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Tortuosity-powered microfluidic device for assessment of thrombosis and antithrombotic therapy in whole blood. Sci Rep 2020; 10:5742. [PMID: 32238835 PMCID: PMC7113244 DOI: 10.1038/s41598-020-62768-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 03/18/2020] [Indexed: 11/29/2022] Open
Abstract
Accurate assessment of blood thrombosis and antithrombotic therapy is essential for the management of patients in a variety of clinical conditions, including surgery and on extracorporeal life support. However, current monitoring devices do not measure the effects of hemodynamic forces that contribute significantly to coagulation, platelet function and fibrin formation. This limits the extent to which current assays can predict clotting status in patients. Here, we demonstrate that a biomimetic microfluidic device consisting stenosed and tortuous arteriolar vessels would analyze blood clotting under flow, while requiring a small blood volume. When the device is connected to an inline pressure sensor a clotting time analysis is applied, allowing for the accurate measurement of coagulation, platelets and fibrin content. Furthermore, this device detects a prolonged clotting time in clinical blood samples drawn from pediatric patients on extracorporeal membrane oxygenation receiving anticoagulant therapy. Thus, this tortuosity activated microfluidic device could lead to a more quantitative and rapid assessment of clotting disorders and their treatment.
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Meyer AD, Rishmawi AR, Kamucheka R, Lafleur C, Batchinsky AI, Mackman N, Cap AP. Effect of blood flow on platelets, leukocytes, and extracellular vesicles in thrombosis of simulated neonatal extracorporeal circulation. J Thromb Haemost 2020; 18:399-410. [PMID: 31628728 PMCID: PMC7350929 DOI: 10.1111/jth.14661] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/10/2019] [Indexed: 12/23/2022]
Abstract
BACKGROUND Extracorporeal membrane oxygenation (ECMO) has frequent and sometimes lethal thrombotic complications. The role that activated platelets, leukocytes, and small (0.3-micron to 1-micron) extracellular vesicles (EVs) play in ECMO thrombosis is not well understood. OBJECTIVES To test the effect of blood flow rate on the generation of activated platelets, leukocytes, and EVs in a simulated neonatal ECMO circuit using heparinized human whole blood. METHODS Simulated neonatal roller pump circuits circulated whole blood at low, nominal, and high flow rates (0.3, 0.5, and 0.7 L/min) for 6 h. Coagulopathy was defined by thromboelastography (TEG), STA® -procoagulant phospholipid clot time (STA®- Procoag-PPL), and calibrated automated thrombogram. High-resolution flow cytometry measured the cellular expression of prothrombotic phospholipids and proteins on platelets, leukocytes, and EV. RESULTS Despite heparinization, occlusive thrombosis halted flow in two of five circuits at 0.3 L/min and three of five circuits at 0.7 L/min. None of the five circuits at 0.5 L/min exhibited occlusive thrombosis. Phosphatidylserine (PS)-positive platelets and EVs increased at all flow rates more than blood under static conditions (P < .0002). Tissue factor (TF)-positive leukocytes and EVs increased only in low-flow and high-flow circuits (P < .0001). Tissue factor pathway inhibitor (TFPI), at 50 times more than the concentration in healthy adults, failed to suppress thrombin initiation in low-flow and high-flow circuits. CONCLUSIONS This in vitro study informs ECMO specialists to avoid low and high blood flow that increases TF expression on leukocytes and EVs, which likely initiate clot formation. Interventions to decrease TF generated by ECMO may be an effective approach to decrease thrombosis.
