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Tomasevic S, Anic M, Arsic B, Gakovic B, Filipovic N, Djukic T. Software that combines deep learning, 3D reconstruction and CFD to analyze the state of carotid arteries from ultrasound imaging. Technol Health Care 2024:THC231306. [PMID: 38393860 DOI: 10.3233/thc-231306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
BACKGROUND Ultrasound is one of the non-invasive techniques that are used in clinical diagnostics of carotid artery disease. OBJECTIVE This paper presents software methodology that can be used in combination with this imaging technique to provide additional information about the state of patient-specific artery. METHODS Overall three modules are combined within the proposed methodology. A clinical dataset is used within the deep learning module to extract the contours of the carotid artery. This data is then used within the second module to perform the three-dimensional reconstruction of the geometry of the carotid bifurcation and ultimately this geometry is used within the third module, where the hemodynamic analysis is performed. The obtained distributions of hemodynamic quantities enable a more detailed analysis of the blood flow and state of the arterial wall and could be useful to predict further progress of present abnormalities in the carotid bifurcation. RESULTS The performance of the deep learning module was demonstrated through the high values of relevant common classification metric parameters. Also, the accuracy of the proposed methodology was shown through the validation of results for the reconstructed parameters against the clinically measured values. CONCLUSION The presented methodology could be used in combination with standard clinical ultrasound examination to quickly provide additional quantitative and qualitative information about the state of the patient's carotid bifurcation and thus ensure a treatment that is more adapted to the specific patient.
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Affiliation(s)
- Smiljana Tomasevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Milos Anic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Branko Arsic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Science, University of Kragujevac, Kragujevac, Serbia
| | - Branko Gakovic
- Clinic for Vascular and Endovascular Surgery, Serbian Clinical Centre, Belgrade, Serbia
| | - Nenad Filipovic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Tijana Djukic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
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Wild NC, Bulusu KV, Plesniak MW. Vortical Structures Promote Atheroprotective Wall Shear Stress Distributions in a Carotid Artery Bifurcation Model. Bioengineering (Basel) 2023; 10:1036. [PMID: 37760138 PMCID: PMC10525770 DOI: 10.3390/bioengineering10091036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/04/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
Carotid artery diseases, such as atherosclerosis, are a major cause of death in the United States. Wall shear stresses are known to prompt plaque formation, but there is limited understanding of the complex flow structures underlying these stresses and how they differ in a pre-disposed high-risk patient cohort. A 'healthy' and a novel 'pre-disposed' carotid artery bifurcation model was determined based on patient-averaged clinical data, where the 'pre-disposed' model represents a pathological anatomy. Computational fluid dynamic simulations were performed using a physiological flow based on healthy human subjects. A main hairpin vortical structure in the internal carotid artery sinus was observed, which locally increased instantaneous wall shear stress. In the pre-disposed geometry, this vortical structure starts at an earlier instance in the cardiac flow cycle and persists over a much shorter period, where the second half of the cardiac cycle is dominated by perturbed secondary flow structures and vortices. This coincides with weaker favorable axial pressure gradient peaks over the sinus for the 'pre-disposed' geometry. The findings reveal a strong correlation between vortical structures and wall shear stress and imply that an intact internal carotid artery sinus hairpin vortical structure has a physiologically beneficial role by increasing local wall shear stresses. The deterioration of this beneficial vortical structure is expected to play a significant role in atherosclerotic plaque formation.
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Affiliation(s)
- Nora C. Wild
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA; (N.C.W.); (K.V.B.)
| | - Kartik V. Bulusu
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA; (N.C.W.); (K.V.B.)
| | - Michael W. Plesniak
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA; (N.C.W.); (K.V.B.)
- Department of Biomedical Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA
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Zalud NC, Bulusu KV, Plesniak MW. Shear stress metrics associated with pro-atherogenic high-risk anatomical features in a carotid artery bifurcation model. Clin Biomech (Bristol, Avon) 2023; 105:105956. [PMID: 37098301 DOI: 10.1016/j.clinbiomech.2023.105956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 04/06/2023] [Accepted: 04/13/2023] [Indexed: 04/27/2023]
Abstract
BACKGROUND Diseases associated with atherosclerotic plaques in the carotid artery are a major cause of deaths in the United States. Blood-flow-induced shear-stresses are known to trigger plaque formation. Prior literature suggests that the internal carotid artery sinus is prone to atherosclerosis, but there is limited understanding of why only certain patients are predisposed towards plaque formation. METHODS We computationally investigate the effect of vessel geometry on wall-shear-stress distribution by comparing flowfields and wall-shear-stress-metrics between a low-risk and a novel predisposed high-risk carotid artery bifurcation anatomy. Both models were developed based on clinical risk estimations and patient-averaged anatomical features. The high-risk geometry has a larger internal carotid artery branching angle and a lower internal-to-carotid-artery-diameter-ratio. A patient-averaged physiological carotid artery inflow waveform is used. FINDINGS The high-risk geometry experiences stronger flow separation in the sinus. Furthermore, it experiences a more equal flow split at the bifurcation, thereby reducing internal carotid artery flowrate and increasing atherosclerosis-prone low-velocity areas. Lowest time-averaged-wall-shear-stresses are present at the sinus outer wall, where plaques are often found, for both geometries. The high-risk geometry has significantly high, unfavorable oscillatory-shear-index values not found in the low-risk geometry. High oscillatory-shear-index areas are located at the vessels outside walls distal to the bifurcation and on the sinus wall. INTERPRETATION These results highlight the effectiveness of oscillatory-shear-index, to augment classical time-averaged-wall-shear-stress, in evaluating pro-atherogenic geometry features. Furthermore, the flow split at the bifurcation is a promising clinical indicator for atherosclerosis risk as it can be directly accessed using clinical imaging, whereas shear-stress-metrics cannot.
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Affiliation(s)
- Nora C Zalud
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, United States
| | - Kartik V Bulusu
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, United States
| | - Michael W Plesniak
- Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, United States; Department of Biomedical Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 5000, Washington, DC 20052, United States.
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Ebrahimi BS, Kumar H, Tawhai MH, Burrowes KS, Hoffman EA, Clark AR. Simulating Multi-Scale Pulmonary Vascular Function by Coupling Computational Fluid Dynamics With an Anatomic Network Model. FRONTIERS IN NETWORK PHYSIOLOGY 2022; 2:867551. [PMID: 36926101 PMCID: PMC10012968 DOI: 10.3389/fnetp.2022.867551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022]
Abstract
The function of the pulmonary circulation is truly multi-scale, with blood transported through vessels from centimeter to micron scale. There are scale-dependent mechanisms that govern the flow in the pulmonary vascular system. However, very few computational models of pulmonary hemodynamics capture the physics of pulmonary perfusion across the spatial scales of functional importance in the lung. Here we present a multi-scale model that incorporates the 3-dimensional (3D) complexities of pulmonary blood flow in the major vessels, coupled to an anatomically-based vascular network model incorporating the multiple contributing factors to capillary perfusion, including gravity. Using the model we demonstrate how we can predict the impact of vascular remodeling and occlusion on both macro-scale functional drivers (flow distribution between lungs, and wall shear stress) and micro-scale contributors to gas exchange. The model predicts interactions between 3D and 1D models that lead to a redistribution of blood between postures, both on a macro- and a micro-scale. This allows us to estimate the effect of posture on left and right pulmonary artery wall shear stress, with predictions varying by 0.75-1.35 dyne/cm2 between postures.
