51
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Audebert C, Bekheit M, Bucur P, Vibert E, Vignon-Clementel IE. Partial hepatectomy hemodynamics changes: Experimental data explained by closed-loop lumped modeling. J Biomech 2017; 50:202-208. [PMID: 27890535 DOI: 10.1016/j.jbiomech.2016.11.037] [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: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023]
Abstract
The liver function may be degraded after partial liver ablation surgery. Adverse liver hemodynamics have been shown to be associated to liver failure. The link between these hemodynamics changes and ablation size is however poorly understood. This article proposes to explain with a closed-loop lumped model the hemodynamics changes observed during twelve surgeries in pigs. The portal venous tree is modeled with a pressure-dependent variable resistor. The variables measured, before liver ablation, are used to tune the model parameters. Then, the liver partial ablation is simulated with the model and the simulated pressures and flows are compared with post-operative measurements. Fluid infusion and blood losses occur during the surgery. The closed-loop model presented accounts for these blood volume changes. Moreover, the impact of blood volume changes and the liver lobe mass estimations on the simulated variables is studied. The typical increase of portal pressure, increase of liver pressure loss, slight decrease of portal flow and major decrease in arterial flow are quantitatively captured by the model for a 75% hepatectomy. It appears that the 75% decrease in hepatic arterial flow can be explained by the resistance increase induced by the surgery, and that no hepatic arterial buffer response (HABR) mechanism is needed to account for this change. The different post-operative states, observed in experiments, are reproduced with the proposed model. Thus, an explanation for inter-subjects post-operative variability is proposed. The presented framework can easily be adapted to other species circulations and to different pathologies for clinical hepatic applications.
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Affiliation(s)
- Chloe Audebert
- Inria, Paris, France; Sorbonne Universités UPMC Univ Paris 6, Laboratoire Jacques-Louis Lions, France
| | | | - Petru Bucur
- Inserm Unité 1193, Villejuif, France; CHRU, hôpitaux de Tours,Chirurgie Hépato-biliaire et Pancréatique, Transplantation Hépatique, Tours, France
| | - Eric Vibert
- Inserm Unité 1193, Villejuif, France; AP-HP, Hôpital Paul Brousse, Centre Hépato-Biliaire, Villejuif, France
| | - Irene E Vignon-Clementel
- Inria, Paris, France; Sorbonne Universités UPMC Univ Paris 6, Laboratoire Jacques-Louis Lions, France.
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53
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Assessment of calcified aortic valve leaflet deformations and blood flow dynamics using fluid-structure interaction modeling. INFORMATICS IN MEDICINE UNLOCKED 2017. [DOI: 10.1016/j.imu.2017.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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54
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Biglino G, Capelli C, Bruse J, Bosi GM, Taylor AM, Schievano S. Computational modelling for congenital heart disease: how far are we from clinical translation? Heart 2016; 103:98-103. [PMID: 27798056 PMCID: PMC5284484 DOI: 10.1136/heartjnl-2016-310423] [Citation(s) in RCA: 43] [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: 08/05/2016] [Revised: 09/26/2016] [Accepted: 09/29/2016] [Indexed: 12/17/2022] Open
Abstract
Computational models of congenital heart disease (CHD) have become increasingly sophisticated over the last 20 years. They can provide an insight into complex flow phenomena, allow for testing devices into patient-specific anatomies (pre-CHD or post-CHD repair) and generate predictive data. This has been applied to different CHD scenarios, including patients with single ventricle, tetralogy of Fallot, aortic coarctation and transposition of the great arteries. Patient-specific simulations have been shown to be informative for preprocedural planning in complex cases, allowing for virtual stent deployment. Novel techniques such as statistical shape modelling can further aid in the morphological assessment of CHD, risk stratification of patients and possible identification of new ‘shape biomarkers’. Cardiovascular statistical shape models can provide valuable insights into phenomena such as ventricular growth in tetralogy of Fallot, or morphological aortic arch differences in repaired coarctation. In a constant move towards more realistic simulations, models can also account for multiscale phenomena (eg, thrombus formation) and importantly include measures of uncertainty (ie, CIs around simulation results). While their potential to aid understanding of CHD, surgical/procedural decision-making and personalisation of treatments is undeniable, important elements are still lacking prior to clinical translation of computational models in the field of CHD, that is, large validation studies, cost-effectiveness evaluation and establishing possible improvements in patient outcomes.
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Affiliation(s)
- Giovanni Biglino
- Bristol Heart Institute, School of Clinical Sciences, University of Bristol, Bristol, UK.,Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Claudio Capelli
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Jan Bruse
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Giorgia M Bosi
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Andrew M Taylor
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
| | - Silvia Schievano
- Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
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55
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Lee P, Carlson BE, Chesler N, Olufsen MS, Qureshi MU, Smith NP, Sochi T, Beard DA. Heterogeneous mechanics of the mouse pulmonary arterial network. Biomech Model Mechanobiol 2016; 15:1245-61. [PMID: 26792789 PMCID: PMC4956606 DOI: 10.1007/s10237-015-0757-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/25/2015] [Indexed: 10/22/2022]
Abstract
Individualized modeling and simulation of blood flow mechanics find applications in both animal research and patient care. Individual animal or patient models for blood vessel mechanics are based on combining measured vascular geometry with a fluid structure model coupling formulations describing dynamics of the fluid and mechanics of the wall. For example, one-dimensional fluid flow modeling requires a constitutive law relating vessel cross-sectional deformation to pressure in the lumen. To investigate means of identifying appropriate constitutive relationships, an automated segmentation algorithm was applied to micro-computerized tomography images from a mouse lung obtained at four different static pressures to identify the static pressure-radius relationship for four generations of vessels in the pulmonary arterial network. A shape-fitting function was parameterized for each vessel in the network to characterize the nonlinear and heterogeneous nature of vessel distensibility in the pulmonary arteries. These data on morphometric and mechanical properties were used to simulate pressure and flow velocity propagation in the network using one-dimensional representations of fluid and vessel wall mechanics. Moreover, wave intensity analysis was used to study effects of wall mechanics on generation and propagation of pressure wave reflections. Simulations were conducted to investigate the role of linear versus nonlinear formulations of wall elasticity and homogeneous versus heterogeneous treatments of vessel wall properties. Accounting for heterogeneity, by parameterizing the pressure/distention equation of state individually for each vessel segment, was found to have little effect on the predicted pressure profiles and wave propagation compared to a homogeneous parameterization based on average behavior. However, substantially different results were obtained using a linear elastic thin-shell model than were obtained using a nonlinear model that has a more physiologically realistic pressure versus radius relationship.
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Affiliation(s)
- Pilhwa Lee
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA
| | - Brian E Carlson
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA
| | - Naomi Chesler
- Department of Biomedical Engineering, University of Wisconsin-Madison, 2146 ECB; 1550 Engineering Drive, Madison, WI, 53706-1609, USA
| | - Mette S Olufsen
- Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA
| | - M Umar Qureshi
- Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA
| | - Nicolas P Smith
- Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK
- Faculty of Engineering, 20 Symonds St, Auckland, 1010, New Zealand
| | - Taha Sochi
- Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK
| | - Daniel A Beard
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA.
