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Effect of Pulsatility on the Transport of Thrombin in an Idealized Cerebral Aneurysm Geometry. Symmetry (Basel) 2022. [DOI: 10.3390/sym14010133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Computational models of cerebral aneurysm thrombosis are designed for use in research and clinical applications. A steady flow assumption is applied in many of these models. To explore the accuracy of this assumption a pulsatile-flow thrombin-transport computational fluid dynamics (CFD) model, which uses a symmetrical idealized aneurysm geometry, was developed. First, a steady-flow computational model was developed and validated using data from an in vitro experiment, based on particle image velocimetry (PIV). The experimental data revealed an asymmetric flow pattern in the aneurysm. The validated computational model was subsequently altered to incorporate pulsatility, by applying a data-derived flow function at the inlet boundary. For both the steady and pulsatile computational models, a scalar function simulating thrombin generation was applied at the aneurysm wall. To determine the influence of pulsatility on thrombin transport, the outputs of the steady model were compared to the outputs of the pulsatile model. The comparison revealed that in the pulsatile case, an average of 10.2% less thrombin accumulates within the aneurysm than the steady case for any given time, due to periodic losses of a significant amount of thrombin-concentrated blood from the aneurysm into the parent vessel’s bloodstream. These findings demonstrate that pulsatility may change clotting outcomes in cerebral aneurysms.
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Tang TQ, Hsu SY, Dahiya A, Soh CH, Lin KC. Numerical modeling of pulsatile blood flow through a mini-oxygenator in artificial lungs. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 208:106241. [PMID: 34247118 DOI: 10.1016/j.cmpb.2021.106241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/12/2021] [Indexed: 06/13/2023]
Abstract
While previous in vitro studies showed divergent results concerning the influence of pulsatile blood flow on oxygen advection in oxygenators, no study was done to investigate the uncertainty affected by blood flow dynamics. The aim of this study is to utilize a computational fluid dynamics model to clarify the debate concerning the influence of pulsatile blood flow on the oxygen transport. The computer model is based on a validated 2D finite volume approach that predicts oxygen transfer in pulsatile blood flow passing through a 300-micron hollow-fiber membrane bundle with a length of 254 mm, a building block for an artificial lung device. In this study, the flow parameters include the steady Reynolds number (Re = 2, 5, 10 and 20), Womersley parameter (Wo = 0.29, 0.38 and 0.53) and sinusoidal amplitude (A = 0.25, 0.5 and 0.75). Specifically, the computer model is extended to verify, for the first time, the previously measured O2 transport that was observed to be hindered by pulsating flow in the Biolung, developed by Michigan Critical Care Consultants. A comprehensive analysis is carried out on computed profiles and fields of oxygen partial pressure (PO2) and oxygen saturation (SO2) as a function of Re, Wo and A. Based on the present results, we observe the positive and negative effects of pulsatile flow on PO2 at different blood flow rates. Besides, the SO2 variation is not much influenced by the pulsatile flow conditions investigated. While being consistent with a recent experimental study, the computed O2 volume flow rate is found to be increased at high blood flow rates operated with low frequency and high amplitude. Furthermore, the present study qualitatively explains that divergent outcomes reported in previous in vitro experimental studies could be owing to the different blood flow rates adopted. Finally, the contour analysis reveals how the spatial distributions of PO2 and SO2 vary over time.