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Affiliation(s)
| | - Haribalan Kumar
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kelly S Burrowes
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Eric A Hoffman
- Department of Radiology, University of Iowa, Iowa City, IA, United States
| | - Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Mathur T, Tronolone JJ, Jain A. Comparative Analysis of Blood-Derived Endothelial Cells for Designing Next-Generation Personalized Organ-on-Chips. J Am Heart Assoc 2021; 10:e022795. [PMID: 34743553 PMCID: PMC8751908 DOI: 10.1161/jaha.121.022795] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background Organ‐on‐chip technology has accelerated in vitro preclinical research of the vascular system, and a key strength of this platform is its promise to impact personalized medicine by providing a primary human cell–culture environment where endothelial cells are directly biopsied from individual tissue or differentiated through stem cell biotechniques. However, these methods are difficult to adopt in laboratories, and often result in impurity and heterogeneity of cells. This limits the power of organ‐chips in making accurate physiological predictions. In this study, we report the use of blood‐derived endothelial cells as alternatives to primary and induced pluripotent stem cell–derived endothelial cells. Methods and Results Here, the genotype, phenotype, and organ‐chip functional characteristics of blood‐derived outgrowth endothelial cells were compared against commercially available and most used primary endothelial cells and induced pluripotent stem cell–derived endothelial cells. The methods include RNA‐sequencing, as well as criterion standard assays of cell marker expression, growth kinetics, migration potential, and vasculogenesis. Finally, thromboinflammatory responses under shear using vessel‐chips engineered with blood‐derived endothelial cells were assessed. Blood‐derived endothelial cells exhibit the criterion standard hallmarks of typical endothelial cells. There are differences in gene expression profiles between different sources of endothelial cells, but blood‐derived cells are relatively closer to primary cells than induced pluripotent stem cell–derived. Furthermore, blood‐derived endothelial cells are much easier to obtain from individuals and yet, they serve as an equally effective cell source for functional studies and organ‐chips compared with primary cells or induced pluripotent stem cell–derived cells. Conclusions Blood‐derived endothelial cells may be used in preclinical research for developing more robust and personalized next‐generation disease models using organ‐on‐chips.
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Affiliation(s)
- Tanmay Mathur
- Department of Biomedical Engineering, College of Engineering Texas A&M University College Station TX
| | - James J Tronolone
- Department of Biomedical Engineering, College of Engineering Texas A&M University College Station TX
| | - Abhishek Jain
- Department of Biomedical Engineering, College of Engineering Texas A&M University College Station TX.,Department of Medical Physiology College of MedicineTexas A&M Health Science Center Bryan TX.,Department of Cardiovascular Sciences Houston Methodist Research Institute Houston TX
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Li Z, Jiang W, Diao J, Chen C, Xu K, Fan H, Yan F. Segmentary strategy in modeling of cardiovascular system with blood supply to regional skin. Biocybern Biomed Eng 2021. [DOI: 10.1016/j.bbe.2021.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Mathur T, Flanagan JM, Jain A. Tripartite collaboration of blood-derived endothelial cells, next generation RNA sequencing and bioengineered vessel-chip may distinguish vasculopathy and thrombosis among sickle cell disease patients. Bioeng Transl Med 2021; 6:e10211. [PMID: 34589594 PMCID: PMC8459595 DOI: 10.1002/btm2.10211] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/24/2020] [Accepted: 12/29/2020] [Indexed: 12/15/2022] Open
Abstract
Sickle cell disease (SCD) is the most prevalent inherited blood disorder in the world. But the clinical manifestations of the disease are highly variable. In particular, it is currently difficult to predict the adverse outcomes within patients with SCD, such as, vasculopathy, thrombosis, and stroke. Therefore, for most effective and timely interventions, a predictive analytic strategy is desirable. In this study, we evaluate the endothelial and prothrombotic characteristics of blood outgrowth endothelial cells (BOECs) generated from blood samples of SCD patients with known differences in clinical severity of the disease. We present a method to evaluate patient-specific vaso-occlusive risk by combining novel RNA-seq and organ-on-chip approaches. Through differential gene expression (DGE) and pathway analysis we find that BOECs from SCD patients exhibit an activated state through cell adhesion molecule (CAM) and cytokine signaling pathways among many others. In agreement with clinical symptoms of patients, DGE analyses reveal that patient with severe SCD had a greater extent of endothelial activation compared to patient with milder symptoms. This difference is confirmed by performing qRT-PCR of endothelial adhesion markers like E-selectin, P-selectin, tissue factor, and Von Willebrand factor. Finally, the differential regulation of the proinflammatory phenotype is confirmed through platelet adhesion readouts in our BOEC vessel-chip. Taken together, we hypothesize that these easily blood-derived endothelial cells evaluated through RNA-seq and organ-on-chips may serve as a biotechnique to predict vaso-occlusive episodes in SCD patients and will ultimately allow better therapeutic interventions.
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Affiliation(s)
- Tanmay Mathur
- Department of Biomedical EngineeringTexas A&M UniversityCollege StationTexasUSA
| | - Jonathan M. Flanagan
- Department of Pediatrics, Section of Hematology‐OncologyBaylor College of MedicineHoustonTexasUSA
| | - Abhishek Jain
- Department of Biomedical EngineeringTexas A&M UniversityCollege StationTexasUSA
- Department of Medical PhysiologyCollege of Medicine, Texas A&M Health Science CenterBryanTexasUSA
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Sharma N, Sastry S, Sankovic JM, Kadambi JR, Banerjee RK. Influence of near-wall PIV data on recirculation hemodynamics in a patient-specific moderate stenosis: Experimental-numerical comparison. Biorheology 2020; 57:53-76. [PMID: 33185583 DOI: 10.3233/bir-201001] [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] [Indexed: 11/15/2022]
Abstract
BACKGROUND Recirculation zones within the blood vessels are known to influence the initiation and progression of atherosclerotic lesions. Quantification of recirculation parameters with accuracy remains subjective due to uncertainties in measurement of velocity and derived wall shear stress (WSS). OBJECTIVE The primary aim is to determine recirculation height and length from PIV experiments while validating with two different numerical methods: finite-element (FE) and -volume (FV). Secondary aim is to analyze how FE and FV compare within themselves. METHODS PIV measurements were performed to obtain velocity profiles at eight cross sections downstream of stenosis at flow rate of 200 ml/min. WSS was obtained by linear/quadratic interpolation of experimental velocity measurements close to wall. RESULTS Recirculation length obtained from PIV technique was 1.47 cm and was within 2.2% of previously reported in-vitro measurements. Derived recirculation length from PIV agreed within 6.8% and 8.2% of the FE and FV calculations, respectively. For lower shear rate, linear interpolation with five data points results in least error. For higher shear rate either higher order (quadratic) interpolation with five data points or lower order (linear) with lesser (three) data points leads to better results. CONCLUSION Accuracy of the recirculation parameters is dependent on number of near wall PIV data points and the type of interpolation algorithm used.
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Affiliation(s)
- Neha Sharma
- Department of Aerospace Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Sudeep Sastry
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
| | | | - Jaikrishnan R Kadambi
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Rupak K Banerjee
- Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH, USA
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Nagargoje M, Gupta R. Effect of sinus size and position on hemodynamics during pulsatile flow in a carotid artery bifurcation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 192:105440. [PMID: 32299026 DOI: 10.1016/j.cmpb.2020.105440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVES Hemodynamics plays a crucial role in the progression of atherosclerosis and the treatment of arterial diseases. Stroke is one of the arterial diseases and a leading cause of death worldwide. Hemodynamics in the carotid artery plays a vital role in the stroke. The common carotid artery bifurcates into the internal carotid artery and the external carotid artery. Carotid sinus, a slightly dilated area, exists in the internal carotid artery just after the bifurcation and acts as a pressure receptor and regulator. The location and size of the sinus can vary in different people; the change in sinus size and location may affect the hemodynamics. It is necessary to study the shift in hemodynamics due to changes in sinus size and position on atherosclerosis. The change in flow behavior may suggest the probable sites of backflow and low wall shear stress, and therefore the sites prone to atherosclerosis. METHODS The model of the carotid artery has been constructed using patient data. Transient computational fluid dynamics simulations have been performed using a finite volume method for the numerical solution in a three-dimensional computational domain using ANSYS Fluent 19.2. Pulsatile flow is specified at the inlet boundary. The coupled scheme is used for the pressure-velocity coupling. The second-order discretization scheme is used for pressure interpolation and second-order upwind scheme is used for the discretisation of momentum equation. The temporal term is discretized using the first-order implicit scheme. RESULTS The effect of sinus size and location on the overall flow behavior, wall shear stress, and secondary flow are presented. Results show that the outer wall of bifurcation has low wall shear stress and bigger recirculation as compared with that on the inner wall of bifurcation. Numerical results obtained for varying sinus size and position are shown in graphs and contours, including wall shear stress, secondary flow, and velocity streamlines. CONCLUSION Numerical results reveal that sinus away from bifurcation, and larger diameter sinus has more recirculation and low wall shear stress. Therefore, the person having sinus away from bifurcation and larger sinus diameter are more susceptible to plaque formation.
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Affiliation(s)
- Mahesh Nagargoje
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam, 781039, India
| | - Raghvendra Gupta
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam, 781039, India.
