart Valve Engineering: Part II. Novel and Standard Technologies for Aortic Valve Replacement. Ann Biomed Eng 2014; 43:844-57. [DOI: 10.1007/s10439-014-1191-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/13/2014] [Indexed: 11/29/2022]
|
27
|
Kheradvar A, Groves EM, Simmons CA, Griffith B, Alavi SH, Tranquillo R, Dasi LP, Falahatpisheh A, Grande-Allen KJ, Goergen CJ, Mofrad MRK, Baaijens F, Canic S, Little SH. Emerging trends in heart valve engineering: Part III. Novel technologies for mitral valve repair and replacement. Ann Biomed Eng 2014; 43:858-70. [PMID: 25287646 DOI: 10.1007/s10439-014-1129-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/17/2014] [Indexed: 11/29/2022]
Abstract
In this portion of an extensive review of heart valve engineering, we focus on the current and emerging technologies and techniques to repair or replace the mitral valve. We begin with a discussion of the currently available mechanical and bioprosthetic mitral valves followed by the rationale and limitations of current surgical mitral annuloplasty methods; a discussion of the technique of neo-chordae fabrication and implantation; a review the procedures and clinical results for catheter-based mitral leaflet repair; a highlight of the motivation for and limitations of catheter-based annular reduction therapies; and introduce the early generation devices for catheter-based mitral valve replacement.
Collapse
Affiliation(s)
- Arash Kheradvar
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA,
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Multiscale Particle-Based Modeling of Flowing Platelets in Blood Plasma Using Dissipative Particle Dynamics and Coarse Grained Molecular Dynamics. Cell Mol Bioeng 2014; 7:552-574. [PMID: 25530818 DOI: 10.1007/s12195-014-0356-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
We developed a multiscale particle-based model of platelets, to study the transport dynamics of shear stresses between the surrounding fluid and the platelet membrane. This model facilitates a more accurate prediction of the activation potential of platelets by viscous shear stresses - one of the major mechanisms leading to thrombus formation in cardiovascular diseases and in prosthetic cardiovascular devices. The interface of the model couples coarse-grained molecular dynamics (CGMD) with dissipative particle dynamics (DPD). The CGMD handles individual platelets while the DPD models the macroscopic transport of blood plasma in vessels. A hybrid force field is formulated for establishing a functional interface between the platelet membrane and the surrounding fluid, in which the microstructural changes of platelets may respond to the extracellular viscous shear stresses transferred to them. The interaction between the two systems preserves dynamic properties of the flowing platelets, such as the flipping motion. Using this multiscale particle-based approach, we have further studied the effects of the platelet elastic modulus by comparing the action of the flow-induced shear stresses on rigid and deformable platelet models. The results indicate that neglecting the platelet deformability may overestimate the stress on the platelet membrane, which in turn may lead to erroneous predictions of the platelet activation under viscous shear flow conditions. This particle-based fluid-structure interaction multiscale model offers for the first time a computationally feasible approach for simulating deformable platelets interacting with viscous blood flow, aimed at predicting flow induced platelet activation by using a highly resolved mapping of the stress distribution on the platelet membrane under dynamic flow conditions.