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Affiliation(s)
- Tao-Qian Tang
- Department of Internal Medicine, E-Da Hospital/I-Shou University, Kaohsiung 82445, Taiwan; School of Medicine, College of Medicine, I-Shou University, Kaohsiung 82445, Taiwan; International Intercollegiate Ph.D. Program, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sheng-Yen Hsu
- Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
| | - Anurag Dahiya
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chang Hwei Soh
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Kuang C Lin
- International Intercollegiate Ph.D. Program, National Tsing Hua University, Hsinchu 30013, Taiwan; Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan; Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
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Wang T, Zhou Z, Liang F. Influences of Anatomorphological Features of the Portal Venous System on Postsplenectomy Hemodynamic Characteristics in Patients With Portal Hypertension: A Computational Model-Based Study. Front Physiol 2021; 12:661030. [PMID: 33912074 PMCID: PMC8072460 DOI: 10.3389/fphys.2021.661030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Splenectomy, as an effective surgery for relieving complications caused by portal hypertension, is often accompanied by a significantly increased incidence of postoperative thrombosis in the portal venous system (PVS). While the underlying mechanisms remain insufficiently understood, the marked changes in hemodynamic conditions in the PVS following splenectomy have been suggested to be a potential contributing factor. The aim of this study was to investigate the influences of the anatomorphological features of the PVS on hemodynamic characteristics before and after splenectomy, with emphasis on identifying the specific anatomorphological features that make postoperative hemodynamic conditions more clot-promoting. For this purpose, idealized computational hemodynamics models of the PVS were constructed based on general anatomical structures and population-averaged geometrical parameters of the PVS. In the models, we incorporated various anatomorphological variations to represent inter-patient variability. The analyses of hemodynamic data were focused on the spatial distribution of wall shear stress (WSS) and the area ratio of wall regions exposed to low WSS (ALS). Obtained results showed that preoperative hemodynamic conditions were comparable among different models in terms of space-averaged WSS and ALS (all were small) irrespective of the considerable differences in spatial distribution of WSS, whereas, the inter-model differences in ALS were significantly augmented after splenectomy, with the value of ALS reaching up to over 30% in some models, while being smaller than 15% in some other models. Postoperative ALS was mainly determined by the anatomical structure of the PVS, followed by some morphogeometrical parameters, such as the diameter and curvature of the splenic vein, and the distance between the inferior mesenteric vein and splenoportal junction. Relatively, the angles between tributary veins and trunk veins only had mild influences on ALS. In addition, a marked increase in blood viscosity was predicted after splenectomy, especially in regions with low WSS, which may play an additive role to low WSS in initiating thrombosis. These findings suggest that the anatomical structure and some morphogeometrical features of the PVS are important determinants of hemodynamic conditions following splenectomy, which may provide useful clues to assessing the risk of postsplenectomy thrombosis based on medical imaging data.
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Affiliation(s)
- Tianqi Wang
- State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zunqiang Zhou
- Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Fuyou Liang
- State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Hydrodynamics (Ministry of Education), School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China
- World-Class Research Center “Digital Biodesign and Personalized Healthcare,” Sechenov First Moscow State Medical University, Moscow, Russia
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Complications in children with ventricular assist devices: systematic review and meta-analyses. Heart Fail Rev 2021; 27:903-913. [PMID: 33661404 DOI: 10.1007/s10741-021-10093-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/23/2021] [Indexed: 10/22/2022]
Abstract
Heart failure is a significant cause of mortality in children with cardiovascular diseases. Treatment of heart failure depends on patients' symptoms, age, and severity of their condition, with heart transplantation required when other treatments are unsuccessful. However, due to lack of fitting donor organs, many patients are left untreated, or their transplant is delayed. In these patients, ventricular assist devices (VADs) are used to bridge to heart transplant. However, VAD support presents various complications in patients. The aim of this study was to compile, review, and analyse the studies reporting risk factors and aetiologies of complications of VAD support in children. Random effect risk ratios (RR) with 95% confidence intervals were calculated to analyse relative risk of thrombosis (RR = 3.53 [1.04, 12.06] I2 = 0% P = 0.04), neurological problems (RR = 0.95 [0.29, 3.15] I2 = 53% P = 0.93), infection (RR = 0.31 [0.05, 2.03] I2 = 86% P = 0.22), bleeding (RR = 2.57 [0.76, 8.66] I2 = 0% P = 0.13), and mortality (RR = 2.20 [1.36, 3.55] I2 = 0% P = 0.001) under pulsatile-flow and continuous-flow VAD support, relative risk of mortality (RR = 0.45 [0.15, 1.37] I2 = 36% P = 0.16) under left VAD and biVAD support, relative risk of thrombosis (RR = 1.72 [0.46, 6.44] I2 = 0% P = 0.42), infection (RR = 1.77 [0.10, 32.24] I2 = 46% P = 0.70) and mortality (RR = 0.92 [0.14, 6.28] I2 = 45% P = 0.93) in children with body surface area < 1.2 m2 and > 1.2 m2 under VAD support, relative risk of mortality in children supported with VAD and diagnosed with cardiomyopathy and congenital heart diseases (RR = 1.31 [0.10, 16.61] I2 = 73% P = 0.84), and cardiomyopathy and myocarditis (RR = 0.91 [0.13, 6.24] I2 = 58% P = 0.92). Meta-analyses results show that further research is necessary to reduce complications under VAD support.
