scholarly journals Numerical simulations of patient-specific models with multiple plaques in human peripheral artery: a fluid-structure interaction analysis

2020 ◽  
Author(s):  
Danyang Wang ◽  
Ferdinand Serracino-Inglott ◽  
Jiling Feng
Keyword(s):  
Interaction Analysis ◽  
Experimental Studies ◽  
Specific Model ◽  
Patient Specific ◽  
Peripheral Artery ◽  
Fluid Structure ◽  
Femoral Arteries ◽  
Risk Of Rupture ◽  
Artery Disease ◽  
Hemodynamic Performance

Abstract Atherosclerotic plaque in the femoral is the leading cause of peripheral artery disease (PAD), the worse consequence of which may lead to ulceration and gangrene of the feet. Numerical studies on fluid-structure interactions (FSI) of atherosclerotic femoral arteries enable quantitative analysis of biomechanical features in arteries. This study aims to investigate the hemodynamic performance and its interaction with femoral arterial wall based on the patient-specific model with multiple plaques (calcified and lipid plaques). Three types of models, calcification-only, lipid-only and calcification-lipid models, are established. Hyperelastic material coefficients of the human femoral arteries obtained from experimental studies are employed for all simulations. Oscillation of WSS is observed in the healthy downstream region in the lipid-only model. The pressure around the plaques in the two-plaque model is lower than that in the corresponding one-plaque models due to the reduction of blood flow domain, which consequently diminishes the loading forces on both plaques. Therefore, we found that stress acting on the plaques in the two-plaque model is lower than that in the corresponding one-plaque models. This finding implies that the lipid plaque, accompanied by the calcified plaque around, might reduce its risk of rupture due to the reduced the stress acting on it.

scholarly journals Microparticles Carrying Sonic Hedgehog Are Increased in Humans with Peripheral Artery Disease

2018 ◽  
Author(s):  
Igor Giarretta ◽  
Ilaria Gatto ◽  
Margherita Marcantoni ◽  
Giulia Lupi ◽  
Diego Tonello ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Peripheral Artery Disease ◽  
Sonic Hedgehog ◽  
Crucial Role ◽  
Experimental Studies ◽  
Clinical Implications ◽  
Peripheral Artery ◽  
Circulating Microparticles ◽  
Artery Disease ◽  
And Control

Sonic Hedgehog (Shh) is a prototypical angiogenic agent with a crucial role in the regulation of angiogenesis. Experimental studies have shown that Shh is upregulated in response to ischemia. Also, Shh may be found on the surface of circulating microparticles (MPs) and MPs bearing Shh (Shh+ MPs) have shown the ability to contribute to reparative neovascularization after ischemic injury in mice. In this study, the plasma  number of Shh+ MPs in patients with peripheral artery disease (PAD) and control subjects without PAD. We found significantly higher number of Shh+ MPs in plasma of subjects with PAD, compared to controls, while the global number of MPs – produced either by endothelial cells, platelets, leukocytes, and erythrocytes – was not different between PAD patients and controls. Interestingly, the concentration of Shh protein unbound to MPs – which was measured in MP-depleted plasma – was not different between subjects with PAD and controls, indicating that, in the setting of PAD, the call for Shh recapitulation does not lead to secretion of protein into the blood but to binding of the protein to the membrane of MPs. These findings provide novel insights on the mechanisms through which the Shh signaling is reactivated during ischemia in humans, with potentially important fundamental and clinical implications.

scholarly journals Microparticles Carrying Sonic Hedgehog Are Increased in Humans with Peripheral Artery Disease

2018 ◽  
Vol 19 (12) ◽  
pp. 3954 ◽  
Author(s):  
Igor Giarretta ◽  
Ilaria Gatto ◽  
Margherita Marcantoni ◽  
Giulia Lupi ◽  
Diego Tonello ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Peripheral Artery Disease ◽  
Sonic Hedgehog ◽  
Experimental Studies ◽  
Clinical Implications ◽  
Peripheral Artery ◽  
Circulating Microparticles ◽  
Artery Disease ◽  
Collateral Vessels ◽  
And Control

Sonic hedgehog (Shh) is a prototypical angiogenic agent with a crucial role in the regulation of angiogenesis. Experimental studies have shown that Shh is upregulated in response to ischemia. Also, Shh may be found on the surface of circulating microparticles (MPs) and MPs bearing Shh (Shh + MPs) have shown the ability to contribute to reparative neovascularization after ischemic injury in mice. The goal of this study was to test the hypothesis that, in humans with peripheral artery disease (PAD), there is increased number of circulating Shh + MPs. This was done by assessing the number of Shh + MPs in plasma of patients with PAD and control subjects without PAD. We found significantly higher number of Shh + MPs in plasma of subjects with PAD, compared to controls, while the global number of MPs—produced either by endothelial cells, platelets, leukocytes, and erythrocytes—was not different between PAD patients and controls. We also found a significant association between the number of Shh + MPs and the number of collateral vessels in the ischemic limbs of PAD patients. Interestingly, the concentration of Shh protein unbound to MPs—which was measured in MP-depleted plasma—was not different between subjects with PAD and the controls, indicating that, in the setting of PAD, the call for Shh recapitulation does not lead to secretion of protein into the blood but to binding of the protein to the membrane of MPs. These findings provide novel information on Shh signaling during ischemia in humans, with potentially important biological and clinical implications.

scholarly journals Peripheral µ-opioid receptors attenuate the responses of group III and IV afferents to contraction in rats with simulated peripheral artery disease