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Affiliation(s)
- Andrew D. Meyer
- Division of Pediatric Critical Care, Department of Pediatrics, University of Texas Health, San Antonio, Texas
- Coagulation and Blood Research, U.S. Army Institute of Surgical Research (USAISR), Ft. Sam Houston, Texas
| | - Anjana R. Rishmawi
- Division of Pediatric Critical Care, Department of Pediatrics, University of Texas Health, San Antonio, Texas
| | - Robin Kamucheka
- Coagulation and Blood Research, U.S. Army Institute of Surgical Research (USAISR), Ft. Sam Houston, Texas
| | - Crystal Lafleur
- Coagulation and Blood Research, U.S. Army Institute of Surgical Research (USAISR), Ft. Sam Houston, Texas
| | - Andriy I. Batchinsky
- Extracorporeal Life Support, U.S. Army Institute of Surgical Research (USAISR), Ft. Sam Houston, Texas
| | - Nigel Mackman
- Thrombosis and Hemostasis Program, Division of Hematology and Oncology, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Andrew P. Cap
- Coagulation and Blood Research, U.S. Army Institute of Surgical Research (USAISR), Ft. Sam Houston, Texas
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In Vitro Benchmarking Study of Ventricular Assist Devices in Current Clinical Use. J Card Fail 2020; 26:70-79. [DOI: 10.1016/j.cardfail.2019.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 09/24/2019] [Accepted: 09/28/2019] [Indexed: 01/26/2023]
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Coronary plaque erosion developing in an area of high endothelial shear stress: insights from serial optical coherence tomography imaging. Coron Artery Dis 2019; 30:74-75. [PMID: 30407208 DOI: 10.1097/mca.0000000000000673] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Mehta R, Athar M, Girgis S, Hassan A, Becker RC. Acquired Von Willebrand Syndrome (AVWS) in cardiovascular disease: a state of the art review for clinicians. J Thromb Thrombolysis 2019; 48:14-26. [PMID: 31004311 DOI: 10.1007/s11239-019-01849-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Von Willebrand Factor (vWF) is a large glycoprotein with a broad range of physiological and pathological functions in health and disease. While vWF is critical for normal hemostasis, vascular integrity and repair, quantitative and qualitative abnormalities in the molecule can predispose to serious bleeding and thrombosis. The heritable form of von Willebrand Disease was first described nearly a century ago, but more recently, recognition of an acquired condition known as acquired von Willebrand Syndrome (AVWF) has emerged in persons with hematological, endocrine and cardiovascular diseases, disorders and conditions. An in-depth understanding of the causes, diagnostic approach and management of AVWS is important for practicing clinicians.
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Affiliation(s)
- Radha Mehta
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Muhammad Athar
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Sameh Girgis
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Atif Hassan
- Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Richard C Becker
- Stonehill Professor of Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, CVC 4th Floor, Room 4936, Cincinnati, 45267, OH, USA.
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Shiraz Bhurwani MM, Waqas M, Podgorsak AR, Williams KA, Davies JM, Snyder K, Levy E, Siddiqui A, Ionita CN. Feasibility study for use of angiographic parametric imaging and deep neural networks for intracranial aneurysm occlusion prediction. J Neurointerv Surg 2019; 12:714-719. [DOI: 10.1136/neurintsurg-2019-015544] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/22/2019] [Accepted: 11/24/2019] [Indexed: 01/27/2023]
Abstract
BackgroundAngiographic parametric imaging (API), based on digital subtraction angiography (DSA), is a quantitative imaging tool that may be used to extract contrast flow parameters related to hemodynamic conditions in abnormal pathologies such as intracranial aneurysms (IAs).ObjectiveTo investigate the feasibility of using deep neural networks (DNNs) and API to predict IA occlusion using pre- and post-intervention DSAs.MethodsWe analyzed DSA images of IAs pre- and post-treatment to extract API parameters in the IA dome and the corresponding main artery (un-normalized data). We implemented a two-step correction to account for injection variability (normalized data) and projection foreshortening (relative data). A DNN was trained to predict a binary IA occlusion outcome: occluded/unoccluded. Network performance was assessed with area under the receiver operating characteristic curve (AUROC) and classification accuracy. To evaluate the effect of the proposed corrections, prediction accuracy analysis was performed after each normalization step.ResultsThe study included 190 IAs. The mean and median duration between treatment and follow-up was 9.8 and 8.0 months, respectively. For the un-normalized, normalized, and relative subgroups, the DNN average prediction accuracies for IA occlusion were 62.5% (95% CI 60.5% to 64.4%), 70.8% (95% CI 68.2% to 73.4%), and 77.9% (95% CI 76.2% to 79.6%). The average AUROCs for the same subgroups were 0.48 (0.44–0.52), 0.67 (0.61–0.73), and 0.77 (0.74–0.80).ConclusionsThe study demonstrated the feasibility of using API and DNNs to predict IA occlusion using only pre- and post-intervention angiographic information.