Collapse
|
29
|
Menon PG, Antaki JF, Undar A, Pekkan K. Aortic outflow cannula tip design and orientation impacts cerebral perfusion during pediatric cardiopulmonary bypass procedures. Ann Biomed Eng 2013; 41:2588-602. [PMID: 23817768 DOI: 10.1007/s10439-013-0857-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
Abstract
Poor perfusion of the aortic arch is a suspected cause for peri- and post-operative neurological complications associated with cardiopulmonary bypass (CPB). High-speed jets from 8 to 10FR pediatric/neonatal cannulae delivering ~1 L/min of blood can accrue sub-lethal hemolytic damage while also subjecting the aorta to non-physiologic flow conditions that compromise cerebral perfusion. Therefore, we emphasize the importance of cannulation strategy and hypothesize engineering better CPB perfusion through a redesigned aortic cannula tip. This study employs computational fluid dynamics to investigate novel diffuser-tipped aortic cannulae for shape sensitivity to cerebral perfusion, in an in silico cross-clamped aortic arch model modeled with fixed outflow resistances. 17 parametrically altered configurations of an 8FR end-hole and several diffuser cone angled tips in combination with jet incidence angles toward or away from the head-neck vessels were studied. Experimental pressure-flow characterizations were also conducted on these cannula tip designs. An 8FR end-hole aortic cannula delivering 1 L/min along the transverse aortic arch was found to give rise to backflow from the brachicephalic artery (BCA), irrespective of angular orientation, for the chosen ascending aortic insertion location. Parametric alteration of the cannula tip to include a diffuser cone angle (tested up to 7°) eliminated BCA backflow for any tested angle of jet incidence. Experiments revealed that a 1 cm long 10° diffuser cone tip demonstrated the best pressure-flow performance improvement in contrast with either an end-hole tip or diffuser cone angles greater than 10°. Performance further improved when the diffuser was preceded by an expanded four-lobe swirl inducer attachment-a novel component. In conclusion, aortic cannula orientation is crucial in determining net head-neck perfusion but precise angulations and insertion-depths are difficult to achieve practically. Altering the cannula tip to include a diffuser cone angle has been shown for the first time to have potential in ensuring a net positive outflow at the BCA. Cannula insertion distanced from the BCA inlet may also avoid backflow owing to the Venturi effect, but the diffuser tipped cannula design presents a promising solution to mitigate this issue irrespective of in vivo cannula tip orientation.
Collapse
Affiliation(s)
- Prahlad G Menon
- Department of Biomedical Engineering, Carnegie Mellon University, 700 Technology Drive, #4319, Pittsburgh, PA, 15219, USA
| | | | | | | |
Collapse
|
30
|
Lu Q, Hofferbert BV, Koo G, Malinauskas RA. In vitro shear stress-induced platelet activation: sensitivity of human and bovine blood. Artif Organs 2013; 37:894-903. [PMID: 23738621 DOI: 10.1111/aor.12099] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
As platelet activation plays a critical role in physiological hemostasis and pathological thrombosis, it is important in the overall hemocompatibility evaluation of new medical devices and biomaterials to assess their effects on platelet function. However, there are currently no widely accepted in vitro test methods to perform this assessment. In an effort to develop effective platelet tests for potential use in medical device evaluation, this study compared the sensitivity of platelet responses to shear stress stimulation of human and bovine blood using multiple platelet activation markers. Fresh whole blood samples anticoagulated with heparin or anticoagulant citrate dextrose, solution A (ACDA) were exposed to shear stresses up to 40 Pa for 2 min using a cone-and-plate rheometer model. Platelet activation was characterized by platelet counts, platelet surface P-selectin expression, and serotonin release into blood plasma. The results indicated that exposure to shear stresses above 20 Pa caused significant changes in all three of the platelet markers for human blood and that the changes were usually greater with ACDA anticoagulation than with heparin. In contrast, for bovine blood, the markers did not change with shear stress stimulation except for plasma serotonin in heparin anticoagulated blood. The differences observed between human and bovine platelet responses suggest that the value of using bovine blood for in vitro platelet testing to evaluate devices may be limited.