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Nagargoje M, Gupta R. Effect of asymmetry on the flow behavior in an idealized arterial bifurcation. Comput Methods Biomech Biomed Engin 2020; 23:232-247. [DOI: 10.1080/10255842.2019.1711068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Mahesh Nagargoje
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Raghvendra Gupta
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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CardioFAN: open source platform for noninvasive assessment of pulse transit time and pulsatile flow in hyperelastic vascular networks. Biomech Model Mechanobiol 2019; 18:1529-1548. [PMID: 31076923 DOI: 10.1007/s10237-019-01163-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/26/2019] [Indexed: 01/08/2023]
Abstract
A profound analysis of pressure and flow wave propagation in cardiovascular systems is the key in noninvasive assessment of hemodynamic parameters. Pulse transit time (PTT), which closely relates to the physical properties of the cardiovascular system, can be linked to variations of blood pressure and stroke volume to provide information for patient-specific clinical diagnostics. In this work, we present mathematical and numerical tools, capable of accurately predicting the PTT, local pulse wave velocity, vessel compliance, and pressure/flow waveforms, in a viscous hyperelastic cardiovascular network. A new one-dimensional framework, entitled cardiovascular flow analysis (CardioFAN), is presented to describe the pulsatile fluid-structure interaction in the hyperelastic arteries, where pertaining hyperbolic equations are solved using a high-resolution total variation diminishing Lax-Wendroff method. The computational algorithm is validated against well-known numerical, in vitro and in vivo data for networks of main human arteries with 55, 37 and 26 segments, respectively. PTT prediction is improved by accounting for hyperelastic nonlinear waves between two arbitrary sections of the arterial tree. Consequently, arterial compliance assignments at each segment are improved in a personalized model of the human aorta and supra-aortic branches with 26 segments, where prior in vivo data were available for comparison. This resulted in a 1.5% improvement in overall predictions of the waveforms, or average relative errors of 5.5% in predicting flow, luminal area and pressure waveforms compared to prior in vivo measurements. The open source software, CardioFAN, can be calibrated for arbitrary patient-specific vascular networks to conduct noninvasive diagnostics.
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Prashantha B, Anish S. Computational investigations on the hemodynamic performance of a new swirl generator in bifurcated arteries. Comput Methods Biomech Biomed Engin 2019; 22:364-375. [DOI: 10.1080/10255842.2018.1556974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- B. Prashantha
- Department of Mechanical Engineering, M S Ramaiah Institute of Technology, Bengaluru, Karnataka, India
| | - S. Anish
- Advanced Fluid Mechanics Laboratory, Department of Mechanical Engineering, National Institute of Technology, Surathkal, Karnataka, India
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14
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Discrete-Phase Modelling of an Asymmetric Stenosis Artery Under Different Womersley Numbers. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2019. [DOI: 10.1007/s13369-018-3391-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Wain RAJ, Gaskell NJ, Fsadni AM, Francis J, Whitty JPM. Finite Element Predictions of Sutured and Coupled Microarterial Anastomoses. ADVANCED BIOMEDICAL ENGINEERING 2019. [DOI: 10.14326/abe.8.63] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Richard AJ Wain
- John Tyndall Institute, School of Engineering, University of Central Lancashire
- School of Medicine and Dentistry, University of Central Lancashire
- Department of Plastic & Reconstructive Surgery, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust
| | - Nicolas J Gaskell
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Andrew M Fsadni
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Jonathan Francis
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Justin PM Whitty
- John Tyndall Institute, School of Engineering, University of Central Lancashire
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Wain RAJ, Smith DJ, Hammond DR, Whitty JPM. Influence of microvascular sutures on shear strain rate in realistic pulsatile flow. Microvasc Res 2018. [PMID: 29522755 DOI: 10.1016/j.mvr.2018.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Arterial thrombus formation is directly related to the mechanical shear experienced by platelets within flow. High shear strain rates (SSRs) and large shear gradients cause platelet activation, aggregation and production of thrombus. This study, for the first time, investigates the influence of pulsatile flow on local haemodynamics within sutured microarterial anastomoses. We measured physiological arterial waveform velocities experimentally using Doppler ultrasound velocimetry, and a representative example was applied to a realistic sutured microarterial geometry. Computational geometries were created using measurements taken from sutured chicken femoral arteries. Arterial SSRs were predicted using computational fluid dynamics (CFD) software, to indicate the potential for platelet activation, deposition and thrombus formation. Predictions of steady and sinusoidal inputs were compared to analyse whether the addition of physiological pulse characteristics affects local intravascular flow characteristics. Simulations were designed to evaluate flow in pristine and hand-sutured microarterial anastomoses, each with a steady-state and sinusoidal pulse component. The presence of sutures increased SSRmax in the anastomotic region by factors of 2.1 and 2.3 in steady-state and pulsatile flows respectively, when compared to a pristine vessel. SSR values seen in these simulations are analogous to the presence of moderate arterial stenosis. Steady-state simulations, driven by a constant inflow velocity equal to the peak systolic velocity (PSV) of the measured pulsatile flow, underestimated SSRs by ∼ 9% in pristine, and ∼ 19% in sutured vessels compared with a realistic pulse. Sinusoidal flows, with equivalent frequency and amplitude to a measured arterial waveform, represent a slight improvement on steady-state simulations, but still SSRs are underestimated by 1-2%. We recommend using a measured arterial waveform, of the form presented here, for simulating pulsatile flows in vessels of this nature. Under realistic pulsatile flow, shear gradients across microvascular sutures are high, of the order ∼ 7.9 × 106 m-1 s-1, which may also be associated with activation of platelets and formation of aggregates.
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Affiliation(s)
- R A J Wain
- School of Mathematics, University of Birmingham, B15 2TT, UK; Institute of Translational Medicine, University of Birmingham, B15 2TT, UK; School of Medicine and Dentistry, University of Central Lancashire, Preston PR1 2HE, UK; Computational Mechanics Research Group, School of Engineering, University of Central Lancashire, Preston PR1 2HE, UK.
| | - D J Smith
- School of Mathematics, University of Birmingham, B15 2TT, UK; Institute for Metabolism and Systems Research, University of Birmingham, B15 2TT, UK
| | - D R Hammond
- School of Medicine and Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - J P M Whitty
- Computational Mechanics Research Group, School of Engineering, University of Central Lancashire, Preston PR1 2HE, UK
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Sharzehee M, Khalafvand SS, Han HC. Fluid-structure interaction modeling of aneurysmal arteries under steady-state and pulsatile blood flow: a stability analysis. Comput Methods Biomech Biomed Engin 2018; 21:219-231. [PMID: 29446991 PMCID: PMC5879495 DOI: 10.1080/10255842.2018.1439478] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tortuous aneurysmal arteries are often associated with a higher risk of
rupture but the mechanism remains unclear. The goal of this study was to analyze
the buckling and post-buckling behaviors of aneurysmal arteries under pulsatile
flow. To accomplish this goal, we analyzed the buckling behavior of model
carotid and abdominal aorta with aneurysms by utilizing fluid-structure
interaction (FSI) method with realistic waveforms boundary conditions. FSI
simulations were done under steady-state and pulsatile flow for normal (1.5) and
reduced (1.3) axial stretch ratios to investigate the influence of aneurysm,
pulsatile lumen pressure and axial tension on stability. Our results indicated
that aneurysmal artery buckled at the critical buckling pressure and its
deflection nonlinearly increased with increasing lumen pressure. Buckling
elevates the peak stress (up to 118%). The maximum aneurysm wall stress
at pulsatile FSI flow was (29%) higher than under static pressure at the
peak lumen pressure of 130 mmHg. Buckling results show an increase in lumen
shear stress at the inner side of the maximum deflection. Vortex flow was
dramatically enlarged with increasing lumen pressure and artery diameter.
Aneurysmal arteries are more susceptible than normal arteries to mechanical
instability which causes high stresses in the aneurysm wall that could lead to
aneurysm rupture.