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Tricarico R, Tran-Son-Tay R, Laquian L, Scali ST, Lee TC, Beck AW, Berceli SA, He Y. Haemodynamics of Different Configurations of a Left Subclavian Artery Stent Graft for Thoracic Endovascular Aortic Repair. Eur J Vasc Endovasc Surg 2019; 59:7-15. [PMID: 31761570 DOI: 10.1016/j.ejvs.2019.06.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/16/2019] [Accepted: 06/09/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Branched stent grafts represent a viable option for left subclavian artery (LSA) revascularisation in patients treated by thoracic endovascular aortic repair (TEVAR) for Zone 2 lesions. This study investigated the haemodynamic performance of different LSA branched stent graft configurations as potential determinants of thrombotic and stroke risks. METHODS A three dimensional aortic arch geometry extracted from post-operative computed tomography images of a TEVAR patient using a single LSA branched aortic endograft was modified in silico to obtain ten potential LSA branched stent graft configurations: five down facing (0-5 - 10 mm aortic protrusion with 10-12 mm internal diameter), four curved (30-60° with antegrade/retrograde orientation), and one LSA orifice misalignment. The 0 mm down facing stent graft was considered base configuration. Computational fluid dynamic analyses were performed to identify differences in pressure, energy, and wall shear stress (WSS) based parameters. RESULTS Total pressure drop and energy loss variations among configurations were not greater than 5 mmHg (6% of mean arterial pressure) and 5.7 mW (0.7% of cardiac power), respectively. Protrusions up to 5 mm created clinically insignificant flow disturbances. However, stent graft protrusions further into the aortic lumen created more complex haemodynamics, characterised by larger energy loss and more prominent flow recirculation. Protrusion greater than 5 mm into the lumen was associated with larger areas of elevated maximum WSS (>20 Pa) along the outer surface of the branched stent graft. CONCLUSION Arterial haemodynamic characteristics are affected by LSA branched stent graft configurations, with pressure drops and energy losses likely to be clinically insignificant. The length of the stent graft protrusion into the aortic lumen generated the largest haemodynamic variations in the aortic system. Protrusions up to 5 mm have smaller risk of potential thrombus generation. Conversely, larger protrusions into the aortic lumen showed more disturbed haemodynamics, suggesting a greater risk of potential thrombus formation, which may be clinically important over time.
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Affiliation(s)
- Rosamaria Tricarico
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Roger Tran-Son-Tay
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Liza Laquian
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA
| | - Salvatore T Scali
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA; North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - Teng-Chun Lee
- Division of Thoracic and Cardiovascular Surgery, University of Florida, Gainesville, FL, USA
| | - Adam W Beck
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA
| | - Scott A Berceli
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA; North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA.