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Lewis AL, Caine M, Garcia P, Ashrafi K, Tang Y, Hinchcliffe L, Guo W, Bascal Z, Kilpatrick H, Willis SL. Handling and performance characteristics of a new small caliber radiopaque embolic microsphere. J Biomed Mater Res B Appl Biomater 2020; 108:2878-2888. [PMID: 32578348 PMCID: PMC7496950 DOI: 10.1002/jbm.b.34619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 03/19/2020] [Accepted: 04/13/2020] [Indexed: 12/24/2022]
Abstract
The in vitro and in vivo handling and performance characteristics of a small caliber radiopaque embolic microsphere, 40–90 μm DC Bead LUMI™ (LUMI40‐90), were studied. Microsphere drug loading and elution and effects on size, suspension, and microcatheter delivery were evaluated using established in vitro methodologies. In vivo evaluations of vascular penetration (rabbit renal artery embolization), long‐term biocompatibility and X‐ray imaging properties, pharmacokinetics and local tissue effects of both doxorubicin (Dox) and irinotecan (Iri) loaded microspheres (swine hepatic artery embolization) were conducted. Compared to 70–150 μm DC Bead LUMI (LUMI70‐150), LUMI40‐90 averaged 70 μm versus 100 μm, which was unchanged upon drug loading. Handling, suspension, and microsphere delivery studies were successfully performed. Dox loading was faster (20 min) and Iri equivalent (<10 min) while drug elution rates were similar. Contrast suspension times were longer with no delivery complications. Vascular penetration was statistically greater (rabbit) with no unexpected adverse safety findings (swine). Microspheres ± drug were visible under X‐ray imaging (CT) at 90 days. Peak plasma drug levels and area under the curve were greater for LUMI40‐90 compared to LUMI70‐150 but comparable to 70–150 μm DC BeadM1™ (DC70‐150). Local tissue effects showed extensive hepatic necrosis for Dox, whereas Iri displayed lower toxicity with more pronounced lobar fibrosis. LUMI40‐90 remains suspended for longer and have greater vessel penetration compared to the other DC Bead LUMI sizes and are similarly highly biocompatible with long‐term visibility under X‐ray imaging. Drug loading is equivalent or faster with pharmacokinetics similar to DC70‐150 for both Dox and Iri.
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Affiliation(s)
- Andrew L Lewis
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Marcus Caine
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Pedro Garcia
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Koorosh Ashrafi
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Yiqing Tang
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Lorcan Hinchcliffe
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Wei Guo
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Zainab Bascal
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Hugh Kilpatrick
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
| | - Sean L Willis
- Biocompatibles UK Ltd., a BTG International Group Company, Camberley, Surrey, UK
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Goode D, Dhaliwal R, Mohammadi H. Transcatheter Mitral Valve Replacement: State of the Art. Cardiovasc Eng Technol 2020; 11:229-253. [DOI: 10.1007/s13239-020-00460-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
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7
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Sarode DN, Roy S. In Vitro models for thrombogenicity testing of blood-recirculating medical devices. Expert Rev Med Devices 2019; 16:603-616. [PMID: 31154869 DOI: 10.1080/17434440.2019.1627199] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Blood-recirculating medical devices, such as mechanical circulatory support (MCS), extracorporeal membrane oxygenators (ECMO), and hemodialyzers, are commonly used to treat or improve quality of life in patients with cardiac, pulmonary, and renal failure, respectively. As part of their regulatory approval, guidelines for thrombosis evaluation in pre-clinical development have been established. In vitro testing evaluates a device's potential to produce thrombosis markers in static and dynamic flow loops. AREAS COVERED This review focuses on in vitro static and dynamic models to assess thrombosis in blood-recirculating medical devices. A summary of key devices is followed by a review of molecular markers of contact activation. Current thrombosis testing guidance documents, ISO 10993-4, ASTM F-2888, and F-2382 will be discussed, followed by analysis of their application to in vitro testing models. EXPERT OPINION In general, researchers have favored in vivo models to thoroughly evaluate thrombosis, limiting in vitro evaluation to hemolysis. In vitro studies are not standardized and it is often difficult to compare studies on similar devices. As blood-recirculating devices have advanced to include wearable and implantable artificial organs, expanded guidelines standardizing in vitro testing are needed to identify the thrombotic potential without excessive use of in vivo resources during pre-clinical development.