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Affiliation(s)
- Mohammadali Sharzehee
- a Department of Mechanical Engineering , The University of Texas at San Antonio , San Antonio , TX , USA
| | | | - Hai-Chao Han
- a Department of Mechanical Engineering , The University of Texas at San Antonio , San Antonio , TX , USA
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18
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Analysis of non-Newtonian effects within an aorta-iliac bifurcation region. J Biomech 2017; 64:153-163. [DOI: 10.1016/j.jbiomech.2017.09.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/25/2017] [Indexed: 11/15/2022]
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19
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20
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Mohammadi H, Cartier R, Mongrain R. Fiber-reinforced computational model of the aortic root incorporating thoracic aorta and coronary structures. Biomech Model Mechanobiol 2017; 17:263-283. [PMID: 28929388 DOI: 10.1007/s10237-017-0959-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 08/31/2017] [Indexed: 01/03/2023]
Abstract
Cardiovascular diseases are still the leading causes of death in the developed world. The decline in the mortality associated with circulatory system diseases is accredited to development of new diagnostic and prognostic tools. It is well known that there is an inter relationship between the aortic valve impairment and pathologies of the aorta and coronary vessels. However, due to the limitations of the current tools, the possible link is not fully elucidated. Following our previous model of the aortic root including the coronaries, in this study, we have further developed the global aspect of the model by incorporating the anatomical structure of the thoracic aorta. This model is different from all the previous studies in the sense that inclusion of the coronary structures and thoracic aorta into the natural aortic valve introduces the notion of globality into the model enabling us to explore the possible link between the regional pathologies. The developed model was first validated using the available data in the literature under physiological conditions. Then, to provide a support for the possible association between the localized cardiovascular pathologies and global variations in hemodynamic conditions, we simulated the model for two pathological conditions including moderate and severe aortic valve stenoses. The findings revealed that malformations of the aortic valve are associated with development of low wall shear stress regions and helical blood flow in thoracic aorta that are considered major contributors to aortic pathologies.
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Affiliation(s)
- Hossein Mohammadi
- Mechanical Engineering Department, McGill University, Montreal, QC, H3A 0C3, Canada
| | - Raymond Cartier
- Department of Cardiovascular Surgery, Montreal Heart Institute, Montreal, QC, H1T 1C8, Canada
| | - Rosaire Mongrain
- Mechanical Engineering Department, McGill University, Montreal, QC, H3A 0C3, Canada.
- Department of Cardiovascular Surgery, Montreal Heart Institute, Montreal, QC, H1T 1C8, Canada.
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21
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BASAVARAJA PRASHANTH, SURENDRAN ANISH, GUPTA AJAY, SABA LUCA, LAIRD JOHNR, NICOLAIDES ANDREW, MTUI EDWARDE, BARADARAN HEDIYEH, LAVRA FRANCESCO, SURI JASJITS. WALL SHEAR STRESS AND OSCILLATORY SHEAR INDEX DISTRIBUTION IN CAROTID ARTERY WITH VARYING DEGREE OF STENOSIS: A HEMODYNAMIC STUDY. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417500373] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A significant proportion of cerebral stroke is a consequence of the arterial stenotic plaque rupture causing local thrombosis or distal embolization. The formation and subsequent rupture of the plaque depends on wall shear stress (WSS) and oscillatory shear index (OSI). The purpose of the present study was to understand the effect of hemodynamics on the spatial and temporal variations of WSS and OSI using realistic models with varying degree of carotid artery stenosis (DOS). Multiple CT volumes were obtained from subjects in the carotid bifurcation zone and the 3D models were generated. A finite volume-based computational fluid dynamics (CFD) method was utilized to understand the hemodynamics in pulsatile flow conditions. It was observed that high stenosis models occupied a large value of normalized WSS in the internal carotid artery (ICA) whereas they had smaller values of normalized WSS in the common carotid artery (CCA). For clinical use, the authors recommend using the spatial average value of oscillatory shear rather than the maximum value for an accurate knowledge about the severity of stenosis. The resultant vorticity changes the direction of spin after the bifurcation zone. Additionally, we propose the use of limiting streamlines as a novel and convenient method to identify the disturbed flow regions that are prone to atherogenesis.
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Affiliation(s)
- PRASHANTH BASAVARAJA
- Department of Mechanical Engineering, National Institute of Technology Karnataka Surathkal, Mangalore 575025, Karnataka, India
| | - ANISH SURENDRAN
- Department of Mechanical Engineering, National Institute of Technology Karnataka Surathkal, Mangalore 575025, Karnataka, India
| | - AJAY GUPTA
- Department of Radiology, Weill Cornell Medical College, New York NY 10065, USA
| | - LUCA SABA
- Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari — Polo di Monserrato, S. S. 554 Monserrato, Cagliari 09045, Italy
| | - JOHN R. LAIRD
- UC Davis Vascular Center, University of California Sacramento, CA 95817, USA
| | - ANDREW NICOLAIDES
- Vascular Screening and Diagnostic Centre, London W1G 6LF, UK
- Department of Biological Sciences, University of Cyprus, 1678 Nicosia, Cyprus
| | - EDWARD E. MTUI
- Department of Radiology, Weill Cornell Medical College, New York NY 10065, USA
| | - HEDIYEH BARADARAN
- Department of Radiology, Weill Cornell Medical College, New York NY 10065, USA
| | - FRANCESCO LAVRA
- Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari — Polo di Monserrato, S. S. 554 Monserrato, Cagliari 09045, Italy
| | - JASJIT S. SURI
- Point of Care Devices, Global Biomedical Technologies, Inc., Roseville, CA 95661, USA
- Diagnostic and Monitoring Division, AtheroPointTM LLC, Roseville, CA 95661, USA
- Electrical Engineering Department, Idaho State University, Pocatello, ID 83209, USA
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22
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Jordanski M, Radovic M, Milosevic Z, Filipovic N, Obradovic Z. Machine Learning Approach for Predicting Wall Shear Distribution for Abdominal Aortic Aneurysm and Carotid Bifurcation Models. IEEE J Biomed Health Inform 2016; 22:537-544. [PMID: 28113333 DOI: 10.1109/jbhi.2016.2639818] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Computer simulations based on the finite element method represent powerful tools for modeling blood flow through arteries. However, due to its computational complexity, this approach may be inappropriate when results are needed quickly. In order to reduce computational time, in this paper, we proposed an alternative machine learning based approach for calculation of wall shear stress (WSS) distribution, which may play an important role in mechanisms related to initiation and development of atherosclerosis. In order to capture relationships between geometric parameters, blood density, dynamic viscosity and velocity, and WSS distribution of geometrically parameterized abdominal aortic aneurysm (AAA) and carotid bifurcation models, we proposed multivariate linear regression, multilayer perceptron neural network and Gaussian conditional random fields (GCRF). Results obtained in this paper show that machine learning approaches can successfully predict WSS distribution at different cardiac cycle time points. Even though all proposed methods showed high potential for WSS prediction, GCRF achieved the highest coefficient of determination (0.930-0.948 for AAA model and 0.946-0.954 for carotid bifurcation model) demonstrating benefits of accounting for spatial correlation. The proposed approach can be used as an alternative method for real time calculation of WSS distribution.
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23
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Xu XY, Collins MW. Studies of Blood Flow in Arterial Bifurcations Using Computational Fluid Dynamics. Proc Inst Mech Eng H 2016. [DOI: 10.1243/pime_proc_1994_208_282_02] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The local blood flow in arteries, especially at bends and bifurcations, is correlated with the distribution of atherosclerotic lesions. The flow is three-dimensional, unsteady and difficult to measure in vivo. In this paper a numerical treatment of blood flow in general three-dimensional arterial bifurcations is presented. The flow is assumed to be laminar and incompressible, the blood non-Newtonian and the vessel wall rigid. The three-dimensional time-dependent Navier-Stokes equations are employed to describe the flow, and a newly developed computational fluid dynamics (CFD) code AST EC based on finite volume methods is used to solve the equations. A comprehensive range of code validations has been carried out. Good agreement between numerical predictions and in vitro model data is demonstrated, but the correlation with in vivo measurements is less satisfactory. Effects of the non-Newtonian viscosity have also been investigated. It is demonstrated that differences between Newtonian and non-Newtonian flows occur mainly in regions of flow separation. With the non-Newtonian fluid, the duration of flow separation is shorter and the reverse flow is weaker. Nevertheless, it does not have significant effects on the basic features of the flow field. As for the magnitude of wall shear stress, the effect of non-Newtonian viscosity might not be negligible.