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Kim D, Bresette C, Liu Z, Ku DN. Occlusive thrombosis in arteries. APL Bioeng 2019; 3:041502. [PMID: 31768485 PMCID: PMC6863762 DOI: 10.1063/1.5115554] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/16/2019] [Indexed: 12/18/2022] Open
Abstract
Thrombus formation in major arteries is life threatening. In this review article, we discuss how an arterial thrombus can form under pathologically high shear stresses, with bonding rates estimated to be the fastest Kon values in biochemistry. During occlusive thrombosis in arteries, the growth rate of the thrombus explodes to capture a billion platelets in about 10 min. Close to 100% of all platelets passing the thrombus are captured by long von Willebrand factor (vWF) strands that quickly form tethered nets. The nets grow in patches where shear stress is high, and the local concentration of vWF is elevated due to α-granule release by previously captured platelets. This rapidly formed thrombus has few red blood cells and so has a white appearance and is much stronger and more porous than clots formed through coagulation. Understanding and modeling the biophysics of this event can predict totally new approaches to prevent and treat heart attacks and strokes.
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Affiliation(s)
- Dongjune Kim
- GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA
| | - Christopher Bresette
- GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA
| | - Zixiang Liu
- GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA
| | - David N Ku
- GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA
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van Rooij BJM, Závodszky G, Azizi Tarksalooyeh VW, Hoekstra AG. Identifying the start of a platelet aggregate by the shear rate and the cell-depleted layer. J R Soc Interface 2019; 16:20190148. [PMID: 31575344 PMCID: PMC6833312 DOI: 10.1098/rsif.2019.0148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Computer simulations were performed to study the transport of red blood cells and platelets in high shear flows, mimicking earlier published in vitro experiments in microfluidic devices with high affinity for platelet aggregate formation. The goal is to understand and predict where thrombus formation starts. Additionally, the need of cell-based modelling in these microfluidic devices is demonstrated by comparing our results with macroscopic models, wherein blood is modelled as a continuous fluid. Hemocell, a cell-based blood flow simulation framework is used to investigate the transport physics in the microfluidic devices. The simulations show an enlarged cell-depleted layer at the site where a platelet aggregate forms in the experiments. In this enlarged cell-depleted layer, the probability to find a platelet is higher than in the rest of the microfluidic device. In addition, the shear rates are sufficiently high to allow for the von Willebrand factor to elongate in this region. We hypothesize that the enlarged cell-depleted layer combined with a sufficiently large platelet flux and sufficiently high shear rates result in an haemodynamic environment that is a preferred location for initial platelet aggregation.
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Affiliation(s)
- B J M van Rooij
- Computational Science, Institute for Informatics, University of Amsterdam, Amsterdam, The Netherlands
| | - G Závodszky
- Computational Science, Institute for Informatics, University of Amsterdam, Amsterdam, The Netherlands
| | - V W Azizi Tarksalooyeh
- Computational Science, Institute for Informatics, University of Amsterdam, Amsterdam, The Netherlands
| | - A G Hoekstra
- Computational Science, Institute for Informatics, University of Amsterdam, Amsterdam, The Netherlands
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60
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Steiger T, Foltan M, Philipp A, Mueller T, Gruber M, Bredthauer A, Krenkel L, Birkenmaier C, Lehle K. Accumulations of von Willebrand factor within ECMO oxygenators: Potential indicator of coagulation abnormalities in critically ill patients? Artif Organs 2019; 43:1065-1076. [PMID: 31192471 PMCID: PMC6899554 DOI: 10.1111/aor.13513] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022]
Abstract
Clot formation within membrane oxygenators (MOs) remains a critical problem during extracorporeal membrane oxygenation (ECMO). The composition of the clots-in particular, the presence of von Willebrand factor (vWF)-may be an indicator for prevalent nonphysiological flow conditions, foreign body reactions, or coagulation abnormalities in critically ill patients. Mats of interwoven gas exchange fibers from randomly collected MOs (PLS, Maquet, Rastatt, Germany) of 21 patients were stained with antibodies (anti-vWF and anti-P-selectin) and counterstained with 4',6-diamidino-2-phenylindole. The extent of vWF-loading was correlated with patient and technical data. While 12 MOs showed low vWF-loadings, 9 MOs showed high vWF-loading with highest accumulations close to crossing points of adjacent gas fibers. The presence and the extent of vWF-fibers/"cobwebs," leukocytes, platelet-leukocyte aggregates (PLAs), and P-selectin-positive platelet aggregates were independent of the extent of vWF-loading. However, the highly loaded MOs were obtained from patients with a significantly elevated SOFA score, severe thrombocytopenia, and persistent liver dysfunction. The coagulation abnormalities of these critically ill patients may cause an accumulation of the highly thrombogenic and elongated high-molecular-weight vWF multimers in the plasma which will be trapped in the MOs during the ECMO therapy.