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56
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Maschietto N, Semplicini L, Ceolotto G, Cattelan A, Poser Dvm H, Iacopetti I, Gerardi G, De Benedictis GM, Pilla T, Bernardini D, Aresu L, Rizzo S, Basso C, Semplicini A, Milanesi O. Aortic stenting in the growing sheep causes aortic endothelial dysfunction but not hypertension: Clinical implications for coarctation repair. CONGENIT HEART DIS 2016; 12:74-83. [PMID: 27600478 DOI: 10.1111/chd.12406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/21/2016] [Accepted: 07/24/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND Stent implantation is the treatment of choice for adolescents and adults with aortic coarctation (CoAo). Despite excellent short-term results, 20%-40% of the patients develop arterial hypertension later in life, which was attributed to inappropriate response of the aortic baroreceptors to increased stiffness of the ascending aorta (ASAO), either congenital or induced by CoAo repair. In particular, it has been hypothesized that stent itself may cause or sustain hypertension. Therefore, we aimed to study the hemodynamic and structural impact following stent implantation in the normal aorta of a growing animal. METHODS Eight female sheep completed the study and a stent was implanted in four. Every 3 mo we measured blood pressure of the anterior and posterior limbs and left ventricular function by echocardiography. Twelve months later invasive pressure was measured under baseline and simulated stress conditions. Expression of genes indicating oxidative stress (OS), endothelial dysfunction (ED) and stiffness, as well as pathological examination were performed in ascending (ASAO) and descending aorta (DSAO). RESULTS SOD1 and MMP9 gene expression were higher in ASAO of the stented animals, compared to DSAO and controls, while NOS3 was decreased. No differences were found in blood pressure and echocardiographic parameters. No histological differences were found in the aorta of the two groups of animals. CONCLUSIONS Stent does not affect central and peripheral hemodynamics, cardiac structure and function even in the long term. However, the finding of markers of OS and increased stiffness of ASAO, proximal to the stent, points to molecular mechanisms for increased cardiovascular risk of patients with stented CoAo.
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Affiliation(s)
- Nicola Maschietto
- Pediatric Cardiology Unit, Department of Women's and Children's Health, University of Padua, Padova, Italy
| | | | | | | | - Helen Poser Dvm
- Department of Animal Medicine, Production and Health, University of Padua, Padova, Italy
| | - Ilaria Iacopetti
- Department of Animal Medicine, Production and Health, University of Padua, Padova, Italy
| | - Gabriele Gerardi
- Department of Animal Medicine, Production and Health, University of Padua, Padova, Italy
| | | | - Tommaso Pilla
- Department of Animal Medicine, Production and Health, University of Padua, Padova, Italy
| | - Daniele Bernardini
- Department of Animal Medicine, Production and Health, University of Padua, Padova, Italy
| | - Luca Aresu
- Department of Comparative BioMedicine and Food Science, University of Padua, Padova, Italy
| | - Stefania Rizzo
- Cardiovascular Pathology Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padova, Italy
| | - Cristina Basso
- Cardiovascular Pathology Unit, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padova, Italy
| | | | - Ornella Milanesi
- Pediatric Cardiology Unit, Department of Women's and Children's Health, University of Padua, Padova, Italy
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57
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Wendell DC, Samyn MM, Cava JR, Krolikowski MM, LaDisa JF. The Impact of Cardiac Motion on Aortic Valve Flow Used in Computational Simulations of the Thoracic Aorta. J Biomech Eng 2016; 138:2531718. [PMID: 27367143 DOI: 10.1115/1.4033964] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Indexed: 02/04/2023]
Abstract
Advancements in image-based computational modeling are producing increasingly more realistic representations of vasculature and hemodynamics, but so far have not compensated for cardiac motion when imposing inflow boundary conditions. The effect of cardiac motion on aortic flow is important when assessing sequelae in this region including coarctation of the aorta (CoA) or regurgitant fraction. The objective of this investigation was to develop a method to assess and correct for the influence of cardiac motion on blood flow measurements through the aortic valve (AoV) and to determine its impact on patient-specific local hemodynamics quantified by computational fluid dynamics (CFD). A motion-compensated inflow waveform was imposed into the CFD model of a patient with repaired CoA that accounted for the distance traveled by the basal plane during the cardiac cycle. Time-averaged wall shear stress (TAWSS) and turbulent kinetic energy (TKE) values were compared with CFD results of the same patient using the original waveform. Cardiac motion resulted in underestimation of flow during systole and overestimation during diastole. Influences of inflow waveforms on TAWSS were greatest along the outer wall of the ascending aorta (AscAo) (∼30 dyn/cm2). Differences in TAWSS were more pronounced than those from the model creation or mesh dependence aspects of CFD. TKE was slightly higher for the motion-compensated waveform throughout the aortic arch. These results suggest that accounting for cardiac motion when quantifying blood flow through the AoV can lead to different conclusions for hemodynamic indices, which may be important if these results are ultimately used to predict patient outcomes.
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58
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Mirzaee H, Henn T, Krause MJ, Goubergrits L, Schumann C, Neugebauer M, Kuehne T, Preusser T, Hennemuth A. MRI-based computational hemodynamics in patients with aortic coarctation using the lattice Boltzmann methods: Clinical validation study. J Magn Reson Imaging 2016; 45:139-146. [PMID: 27384018 PMCID: PMC5213689 DOI: 10.1002/jmri.25366] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/15/2016] [Indexed: 11/17/2022] Open
Abstract
Purpose To introduce a scheme based on a recent technique in computational hemodynamics, known as the lattice Boltzmann methods (LBM), to noninvasively measure pressure gradients in patients with a coarctation of the aorta (CoA). To provide evidence on the accuracy of the proposed scheme, the computed pressure drop values are compared against those obtained using the reference standard method of catheterization. Materials and Methods Pre‐ and posttreatment LBM‐based pressure gradients for 12 patients with CoA were simulated for the time point of peak systole using the open source library OpenLB. Four‐dimensional (4D) flow‐sensitive phase‐contrast MRI at 1.5 Tesla was used to acquire flow and to setup the simulation. The vascular geometry was reconstructed using 3D whole‐heart MRI. Patients underwent pre‐ and postinterventional pressure catheterization as a reference standard. Results There is a significant linear correlation between the pretreatment catheter pressure drops and those computed based on the LBM simulation,
r=.85,
P<.001. The bias was ‐0.58 ± 4.1 mmHg and was not significant (
P=0.64) with a 95% confidence interval (CI) of ‐3.22 to 2.06. For the posttreatment results, the bias was larger and at ‐2.54 ± 3.53 mmHg with a 95% CI of ‐0.17 to ‐4.91 mmHg. Conclusion The results indicate a reasonable agreement between the simulation results and the catheter measurements. LBM‐based computational hemodynamics can be considered as an alternative to more traditional computational fluid dynamics schemes for noninvasive pressure calculations and can assist in diagnosis and therapy planning. Level of Evidence: 3 J. Magn. Reson. Imaging 2017;45:139–146.