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Affiliation(s)
- X Y Xu
- Department of Mechanical Engineering and Aeronautics, City University, London
| | - M W Collins
- Department of Mechanical Engineering and Aeronautics, City University, London
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24
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Secchi F, Alì M, Faggiano E, Cannaò PM, Fedele M, Tresoldi S, Di Leo G, Auricchio F, Sardanelli F. Fractional flow reserve based on computed tomography: an overview. Eur Heart J Suppl 2016; 18:E49-E56. [PMID: 28533717 DOI: 10.1093/eurheartj/suw014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Computed tomography coronary angiography (CTCA) is a technique proved to provide high sensitivity and negative predictive value for the identification of anatomically significant coronary artery disease (CAD) when compared with invasive X-ray coronary angiography. While the CTCA limitation of a ionizing radiation dose delivered to patients is substantially overcome by recent technical innovations, a relevant limitation remains the only anatomical assessment of coronary stenoses in the absence of evaluation of their functional haemodynamic significance. This limitation is highly important for those stenosis graded as intermediate at the anatomical assessment. Recently, non-invasive methods based on computational fluid dynamics were developed to calculate vessel-specific fractional flow reserve (FFR) using data routinely acquired by CTCA [computed tomographic fractional flow reserve (CT-FFR)]. Here we summarize methods for CT-FFR and review the evidence available in the literature up to June 26, 2016, including 16 original articles and one meta-analysis. The perspective of CT-FFR may greatly impact on CAD diagnosis, prognostic evaluation, and treatment decision-making. The aim of this review is to describe technical characteristics and clinical applications of CT-FFR, also in comparison with catheter-based invasive FFR, in order to make a cost-benefit balance in terms of clinical management and patient's health.
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Affiliation(s)
- Francesco Secchi
- Unit of Radiology, IRCCS Policlinico San Donato, Via Morandi 30, San Donato Milanese, Milan 20097, Italy
| | - Marco Alì
- PhD Course in Integrative Biomedical Research, Università degli Studi di Milano, Via Mangiagalli 31, Milano 20133, Italy
| | - Elena Faggiano
- Computational Mechanics & Advanced Material Group, Department of Civil Engineering and Architecture (DICAr), Università degli Studi di Pavia, Via Ferrata 3, Pavia 27100, Italy
| | - Paola Maria Cannaò
- Postgraduation School in Radiodiagnostics, Università degli Studi di Milano, Via Festa del Perdono 7, Milan 20100, Italy
| | - Marco Fedele
- Computational Mechanics & Advanced Material Group, Department of Civil Engineering and Architecture (DICAr), Università degli Studi di Pavia, Via Ferrata 3, Pavia 27100, Italy
| | - Silvia Tresoldi
- Unit of Diagnostic and Interventional Radiology, Azienda Ospedaliera San Paolo, Via A. di Rudinì 8, Milan 20142, Italy
| | - Giovanni Di Leo
- Unit of Radiology, IRCCS Policlinico San Donato, Via Morandi 30, San Donato Milanese, Milan 20097, Italy
| | - Ferdinando Auricchio
- Computational Mechanics & Advanced Material Group, Department of Civil Engineering and Architecture (DICAr), Università degli Studi di Pavia, Via Ferrata 3, Pavia 27100, Italy
| | - Francesco Sardanelli
- Unit of Radiology, IRCCS Policlinico San Donato, Via Morandi 30, San Donato Milanese, Milan 20097, Italy
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Morandi 30, San Donato Milanese, Milan 20097, Italy
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25
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Three-dimensional modeling and numerical analysis of fractional flow reserve in human coronary arteries. ADVANCES IN INTERVENTIONAL CARDIOLOGY 2016; 12:25-31. [PMID: 26966446 PMCID: PMC4777703 DOI: 10.5114/pwki.2016.56946] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 08/10/2015] [Indexed: 01/25/2023] Open
Abstract
Introduction Noninvasive fractional flow reserve (FFR) computed from CT (FFRCT) is a novel method for determining the physiologic significance of coronary artery disease (CAD). Several clinical trials have been conducted, but its diagnostic performance varied among different trials. Aim To determine the cut-off value of FFRCT and its correlation with the gold standard used to diagnose CAD in clinical practice. Material and methods Forty patients with single vessel disease were included in our study. Computed tomography scan and coronary angiography with FFR were conducted for these patients. Three-dimensional geometric reconstruction and numerical analysis based on the computed tomographic angiogram (CTA) of coronary arteries were applied to obtain the values of FFRCT. The correlation between FFRCT and the gold standard used in clinical practice was tested. Results For FFRCT, the best cut-off value was 0.76, with the sensitivity, specificity, positive predictive value and negative predictive values of 84.6%, 92.9%, 88% and 73.3%, respectively. The area under the receiver-operator characteristics curve was 0.945 (p < 0.0001). There was a good correlation of FFRCT values with FFR values (r = 0.94, p < 0.0001), with a slight overestimation of FFRCT as compared with measured FFR (mean difference 0.01 ±0.11, p < 0.05). For inter-observer agreement, the mean κ value was 0.69 (0.61 to 0.78) and for intra-observer agreement the mean κ value was 0.61 (0.50 to 0.72). Conclusions FFRCT derived from CT of the coronary artery is a reliable non-invasive way providing reliable functional information of coronary artery stenosis.
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26
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LI GUOJIE, CHEN BIN. COMPUTATIONAL MODEL OF PLATELET FLOW IN CAROTID ARTERY BIFURCATION. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415400424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Atherosclerotic plaque tends to occur and develop in carotid artery sinus, where stenoses and other lesions can cause cerebral disturbances. The hemodynamics and the platelet profiles in the carotid artery are simultaneously simulated in the present study to reveal the mechanism of the atherosclerotic plaque formation. Firstly, an unsteady PISO solver on unstructured tetrahedral grids is developed to simulate the hemodynamics of carotid artery bifurcation. And small platelets are treated as spherical solid particle described by Newtonian motion equation in the simulation, including inertial force, drag force, shear lift force, virtual mass force and pressure gradient force. Secondly, the visualization experiment for the platelet flow in the straight micro-channel is setup to validate the numerical model. Using the present method, the platelet flow in a carotid artery bifurcation is analyzed. The results show that the outer vascular wall near the bifurcation is more vulnerable in carotid artery sinus, which is mainly due to the lower wall shear stress (WSS) and platelets backflow in the region.
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Affiliation(s)
- GUOJIE LI
- State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University, Xi’an 710049, P. R. China
| | - BIN CHEN
- State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University, Xi’an 710049, P. R. China
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27
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Marrero VL, Tichy JA, Sahni O, Jansen KE. Numerical study of purely viscous non-Newtonian flow in an abdominal aortic aneurysm. J Biomech Eng 2015; 136:101001. [PMID: 24769921 DOI: 10.1115/1.4027488] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 04/24/2014] [Indexed: 11/08/2022]
Abstract
It is well known that blood has non-Newtonian properties, but it is generally accepted that blood behaves as a Newtonian fluid at shear rates above 100 s-1. However, in transient conditions, there are times and locations where the shear rate is well below 100 s-1, and it is reasonable to infer that non-Newtonian effects could become important. In this study, purely viscous non-Newtonian (generalized Newtonian) properties of blood are incorporated into the simulation-based framework for cardiovascular surgery planning developed by Taylor et al. (1999, "Predictive Medicine: Computational Techniques in Therapeutic Decision Making," Comput. Aided Surg., 4, pp. 231-247; 1998, "Finite Element Modeling of Blood Flow in Arteries," Comput. Methods Appl. Mech. Eng., 158, pp. 155-196). Equations describing blood flow are solved in a patient-based abdominal aortic aneurysm model under steady and physiological flow conditions. Direct numerical simulation (DNS) is used, and the complex flow is found to be constantly transitioning between laminar and turbulent in both the spatial and temporal sense. It is found for the case simulated that using the non-Newtonian viscosity modifies the solution in subtle ways that yield a mesh-independent solution with fewer degrees of freedom than the Newtonian counterpart. It appears that in regions of separated flow, the lower shear rate produces higher viscosity with the non-Newtonian model, which reduces the associated resolution needs. When considering the real case of pulsatile flow, high shear layers lead to greater unsteadiness in the Newtonian case relative to the non-Newtonian case. This, in turn, results in a tendency for the non-Newtonian model to need fewer computational resources even though it has to perform additional calculations for the viscosity. It is also shown that both viscosity models predict comparable wall shear stress distribution. This work suggests that the use of a non-Newtonian viscosity models may be attractive to solve cardiovascular flows since it can provide simulation results that are presumably physically more realistic with at least comparable computational effort for a given level of accuracy.