Collapse
Affiliation(s)
- Qijin Lu
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USA
| | | | | | | |
Collapse
|
31
|
Sheriff J, Soares JS, Xenos M, Jesty J, Slepian MJ, Bluestein D. Evaluation of shear-induced platelet activation models under constant and dynamic shear stress loading conditions relevant to devices. Ann Biomed Eng 2013; 41:1279-96. [PMID: 23400312 DOI: 10.1007/s10439-013-0758-x] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/31/2013] [Indexed: 11/30/2022]
Abstract
The advent of implantable blood-recirculating devices such as left ventricular assist devices and prosthetic heart valves provides a viable therapy for patients with end-stage heart failure and valvular disease. However, device-generated pathological flow patterns result in thromboembolic complications that require complex and lifelong anticoagulant therapy, which entails hemorrhagic risks and is not appropriate for certain patients. Optimizing the thrombogenic performance of such devices utilizing numerical simulations requires the development of predictive platelet activation models that account for variations in shear-loading rates characterizing blood flow through such devices. Platelets were exposed in vitro to both dynamic and constant shear stress conditions emulating those found in blood-recirculating devices in order to determine their shear-induced activation and sensitization response. Both these behaviors were found to be dependent on the shear loading rates, in addition to shear stress magnitude and exposure time. We then critically examined several current models and evaluated their predictive capabilities using these results. Shear loading rate terms were then included to account for dynamic aspects that are either ignored or partially considered by these models, and model parameters were optimized. Independent optimization for each of the two types of shear stress exposure conditions tested resulted in different sets of best-fit constants, indicating that universal optimization may not be possible. Inherent limitations of the current models require a paradigm shift from these integral-based discretized power law models to better address the dynamic conditions encountered in blood-recirculating devices.
Collapse
Affiliation(s)
- Jawaad Sheriff
- Department of Biomedical Engineering, T15-090 Health Sciences Center, Stony Brook University, Stony Brook, NY 11794-8151, USA
| | | | | | | | | | | |
Collapse
|
32
|
A novel mathematical model of activation and sensitization of platelets subjected to dynamic stress histories. Biomech Model Mechanobiol 2013; 12:1127-41. [PMID: 23359062 DOI: 10.1007/s10237-013-0469-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/07/2013] [Indexed: 02/07/2023]
Abstract
Blood recirculating devices, such as ventricular assist devices and prosthetic heart valves, are burdened by thromboembolic complications requiring complex and lifelong anticoagulant therapy with its inherent hemorrhagic risks. Pathologic flow patterns occurring in such devices chronically activate platelets, and the optimization of their thrombogenic performance requires the development of flow-induced platelet activation models. However, existing models are based on empirical correlations using the well-established power law paradigm of constant levels of shear stress during certain exposure times as factors for mechanical platelet activation. These models are limited by their range of application and do not account for other relevant phenomena, such as loading rate dependence and platelet sensitization to high stress conditions, which characterize the dynamic flow conditions in devices. These limitations were addressed by developing a new class of phenomenological stress-induced platelet activation models that specifies the rate of platelet activation as a function of the entire stress history and results in a differential equation that can be directly integrated to calculate the cumulative levels of activation. The proposed model reverts to the power law under constant shear stress conditions and is able to describe experimental results in response to a diverse range of highly dynamic stress conditions found in blood recirculating devices. The model was tested in vitro under emulated device flow conditions and correlates well with experimental results. This new model provides a reliable and robust mathematical tool that can be incorporated into computational fluid dynamic studies in order to optimize design, with the goal of improving the thrombogenic performance of blood recirculating devices.