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Affiliation(s)
- Hanieh Mirzaee
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
| | - Thomas Henn
- Institute for Mechanical Process Engineering and Mechanics, Karlsruher Institute of Technology, Karlsruhe, Germany
| | - Mathias J Krause
- Institute for Mechanical Process Engineering and Mechanics, Karlsruher Institute of Technology, Karlsruhe, Germany
| | - Leonid Goubergrits
- Biofluid Mechanics Laboratory, Charité-Universitätsmedizin, Berlin, Germany.,Non-Invasive Cardiac Imaging in Congenital Heart Disease Unit, Charité-Universitätsmedizin, Berlin, and German Heart Institute, Berlin, Germany
| | - Christian Schumann
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
| | - Mathias Neugebauer
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
| | - Titus Kuehne
- Non-Invasive Cardiac Imaging in Congenital Heart Disease Unit, Charité-Universitätsmedizin, Berlin, and German Heart Institute, Berlin, Germany
| | - Tobias Preusser
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
| | - Anja Hennemuth
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
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Toward translating near-infrared spectroscopy oxygen saturation data for the non-invasive prediction of spatial and temporal hemodynamics during exercise. Biomech Model Mechanobiol 2016; 16:75-96. [PMID: 27376865 DOI: 10.1007/s10237-016-0803-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 06/21/2016] [Indexed: 01/08/2023]
Abstract
Image-based computational fluid dynamics (CFD) studies conducted at rest have shown that atherosclerotic plaque in the thoracic aorta (TA) correlates with adverse wall shear stress (WSS), but there is a paucity of such data under elevated flow conditions. We developed a pedaling exercise protocol to obtain phase contrast magnetic resonance imaging (PC-MRI) blood flow measurements in the TA and brachiocephalic arteries during three-tiered supine pedaling at 130, 150, and 170 % of resting heart rate (HR), and relate these measurements to non-invasive tissue oxygen saturation [Formula: see text] acquired by near-infrared spectroscopy (NIRS) while conducting the same protocol. Local quantification of WSS indices by CFD revealed low time-averaged WSS on the outer curvature of the ascending aorta and the inner curvature of the descending aorta (dAo) that progressively increased with exercise, but that remained low on the anterior surface of brachiocephalic arteries. High oscillatory WSS observed on the inner curvature of the aorta persisted during exercise as well. Results suggest locally continuous exposure to potentially deleterious indices of WSS despite benefits of exercise. Linear relationships between flow distributions and tissue oxygen extraction calculated from [Formula: see text] were found between the left common carotid versus cerebral tissue [Formula: see text] and the dAo versus leg tissue [Formula: see text]. A resulting six-step procedure is presented to use NIRS data as a surrogate for exercise PC-MRI when setting boundary conditions for future CFD studies of the TA under simulated exercise conditions. Relationships and ensemble-averaged PC-MRI inflow waveforms are provided in an online repository for this purpose.
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60
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Brass LF, Diamond SL. Transport physics and biorheology in the setting of hemostasis and thrombosis. J Thromb Haemost 2016; 14:906-17. [PMID: 26848552 PMCID: PMC4870125 DOI: 10.1111/jth.13280] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/20/2016] [Accepted: 01/26/2016] [Indexed: 02/02/2023]
Abstract
The biophysics of blood flow can dictate the function of molecules and cells in the vasculature with consequent effects on hemostasis, thrombosis, embolism, and fibrinolysis. Flow and transport dynamics are distinct for (i) hemostasis vs. thrombosis and (ii) venous vs. arterial episodes. Intraclot transport changes dramatically the moment hemostasis is achieved or the moment a thrombus becomes fully occlusive. With platelet concentrations that are 50- to 200-fold greater than platelet-rich plasma, clots formed under flow have a different composition and structure compared with blood clotted statically in a tube. The platelet-rich, core/shell architecture is a prominent feature of self-limiting hemostatic clots formed under flow. Importantly, a critical threshold concentration of surface tissue factor is required for fibrin generation under flow. Once initiated by wall-derived tissue factor, thrombin generation and its spatial propagation within a clot can be modulated by γ'-fibrinogen incorporated into fibrin, engageability of activated factor (FIXa)/activated FVIIIa tenase within the clot, platelet-derived polyphosphate, transclot permeation, and reduction of porosity via platelet retraction. Fibrin imparts tremendous strength to a thrombus to resist embolism up to wall shear stresses of 2400 dyne cm(-2) . Extreme flows, as found in severe vessel stenosis or in mechanical assist devices, can cause von Willebrand factor self-association into massive fibers along with shear-induced platelet activation. Pathological von Willebrand factor fibers are A Disintegrin And Metalloprotease with ThromboSpondin-1 domain 13 resistant but are a substrate for fibrin generation due to FXIIa capture. Recently, microfluidic technologies have enhanced the ability to interrogate blood in the context of stenotic flows, acquired von Willebrand disease, hemophilia, traumatic bleeding, and drug action.
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Affiliation(s)
- Lawrence F. Brass
- Departments of Medicine and Systems Pharmacology, University of Pennsylvania, Philadelphia, PA, USA
| | - Scott L. Diamond
- Departments of Medicine and Systems Pharmacology, University of Pennsylvania, Philadelphia, PA, USA
- Institute for Medicine and Engineering, Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA, USA
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61
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Ralovich K, Itu L, Vitanovski D, Sharma P, Ionasec R, Mihalef V, Krawtschuk W, Zheng Y, Everett A, Pongiglione G, Leonardi B, Ringel R, Navab N, Heimann T, Comaniciu D. Noninvasive hemodynamic assessment, treatment outcome prediction and follow-up of aortic coarctation from MR imaging. Med Phys 2016; 42:2143-56. [PMID: 25979009 DOI: 10.1118/1.4914856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Coarctation of the aorta (CoA) is a congenital heart disease characterized by an abnormal narrowing of the proximal descending aorta. Severity of this pathology is quantified by the blood pressure drop (△P) across the stenotic coarctation lesion. In order to evaluate the physiological significance of the preoperative coarctation and to assess the postoperative results, the hemodynamic analysis is routinely performed by measuring the △P across the coarctation site via invasive cardiac catheterization. The focus of this work is to present an alternative, noninvasive measurement of blood pressure drop △P through the introduction of a fast, image-based workflow for personalized computational modeling of the CoA hemodynamics. METHODS The authors propose an end-to-end system comprised of shape and computational models, their personalization setup using MR imaging, and a fast, noninvasive method based on computational fluid dynamics (CFD) to estimate the pre- and postoperative hemodynamics for coarctation patients. A virtual treatment method is investigated to assess the predictive power of our approach. RESULTS Automatic thoracic aorta segmentation was applied on a population of 212 3D MR volumes, with mean symmetric point-to-mesh error of 3.00 ± 1.58 mm and average computation time of 8 s. Through quantitative evaluation of 6 CoA patients, good agreement between computed blood pressure drop and catheter measurements is shown: average differences are 2.38 ± 0.82 mm Hg (pre-), 1.10 ± 0.63 mm Hg (postoperative), and 4.99 ± 3.00 mm Hg (virtual stenting), respectively. CONCLUSIONS The complete workflow is realized in a fast, mostly-automated system that is integrable in the clinical setting. To the best of our knowledge, this is the first time that three different settings (preoperative--severity assessment, poststenting--follow-up, and virtual stenting--treatment outcome prediction) of CoA are investigated on multiple subjects. We believe that in future-given wider clinical validation-our noninvasive in-silico method could replace invasive pressure catheterization for CoA.