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Affiliation(s)
- Tamara Steiger
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, Regensburg, Germany
| | - Maik Foltan
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, Regensburg, Germany
| | - Alois Philipp
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, Regensburg, Germany
| | - Thomas Mueller
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Michael Gruber
- Department of Anesthesiology, University Medical Center Regensburg, Regensburg, Germany
| | - Andre Bredthauer
- Department of Anesthesiology, University Medical Center Regensburg, Regensburg, Germany
| | - Lars Krenkel
- Regensburg Center of Biomedical Engineering, Ostbayerische Technische Hochschule, Regensburg, Germany
| | - Clemens Birkenmaier
- Regensburg Center of Biomedical Engineering, Ostbayerische Technische Hochschule, Regensburg, Germany
| | - Karla Lehle
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, Regensburg, Germany
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Modeling sensitivity and uncertainties in platelet activation models applied on centrifugal pumps for extracorporeal life support. Sci Rep 2019; 9:8809. [PMID: 31217491 PMCID: PMC6584555 DOI: 10.1038/s41598-019-45121-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 05/29/2019] [Indexed: 11/08/2022] Open
Abstract
Two platelet activation models were studied with respect to uncertainties of model parameters and variables. The sensitivity was assessed using two direct/deterministic approaches as well as the statistical Monte Carlo method. The first two, are linear in character whereas the latter is non-linear. The platelet activation models were applied on platelets moving within an extracorporeal centrifugal blood pump. The phenomenological, Lagrangian stress- and time-based power law-based models under consideration, have experimentally calibrated parameters and the stress expressed in a scalar form. The sensitivity of the model with respect to model parameters and the expression of the scalar stress was examined focusing on a smaller group of platelets associated with an elevated risk of activation. The results showed a high disparity between the models in terms of platelet activation state, found to depend on the platelets’ trajectory in the pump and the expression used for the scalar stress. Monte Carlo statistics was applied to the platelets at risk for activation and not to the entire platelet population. The method reveals the non-linear sensitivity of the activation models. The results imply that power-law based models have a restricted range of validity. The conclusions of this study apply to both platelet activation and hemolysis models.
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Microfluidic and computational study of structural properties and resistance to flow of blood clots under arterial shear. Biomech Model Mechanobiol 2019; 18:1461-1474. [PMID: 31055691 PMCID: PMC6748893 DOI: 10.1007/s10237-019-01154-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 04/20/2019] [Indexed: 01/01/2023]
Abstract
The ability of a blood clot to modulate blood flow is determined by the clot’s resistance, which depends on its structural features. For a flow with arterial shear, we investigated the characteristic patterns relating to clot shape, size, and composition on the one hand, and its viscous resistance, intraclot axial flow velocity, and shear distributions on the other. We used microfluidic technology to measure the kinetics of platelet, thrombin, and fibrin accumulation at a thrombogenic surface coated with collagen and tissue factor (TF), the key clot-formation trigger. We subsequently utilized the obtained data to perform additional calibration and validation of a detailed computational fluid dynamics model of spatial clot growth under flow. We then ran model simulations to gain insights into the resistance of clots formed under our experimental conditions. We found that increased thrombogenic surface length and TF surface density enhanced the bulk thrombin and fibrin generation in a nonadditive, synergistic way. The height of the platelet deposition domain—and, therefore, clot occlusivity—was rather robust to thrombogenic surface length and TF density variations, but consistently increased with time. Clot viscous resistance was non-uniform and tended to be higher in the fibrin-rich, inner “core” region of the clot. Interestingly, despite intraclot structure and viscous resistance variations, intraclot flow velocity variations were minor compared to the abrupt decrease in flow velocity around the platelet deposition region. Our results shed new light on the connection between the structure of clots under arterial shear and spatiotemporal variations in their resistance to flow.