Collapse
|
33
|
Slepian MJ, Alemu Y, Girdhar G, Soares JS, Smith RG, Einav S, Bluestein D. The Syncardia(™) total artificial heart: in vivo, in vitro, and computational modeling studies. J Biomech 2013; 46:266-75. [PMID: 23305813 DOI: 10.1016/j.jbiomech.2012.11.032] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 11/15/2012] [Indexed: 02/07/2023]
Abstract
The SynCardia(™) total artificial heart (TAH) is the only FDA-approved TAH in the world. The SynCardia(™) TAH is a pneumatically driven, pulsatile system capable of flows of >9L/min. The TAH is indicated for use as a bridge to transplantation (BTT) in patients at imminent risk of death from non-reversible bi-ventricular failure. In the Pivotal US approval trial the TAH achieved a BTT rate of >79%. Recently a multi-center, post-market approval study similarly demonstrated a comparable BTT rate. A major milestone was recently achieved for the TAH, with over 1100 TAHs having been implanted to date, with the bulk of implantation occurring at an ever increasing rate in the past few years. The TAH is most commonly utilized to save the lives of patients dying from end-stage bi-ventricular heart failure associated with ischemic or non-ischemic dilated cardiomyopathy. Beyond progressive chronic heart failure, the TAH has demonstrated great efficacy in supporting patients with acute irreversible heart failure associated with massive acute myocardial infarction. In recent years several diverse clinical scenarios have also proven to be well served by the TAH including severe heart failure associated with advanced congenital heart disease. failed or burned-out transplants, infiltrative and restrictive cardiomyopathies and failed ventricular assist devices. Looking to the future a major unmet need remains in providing total heart support for children and small adults. As such, the present TAH design must be scaled to fit the smaller patient, while providing equivalent, if not superior flow characteristics, shear profiles and overall device thrombogenicity. To aid in the development of a new "pediatric," TAH an engineering methodology known as "Device Thrombogenicity Emulation (DTE)", that we have recently developed and described, is being employed. Recently, to further our engineering understanding of the TAH, as steps towards next generation designs we have: (1) assessed of the degree of platelet reactivity induced by the present clinical 70 cc TAH using a closed loop platelet activity state assay, (2) modeled the motion of the TAH pulsatile mobile diaphragm, and (3) performed fluid-structure interactions and assessment of the flow behavior through inflow and outflow regions of the TAH fitted with modern bi-leaflet heart valves. Developing a range of TAH devices will afford biventricular replacement therapy to a wide range of patients, for both short and long-term therapy.
Collapse
Affiliation(s)
- Marvin J Slepian
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
| | | | | | | | | | | | | |
Collapse
|
34
|
Bluestein D, Girdhar G, Einav S, Slepian MJ. Device thrombogenicity emulation: a novel methodology for optimizing the thromboresistance of cardiovascular devices. J Biomech 2012; 46:338-44. [PMID: 23219278 DOI: 10.1016/j.jbiomech.2012.11.033] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 11/15/2012] [Indexed: 11/18/2022]
Abstract
Thrombotic complications with mechanical circulatory support (MCS) devices remain a critical limitation to their long-term use. Device-induced shear forces may enhance the thrombotic potential of MCS devices through chronic activation of platelets, with a known dose-time response of the platelets to the accumulated stress experienced while flowing through the device-mandating complex, lifelong anticoagulation therapy. To enhance the thromboresistance of these devices for facilitating their long-term use, a universal predictive methodology entitled device thrombogenicity emulation (DTE) was developed. DTE is aimed at optimizing the thromboresistance of any MCS device. It is designed to test device-mediated thrombogenicity, coupled with virtual design modifications, in an iterative approach. This disruptive technology combines in silico numerical simulations with in vitro measurements, by correlating device hemodynamics with platelet activity coagulation markers-before and after iterative design modifications aimed at achieving optimized thrombogenic performance. The design changes are first tested in the numerical domain, and the resultant device conditions are then emulated in a hemodynamic shearing device (HSD) in which platelet activity is measured under device emulated conditions. As such, DTE can be easily incorporated during the device research and development phase-achieving minimization of the device thrombogenicity before prototypes are built and tested thereby reducing the ultimate cost of preclinical and clinical trials. The robust capability of this predictive technology is demonstrated here in various MCS devices. The presented examples indicate the potential of DTE for reducing device thrombogenicity to a level that may obviate or significantly reduce the extent of anticoagulation currently mandated for patients implanted with MCS devices for safe long-term clinical use.
Collapse
Affiliation(s)
- Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8151, USA.