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Affiliation(s)
- Kristóf Ralovich
- Siemens AG, Imaging and Computer Vision, San-Carlos-Strasse 7, 91058 Erlangen, Germany and Technical University of Munich, Boltzmannstrasse 3, Munich 85748, Germany
| | - Lucian Itu
- Siemens S.r.l., Imaging and Computer Vision, B-dul Eroilor nr. 5, 500007 Brasov, Romania and Transilvania University of Brasov, B-dul Eroilor nr. 29, 500036 Brasov, Romania
| | - Dime Vitanovski
- Siemens AG, Imaging and Computer Vision, San-Carlos-Strasse 7, 91058 Erlangen, Germany and Pattern Recognition Lab, Friedrich-Alexander University Erlangen-Nuremberg, Martensstrasse 3, 91058 Erlangen, Germany
| | - Puneet Sharma
- Siemens Corporation, Imaging and Computer Vision, 755 College Road East, Princeton, New Jersey 08540
| | - Razvan Ionasec
- Siemens Corporation, Imaging and Computer Vision, 755 College Road East, Princeton, New Jersey 08540
| | - Viorel Mihalef
- Siemens Corporation, Imaging and Computer Vision, 755 College Road East, Princeton, New Jersey 08540
| | - Waldemar Krawtschuk
- Siemens AG, Imaging and Computer Vision, San-Carlos-Strasse 7, 91058 Erlangen, Germany
| | - Yefeng Zheng
- Siemens Corporation, Imaging and Computer Vision, 755 College Road East, Princeton, New Jersey 08540
| | - Allen Everett
- The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, Maryland 21287
| | | | - Benedetta Leonardi
- Ospedale Pediatrico Bambino Gesù, Piazza Sant'Onofrio 4, 00165 Rome, Italy
| | - Richard Ringel
- The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, Maryland 21287
| | - Nassir Navab
- Technical University of Munich, Boltzmannstrasse 3, Munich 85748, Germany
| | - Tobias Heimann
- Siemens AG, Imaging and Computer Vision, San-Carlos-Strasse 7, 91058 Erlangen, Germany
| | - Dorin Comaniciu
- Siemens Corporation, Imaging and Computer Vision, 755 College Road East, Princeton, New Jersey 08540
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Donati F, Figueroa CA, Smith NP, Lamata P, Nordsletten DA. Non-invasive pressure difference estimation from PC-MRI using the work-energy equation. Med Image Anal 2015; 26:159-72. [PMID: 26409245 PMCID: PMC4686008 DOI: 10.1016/j.media.2015.08.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 08/21/2015] [Accepted: 08/31/2015] [Indexed: 01/15/2023]
Abstract
Pressure difference is an accepted clinical biomarker for cardiovascular disease conditions such as aortic coarctation. Currently, measurements of pressure differences in the clinic rely on invasive techniques (catheterization), prompting development of non-invasive estimates based on blood flow. In this work, we propose a non-invasive estimation procedure deriving pressure difference from the work-energy equation for a Newtonian fluid. Spatial and temporal convergence is demonstrated on in silico Phase Contrast Magnetic Resonance Image (PC-MRI) phantoms with steady and transient flow fields. The method is also tested on an image dataset generated in silico from a 3D patient-specific Computational Fluid Dynamics (CFD) simulation and finally evaluated on a cohort of 9 subjects. The performance is compared to existing approaches based on steady and unsteady Bernoulli formulations as well as the pressure Poisson equation. The new technique shows good accuracy, robustness to noise, and robustness to the image segmentation process, illustrating the potential of this approach for non-invasive pressure difference estimation.
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Affiliation(s)
- Fabrizio Donati
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St. Thomas' Hospital, 4th floor Lambeth Wing, The Rayne Institute, London SE1 7EH, United Kingdom.
| | - C Alberto Figueroa
- University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48105, United States.
| | - Nicolas P Smith
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St. Thomas' Hospital, 4th floor Lambeth Wing, The Rayne Institute, London SE1 7EH, United Kingdom; University of Auckland, Engineering School Block 1, Level 5, 20 Symonds St, Auckland 101, New Zealand.
| | - Pablo Lamata
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St. Thomas' Hospital, 4th floor Lambeth Wing, The Rayne Institute, London SE1 7EH, United Kingdom; University of Oxford, Department of Computer Science, Wolfson Building, Parks Road, Oxford OX1 3QD, United Kingdom.
| | - David A Nordsletten
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St. Thomas' Hospital, 4th floor Lambeth Wing, The Rayne Institute, London SE1 7EH, United Kingdom.
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Erratum to: Quantitative Assessment of Turbulence and Flow Eccentricity in an Aortic Coarctation: Impact of Virtual Interventions. Cardiovasc Eng Technol 2015; 6:577-89. [DOI: 10.1007/s13239-015-0243-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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64
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Zhang N, Fan Z, Luo N, Bi X, Zhao Y, An J, Liu J, Chen Z, Fan Z, Li D. Noncontrast MR angiography (MRA) of infragenual arteries using flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) at 3.0 Tesla: Comparison with contrast-enhanced MRA. J Magn Reson Imaging 2015; 43:364-72. [PMID: 26185106 DOI: 10.1002/jmri.25003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/26/2015] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND To evaluate the feasibility and diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) MR angiography (MRA) for imaging infragenual arteries at 3.0T, with contrast enhanced MR angiography (CE MRA) as reference. METHODS Twenty consecutive patients with suspicion of lower extremity arterial disease undergoing routine CE MRA were recruited. FSD MRA was performed at calf before CE MRA. Image quality and stenosis degree of infragenual arteries from both techniques were independently evaluated and compared. Six patients in this study underwent DSA examination. RESULTS Three undiagnostic segments were excluded with severe venous contamination in CE MRA. A total of 197 calf arterial segments images were analyzed. No significant difference existed in the relative signal intensity (rSI) of arterial segments between FSD MRA and CE MRA techniques (0.92 ± 0.09 versus 0.93 ± 0.05; P = 0.207). However, the subjective image quality score was slightly higher in FSD MRA (3.66 ± 0.81 versus 3.49 ± 0.87; P = 0.050). With CE MRA images as reference standard, slight overestimation existed in FSD MRA (2.19 ± 1.24 versus 2.09 ± 1.18; P = 0.019), with total agreement of 84.3% on the basis of all arterial segments. The sensitivity, specificity, negative predictive value, and positive predictive value of FSD MRA was 96.4%, 93.0%, 98.5%, and 84.1%. No significant difference in the stenosis degree score was detected between MRA (FSD MRA and CE MRA) and DSA (P > 0.05). CONCLUSION FSD MRA performed on at 3.0T without the use of contrast medium provides diagnostic images allowing for arterial stenosis assessment of calf arteries that was highly comparable with CE MRA. Moreover, venous contamination was less problematic with FSD MRA.
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Affiliation(s)
- Nan Zhang
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhaoyang Fan
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Nan Luo
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Xiaoming Bi
- Siemens Medical Solutions USA, Inc., Chicago, Illinois, USA
| | - Yike Zhao
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Jing An
- Siemens Healthcare, China, MR Collaborations NE Asia, Beijing, China
| | - Jiayi Liu
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhong Chen
- Department of Vascular Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhanming Fan
- Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
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Taelman L, Bols J, Degroote J, Muthurangu V, Panzer J, Vierendeels J, Segers P. Differential impact of local stiffening and narrowing on hemodynamics in repaired aortic coarctation: an FSI study. Med Biol Eng Comput 2015; 54:497-510. [PMID: 26142885 DOI: 10.1007/s11517-015-1336-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 06/15/2015] [Indexed: 12/22/2022]
Abstract
Even after successful treatment of aortic coarctation, a high risk of cardiovascular morbidity and mortality remains. Uncertainty exists on the factors contributing to this increased risk among which are the presence of (1) a residual narrowing leading to an additional resistance and (2) a less distensible zone disturbing the buffer function of the aorta. As the many interfering factors and adaptive physiological mechanisms present in vivo prohibit the study of the isolated impact of these individual factors, a numerical fluid-structure interaction model is developed to predict central hemodynamics in coarctation treatment. The overall impact of a stiffening on the hemodynamics is limited, with a small increase in systolic pressure (up to 8 mmHg) proximal to the stiffening which is amplified with increasing stiffening and length. A residual narrowing, on the other hand, affects the hemodynamics significantly. For a short segment (10 mm), the combination of a stiffening and narrowing (coarctation index 0.5) causes an increase in systolic pressure of 58 mmHg, with 31 mmHg due to narrowing and an additional 27 mmHg due to stiffening. For a longer segment (25 mm), an increase in systolic pressure of 50 mmHg is found, of which only 9 mmHg is due to stiffening.