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Konnigk L, Torner B, Hallier S, Witte M, Wurm FH. Grid-Induced Numerical Errors for Shear Stresses and Essential Flow Variables in a Ventricular Assist Device: Crucial for Blood Damage Prediction? ACTA ACUST UNITED AC 2019. [DOI: 10.1115/1.4042989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adverse events due to flow-induced blood damage remain a serious problem for blood pumps as cardiac support systems. The numerical prediction of blood damage via computational fluid dynamics (CFD) is a helpful tool for the design and optimization of reliable pumps. Blood damage prediction models primarily are based on the acting shear stresses, which are calculated by solving the Navier–Stokes equations on computational grids. The purpose of this paper is to analyze the influence of the spatial discretization and the associated discretization error on the shear stress calculation in a blood pump in comparison to other important flow quantities like the pressure head of the pump. Therefore, CFD analysis using seven unsteady Reynolds-averaged Navier–Stokes (URANS) simulations was performed. Two simple stress calculation indicators were applied to estimate the influence of the discretization on the results using an approach to calculate numerical uncertainties, which indicates discretization errors. For the finest grid with 19 × 106 elements, numerical uncertainties up to 20% for shear stresses were determined, while the pressure heads show smaller uncertainties with a maximum of 4.8%. No grid-independent solution for velocity gradient-dependent variables could be obtained on a grid size that is comparable to mesh sizes in state-of-the-art blood pump studies. It can be concluded that the grid size has a major influence on the shear stress calculation, and therefore, the potential blood damage prediction, and that the quantification of this error should always be taken into account.
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Affiliation(s)
- Lucas Konnigk
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Straße 2, Rostock 18055, Germany e-mail:
| | - Benjamin Torner
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Straße 2, Rostock 18055, Germany e-mail:
| | - Sebastian Hallier
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Straße 2, Rostock 18055, Germany e-mail:
| | - Matthias Witte
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Straße 2, Rostock 18055, Germany e-mail:
| | - Frank-Hendrik Wurm
- Institute of Turbomachinery, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Albert-Einstein-Straße 2, Rostock 18055, Germany e-mail:
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Vu V, May-Newman K. Bileaflet Prosthesis Design and Orientation Affect Fluid Shear, Residence Time, and Thrombus Formation. J Cardiothorac Vasc Anesth 2019; 33:2870-2872. [PMID: 31060942 DOI: 10.1053/j.jvca.2019.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/08/2019] [Accepted: 03/09/2019] [Indexed: 11/11/2022]
Abstract
The orientation and design of bileaflet valve prosthesis in the mitral position affects the intraventricular blood flow and exposure to shear. The combination of the anatomic orientation and a small gap size of the St. Jude Medical valve produces an increase in shear exposure and blood residence time, which both predispose the formation of thrombus in the high shear gaps of the valve hinges.
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Affiliation(s)
- Vi Vu
- Bioengineering Program, Dept. of Mechanical Engineering, San Diego State University, San Diego, CA
| | - Karen May-Newman
- Bioengineering Program, Dept. of Mechanical Engineering, San Diego State University, San Diego, CA.