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Affiliation(s)
- Deepika N Sarode
- a Department of Bioengineering and Therapeutic Sciences , University of California , San Francisco , CA , USA
| | - Shuvo Roy
- a Department of Bioengineering and Therapeutic Sciences , University of California , San Francisco , CA , USA
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8
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Schraven L, Kaesler A, Flege C, Kopp R, Schmitz-Rode T, Steinseifer U, Arens J. Effects of Pulsatile Blood Flow on Oxygenator Performance. Artif Organs 2018; 42:410-419. [DOI: 10.1111/aor.13088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/01/2017] [Accepted: 11/02/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Lotte Schraven
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering; RWTH Aachen University; Aachen Germany
| | - Andreas Kaesler
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering; RWTH Aachen University; Aachen Germany
| | - Christian Flege
- Department of Intensive Care; University Hospital, RWTH Aachen University; Aachen Germany
| | - Rüdger Kopp
- Department of Intensive Care; University Hospital, RWTH Aachen University; Aachen Germany
| | - Thomas Schmitz-Rode
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering; RWTH Aachen University; Aachen Germany
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering; RWTH Aachen University; Aachen Germany
| | - Jutta Arens
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering; RWTH Aachen University; Aachen Germany
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9
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Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting. Med Biol Eng Comput 2017; 55:1519-1548. [DOI: 10.1007/s11517-017-1688-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/10/2017] [Indexed: 11/26/2022]
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10
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Bianchi D, Monaldo E, Gizzi A, Marino M, Filippi S, Vairo G. A FSI computational framework for vascular physiopathology: A novel flow-tissue multiscale strategy. Med Eng Phys 2017; 47:25-37. [PMID: 28690045 DOI: 10.1016/j.medengphy.2017.06.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/05/2017] [Accepted: 06/01/2017] [Indexed: 11/27/2022]
Abstract
A novel fluid-structure computational framework for vascular applications is herein presented. It is developed by combining the double multi-scale nature of vascular physiopathology in terms of both tissue properties and blood flow. Addressing arterial tissues, they are modelled via a nonlinear multiscale constitutive rationale, based only on parameters having a clear histological and biochemical meaning. Moreover, blood flow is described by coupling a three-dimensional fluid domain (undergoing physiological inflow conditions) with a zero-dimensional model, which allows to reproduce the influence of the downstream vasculature, furnishing a realistic description of the outflow proximal pressure. The fluid-structure interaction is managed through an explicit time-marching approach, able to accurately describe tissue nonlinearities within each computational step for the fluid problem. A case study associated to a patient-specific aortic abdominal aneurysmatic geometry is numerically investigated, highlighting advantages gained from the proposed multiscale strategy, as well as showing soundness and effectiveness of the established framework for assessing useful clinical quantities and risk indexes.
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Affiliation(s)
- Daniele Bianchi
- Department of Civil Engineering and Computer Science (DICII), Universitá degli Studi di Roma "Tor Vergata", Via del Politecnico 1, Rome 00133, Italy.
| | - Elisabetta Monaldo
- Department of Engineering, Universitá degli Studi "Niccoló Cusano" - Telematica, Roma, Via Don C. Gnocchi 3, Rome 00166, Italy
| | - Alessio Gizzi
- Department of Engineering, Unit of Nonlinear Physics and Mathematical Modeling, University Campus Bio-Medico of Rome, Via A. del Portillo 21, Rome 00128, Italy
| | - Michele Marino
- Institute of Continuum Mechanics, Leibniz Universität Hannover, Appelstr. 11, Hannover 30167, Germany
| | - Simonetta Filippi
- Department of Engineering, Unit of Nonlinear Physics and Mathematical Modeling, University Campus Bio-Medico of Rome, Via A. del Portillo 21, Rome 00128, Italy
| | - Giuseppe Vairo
- Department of Civil Engineering and Computer Science (DICII), Universitá degli Studi di Roma "Tor Vergata", Via del Politecnico 1, Rome 00133, Italy
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11
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Fukamachi K, Karimov JH, Sunagawa G, Horvath DJ, Byram N, Kuban BD, Dessoffy R, Sale S, Golding LAR, Moazami N. Generating pulsatility by pump speed modulation with continuous-flow total artificial heart in awake calves. J Artif Organs 2017; 20:381-385. [PMID: 28391521 DOI: 10.1007/s10047-017-0958-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/27/2017] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to evaluate the effects of sinusoidal pump speed modulation of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) on hemodynamics and pump flow in an awake chronic calf model. The sinusoidal pump speed modulations, performed on the day of elective sacrifice, were set at ±15 and ± 25% of mean pump speed at 80 bpm in four awake calves with a CFTAH. The systemic and pulmonary arterial pulse pressures increased to 12.0 and 12.3 mmHg (±15% modulation) and to 15.9 and 15.7 mmHg (±25% modulation), respectively. The pulsatility index and surplus hemodynamic energy significantly increased, respectively, to 1.05 and 1346 ergs/cm at ±15% speed modulation and to 1.51 and 3381 ergs/cm at ±25% speed modulation. This study showed that it is feasible to generate pressure pulsatility with pump speed modulation; the platform is suitable for evaluating the physiologic impact of pulsatility and allows determination of the best speed modulations in terms of magnitude, frequency, and profiles.