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28
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Kabinejadian F, Kaabi Nezhadian M, Cui F, Ho P, Leo HL. Covered Stent Membrane Design for Treatment of Atheroembolic Disease at Carotid Artery Bifurcation and Prevention of Thromboembolic Stroke: An In Vitro Experimental Study. Artif Organs 2015; 40:159-68. [DOI: 10.1111/aor.12520] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Foad Kabinejadian
- Department of Biomedical Engineering; National University of Singapore; Singapore Singapore
- Department of Surgery; National University of Singapore; Singapore Singapore
| | | | - Fangsen Cui
- Institute of High Performance Computing (IHPC); Agency for Science, Technology and Research (A*STAR); Singapore Singapore
| | - Pei Ho
- Department of Surgery; National University of Singapore; Singapore Singapore
- Department of Cardiac, Thoracic & Vascular Surgery; National University Health System; Singapore Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering; National University of Singapore; Singapore Singapore
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29
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Sun Z, Xu L. Computational fluid dynamics in coronary artery disease. Comput Med Imaging Graph 2014; 38:651-63. [PMID: 25262321 DOI: 10.1016/j.compmedimag.2014.09.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 08/22/2014] [Accepted: 09/03/2014] [Indexed: 01/01/2023]
Abstract
Computational fluid dynamics (CFD) is a widely used method in mechanical engineering to solve complex problems by analysing fluid flow, heat transfer, and associated phenomena by using computer simulations. In recent years, CFD has been increasingly used in biomedical research of coronary artery disease because of its high performance hardware and software. CFD techniques have been applied to study cardiovascular haemodynamics through simulation tools to predict the behaviour of circulatory blood flow in the human body. CFD simulation based on 3D luminal reconstructions can be used to analyse the local flow fields and flow profiling due to changes of coronary artery geometry, thus, identifying risk factors for development and progression of coronary artery disease. This review aims to provide an overview of the CFD applications in coronary artery disease, including biomechanics of atherosclerotic plaques, plaque progression and rupture; regional haemodynamics relative to plaque location and composition. A critical appraisal is given to a more recently developed application, fractional flow reserve based on CFD computation with regard to its diagnostic accuracy in the detection of haemodynamically significant coronary artery disease.
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Affiliation(s)
- Zhonghua Sun
- Discipline of Medical Imaging, Department of Imaging and Applied Physics, Curtin University, Perth, Western Australia 6845, Australia.
| | - Lei Xu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
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30
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Al-Hassan D, Leipsic J. Noninvasive fractional flow reserve derived from coronary computed tomography angiography: integrated anatomical and functional assessment. Future Cardiol 2013; 9:243-51. [PMID: 23463976 DOI: 10.2217/fca.13.2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Coronary computed tomographic angiography (CCTA) provides anatomic detail of lumen stenosis and information on plaque burden, plaque extent and plaque characteristics. CCTA does not, however, provide insight into the hemodynamic significance of a stenosis, which is essential to allow appropriate revascularization decision-making. This could reduce downstream invasive coronary angiography and nonbeneficial coronary revascularization, particularly with intermediate coronary stenosis. Invasive fractional flow reserve (FFR) is the gold standard for the determination of lesion-specific ischemia and the need for revascularization. Advances in computational technology now permit calculation of FFR using resting CCTA image data, without the need for additional radiation or medication. Early data demonstrate improved accuracy and a discriminatory ability of FFR computed tomography to identify ischemia-producing lesions compared with CCTA alone. This new, combined anatomic-functional assessment has the potential to simplify the noninvasive diagnosis of coronary artery disease with a single study to identify patients with ischemia-causing stenosis who may benefit from revascularization.
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Affiliation(s)
- Donya Al-Hassan
- Department of Diagnostic Radiology, King Fahd Military Medical Complex, Dhahran 31932, Kingdom of Saudi Arabia
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31
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Canton G, Chiu B, Chen H, Chen Y, Hatsukami TS, Kerwin WS, Yuan C. A framework for the co-registration of hemodynamic forces and atherosclerotic plaque components. Physiol Meas 2013; 34:977-90. [PMID: 23945133 DOI: 10.1088/0967-3334/34/9/977] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Local hemodynamic forces, such as wall shear stress (WSS), are thought to trigger cellular and molecular mechanisms that determine atherosclerotic plaque vulnerability to rupture. Magnetic resonance imaging has emerged as a powerful tool to characterize human carotid atherosclerotic plaque composition and morphology, and to identify plaque features shown to be key determinants of plaque vulnerability. Image-based computational fluid dynamics has allowed researchers to obtain time-resolved WSS information of atherosclerotic carotid arteries. A deeper understanding of the mechanisms of initiation and progression of atherosclerosis can be obtained through the comparison of WSS and plaque composition and morphology. To date, however, advance in knowledge has been limited greatly due to the lack of a reliable infrastructure to perform such analysis. The aim of this study is to establish a framework that will allow for the co-registration and analysis of the three-dimensional distribution of WSS and plaque components and morphology. The use of this framework will lead to future studies targeted to determining the role of WSS in atherosclerotic plaque progression and vulnerability.
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Affiliation(s)
- Gador Canton
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
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32
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Zarins CK, Taylor CA, Min JK. Computed fractional flow reserve (FFTCT) derived from coronary CT angiography. J Cardiovasc Transl Res 2013; 6:708-14. [PMID: 23934536 PMCID: PMC3790916 DOI: 10.1007/s12265-013-9498-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/07/2013] [Indexed: 01/10/2023]
Abstract
Recent advances in image-based modeling and computational fluid dynamics permit the calculation of coronary artery pressure and flow from typically acquired coronary computed tomography (CT) scans. Computed fractional flow reserve is the ratio of mean coronary artery pressure divided by mean aortic pressure under conditions of simulated maximal coronary hyperemia, thus providing a noninvasive estimate of fractional flow reserve (FFRCT) at every point in the coronary tree. Prospective multicenter clinical trials have shown that computed FFRCT improves diagnostic accuracy and discrimination compared to CT stenosis alone for the diagnosis of hemodynamically significant coronary artery disease (CAD), when compared to invasive FFR as the reference gold standard. This promising new technology provides a combined anatomic and physiologic assessment of CAD in a single noninvasive test that can help select patients for invasive angiography and revascularization or best medical therapy. Further evaluation of the clinical effectiveness and economic implications of noninvasive FFRCT are now being explored.
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33
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Kabinejadian F, Cui F, Zhang Z, Ho P, Leo HL. A novel carotid covered stent design: in vitro evaluation of performance and influence on the blood flow regime at the carotid artery bifurcation. Ann Biomed Eng 2013; 41:1990-2002. [PMID: 23842696 DOI: 10.1007/s10439-013-0863-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 07/03/2013] [Indexed: 10/26/2022]
Abstract
In the present study, a novel carotid covered stent design has been developed. Prototypes of different geometrical design parameters have been fabricated and their performance has been evaluated in vitro under physiological pulsatile flow condition, utilizing flow visualization (dye injection), and particle image velocimetry techniques. These evaluations include the assessment of emboli prevention capability, side-branch flow preservation, and influence on the branch flow pattern and velocity field. The novel covered stents demonstrated significantly higher emboli prevention capability than the corresponding bare metal stent, while preserving more than 83% of the original flow of the external carotid artery (ECA). Flow in the ECA through these covered stents was uniform without evidence of undesirable flow recirculation and reversed flow that might predispose the vessel wall to post-stenting intimal thickening and atherosclerotic plaque formation. This study demonstrated the potential of these novel covered stent designs for the treatment of carotid atherosclerotic stenosis. However, further computational and in vivo investigations of hemodynamics, biological effects, and mechanical performance of this covered stent design is warranted.
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Affiliation(s)
- Foad Kabinejadian
- Department of Bioengineering, National University of Singapore, 9 Engineering Drive 1, Block EA #03-12, Singapore, 117576, Singapore
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34
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Abstract
Fractional flow reserve (FFR) at the time of invasive coronary angiography is the current gold standard for determination of ischemia. Coronary CT angiography (coronary CTA) has emerged as an effective noninvasive method for direct visualization of coronary artery disease. However, severe stenosis by coronary CTA are only modestly predictive of ischemia. Recent technological innovations enable non-invasive calculation of FFR from CT. FFRCT is superior to anatomic assessment of stenoses in coronary CTA for the diagnosis of ischemia-causing lesions on both a per-patient and a per-vessel basis. FFRCT improves the diagnostic accuracy mostly by reducing the false positive rate of stenosis assessment alone. Furthermore, in patients where CT demonstrates an intermediate stenosis, FFRCT demonstrates significantly higher diagnostic performance than anatomic assessment alone.