| | | | | | | |
Collapse
|
35
|
Computational evaluation of the thrombogenic potential of a hollow-fiber oxygenator with integrated heat exchanger during extracorporeal circulation. Biomech Model Mechanobiol 2012; 13:349-61. [PMID: 23053595 DOI: 10.1007/s10237-012-0445-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 09/21/2012] [Indexed: 10/27/2022]
Abstract
The onset of thromboembolic phenomena in blood oxygenators, even in the presence of adequate anticoagulant strategies, is a relevant concern during extracorporeal circulation (ECC). For this reason, the evaluation of the thrombogenic potential associated with extracorporeal membrane oxygenators should play a critical role into the preclinical design process of these devices. This study extends the use of computational fluid dynamics simulations to guide the hemodynamic design optimization of oxygenators and evaluate their thrombogenic potential during ECC. The computational analysis accounted for both macro- (i.e., vortex formation) and micro-scale (i.e., flow-induced platelet activation) phenomena affecting the performances of a hollow-fiber membrane oxygenator with integrated heat exchanger. A multiscale Lagrangian approach was adopted to infer the trajectory and loading history experienced by platelet-like particles in the entire device and in a repetitive subunit of the fiber bundles. The loading history was incorporated into a damage accumulation model in order to estimate the platelet activation state (PAS) associated with repeated passes of the blood within the device. Our results highlighted the presence of blood stagnation areas in the inlet section that significantly increased the platelet activation levels in particles remaining trapped in this region. The order of magnitude of PAS in the device was the same as the one calculated for the components of the ECC tubing system, chosen as a term of comparison for their extensive diffusion. Interpolating the mean PAS values with respect to the number of passes, we obtained a straightforward prediction of the thrombogenic potential as a function of the duration of ECC.
Collapse
|
36
|
Rowley JW, Finn AV, French PA, Jennings LK, Bluestein D, Gross PL, Freedman JE, Steinhubl SR, Zimmerman GA, Becker RC, Dauerman HL, Smyth SS. Cardiovascular devices and platelet interactions: understanding the role of injury, flow, and cellular responses. Circ Cardiovasc Interv 2012; 5:296-304. [PMID: 22511738 DOI: 10.1161/circinterventions.111.965426] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
37
|
Girdhar G, Xenos M, Alemu Y, Chiu WC, Lynch BE, Jesty J, Einav S, Slepian MJ, Bluestein D. Device thrombogenicity emulation: a novel method for optimizing mechanical circulatory support device thromboresistance. PLoS One 2012; 7:e32463. [PMID: 22396768 PMCID: PMC3292570 DOI: 10.1371/journal.pone.0032463] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 01/27/2012] [Indexed: 12/22/2022] Open
Abstract
Mechanical circulatory support (MCS) devices provide both short and long term hemodynamic support for advanced heart failure patients. Unfortunately these devices remain plagued by thromboembolic complications associated with chronic platelet activation--mandating complex, lifelong anticoagulation therapy. To address the unmet need for enhancing the thromboresistance of these devices to extend their long term use, we developed a universal predictive methodology entitled Device Thrombogenicity Emulation (DTE) that facilitates optimizing the thrombogenic performance of any MCS device--ideally to a level that may obviate the need for mandatory anticoagulation. DTE combines in silico numerical simulations with in vitro measurements by correlating device hemodynamics with platelet activity coagulation markers--before and after iterative design modifications aimed at achieving optimized thrombogenic performance. DTE proof-of-concept is demonstrated by comparing two rotary Left Ventricular Assist Devices (LVADs) (DeBakey vs HeartAssist 5, Micromed Houston, TX), the latter a version of the former following optimization of geometrical features implicated in device thrombogenicity. Cumulative stresses that may drive platelets beyond their activation threshold were calculated along multiple flow trajectories and collapsed into probability density functions (PDFs) representing the device 'thrombogenic footprint', indicating significantly reduced thrombogenicity for the optimized design. Platelet activity measurements performed in the actual pump prototypes operating under clinical conditions in circulation flow loops--before and after the optimization with the DTE methodology, show an order of magnitude lower platelet activity rate for the optimized device. The robust capability of this predictive technology--demonstrated here for attaining safe and cost-effective pre-clinical MCS thrombo-optimization--indicates its potential for reducing device thrombogenicity to a level that may significantly limit the extent of concomitant antithrombotic pharmacotherapy needed for safe clinical device use.