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Affiliation(s)
- Kiyotaka Fukamachi
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
| | - Jamshid H Karimov
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
| | - Gengo Sunagawa
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - David J Horvath
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
- R1 Engineering, Cleveland, OH, USA
| | - Nicole Byram
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Barry D Kuban
- Electronics Core, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Raymond Dessoffy
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Shiva Sale
- Department of Cardiothoracic Anesthesiology, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Leonard A R Golding
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Nader Moazami
- Cardiovascular Dynamics Laboratory, Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
- Department of Thoracic and Cardiovascular Surgery, Kaufman Center for Heart Failure, Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH, USA
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12
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Nammakie E, Niroomand-Oscuii H, Koochaki M, Ghalichi F. Computational fluid dynamics-based study of possibility of generating pulsatile blood flow via a continuous-flow VAD. Med Biol Eng Comput 2016; 55:167-178. [PMID: 27234039 DOI: 10.1007/s11517-016-1523-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 05/11/2016] [Indexed: 10/21/2022]
Abstract
Until recent years, it was almost beyond remedy to save the life of end-stage heart failure patients without considering a heart transplant. This is while the need for healthy organs has always far exceeded donations. However, the evolution of VAD technology has certainly changed the management of these patients. Today, blood pumps are designed either pulsatile flow or continuous flow, each of which has its own concerns and limitations. For instance, pulsatile pumps are mostly voluminous and hardly can be used for children. On the other hand, the flow generated by continuous-flow pumps is in contrast with pulsatile flow of the natural heart. In this project, having used computational fluid dynamics, we studied the possibility of generating pulsatile blood flow via a continuous-flow blood pump by adjusting the rotational speed of the pump with two distinct patterns (sinusoidal and trapezoidal), both of which have been proposed and set based on physiological needs and blood flow waveform of the natural heart. An important feature of this study is setting the outlet pressure of the pump similar to the physiological conditions of a patient with heart failure, and since these axial pumps are sensitive to outlet pressures, more secure and reliable results of their performance are achieved. Our results show a slight superiority of a sinusoidal pattern compared to a trapezoidal one with the potential to achieve an adequate pulsatile flow by precisely controlling the rotational speed.
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Affiliation(s)
- Erfan Nammakie
- Division of Biomechanics, Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran
| | - Hanieh Niroomand-Oscuii
- Division of Biomechanics, Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran.
| | - Mojtaba Koochaki
- Division of Biomechanics, Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran
| | - Farzan Ghalichi
- Division of Biomechanics, Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran
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13
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Horner M, Metcalfe G, Ottino JM. Convection-Enhanced Transport into Open Cavities : Effect of Cavity Aspect Ratio. Cardiovasc Eng Technol 2015; 6:352-63. [PMID: 26577366 DOI: 10.1007/s13239-015-0217-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 01/28/2015] [Indexed: 11/27/2022]
Abstract
Recirculating fluid regions occur in the human body both naturally and pathologically. Diffusion is commonly considered the predominant mechanism for mass transport into a recirculating flow region. While this may be true for steady flows, one must also consider the possibility of convective fluid exchange when the outer (free stream) flow is transient. In the case of an open cavity, convective exchange occurs via the formation of lobes at the downstream attachment point of the separating streamline. Previous studies revealed the effect of forcing amplitude and frequency on material transport rates into a square cavity (Horner in J Fluid Mech 452:199-229, 2002). This paper summarizes the effect of cavity aspect ratio on exchange rates. The transport process is characterized using both computational fluid dynamics modeling and dye-advection experiments. Lagrangian analysis of the computed flow field reveals the existence of turnstile lobe transport for this class of flows. Experiments show that material exchange rates do not vary linearly as a function of the cavity aspect ratio (A = W/H). Rather, optima are predicted for A ≈ 2 and A ≈ 2.73, with a minimum occurring at A ≈ 2.5. The minimum occurs at the point where the cavity flow structure bifurcates from a single recirculating flow cell into two corner eddies. These results have significant implications for mass transport environments where the geometry of the flow domain evolves with time, such as coronary stents and growing aneurysms. Indeed, device designers may be able to take advantage of the turnstile-lobe transport mechanism to tailor deposition rates near newly implanted medical devices.