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Affiliation(s)
- Liesbeth Taelman
- IBiTech-bioMMeda, iMinds Medical IT, Faculty of Engineering and Architecture, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Joris Bols
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Joris Degroote
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Vivek Muthurangu
- Centre for Cardiovascular MR, UCL Institute of Child Health, London Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK
| | - Joseph Panzer
- Paediatric Cardiology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium
| | - Jan Vierendeels
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Patrick Segers
- IBiTech-bioMMeda, iMinds Medical IT, Faculty of Engineering and Architecture, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
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66
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Sotelo J, Urbina J, Valverde I, Tejos C, Irarrázaval P, Hurtado DE, Uribe S. Quantification of wall shear stress using a finite-element method in multidimensional phase-contrast MR data of the thoracic aorta. J Biomech 2015; 48:1817-27. [DOI: 10.1016/j.jbiomech.2015.04.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/20/2015] [Accepted: 04/27/2015] [Indexed: 10/23/2022]
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67
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Cardiovascular magnetic resonance imaging-based computational fluid dynamics/fluid-structure interaction pilot study to detect early vascular changes in pediatric patients with type 1 diabetes. Pediatr Cardiol 2015; 36:851-61. [PMID: 25577225 DOI: 10.1007/s00246-014-1071-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 11/27/2014] [Indexed: 12/19/2022]
Abstract
We hypothesized that pediatric patients with type 1 diabetes have cardiac magnetic resonance (CMR) detectable differences in thoracic aortic wall properties and hemodynamics leading to significant local differences in indices of wall shear stress, when compared with age-matched control subjects without diabetes. Pediatric patients with type 1 diabetes were recruited from Children's Hospital of Wisconsin and compared with controls. All underwent morning CMR scanning, 4-limb blood pressure, brachial artery reactivity testing, and venipuncture. Patient-specific computational fluid dynamics modeling with fluid-structure interaction, based on CMR data, determined regional time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI). Twenty type 1 diabetic subjects, median age 15.8 years (11.6-18.4) and 8 controls 15.4 years (10.3-18.2) were similar except for higher glucose, hemoglobin A1c, and triglycerides for type 1 diabetic subjects. Lower flow-mediated dilation was seen for those with type 1 diabetes (6.5) versus controls (7.8), p = 0.036. For type 1 diabetic subjects, the aorta had more regions with high TAWSS when compared to controls. OSI maps appeared similar. Flow-mediated dilation positively correlated with age at diabetes diagnosis (r = 0.468, p = 0.038) and hemoglobin A1c (r = 0.472, p = 0.036), but did not correlate with aortic distensibility, TAWSS, or OSI. TAWSS did not correlate with any clinical parameter for either group. CMR shows regional differences in aortic wall properties for young diabetic patients. Some local differences in wall shear stress indices were also observed, but a longitudinal study is now warranted.
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68
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Andersson M, Lantz J, Ebbers T, Karlsson M. Quantitative Assessment of Turbulence and Flow Eccentricity in an Aortic Coarctation: Impact of Virtual Interventions. Cardiovasc Eng Technol 2015; 6:281-93. [PMID: 26577361 DOI: 10.1007/s13239-015-0218-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 02/13/2015] [Indexed: 01/01/2023]
Abstract
Turbulence and flow eccentricity can be measured by magnetic resonance imaging (MRI) and may play an important role in the pathogenesis of numerous cardiovascular diseases. In the present study, we propose quantitative techniques to assess turbulent kinetic energy (TKE) and flow eccentricity that could assist in the evaluation and treatment of stenotic severities. These hemodynamic parameters were studied in a pre-treated aortic coarctation (CoA) and after several virtual interventions using computational fluid dynamics (CFD), to demonstrate the effect of different dilatation options on the flow field. Patient-specific geometry and flow conditions were derived from MRI data. The unsteady pulsatile flow was resolved by large eddy simulation including non-Newtonian blood rheology. Results showed an inverse asymptotic relationship between the total amount of TKE and degree of dilatation of the stenosis, where turbulent flow proximal the constriction limits the possible improvement by treating the CoA alone. Spatiotemporal maps of TKE and flow eccentricity could be linked to the characteristics of the jet, where improved flow conditions were favored by an eccentric dilatation of the CoA. By including these flow markers into a combined MRI-CFD intervention framework, CoA therapy has not only the possibility to produce predictions via simulation, but can also be validated pre- and immediate post treatment, as well as during follow-up studies.
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Affiliation(s)
- Magnus Andersson
- Department of Management and Engineering (IEI), Linköping University, 581 83, Linköping, Sweden. .,Swedish e-Science Research Center (SeRC), Stockholm, Sweden.
| | - Jonas Lantz
- Department of Science and Technology, Linköping University, Linköping, Sweden.,Swedish e-Science Research Center (SeRC), Stockholm, Sweden
| | - Tino Ebbers
- Department of Science and Technology, Linköping University, Linköping, Sweden.,Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.,Swedish e-Science Research Center (SeRC), Stockholm, Sweden
| | - Matts Karlsson
- Department of Management and Engineering (IEI), Linköping University, 581 83, Linköping, Sweden.,Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.,Swedish e-Science Research Center (SeRC), Stockholm, Sweden
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69
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Pant S, Fabrèges B, Gerbeau JF, Vignon-Clementel IE. A methodological paradigm for patient-specific multi-scale CFD simulations: from clinical measurements to parameter estimates for individual analysis. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2014; 30:1614-1648. [PMID: 25345820 DOI: 10.1002/cnm.2692] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 09/19/2014] [Accepted: 10/19/2014] [Indexed: 06/04/2023]
Abstract
A new framework for estimation of lumped (for instance, Windkessel) model parameters from uncertain clinical measurements is presented. The ultimate aim is to perform patient-specific haemodynamic analysis. This framework is based on sensitivity analysis tools and the sequential estimation approach of the unscented Kalman filter. Sensitivity analysis and parameter estimation are performed in lumped parameter models, which act as reduced order surrogates of the 3D domain for haemodynamic analysis. While the goal of sensitivity analysis is to assess potential identifiability problems, the unscented Kalman filter estimation leads to parameter estimates based on clinical measurements and modelling assumptions. An application of such analysis and parameter estimation methodology is demonstrated for synthetic and real data. Equality constraints on various physiological parameters are enforced. Since the accuracy of the Windkessel parameter estimates depends on the lumped parameter representativeness, the latter is iteratively improved by running few 3D simulations while simultaneously improving the former. Such a method is applied on a patient-specific aortic coarctation case. Less than 3% and 9% errors between the clinically measured quantities and 3D simulation results for rest and stress are obtained, respectively. Knowledge on how these Windkessel parameters change from rest to stress can thus be learned by such an approach. Lastly, it is demonstrated that the proposed approach is capable of dealing with a wide variety of measurements and cases where the pressure and flow clinical measurements are not taken simultaneously.