2018 ◽  
Vol 119 (6) ◽  
pp. 2052-2058 ◽  
Author(s):  
Jonathan Harms ◽  
Audrey J. Stone ◽  
Marc P. Kaufman
Keyword(s):  
Peripheral Artery Disease ◽  
Group Iv ◽  
Peripheral Artery ◽  
Opioid Agonist ◽  
Group Iii ◽  
Femoral Arteries ◽  
Exercise Pressor Reflex ◽  
Static Contraction ◽  
Pressor Reflex ◽  
Artery Disease

Patients with peripheral artery disease show an exaggerated pressor response to mild exercise, an effect attributable to the exercise pressor reflex, whose afferent arm comprises the thinly myelinated group III and unmyelinated group IV afferents. Previously, we found that DAMGO, a µ-opioid agonist injected into the femoral artery, attenuated the exaggerated exercise pressor reflex in rats with ligated femoral arteries, a preparation that simulates the blood flow patterns to muscle that is seen in patients with peripheral artery disease. Continuing this line of investigation, we recorded the responses of group III and IV afferents to static contraction before and after injecting DAMGO (1 µg) into the superficial epigastric artery in rats with patent femoral arteries and in rats with ligated femoral arteries. In rats with patent arteries, DAMGO did not change the responses to contraction of either group III ( n = 9; P = 0.83) or group IV ( n = 8; P = 0.34) afferents. In contrast, in rats with ligated femoral arteries, DAMGO injection (1 µg) significantly decreased the responses to contraction of both group III afferents ( n = 9, P < 0.01) and group IV afferents ( n = 9; P < 0.01). DAMGO did not significantly attenuate the responses of either group III or IV afferents to capsaicin in rats with either patent or ligated femoral arteries. These findings are in agreement with our previous studies that showed that peripheral DAMGO injection attenuated the exercise pressor reflex in rats with ligated femoral arteries but had only a modest effect on the exercise pressor reflex in rats with patent femoral arteries. NEW & NOTEWORTHY In an animal model of peripheral artery disease, we show that the µ-opioid agonist, DAMGO reduces the afferent response rate resulting from stimulated static contraction. These results suggest that peripherally active opioid agonists that do not cross the blood-brain barrier may be therapeutic for treatment of peripheral artery disease without the negative and addictive side effects associated with opioids in the central nervous system.

Risk of Rupture in Abdominal Aortic Aneurysms and Vulnerable Plaques: A Patient Based Fluid Structure Interaction Approach

2008 ◽  
Author(s):  
Danny Bluestein ◽  
Yared Alemu ◽  
Michalis Xenos ◽  
Peter Rissland ◽  
Jawaad Sheriff ◽  
...  
Keyword(s):  
Vulnerable Plaque ◽  
Fluid Structure Interaction ◽  
Material Model ◽  
Patient Specific ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Fibrous Cap ◽  
Vulnerable Plaques ◽  
Abdominal Aortic ◽  
Risk Of Rupture

In this study we performed two separate fluid structure interaction (FSI) simulations. A patient-specific Abdominal Aortic Aneurysm (AAA) geometry, and coronary vulnerable plaque (VP) geometry in idealized and in patient based geometries reconstructed from intravascular (IVUS) measurements. The patient specific AAA FSI simulations were carried out with both isotropic and anisotropic wall properties. An orthotropic material model was used to describe wall properties, closely approximating experimental results of AAA specimens [1]. The results predict larger deformations and stress values for the anisotropic material model as compared to the isotropic one. This difference indicates that the isotropic formulation may underestimate the risk of rupture. The ability to quantify stresses developing within the aneurysm wall based on FSI simulations will help clinicians to reach informed decisions in determining rupture risk of AAA and the need for surgical intervention. The risk of rupture of vulnerable plaques was studied in both idealized and patient specific geometries using FSI simulations. The idealized model included vessel wall, fibrous cap, and a lipid core. Regions susceptible to failure and the contribution of the various components were studied. The upstream side of the vulnerable plaque fibrous cap had the highest stresses. The presence of a calcified spot embedded within the fibrous cap proper was studied, and was demonstrated to enhance stresses within the fibrous cap, significantly contributing to its risk of rupture.

A Patient Based Approach for Fluid Structure Interaction in Ruptured Abdominal Aortic Aneurysms

2009 ◽  
Author(s):  
Michalis Xenos ◽  
Suraj Rambhia ◽  
Yared Alemu ◽  
Shmuel Einav ◽  
John J. Ricotta ◽  
...  
Keyword(s):  
Fluid Structure Interaction ◽  
Wall Stress ◽  
Material Model ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Bifurcation Angle ◽  
Risk Of Rupture ◽  
Iliac Bifurcation

Fluid structure interaction (FSI) simulations were conducted to assess the risk of rupture in reconstructed AAA from patients who had contained ruptured AAAs. The goal was to test to ability of our FSI methodology to predict the location of rupture, by correlating the high wall stress regions with the actual rupture location. We also present a parametric study in which the relationship of iliac bifurcation angle and the role of embedded calcifications were studied in respect to the aneurismal wall stress. The patient specific AAA FSI simulations were carried out with advanced constitutive material models of the various components of AAA, including models that describe the wall anisotropy, structural strength based on collagen fibers orientation within the arterial wall, AAA intraluminal thrombus (ILT), and embedded calcifications. The anisotropic material model used to describe the wall properties closely correlated with experimental results of AAA specimens [1]. The results demonstrate that the region of rupture can be predicted by the region of the highest wall stress distribution. Embedded wall calcifications increase the local wall stress surrounding calcified spots, and eventually increases the risk of rupture. FSI results in streamlined AAA geometries show that the maximum stress on the aneurismal wall increases as the iliac bifurcation angle increases.

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