Arterial stiffness identification of the human carotid artery using the stress–strain relationship in vivo

To investigate the dynamic behavior of the aorta of freely moving rats during the maintenance of hypertension, a longitudinal study was performed in renal hypertensive (Goldblatt 1 kidney, 1 clip) rats aged 3, 6, and 9 mo in which hypertension was maintained for 1, 3, and 6 mo, respectively. The pulsatile caliber of the thoracic aorta was measured (electrolytic strain gauge chronically implanted) simultaneously with aortic pressure under basal conditions and during transient changes of blood pressure. Aortic thickness was determined postmortem by morphometry. Establishment of hypertension (179 +/- 5 mmHg) by increasing the stress developed by the aorta caused increases in the resting values of caliber (20%), thickness (21%), and strain (95%); the maintenance of hypertension for a 6-mo period caused a further increase in thickness (58% vs. age-matched normotensive aortas) but not in aortic caliber and strain, the subsequent alterations of which were due only to growth/aging. Although different calibers, thicknesses, and dynamic strains were presented, the stress-strain relationship during transient blood pressure changes was similar for all hypertensive and normotensive groups with the exception of renal hypertensive rats aged 6 mo, which presented a steeper relationship (a large transitory increase in aortic distensibility was observed at that age). Dynamic adaptive responses of the aorta to hypertension compensate for geometric changes in such a way as to maintain a near-constant distensibility. It was concluded that, in contrast to the extrathoracic vessels, the adaptive responses of the aorta to hypertension were directed to maintain its compliance without changing the distensibility and stress-strain relationship, contributing to partially counterbalance the increased pressure and the decreased compliance of the more peripheral components of the arterial tree.

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Construction of an in vivo carotid siphon model for testing endovascular devices for neuro-interventions

Interventional Neuroradiology ◽

10.1177/1591019916688649 ◽

2017 ◽

Vol 23 (3) ◽

pp. 325-329

Author(s):

Bu-Lang Gao ◽

Yong-Li Wang ◽

Xue-Jing Zhang ◽

Qiong-Ying Fan ◽

Wei-Li Hao ◽

...

Keyword(s):

Carotid Artery ◽

Glass Tube ◽

Covered Stent ◽

Covered Stents ◽

Carotid Siphon ◽

Endovascular Interventions ◽

Pass Through ◽

Endovascular Devices ◽

Human Carotid

Objective The aim of this study was to construct an in vivo carotid siphon model for testing neurovascular devices for endovascular interventions. Methods A model of a human carotid siphon was pre-shaped using a glass tube from a human cadaver and used to confine a segment of one side of the common carotid artery (CCA) in canines. This segment of CCA with the glass carotid siphon on was interposed end-to-end onto the contralateral CCA so as to simulate a human carotid artery siphon in vivo. Two weeks later, the siphon model was evaluated using computed tomography angiography and digital subtraction angiography, and the covered stent specially designed for intracranial vasculature was navigated through the siphon model for a longitudinal flexibility test. Results All dogs tolerated the procedures well, and the artificial siphon model in vivo provided realistic conditions for device testing. Two weeks later, the in vivo carotid siphon model remained patent with no thrombosis. Five covered stents were navigated to pass through five siphon models successfully, with vasospasm occurring in two siphons. Conclusion Construction of an in vivo siphon model in dogs with a glass tube is feasible and useful for the test of endovascular devices for treating neurovascular diseases.

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VEGF-targeted multispectral optoacoustic tomography and fluorescence molecular imaging in human carotid atherosclerotic plaques

10.21203/rs.3.rs-428529/v1 ◽

2021 ◽

Author(s):

Pieter J. Steinkamp ◽

Jasper Vonk ◽

Lydian A. Huisman ◽

Gert-Jan Meersma ◽

Gilles F.H. Diercks ◽

...

Keyword(s):