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Affiliation(s)
- S Pant
- INRIA Paris-Rocquencourt, 78153 Le Chesnay, France; UPMC Université Paris 6, Laboratoire Jacques-Louis Lions, 75005 Paris, France
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70
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Szopos M, Poussineau N, Maday Y, Canniffe C, Celermajer DS, Bonnet D, Ou P. Computational modeling of blood flow in the aorta—insights into eccentric dilatation of the ascending aorta after surgery for coarctation. J Thorac Cardiovasc Surg 2014; 148:1572-82. [DOI: 10.1016/j.jtcvs.2013.11.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/01/2013] [Accepted: 11/15/2013] [Indexed: 12/31/2022]
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71
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Goubergrits L, Riesenkampff E, Yevtushenko P, Schaller J, Kertzscher U, Berger F, Kuehne T. Is MRI-Based CFD Able to Improve Clinical Treatment of Coarctations of Aorta? Ann Biomed Eng 2014; 43:168-76. [DOI: 10.1007/s10439-014-1116-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/06/2014] [Indexed: 01/16/2023]
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72
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Rademakers FE, Claus P. Imaging hemodynamics: the next frontier for CMR. JACC Cardiovasc Imaging 2014; 7:927-9. [PMID: 25212798 DOI: 10.1016/j.jcmg.2014.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 06/26/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Frank E Rademakers
- Laboratory on Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Piet Claus
- Laboratory on Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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73
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Lee JJ, D'Ancona G, Amaducci A, Follis F, Pilato M, Pasta S. Role of Computational Modeling in Thoracic Aortic Pathology:
A Review. J Card Surg 2014; 29:653-62. [DOI: 10.1111/jocs.12413] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jake J. Lee
- School of Medicine; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Giuseppe D'Ancona
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT); Palermo Italy
| | - Andrea Amaducci
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT); Palermo Italy
| | - Fabrizio Follis
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT); Palermo Italy
| | - Michele Pilato
- Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT); Palermo Italy
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74
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Goubergrits L, Riesenkampff E, Yevtushenko P, Schaller J, Kertzscher U, Hennemuth A, Berger F, Schubert S, Kuehne T. MRI-based computational fluid dynamics for diagnosis and treatment prediction: clinical validation study in patients with coarctation of aorta. J Magn Reson Imaging 2014; 41:909-16. [PMID: 24723299 DOI: 10.1002/jmri.24639] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/27/2014] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To reduce the need for diagnostic catheterization and optimize treatment in a variety of congenital heart diseases, magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) is proposed. However, data about the accuracy of CFD in a clinical context are still sparse. To fill this gap, this study compares MRI-based CFD to catheterization in the coarctation of aorta (CoA) setting. MATERIALS AND METHODS Thirteen patients with CoA were investigated by routine MRI prior to catheterization. 3D whole-heart MRI was used to reconstruct geometries and 4D flow-sensitive phase-contrast MRI was used to acquire flows. Peak systolic flows were simulated using the program FLUENT. RESULTS Peak systolic pressure drops in CoA measured by catheterization and CFD correlated significantly for both pre- and posttreatment measurements (pre: r = 0.98, p = 0.00; post: r = 0.87, p = 0.00). The pretreatment bias was -0.5 ± 3.33 mmHg (95% confidence interval -2.55 to 1.47 mmHg). CFD predicted a reduction of the peak systolic pressure drop after treatment that ranged from 17.6 ± 5.56 mmHg to 6.7 ± 5.58 mmHg. The posttreatment bias was 3.0 ± 2.91 mmHg (95% CI -1.74 to 5.43 mmHg). CONCLUSION Peak systolic pressure drops can be reliably calculated using MRI-based CFD in a clinical setting. Therefore, CFD might be an attractive noninvasive alternative to diagnostic catheterization.
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Affiliation(s)
- Leonid Goubergrits
- Biofluid Mechanics Laboratory, Charité-Universitätsmedizin, Berlin, Germany; Non-Invasive Cardiac Imaging in Congenital Heart Disease Unit, Charité-Universitätsmedizin, Berlin, and German Heart Institute, Berlin, Germany
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75
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Yang AS, Wen CY, Tseng LY, Chiang CC, Tseng WYI, Yu HY. An innovative numerical approach to resolve the pulse wave velocity in a healthy thoracic aorta model. Comput Methods Biomech Biomed Engin 2014; 17:461-73. [PMID: 22657104 DOI: 10.1080/10255842.2012.691476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Aortic dissection and atherosclerosis are highly fatal diseases. The development of both diseases is closely associated with highly complex haemodynamics. Thus, in predicting the onset of cardiac disease, it is desirable to obtain a detailed understanding of the flowfield characteristics in the human cardiovascular circulatory system. Accordingly, in this study, a numerical model of a normal human thoracic aorta is constructed using the geometry information obtained from a phase-contrast magnetic resonance imaging (PC-MRI) technique. The interaction between the blood flow and the vessel wall dynamics is then investigated using a coupled fluid-structure interaction (FSI) analysis. The simulations focus specifically on the flowfield characteristics and pulse wave velocity (PWV) of the blood flow. Instead of using a conventional PC-MRI method to measure PWV, we present an innovative application of using the FSI approach to numerically resolve PWV for the assessment of wall compliance in a thoracic aorta model. The estimated PWV for a normal thoracic aorta agrees well with the results obtained via PC-MRI measurement. In addition, simulations which consider the FSI effect yield a lower predicted value of the wall shear stress at certain locations in the cardiac cycle than models which assume a rigid vessel wall. Consequently, the model provides a suitable basis for the future development of more sophisticated methods capable of performing the computer-aided analysis of aortic blood flows.
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Affiliation(s)
- An-Shik Yang
- a Department of Energy and Refrigerating Air-Conditioning Engineering , National Taipei University of Technology , 1, Section 3, Chung-Hsiao E. Road, Taipei 106 , Taiwan R.O.C
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76
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Kwon S, Feinstein JA, Dholakia RJ, LaDisa JF. Quantification of local hemodynamic alterations caused by virtual implantation of three commercially available stents for the treatment of aortic coarctation. Pediatr Cardiol 2014; 35:732-40. [PMID: 24259013 PMCID: PMC3959287 DOI: 10.1007/s00246-013-0845-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 11/06/2013] [Indexed: 12/18/2022]
Abstract
Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of Genesis XD and modified NuMED CP stents, also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured data and generate blood flow velocity and time-averaged WSS (TAWSS) results. TAWSS was quantified longitudinally and circumferentially in the stented region and dAo. While modest differences were seen in the distal portion of the stented region, marked differences were observed downstream along the posterior dAo and depended on stent type. The Genesis XD model had the least area of TAWSS values exceeding the threshold for platelet aggregation in vitro, followed by the Palmaz and NuMED CP stents. Alterations in local blood flow patterns and WSS imparted on the dAo appear to depend on the type of stent implanted for CoA. Following confirmation in larger studies, these findings may aid pediatric interventional cardiologists in selecting the most appropriate stent for each patient, and ultimately reduce long-term morbidity following treatment for CoA by stenting.