Collapse
Affiliation(s)
- Gaurav Girdhar
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Michalis Xenos
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Yared Alemu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Bryan E. Lynch
- MicroMed Cardiovascular Inc., Houston, Texas, United States of America
| | - Jolyon Jesty
- Department of Hematology, Stony Brook University, Stony Brook, New York, United States of America
| | - Shmuel Einav
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Marvin J. Slepian
- Sarver Heart Center, University of Arizona, Tucson, Arizona, United States of America
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| |
Collapse
|
38
|
Yun BM, Wu J, Simon HA, Arjunon S, Sotiropoulos F, Aidun CK, Yoganathan AP. A numerical investigation of blood damage in the hinge area of aortic bileaflet mechanical heart valves during the leakage phase. Ann Biomed Eng 2012; 40:1468-85. [PMID: 22215278 DOI: 10.1007/s10439-011-0502-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 12/23/2011] [Indexed: 11/25/2022]
Abstract
Previous experimental and numerical blood studies have shown that high shear stress levels, long exposure times to these shear stresses, and flow recirculation promote thromboembolism. Artificial heart valves, in particular bileaflet mechanical heart valves (BMHVs), are prone to developing thromboembolic complications. These complications often form at the hinge regions of BMHVs and the associated geometry has been shown to affect the local flow dynamics and the associated thrombus formation. However, to date no study has focused on simulating the motion of realistically modeled blood elements within the hinge region to numerically estimate the hinge-related blood damage. Consequently, this study aims at (a) simulating the motion of realistically modeled platelets during the leakage (mid-diastole) phase in different BMHV hinge designs placed in the aortic position and (b) quantitatively comparing the blood damage associated with different designs. Three designs are investigated to assess the effects of hinge geometry and dimensions: a 23 mm St. Jude Medical Regent™ valve hinge with two different gap distances between the leaflet ear and hinge recess; and a 23 mm CarboMedics (CM) aortic valve hinge. The recently developed lattice-Boltzmann method with external boundary force method is used to simulate the hinge flow and capture the dynamics and surface shear stresses of individual platelets. A blood damage index (BDI) value is then estimated based on a linear shear stress-exposure time BDI model. The velocity boundary conditions are obtained from previous 3D large-scale simulations of the hinge flow fields. The trajectories of the blood elements in the hinge region are found to be qualitatively similar for all three hinges, but the shear stresses experienced by individual platelets are higher for the CM hinge design, leading to a higher BDI. The results of this study are also shown to be in good agreement with previous studies, thus validating the numerical method for future research in BMHV flows. This study provides a general numerical tool to optimize the hinge design based on both hemodynamic and thromboembolic performance.
Collapse
Affiliation(s)
- B Min Yun
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Thrombogenic potential of Innovia polymer valves versus Carpentier-Edwards Perimount Magna aortic bioprosthetic valves. ASAIO J 2011; 57:26-31. [PMID: 20930618 DOI: 10.1097/mat.0b013e3181fcbd86] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Trileaflet polymeric prosthetic aortic valves (AVs) produce hemodynamic characteristics akin to the natural AV and may be most suitable for applications such as transcatheter implantation and mechanical circulatory support (MCS) devices. Their success has not yet been realized due to problems of calcification, durability, and thrombosis. We address the latter by comparing the platelet activation rates (PARs) of an improved polymer valve design (Innovia LLC) made from poly(styrene-block-isobutylene-block-styrene) (SIBS) with the commercially available Carpentier-Edwards Perimount Magna Aortic Bioprosthetic Valve. We used our modified prothrombinase platelet activity state (PAS) assay and flow cytometry methods to measure platelet activation of a pair of 19 mm valves mounted inside a pulsatile Berlin left ventricular assist device (LVAD). The PAR of the polymer valve measured with the PAS assay was fivefold lower than that of the tissue valve (p = 0.005) and fourfold lower with flow cytometry measurements (p = 0.007). In vitro hydrodynamic tests showed clinically similar performance of the Innovia and Magna valves. These results demonstrate a significant improvement in thrombogenic performance of the polymer valve compared with our previous study of the former valve design and encourage further development of SIBS for use in heart valve prostheses.
Collapse
|