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Affiliation(s)
- Gilat L Grunau
- Department of Medical Imaging, St. Paul's Hospital, University of British Columbia, Vancouver, Canada.
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35
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Xie X, Tan J, Wei D, Lei D, Yin T, Huang J, Zhang X, Qiu J, Tang C, Wang G. In vitro and in vivo investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish. J R Soc Interface 2013; 10:20121053. [PMID: 23449959 DOI: 10.1098/rsif.2012.1053] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Atherosclerosis (AS) commonly occurs in the regions of the arterial tree with haemodynamic peculiarities, including local flow field disturbances, and formation of swirling flow and vortices. The aim of our study was to confirm low-density lipoprotein (LDL) concentration polarization in the vascular system in vitro and in vivo, and investigate the effects of LDL concentration polarization and flow field alterations on atherosclerotic localization. Red fluorescent LDL was injected into optically transparent Flk1: GFP zebrafish embryos, and the LDL distribution in the vascular lumen was investigated in vivo using laser scanning confocal microscopy. LDL concentration at the vascular luminal surface was found to be higher than that in the bulk. The flow field conditions in blood vessel segments were simulated and measured, and obvious flow field disturbances were found in the regions of vascular geometry change. The LDL concentration at the luminal surface of bifurcation was significantly higher than that in the straight segment, possibly owing to the atherogenic effect of disturbed flow. Additionally, a stenosis model of rabbit carotid arteries was generated. Atherosclerotic plaques were found to have occurred in the stenosis group and were more severe in the stenosis group on a high-fat diet. Our findings provide the first ever definite proof that LDL concentration polarization occurs in the vascular system in vivo. Both lipoprotein concentration polarization and flow field changes are involved in the infiltration/accumulation of atherogenic lipids within the location of arterial luminal surface and promote the development of AS.
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Affiliation(s)
- Xiang Xie
- Chongqing University, Chongqing, People's Republic of China
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Papaharilaou Y, Aristokleous N, Seimenis I, Khozeymeh MI, Georgiou GC, Brott BC, Eracleous E, Anayiotos AS. Effect of head posture on the healthy human carotid bifurcation hemodynamics. Med Biol Eng Comput 2012; 51:207-18. [PMID: 23143389 DOI: 10.1007/s11517-012-0985-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 10/29/2012] [Indexed: 11/25/2022]
Abstract
Head and neck postures may cause morphology changes to the geometry of the carotid bifurcation (CB) that alter the low and oscillating wall shear stress (WSS) regions previously reported as important in the development of atherosclerosis. Here the right and left CB were imaged by MRI in two healthy subjects in the neutral head posture with the subject in the supine position and in two other head postures with the subject in the prone position: (1) rightward rotation up to 80°, and (2) leftward rotation up to 80°. Image-based computational models were constructed to investigate the effect of posture on arterial geometry and local hemodynamics. The area exposure to unfavorable hemodynamics, based on thresholds set for oscillatory shear index (OSI), WSS and relative residence time, was used to quantify the hemodynamic impact on the wall. Torsion of the head was found to: (1) cause notable changes in the bifurcation and internal carotid artery angles and, in most cases, on cross-sectional area ratios for common, internal and external carotid artery, (2) change the spatial distribution of wall regions exposed to unfavorable hemodynamics, and (3) cause a marked change in the hemodynamic burden on the wall when the OSI was considered. These findings suggest that head posture may be associated with the genesis and development of atherosclerotic disease as well as complications in stenotic and stented vessels.
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Affiliation(s)
- Yannis Papaharilaou
- Institute of Applied and Computational Mathematics, Foundation for Research and Technology, Hellas, Heraklion, Crete, Greece
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Cummins M, Rossmann JS. Hemodynamics of ulcerated plaques: before and after. J Biomech Eng 2010; 132:104503. [PMID: 20887021 DOI: 10.1115/1.4002372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The hemodynamics and fluid mechanical forces in blood vessels have long been implicated in the deposition and growth of atherosclerotic plaque. Detailed information about the hemodynamics in vessels affected by significant plaque deposits can also provide insight into the mechanisms and likelihood of plaque weakening and rupture. In the current study, the governing equations are solved in their finite volume formulation in several patient-specific stenotic geometries. Of specific interest are the flow patterns and forces near ulcerations in the plaque. The flow patterns and forces in vessels with ulcerated plaques are compared with those in stenotic vessels without evidence of ulceration and to the hemodynamics in the same vessels as they likely appeared prior to ulceration. Hemodynamics "before" and "after" hemorrhage may suggest fluid mechanical and morphological factors of diagnostic and predictive value. Recirculation zones, vortex shedding, and secondary flows are captured by both laminar and turbulent solutions. The forces on vessel walls are shown to correlate with unstable plaque deposits. Performing before and after studies of vessels in long-term radiology studies may illuminate mechanisms of hemorrhage and other vessel remodeling.
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Affiliation(s)
- Megan Cummins
- Department of Biology, Lafayette College, Easton, PA 18042, USA
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Anor T, Grinberg L, Baek H, Madsen JR, Jayaraman MV, Karniadakis GE. Modeling of blood flow in arterial trees. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2010; 2:612-623. [DOI: 10.1002/wsbm.90] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Tomer Anor
- Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Leopold Grinberg
- Division of Applied Mathematics, Brown University, Providence, RI 02912, USA
| | - Hyoungsu Baek
- Division of Applied Mathematics, Brown University, Providence, RI 02912, USA
| | - Joseph R. Madsen
- Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Mahesh V. Jayaraman
- Department of Diagnostic Imaging, Warren Alpert School of Medicine, Brown University, Providence, RI 02912, USA
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Taylor CA, Draney MT, Ku JP, Parker D, Steele BN, Wang K, Zarins CK. Predictive Medicine: Computational Techniques in Therapeutic Decision-Making. ACTA ACUST UNITED AC 2010. [DOI: 10.3109/10929089909148176] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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41
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Botar C, Vasile T, Sfrangeu S, Clichici S, Agachi P, Badea R, Mircea P, Cristea M. Validation of CFD simulation results in case of portal vein blood flow. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1570-7946(10)28035-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2023]
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BUCHMANN NA, YAMAMOTO M, JERMY M, DAVID T. Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD) Modelling of Carotid Artery Haemodynamics under Steady Flow: A Validation Study. ACTA ACUST UNITED AC 2010. [DOI: 10.1299/jbse.5.421] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Nicolas A. BUCHMANN
- The Centre for Bioengineering University of Canterbury
- Laboratory of Turbulence Research in Aerospace and Combustion Department of Mechanical and Aerospace Engineering, Monash University
| | | | - Mark JERMY
- The Centre for Bioengineering University of Canterbury
| | - Tim DAVID
- The Centre for Bioengineering University of Canterbury
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Ho H, Mithraratne K, Schmid H, Sands G, Hunter P. Computer simulation of vertebral artery occlusion in endovascular procedures. Int J Comput Assist Radiol Surg 2009; 5:29-37. [PMID: 20033514 DOI: 10.1007/s11548-009-0379-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 06/04/2009] [Indexed: 12/01/2022]
Abstract
OBJECTIVE The aim of this work is to establish a computational pipeline for the simulation of blood flow in vasculatures and apply this pipeline to endovascular interventional scenarios, e.g. angioplasty in vertebral arteries. METHODS A patient-specific supra-aortal vasculature is digitized from a 3D CT angiography image. By coupling a reduced formulation of the governing Navier-Stokes equations with a wall constitutive equation we are able to solve the transient flow in elastic vessels. By further incorporating a bifurcation model the blood flow across vascular branches can be evaluated, thus flow in a large vasculature can be modeled. Vascular diseases are simulated by modifying the arterial tree configurations, e.g. the effective diameters, schematic connectivity, etc. Occlusion in an artery is simulated by removing that artery from the arterial tree. RESULTS It takes about 2 min per cardiac cycle to compute blood flow in an arterial tree consisting of 38 vessels and 18 bifurcations on a laptop PC. The simulation results show that blood supply in the posterior region is compensated from the contralateral vertebral artery and the anterior cerebral arteries if one of the vertebral arteries is occluded. CONCLUSION The computational pipeline is computationally efficient and can capture main flow patterns at any point in the arterial tree. With further improvement it can serve as a powerful tool for the haemodynamic analysis in patient-specific vascular structures.