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Affiliation(s)
- Sung Kwon
- Department of Biomedical Engineering, Marquette University
| | - Jeffrey A. Feinstein
- Department of Bioengineering, Stanford University,Department of Pediatrics, Lucile Packard Children’s Hospital
| | | | - John F. LaDisa
- Department of Biomedical Engineering, Marquette University,Herma Heart Center, Children’s Hospital of Wisconsin,Department of Medicine, Medical College of Wisconsin
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77
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Rinaudo A, D'Ancona G, Baglini R, Amaducci A, Follis F, Pilato M, Pasta S. Computational fluid dynamics simulation to evaluate aortic coarctation gradient with contrast-enhanced CT. Comput Methods Biomech Biomed Engin 2014; 18:1066-1071. [PMID: 24460213 DOI: 10.1080/10255842.2013.869321] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Coarctation of aorta (CoA) is a narrowing of the aorta leading to a pressure gradient (ΔP) across the coarctation, increased afterload and reduced peripheral perfusion pressures. Indication to invasive treatment is based on values of maximal (systolic) trans-coarctation ΔP. A computational fluid dynamic (CFD) approach is herein presented for the non-invasive haemodynamic assessment of ΔP across CoA. Patient-specific CFD simulations were created from contrast-enhanced computed tomography (CT) and appropriate flow boundary conditions. Computed ΔP was validated with invasive intravascular trans-CoA pressure measurements. Haemodynamic indices, including pressure loss coefficient (PLc), time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI), were also quantified. CFD-estimated ΔP values were comparable to the invasive ones. Moreover, the aorta proximal to CoA was exposed to altered TAWSS and OSI suggesting hypertension. PLc was found as a further geometric marker of CoA severity. Finally, CFD-estimated ΔP confirmed a significant reduction after percutaneous balloon dilatation and stenting of the CoA in one patient (e.g. from ΔP∼52 mmHg to ΔP∼3 mmHg). The validation of the ΔP computations with catheterisation measurements suggests that CFD simulation, based on CT-derived anatomical data, is a useful tool to readily quantify CoA severity.
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Affiliation(s)
- Antonino Rinaudo
- a Dipartimento di Ingegneria Chimica , Gestionale, Informatica e Meccanica, Universita' di Palermo , Viale delle Scienze Ed. 8, 90128 Palermo , Italy
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78
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Marsden AL. Simulation based planning of surgical interventions in pediatric cardiology. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2013; 25:101303. [PMID: 24255590 PMCID: PMC3820639 DOI: 10.1063/1.4825031] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/22/2013] [Indexed: 05/17/2023]
Abstract
Hemodynamics plays an essential role in the progression and treatment of cardiovascular disease. However, while medical imaging provides increasingly detailed anatomical information, clinicians often have limited access to hemodynamic data that may be crucial to patient risk assessment and treatment planning. Computational simulations can now provide detailed hemodynamic data to augment clinical knowledge in both adult and pediatric applications. There is a particular need for simulation tools in pediatric cardiology, due to the wide variation in anatomy and physiology in congenital heart disease patients, necessitating individualized treatment plans. Despite great strides in medical imaging, enabling extraction of flow information from magnetic resonance and ultrasound imaging, simulations offer predictive capabilities that imaging alone cannot provide. Patient specific simulations can be used for in silico testing of new surgical designs, treatment planning, device testing, and patient risk stratification. Furthermore, simulations can be performed at no direct risk to the patient. In this paper, we outline the current state of the art in methods for cardiovascular blood flow simulation and virtual surgery. We then step through pressing challenges in the field, including multiscale modeling, boundary condition selection, optimization, and uncertainty quantification. Finally, we summarize simulation results of two representative examples from pediatric cardiology: single ventricle physiology, and coronary aneurysms caused by Kawasaki disease. These examples illustrate the potential impact of computational modeling tools in the clinical setting.
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Affiliation(s)
- Alison L Marsden
- Mechanical and Aerospace Engineering Department, University of California San Diego, La Jolla, California 92093, USA
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79
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Fluid dynamics of coarctation of the aorta and effect of bicuspid aortic valve. PLoS One 2013; 8:e72394. [PMID: 24015239 PMCID: PMC3754982 DOI: 10.1371/journal.pone.0072394] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/10/2013] [Indexed: 11/19/2022] Open
Abstract
Up to 80% of patients with coarctation of the aorta (COA) have a bicuspid aortic valve (BAV). Patients with COA and BAV have elevated risks of aortic complications despite successful surgical repair. The development of such complications involves the interplay between the mechanical forces applied on the artery and the biological processes occurring at the cellular level. The focus of this study is on hemodynamic modifications induced in the aorta in the presence of a COA and a BAV. For this purpose, numerical investigations and magnetic resonance imaging measurements were conducted with different configurations: (1) normal: normal aorta and normal aortic valve; (2) isolated COA: aorta with COA (75% reduction by area) and normal aortic valve; (3) complex COA: aorta with the same severity of COA (75% reduction by area) and BAV. The results show that the coexistence of COA and BAV significantly alters blood flow in the aorta with a significant increase in the maximal velocity, secondary flow, pressure loss, time-averaged wall shear stress and oscillatory shear index downstream of the COA. These findings can contribute to a better understanding of why patients with complex COA have adverse outcome even following a successful surgery.
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Lantz J, Ebbers T, Engvall J, Karlsson M. Numerical and experimental assessment of turbulent kinetic energy in an aortic coarctation. J Biomech 2013; 46:1851-8. [PMID: 23746596 DOI: 10.1016/j.jbiomech.2013.04.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 04/26/2013] [Accepted: 04/26/2013] [Indexed: 11/25/2022]
Abstract
The turbulent blood flow through an aortic coarctation in a 63-year old female patient was studied experimentally using magnetic resonance imaging (MRI), and numerically using computational fluid dynamics (CFD), before and after catheter intervention. Turbulent kinetic energy (TKE) was computed in the numerical model using large eddy simulation and compared with direct in vivo MRI measurements. Despite the two totally different methods to obtain TKE values, both quantitative and qualitative results agreed very well. The results showed that even though both blood flow rate and Reynolds number increased after intervention, total turbulent kinetic energy levels decreased in the coarctation. Therefore, the use of the Reynolds number alone as a measure of turbulence in cardiovascular flows should be used with caution. Furthermore, the change in flow field and kinetic energy were assessed, and it was found that before intervention a jet formed in the throat of the coarctation, which impacted the arterial wall just downstream the constriction. After intervention the jet was significantly weaker and broke up almost immediately, presumably resulting in less stress on the wall. As there was a good agreement between measurements and numerical results (the increase and decrease of integrated TKE matched measurements almost perfectly while peak values differed by approximately 1mJ), the CFD results confirmed the MRI measurements while at the same time providing high-resolution details about the flow. Thus, this preliminary study indicates that MR-based TKE measurements might be useful as a diagnostic tool when evaluating intervention outcome, while the detailed numerical results might be useful for further understanding of the flow for treatment planning.
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Affiliation(s)
- Jonas Lantz
- Department of Management and Engineering, Linköping University, SE-581 83 Linköping, Sweden.
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Pennati G, Corsini C, Hsia TY, Migliavacca F. Computational fluid dynamics models and congenital heart diseases. Front Pediatr 2013; 1:4. [PMID: 24432298 PMCID: PMC3882907 DOI: 10.3389/fped.2013.00004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 02/01/2013] [Indexed: 11/13/2022] Open
Abstract
Mathematical modeling is a powerful tool to investigate hemodynamics of the circulatory system. With improving imaging techniques and detailed clinical investigations, it is now possible to construct patient-specific models of reconstructive surgeries for the treatment of congenital heart diseases. These models can help clinicians to better understand the hemodynamic behavior of different surgical options for a treated patient. This review outlines recent advances in mathematical modeling in congenital heart diseases, the discoveries and limitations these models present, and future directions that are on the horizon.