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Erol S, Aydın B, Cinar HG, Yoldas T, Zenciroglu A. Arterial Thrombosis Secondary to Cardiac Catheterization in Neonates. DICLE MEDICAL JOURNAL 2019. [DOI: 10.5798/dicletip.534847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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66
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Stenosis Indicators Applied to Patient-Specific Renal Arteries without and with Stenosis. FLUIDS 2019. [DOI: 10.3390/fluids4010026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pulsatile flow in the abdominal aorta and the renal arteries of three patients was studied numerically. Two of the patients had renal artery stenosis. The aim of the study was to assess the use of four types of indicators for determining the risk of new stenosis after revascularization of the affected arteries. The four indicators considered include the time averaged wall shear stress (TAWSS), the oscillatory shear index (OSI), the relative reference time (RRT) and a power law model based in platelet activation modeling but applied to the endothelium, named endothelium activation indicator (EAI). The results show that the indicators can detect the existing stenosis but are less successful in the revascularized cases. The TAWSS and, more clearly, the EAI approach seem to be better in predicting the risk for stenosis relapse at the original location and close to the post-stenotic dilatation. The shortcomings of the respective indicators are discussed along with potential improvements to endothelial activation modeling and its use as an indicator for risks of restenosis.
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Lawson PJ, Moore HB, Moore EE, Gerich ME, Stettler GR, Banerjee A, Schulick RD, Nydam TL. Microfluidics contrasted to thrombelastography: perplexities in defining hypercoagulability. J Surg Res 2018; 231:54-61. [PMID: 30278969 DOI: 10.1016/j.jss.2018.04.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/07/2018] [Accepted: 04/24/2018] [Indexed: 01/22/2023]
Abstract
BACKGROUND Elevated clot strength (maximum amplitude [MA]) measured by thrombelastography (TEG) is associated with thrombotic complications. However, it remains unclear how MA translates to thrombotic risks, as this measurement is independent of time, blood flow, and clot degradation. We hypothesize that under flow conditions, increased clot strength correlates to time-dependent measurements of coagulation and resistance to fibrinolysis. MATERIALS AND METHODS Surgical patients at high risk of thrombotic complications were analyzed with TEG and total thrombus-formation analysis system (T-TAS). TEG hypercoagulability was defined as an r <10.2 min, angle >59, MA >66 or LY30 <0.2% (based off of healthy control data, n = 141). The T-TAS AR and PL chips were used to measure clotting at arterial shear rates. T-TAS measurements include occlusion start time, occlusion time (OT), occlusion speed (OSp), and total clot generation (area under the curve). These measurements were correlated to TEG indices (R time, angle, MA, and LY30). Both T-TAS and TEG assays were challenged with tissue plasminogen activator (t-PA) to assess clot resistance to fibrinolysis. RESULTS Thirty subjects were analyzed, including five controls. TEG-defined hypercoagulability by MA was detected in 52% of the inflammatory bowel disease/cancer patients; 0% was detected in the controls. There were no TEG measurements that significantly correlated with T-TAS AR and PL chip. However, in the presence of t-PA, T-TAS AR determined OSp to have an inverse relationship with TEG angle (-0.477, P = 0.012) and LY30 (-0.449, P = 0.019), and a positive correlation with R time (0.441 P = 0.021). In hypercoagulability determined by TEG MA, T-TAS PL had a significantly reduced OT (4:07 versus 6:27 min, P = 0.043). In hypercoagulability defined by TEG LY30, T-TAS PL had discordant findings, with a significantly prolonged OT (6:36 versus 4:30 min, P = 0.044) and a slower OSp (10.5 versus 19.0 kPa/min, P = 0.030). CONCLUSIONS Microfluidic coagulation assessment with T-TAS has an overall poor correlation with most TEG measurements in a predominantly hypercoagulable patient population, except in the presence of t-PA. The one anticipated finding was an elevated MA having a shorter time to platelet-mediated microfluidic occlusion, supporting the role of platelets and hypercoagulability. However, hypercoagulability defined by LY30 had opposing results in which a low LY30 was associated with a longer PL time to occlusion and slower OSp. These discordant findings warrant ongoing investigation into the relationship between clot strength and fibrinolysis under different flow conditions.
