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Campbell IC, Suever JD, Timmins LH, Veneziani A, Vito RP, Virmani R, Oshinski JN, Taylor WR. Biomechanics and inflammation in atherosclerotic plaque erosion and plaque rupture: implications for cardiovascular events in women. PLoS One 2014; 9:e111785. [PMID: 25365517 PMCID: PMC4218818 DOI: 10.1371/journal.pone.0111785] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/30/2014] [Indexed: 01/25/2023] Open
Abstract
Objective Although plaque erosion causes approximately 40% of all coronary thrombi and disproportionally affects women more than men, its mechanism is not well understood. The role of tissue mechanics in plaque rupture and regulation of mechanosensitive inflammatory proteins is well established, but their role in plaque erosion is unknown. Given obvious differences in morphology between plaque erosion and rupture, we hypothesized that inflammation in general as well as the association between local mechanical strain and inflammation known to exist in plaque rupture may not occur in plaque erosion. Therefore, our objective was to determine if similar mechanisms underlie plaque rupture and plaque erosion. Methods and Results We studied a total of 74 human coronary plaque specimens obtained at autopsy. Using lesion-specific computer modeling of solid mechanics, we calculated the stress and strain distribution for each plaque and determined if there were any relationships with markers of inflammation. Consistent with previous studies, inflammatory markers were positively associated with increasing strain in specimens with rupture and thin-cap fibroatheromas. Conversely, overall staining for inflammatory markers and apoptosis were significantly lower in erosion, and there was no relationship with mechanical strain. Samples with plaque erosion most closely resembled those with the stable phenotype of thick-cap fibroatheromas. Conclusions In contrast to classic plaque rupture, plaque erosion was not associated with markers of inflammation and mechanical strain. These data suggest that plaque erosion is a distinct pathophysiological process with a different etiology and therefore raises the possibility that a different therapeutic approach may be required to prevent plaque erosion.
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Affiliation(s)
- Ian C. Campbell
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
| | - Jonathan D. Suever
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
| | - Lucas H. Timmins
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Alessandro Veneziani
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
- Department of Mathematics and Computer Science, Emory University, Atlanta, Georgia, United States of America
| | - Raymond P. Vito
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
- George W. Woodruff Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Renu Virmani
- CVPath Institute, Inc., Gaithersburg, Maryland, United States of America
| | - John N. Oshinski
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
- Department of Radiology and Imaging Science, Emory University, Atlanta, Georgia, United States of America
| | - W. Robert Taylor
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States of America
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Cardiology Division, Atlanta Veterans Affairs Medical Center, Decatur, Georgia, United States of America
- * E-mail:
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Boekhoven RW, Lopata RGP, van Sambeek MR, van de Vosse FN, Rutten MCM. A novel experimental approach for three-dimensional geometry assessment of calcified human stenotic arteries in vitro. ULTRASOUND IN MEDICINE & BIOLOGY 2013; 39:1875-1886. [PMID: 23910903 DOI: 10.1016/j.ultrasmedbio.2013.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 01/31/2013] [Accepted: 03/14/2013] [Indexed: 06/02/2023]
Abstract
To improve diagnosis and understanding of the risk of rupture of atherosclerotic plaque, new strategies to realistically determine mechanical properties of atherosclerotic plaque need to be developed. In this study, an in vitro experimental method is proposed for accurate 3-D assessment of (diseased) vessel geometry using ultrasound. The method was applied to a vascular phantom, a healthy porcine carotid artery and human carotid endarterectomy specimens (n = 6). Vessel segments were pressure fixed and rotated in 10 ° steps. Longitudinal cross sections were imaged over 360 °. Findings were validated using micro-computed tomography (μCT). Results show good agreement between ultrasound and μCT-based geometries of the different segment types (ISI phantom = 0.94, ISI healthy = 0.79, ISI diseased = 0.75-0.80). The method does not suffer from acoustic shadowing effects present when imaging stenotic segments and allows future dynamic measurements to determine mechanical properties of atherosclerotic plaque in an in vitro setting.
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Affiliation(s)
- Renate W Boekhoven
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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Lal BK, Beach KW, Sumner DS. Intracranial collateralization determines hemodynamic forces for carotid plaque disruption. J Vasc Surg 2011; 54:1461-71. [PMID: 21820834 DOI: 10.1016/j.jvs.2011.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 05/04/2011] [Accepted: 05/04/2011] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Percent diameter reduction provides an imperfect assessment of the risk for stroke from carotid atheroembolism. Stroke associated with atherosclerotic carotid stenosis commonly results from plaque disruption brought about by hemodynamic shear stress and Bernoulli forces. The aim of the present study was to predict the effect of incomplete intracranial collateralization through the circle of Willis (COW) on disruptive hemodynamic forces acting on carotid plaques. METHODS A simple circuit model of the major pathways and collaterals that form and supply the COW was developed. We modeled the intra- and extracranial arterial circuits from standard anatomic references, and the pressure-flow relationships within these conduits from standard fluid mechanics. The pressure drop caused by (laminar and turbulent) flow along the internal carotid artery path was then computed. Carotid circulation to the brain was classified as being with or without collateral connections through the COW, and the extracranial carotid circuit as being with or without severe stenosis. The pressure drop was computed for each scenario. Finally, a linear circuit model was used to compute brain blood flow in the presence/absence of a disconnected COW. RESULTS Pressure drop across a carotid artery stenosis increased as the flow rate within the carotid conduit increased. Poststenotic turbulence from a sudden expansion distal to the stenosis resulted in an additional pressure drop. Despite the stenosis, mean brain blood flow was sustained at 4.15 mL/s bilaterally. In the presence of an intact (collateralized) COW, this was achieved by enhanced flow in the contralateral (normal) carotid artery. However, in a disconnected COW, this was achieved by sustained systolic and enhanced diastolic flow through the stenosed artery. For a similar degree of stenosis, flow and velocity across the plaque was much higher when the COW was disconnected compared with an intact COW. Furthermore, the pressure drop across a similar stenosis was significantly higher with a disconnected COW compared with an intact COW. CONCLUSIONS Incomplete intracranial collateralization through the COW results in increased flow rates and velocities, and therefore large pressure drops across a carotid artery stenosis. This exerts large disruptive shear stress on the plaque compared with patients with an intact COW. Percent diameter reduction provides an inaccurate assessment of risk for atheroembolic stroke. An assessment of carotid flow rates, flow velocities, and the intracranial collateral circulation may add independent information to refine the estimation of stroke risk in patients with asymptomatic carotid atherosclerosis.
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Affiliation(s)
- Brajesh K Lal
- Center for Vascular Diagnostics, Department of Vascular Surgery, University of Maryland, Baltimore, MD 21201, USA.
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Abstract
Knowledge of blood vessel mechanical properties is fundamental to the understanding of vascular function in health and disease. Analytic results can help physicians in the clinic, both in designing and in choosing appropriate therapies. Understanding the mechanical response of blood vessels to physiologic loads is necessary before ideal therapeutic solutions can be realized. For this reason, blood vessel constitutive models are needed. This article provides a critical review of recent blood vessel constitutive models, starting with a brief overview of the structure and function of arteries and veins, followed by a discussion of experimental techniques used in the characterization of material properties. Current models are classified by type, including pseudoelastic, randomly elastic, poroelastic, and viscoelastic. Comparisons are presented between the various models and existing experimental data. Applications of blood vessel constitutive models are also briefly presented, followed by the identification of future directions in research.
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Affiliation(s)
- Raymond P Vito
- Woodruff School of Mechanical Engineering, Atlanta, Georgia 30332-0405, USA.
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