Molecular Imaging ◽

Carotid Artery ◽

Ex Vivo ◽

Carotid Plaques ◽

Symptomatic Carotid ◽

Optoacoustic Tomography ◽

Imaging Results ◽

Human Carotid ◽

Fluorescence Molecular Imaging

Abstract Background: Vulnerable atherosclerotic carotid plaques are prone to rupture resulting in ischemic strokes. Molecular imaging techniques have the potential to assess plaque vulnerability by visualizing molecular markers. Bevacizumab-800CW is a near-infrared fluorescent contrast agent antibody targeting vascular endothelial growth factor-A (VEGF-A). Here, we study if administration of bevacizumab-800CW is safe and can be visualized using multispectral optoacoustic tomography (MSOT) to evaluate atherosclerotic carotid plaques in vivo by visualizing intra-plaque neovascularization.Methods: Healthy volunteers were imaged with MSOT to determine the technical feasibility of human carotid imaging with MSOT. Patients with symptomatic carotid artery stenosis scheduled for carotid artery endarterectomy were intravenously administered with a bolus injection of 4.5 mg bevacizumab-800CW. Before and two days after tracer administration, in vivo non-invasive MSOT was performed. For validation, ex vivo fluorescence molecular imaging of the surgically removed plaque specimen was performed and correlated with histopathology.Results: Administration of 4.5 mg bevacizumab-800CW was safe in five patients. MSOT achieved accurate visualization of the carotid bifurcation area and assessment of the plaque in all five patients. Bevacizumab-800CW-resolved signal could not be detected with MSOT prior to surgery. However, ex vivo analysis of the carotid plaque showed accumulation of bevacizumab-800CW.Conclusions: These first-in-human MSOT and fluorescence molecular imaging results in carotid artery plaques suggest that bevacizumab is a potential tracer for imaging of vulnerable plaques. However, the microdose used here cannot be detected with MSOT. A subsequent phase I dose-finding study is needed to evaluate bevacizumab-800CW in higher doses as a useful optoacoustic imaging agent. Moreover, the development of dedicated optoacoustic contrast agents for signal attenuation of the targeting moiety is advisable for carotid atherosclerotic plaque assessment using MSOT.

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Pulse wave imaging of the human carotid artery: an in vivo feasibility study

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control ◽

10.1109/tuffc.2012.2170 ◽

2012 ◽

Vol 59 (1) ◽

pp. 174-181 ◽

Cited By ~ 75

Author(s):

Jianwen Luo ◽

R. X. Li ◽

E. E. Konofagou

Keyword(s):

Carotid Artery ◽

Feasibility Study ◽

Pulse Wave ◽

Wave Imaging ◽

Human Carotid

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Choice of In Vivo Versus Idealized Velocity Boundary Conditions Influences Physiologically Relevant Flow Patterns in a Subject-Specific Simulation of Flow in the Human Carotid Bifurcation

Journal of Biomechanical Engineering ◽

10.1115/1.3005157 ◽

2008 ◽

Vol 131 (2) ◽

Cited By ~ 33

Author(s):

Amanda K. Wake ◽

John N. Oshinski ◽

Allen R. Tannenbaum ◽

Don P. Giddens

Keyword(s):

Carotid Artery ◽

Boundary Conditions ◽

Carotid Bifurcation ◽

Flow Patterns ◽

Flow Data ◽

Measured Velocity ◽

Carotid Artery Bifurcation ◽

Subject Specific ◽

Human Carotid

Accurate fluid mechanics models are important tools for predicting the flow field in the carotid artery bifurcation and for understanding the relationship between hemodynamics and the initiation and progression of atherosclerosis. Clinical imaging modalities can be used to obtain geometry and blood flow data for developing subject-specific human carotid artery bifurcation models. We developed subject-specific computational fluid dynamics models of the human carotid bifurcation from magnetic resonance (MR) geometry data and phase contrast MR velocity data measured in vivo. Two simulations were conducted with identical geometry, flow rates, and fluid parameters: (1) Simulation 1 used in vivo measured velocity distributions as time-varying boundary conditions and (2) Simulation 2 used idealized fully-developed velocity profiles as boundary conditions. The position and extent of negative axial velocity regions (NAVRs) vary between the two simulations at any given point in time, and these regions vary temporally within each simulation. The combination of inlet velocity boundary conditions, geometry, and flow waveforms influences NAVRs. In particular, the combination of flow division and the location of the velocity peak with respect to individual carotid geometry landmarks (bifurcation apex position and the departure angle of the internal carotid) influences the size and location of these reversed flow zones. Average axial wall shear stress (WSS) distributions are qualitatively similar for the two simulations; however, instantaneous WSS values vary with the choice of velocity boundary conditions. By developing subject-specific simulations from in vivo measured geometry and flow data and varying the velocity boundary conditions in otherwise identical models, we isolated the effects of measured versus idealized velocity distributions on blood flow patterns. Choice of velocity distributions at boundary conditions is shown to influence pathophysiologically relevant flow patterns in the human carotid bifurcation. Although mean WSS distributions are qualitatively similar for measured and idealized inlet boundary conditions, instantaneous NAVRs differ and warrant imposing in vivo velocity boundary conditions in computational simulations. A simulation based on in vivo measured velocity distributions is preferred for modeling hemodynamics in subject-specific carotid artery bifurcation models when studying atherosclerosis initiation and development.

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