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Affiliation(s)
- Peter J Lawson
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado
| | - Hunter B Moore
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado.
| | - Ernest E Moore
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado; Denver Health Medical Center, Denver, Colorado
| | - Mark E Gerich
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Gregory R Stettler
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado
| | - Anirban Banerjee
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado
| | - Richard D Schulick
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado
| | - Trevor L Nydam
- Department of Surgery, University of Colorado School of Medicine, Aurora, Colorado
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Flow-induced platelet activation in components of the extracorporeal membrane oxygenation circuit. Sci Rep 2018; 8:13985. [PMID: 30228350 PMCID: PMC6143512 DOI: 10.1038/s41598-018-32247-y] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/29/2018] [Indexed: 11/23/2022] Open
Abstract
Extracorporeal membrane oxygenation (ECMO) is used for rescue in severe respiratory and/or circulatory failure. The patient’s blood is pumped over artificial surfaces in the ECMO circuit. A platelet activation model was applied to study the potential thrombogenicity of ECMO circuit components: the centrifugal blood pump, cannulae, and tubing connectors. Based on the accumulated effect of the scalar form of the stress acting on the platelet over time, the activation model enables assessment of platelet activation and pinpoints regions of elevated activation risk in a component. Numerical simulations of the flow in different components of the ECMO circuit was carried out where the activation level is a function of the impact of local stress and its history along the path that the platelets follow. The results showed that the pump carried the largest risk for platelet activation followed by the reinfusion cannula and lastly the connectors. Pump thrombogenicity was mainly due to long residence time and high shear-rate while the connector showed a high level of non-stationary shear-rate that in turn may contribute to the formation of aggregates through direct platelet activation or through high shear-rate modulation of the vWF multimers.
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Bi L, Wacker BK, Dichek DA. A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts. J Vis Exp 2018. [PMID: 30247462 DOI: 10.3791/57231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.
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Affiliation(s)
- Lianxiang Bi
- Department of Medicine, University of Washington School of Medicine
| | - Bradley K Wacker
- Department of Medicine, University of Washington School of Medicine
| | - David A Dichek
- Department of Medicine, University of Washington School of Medicine;
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Rizzi M, Albisetti M. Treatment of arterial thrombosis in children: Methods and mechanisms. Thromb Res 2018; 169:113-119. [DOI: 10.1016/j.thromres.2018.07.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 07/05/2018] [Indexed: 12/17/2022]
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Goubergrits L, Kertzscher U, Lommel M. Past and future of blood damage modelling in a view of translational research. Int J Artif Organs 2018; 42:125-132. [PMID: 30073891 DOI: 10.1177/0391398818790343] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Anatomic pathologies such as stenosed or regurgitating heart valves and artificial organs such as heart assist devices or heart valve prostheses are associated with non-physiological flow. This regime is associated with regions of spatially high-velocity gradients, high-velocity and/or pressure fluctuations as well as neighbouring regions with stagnant flow associated with high residence time. These hemodynamic conditions cause destruction and/or activation of blood components and their accumulation in regions with high residence time. The development of next-generation artificial organs, which allow long-term patient care by reducing adverse events and improve quality of life, requires the development of blood damage models serving as a cost function for device optimization. We summarized the studies underlining the key findings with subsequent elaboration of the requirements for blood damage models as well as a decision tree based on the classification of existing blood damage models. The four major classes are Lagrangian or Eulerian approaches with stress- or strain-based blood damage. Key challenges were identified and future steps towards the translation of blood damage models into the device development pipeline were formulated. The integration of blood damage caused by turbulence into models as well as in vitro and in vivo validation of models remain the major challenges for future developments. Both require the development of novel experimental setups to provide reliable and well-documented experimental data.
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Affiliation(s)
- Leonid Goubergrits
- Institute for Computational and Imaging Science in Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ulrich Kertzscher
- Institute for Computational and Imaging Science in Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Lommel
- Institute for Computational and Imaging Science in Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
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