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Affiliation(s)
- Harvey Ho
- Bioengineering Institute, University of Auckland, Auckland, New Zealand.
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Lee YH, Kweon SS, Choi JS, Rhee JA, Choi SW, Ryu SY, Shin MH. [Association of blood pressure levels with carotid intima-media thickness and plaques]. J Prev Med Public Health 2009; 42:298-304. [PMID: 19806002 DOI: 10.3961/jpmph.2009.42.5.298] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES The aim of this study was to investigate the association of blood pressure levels with the common carotid artery intima-media thickness (CCA-IMT) and carotid plaques. METHODS Data were obtained from 2,635 subjects, aged 50 years and over, who participated in the Community Health Survey (a population-based, cross-sectional study) in Dong-gu, Gwangju city between 2007 and 2008. Participants were categorized into three groups according to blood pressure levels; normotensives (<120/80 mmHg), prehypertensives (120-139/80-89 mmHg), and hypertensives (> or =140/90 mmHg). Prehypertensives were further categorized as low prehypertensives (120-129/80-84 mmHg) and high prehypertensives (130-139/85-89 mmHg). Carotid intima-media thickness and plaques were evaluated with a high-resolution B-mode ultrasound. Statistical analyses were performed using chi-square test, ANOVA, and multiple logistic regression. RESULTS Prehypertensives had significantly greater maximal CCA-IMT values than normotensives, with a multivariate adjusted odds ratio of 1.78 (95% CI=1.36-2.32) for abnormal CCA-IMT (maximal CCA-IMT > or =1.0 mm), and 1.45 (95% CI=1.19-1.77) for carotid plaques. The multivariate adjusted odds ratio of low prehypertensives was 1.64 (95% CI=1.21-2.21) for abnormal CCA-IMT, and 1.30 (95% CI=1.04-1.63) for carotid plaques compared with normotensives. Subject with hypertension had higher frequency of abnormal CCA-IMT (odds ratio, 2.18; 95% CI=1.49-3.18), and carotid plaques (odds ratio, 1.98; 95% CI=1.46-2.67) compared with normotensives after adjustment for other cardiovascular risk factors. CONCLUSIONS Our results indicate that there is a significant increase in the prevalence of carotid atherosclerosis in subjects with prehypertension (even in low prehypertensives) compared with normotensive subjects. Further studies are required to confirm the benefits and role of carotid ultrasonography in persons with prehypertension.
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Affiliation(s)
- Young Hoon Lee
- Department of Preventive Medicine, College of Medicine, Seonam University
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Taylor C, Humphrey J. Open Problems in Computational Vascular Biomechanics: Hemodynamics and Arterial Wall Mechanics. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2009; 198:3514-3523. [PMID: 20161129 PMCID: PMC2743020 DOI: 10.1016/j.cma.2009.02.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The vasculature consists of a complex network of vessels ranging from large arteries to arterioles, capillaries, venules, and veins. This network is vital for the supply of oxygen and nutrients to tissues and the removal of carbon dioxide and waste products from tissues. Because of its primary role as a pressure-driven chemomechanical transport system, it should not be surprising that mechanics plays a vital role in the development and maintenance of the normal vasculature as well as in the progression and treatment of vascular disease. This review highlights some past successes of vascular biomechanics, but emphasizes the need for research that synthesizes complementary advances in molecular biology, biomechanics, medical imaging, computational methods, and computing power for purposes of increasing our understanding of vascular physiology and pathophysiology as well as improving the design of medical devices and clinical interventions, including surgical procedures. That is, computational mechanics has great promise to contribute to the continued improvement of vascular health.
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Affiliation(s)
- C.A. Taylor
- Departments of Bioengineering and Surgery, Stanford University, Stanford, CA, USA,
| | - J.D. Humphrey
- Department of Biomedical Engineering and M.E. DeBakey Institute, Texas A&M University, College Station, TX, USA,
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LÖW M, PERKTOLD K. Numerische Untersuchung der Strömungsaktivität in sakkulären Aneurysmen. BIOMED ENG-BIOMED TE 2009. [DOI: 10.1515/bmte.1992.37.s1.55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Chakravarty S, Sen S. Analysis of pulsatile blood flow in constricted bifurcated arteries with vorticity-stream function approach. J Med Eng Technol 2009; 32:10-22. [DOI: 10.1080/03091900600700822] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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48
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Ai L, Yu H, Takabe W, Paraboschi A, Yu F, Kim ES, Li R, Hsiai TK. Optimization of intravascular shear stress assessment in vivo. J Biomech 2009; 42:1429-1437. [PMID: 19457490 DOI: 10.1016/j.jbiomech.2009.04.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/31/2009] [Accepted: 04/04/2009] [Indexed: 11/29/2022]
Abstract
The advent of microelectromechanical systems (MEMS) sensors has enabled real-time wall shear stress (WSS) measurements with high spatial and temporal resolution in a 3-D bifurcation model. To optimize intravascular shear stress assessment, we evaluated the feasibility of catheter/coaxial wire-based MEMS sensors in the abdominal aorta of the New Zealand white (NZW) rabbits. Theoretical and computational fluid dynamics (CFD) analyses were performed. Fluoroscope and angiogram provided the geometry of aorta, and the Doppler ultrasound system provided the pulsatile flow velocity for the boundary conditions. The physical parameters governing the shear stress assessment in NZW rabbits included (1) the position and distance from which the MEMS sensors were mounted to the terminal end of coaxial wire or the entrance length, (L(e)), (2) diameter ratios of aorta to the coaxial wire (D(aorta) /D(coaxial wire)=1.5-9.5), and (3) the range of Reynolds numbers (116-1550). At an aortic diameter of 2.4mm and a maximum Reynolds number of 212 (a mean Reynolds number of 64.2), the time-averaged shear stress (tau(ave)) was computed to be 10.06 dyn cm(-2) with a systolic peak at 33.18 dyn cm(-2). In the presence of a coaxial wire (D(aorta)/D(coaxial wire)=6 and L(e)=1.18 cm), the tau(ave) value increased to 15.54 dyn cm(-2) with a systolic peak at 51.25 dyn cm(-2). Real-time intravascular shear stress assessment by the MEMS sensor revealed an tau(ave) value of 11.92 dyn cm(-2) with a systolic peak at 47.04 dyn cm(-2). The difference between CFD and experimental tau(ave) was 18.5%. These findings provided important insights into packaging the MEMS sensors to optimize in vivo shear stress assessment.
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Affiliation(s)
- Lisong Ai
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Hongyu Yu
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Wakako Takabe
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Anna Paraboschi
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Fei Yu
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - E S Kim
- Department of Electrical Engineering and Electrophysics, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Rongsong Li
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States
| | - Tzung K Hsiai
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089-1111, United States.
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Transient stenotic-like occlusions as a possible mechanism for renovascular hypertension due to aneurysm. ACTA ACUST UNITED AC 2009; 3:192-200. [DOI: 10.1016/j.jash.2009.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/12/2009] [Accepted: 02/13/2009] [Indexed: 11/22/2022]
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Effects of vessel compliance on flow pattern in porcine epicardial right coronary arterial tree. J Biomech 2009; 42:594-602. [PMID: 19195659 DOI: 10.1016/j.jbiomech.2008.12.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 12/13/2008] [Accepted: 12/15/2008] [Indexed: 11/22/2022]
Abstract
The compliance of the vessel wall affects hemodynamic parameters which may alter the permeability of the vessel wall. Based on experimental measurements, the present study established a finite element (FE) model in the proximal elastic vessel segments of epicardial right coronary arterial (RCA) tree obtained from computed tomography. The motion of elastic vessel wall was measured by an impedance catheter and the inlet boundary condition was measured by an ultrasound flow probe. The Galerkin FE method was used to solve the Navier-Stokes and Continuity equations, where the convective term in the Navier-Stokes equation was changed in the arbitrary Lagrangian-Eulerian (ALE) framework to incorporate the motion due to vessel compliance. Various hemodynamic parameters (e.g., wall shear stress-WSS, WSS spatial gradient-WSSG, oscillatory shear index-OSI) were analyzed in the model. The motion due to vessel compliance affects the time-averaged WSSG more strongly than WSS at bifurcations. The decrease of WSSG at flow divider in elastic bifurcations, as compared to rigid bifurcations, implies that the vessel compliance decreases the permeability of vessel wall and may be atheroprotective. The model can be used to predict coronary flow pattern in subject-specific anatomy as determined by noninvasive imaging.
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