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Affiliation(s)
- Marc Horner
- ANSYS, Inc. 1007 Church Street, Suite 250, Evanston, IL, 60201, USA.
| | - Guy Metcalfe
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Box 56, Highett, VIC, 3190, Australia
| | - J M Ottino
- Departments of Chemical and Biological Engineering, and Mechanical Engineering, The Northwestern Institute on Complex Systems (NICO), Northwestern University, Evanston, IL, 60208, USA
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14
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The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device. ASAIO J 2015; 61:656-63. [DOI: 10.1097/mat.0000000000000261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Moazami N, Dembitsky WP, Adamson R, Steffen RJ, Soltesz EG, Starling RC, Fukamachi K. Does pulsatility matter in the era of continuous-flow blood pumps? J Heart Lung Transplant 2014; 34:999-1004. [PMID: 25447568 DOI: 10.1016/j.healun.2014.09.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/05/2014] [Accepted: 09/19/2014] [Indexed: 10/24/2022] Open
Abstract
Despite significant improved survival with continuous flow left ventricular assist devices (LVADs), complications related to aortic valve insufficiency, gastrointestinal bleeding, stroke, pump thrombosis, and hemolysis have dampened the long term success of these pumps. Evolution has favored a pulsatile heart pump to be able to deliver the maximum flow at different levels of systemic vascular resistance, confer kinetic energy to the flow of blood past areas of stenosis and generate low shear stress on blood elements. In this perspective, we suggest that lack of pulsatility may be one factor that has limited the success of continuous flow LVADs and suggest that research needs to focus on methods to generate pulsatility either by the native heart or by various speed modulation algorithms.
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Affiliation(s)
- Nader Moazami
- Department of Thoracic and Cardiovascular Surgery, Heart and Vascular Institute; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.
| | - Walter P Dembitsky
- Department of Cardiac Surgery, Sharp Memorial Hospital, San Diego, California
| | - Robert Adamson
- Department of Cardiac Surgery, Sharp Memorial Hospital, San Diego, California
| | - Robert J Steffen
- Department of Thoracic and Cardiovascular Surgery, Heart and Vascular Institute
| | - Edward G Soltesz
- Department of Thoracic and Cardiovascular Surgery, Heart and Vascular Institute
| | - Randall C Starling
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Kaufman Center for Heart Failure, Cleveland Clinic, Cleveland, Ohio
| | - Kiyotaka Fukamachi
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
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Gorring N, Kark L, Simmons A, Barber T. Determining possible thrombus sites in an extracorporeal device, using computational fluid dynamics-derived relative residence time. Comput Methods Biomech Biomed Engin 2014; 18:628-34. [DOI: 10.1080/10255842.2013.826655] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
This paper reviews the basic fluid dynamics underlying extracorporeal membrane oxygenation (ECMO) cannula design. General cannula features and their effect on flow are discussed and the specific requirements of different ECMO circuits are explained. The current commercially available cannula options for veno-arterial and veno-venous circuits are reviewed and the main characteristics presented.
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Affiliation(s)
- K Kohler
- Department of Anaesthesia, West Suffolk Hospital, Bury St Edmunds, UK
| | - K Valchanov
- Department of Anaesthesia and Intensive Care, Papworth Hospital, Papworth Everard, Cambridgeshire, UK
| | - G Nias
- Department of Anaesthesia and Intensive Care, Papworth Hospital, Papworth Everard, Cambridgeshire, UK
| | - A Vuylsteke
- Department of Anaesthesia and Intensive Care, Papworth Hospital, Papworth Everard, Cambridgeshire, UK
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