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Affiliation(s)
- Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Chemistry, Materials and Chemical Engineering Department "Giulio Natta", Politecnico di Milano Milano, Italy
| | - Chiara Corsini
- Laboratory of Biological Structure Mechanics, Chemistry, Materials and Chemical Engineering Department "Giulio Natta", Politecnico di Milano Milano, Italy
| | - Tain-Yen Hsia
- Cardiac Unit, Great Ormond Street Hospital for Children London, UK
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics, Chemistry, Materials and Chemical Engineering Department "Giulio Natta", Politecnico di Milano Milano, Italy
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Non-Invasive Hemodynamic Assessment of Aortic Coarctation: Validation with In Vivo Measurements. Ann Biomed Eng 2012; 41:669-81. [DOI: 10.1007/s10439-012-0715-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/27/2012] [Indexed: 11/26/2022]
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Menon A, Eddinger TJ, Wang H, Wendell DC, Toth JM, LaDisa JF. Altered hemodynamics, endothelial function, and protein expression occur with aortic coarctation and persist after repair. Am J Physiol Heart Circ Physiol 2012; 303:H1304-18. [PMID: 23023871 DOI: 10.1152/ajpheart.00420.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Coarctation of the aorta (CoA) is associated with substantial morbidity despite treatment. Mechanically induced structural and functional vascular changes are implicated; however, their relationship with smooth muscle (SM) phenotypic expression is not fully understood. Using a clinically representative rabbit model of CoA and correction, we quantified mechanical alterations from a 20-mmHg blood pressure (BP) gradient in the thoracic aorta and related the expression of key SM contractile and focal adhesion proteins with remodeling, relaxation, and stiffness. Systolic and mean BP were elevated for CoA rabbits compared with controls leading to remodeling, stiffening, an altered force response, and endothelial dysfunction both proximally and distally. The proximal changes persisted for corrected rabbits despite >12 wk of normal BP (~4 human years). Computational fluid dynamic simulations revealed reduced wall shear stress (WSS) proximally in CoA compared with control and corrected rabbits. Distally, WSS was markedly increased in CoA rabbits due to a stenotic velocity jet, which has persistent effects as WSS was significantly reduced in corrected rabbits. Immunohistochemistry revealed significantly increased nonmuscle myosin and reduced SM myosin heavy chain expression in the proximal arteries of CoA and corrected rabbits but no differences in SM α-actin, talin, or fibronectin. These findings indicate that CoA can cause alterations in the SM phenotype contributing to structural and functional changes in the proximal arteries that accompany the mechanical stimuli of elevated BP and altered WSS. Importantly, these changes are not reversed upon BP correction and may serve as markers of disease severity, which explains the persistent morbidity observed in CoA patients.
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Affiliation(s)
- Arjun Menon
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, USA
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84
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Wendell DC, Samyn MM, Cava JR, Ellwein LM, Krolikowski MM, Gandy KL, Pelech AN, Shadden SC, LaDisa JF. Including aortic valve morphology in computational fluid dynamics simulations: initial findings and application to aortic coarctation. Med Eng Phys 2012; 35:723-35. [PMID: 22917990 DOI: 10.1016/j.medengphy.2012.07.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 06/13/2012] [Accepted: 07/29/2012] [Indexed: 12/29/2022]
Abstract
Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a post-surgical CoA patient (BAV). Velocity, turbulent kinetic energy (TKE), time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) results were compared to equivalent simulations using a plug inlet profile. The plug inlet greatly underestimated TKE for both examples. TAWSS differences extended throughout the thoracic aorta for the CoA BAV, but were limited to the arch for the normal example. OSI differences existed mainly in the ascending aorta for both cases. The impact of AoV can now be included with CFD simulations to identify regions of deleterious hemodynamics thereby advancing simulations of the thoracic aorta one step closer to reality.
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Affiliation(s)
- David C Wendell
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233, USA
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85
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Coogan JS, Humphrey JD, Figueroa CA. Computational simulations of hemodynamic changes within thoracic, coronary, and cerebral arteries following early wall remodeling in response to distal aortic coarctation. Biomech Model Mechanobiol 2012; 12:79-93. [PMID: 22415052 DOI: 10.1007/s10237-012-0383-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 02/23/2012] [Indexed: 01/19/2023]
Abstract
Mounting evidence suggests that the pulsatile character of blood pressure and flow within large arteries plays a particularly important role as a mechano-biological stimulus for wall growth and remodeling. Nevertheless, understanding better the highly coupled interactions between evolving wall geometry, structure, and properties and the hemodynamics will require significantly more experimental data. Computational fluid-solid-growth models promise to aid in the design and interpretation of such experiments and to identify candidate mechanobiological mechanisms for the observed arterial adaptations. Motivated by recent aortic coarctation models in animals, we used a computational fluid-solid interaction model to study possible local and systemic effects on the hemodynamics within the thoracic aorta and coronary, carotid, and cerebral arteries due to a distal aortic coarctation and subsequent spatial variations in wall adaptation. In particular, we studied an initial stage of acute cardiac compensation (i.e., maintenance of cardiac output) followed by early arterial wall remodeling (i.e., spatially varying wall thickening and stiffening). Results suggested, for example, that while coarctation increased both the mean and pulse pressure in the proximal vessels, the locations nearest to the coarctation experienced the greatest changes in pulse pressure. In addition, after introducing a spatially varying wall adaptation, pressure, left ventricular work, and wave speed all increased. Finally, vessel wall strain similarly experienced spatial variations consistent with the degree of vascular wall adaptation.
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Affiliation(s)
- Jessica S Coogan
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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Menon A, Wendell DC, Wang H, Eddinger TJ, Toth JM, Dholakia RJ, Larsen PM, Jensen ES, Ladisa JF. A coupled experimental and computational approach to quantify deleterious hemodynamics, vascular alterations, and mechanisms of long-term morbidity in response to aortic coarctation. J Pharmacol Toxicol Methods 2011; 65:18-28. [PMID: 22079597 DOI: 10.1016/j.vascn.2011.10.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/04/2011] [Accepted: 10/25/2011] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Coarctation of the aorta (CoA) is associated with morbidity despite treatment. Although mechanisms remain elusive, abnormal hemodynamics and vascular biomechanics are implicated. We present a novel approach that facilitates quantification of coarctation-induced mechanical alterations and their impact on vascular structure and function, without genetic or confounding factors. METHODS Rabbits underwent thoracic CoA at 10weeks of age (~9 human years) to induce a 20mmHg blood pressure (BP) gradient using permanent or dissolvable suture thereby replicating untreated and corrected CoA. Computational fluid dynamics (CFD) was performed using imaging and BP data at 32weeks to quantify velocity, strain and wall shear stress (WSS) for comparison to vascular structure and function as revealed by histology and myograph results. RESULTS Systolic and mean BP was elevated in CoA compared to corrected and control rabbits leading to vascular thickening, disorganization and endothelial dysfunction proximally and distally. Corrected rabbits had less severe medial thickening, endothelial dysfunction, and stiffening limited to the proximal region despite 12weeks of normal BP (~4 human years) after the suture dissolved. WSS was elevated distally for CoA rabbits, but reduced for corrected rabbits. DISCUSSION These findings are consistent with alterations in humans. We are now poised to investigate mechanical contributions to mechanisms of morbidity in CoA using these methods.
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Affiliation(s)
- Arjun Menon
- Department of Biomedical Engineering, Marquette University, United States
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