Reverse arterial wall shear stress causes nitric oxide-dependent vasodilatation in the anaesthetised dog

2002 ◽  
Vol 445 (1) ◽  
pp. 51-54 ◽  
Author(s):  
Markos F. ◽  
Hennessy B. ◽  
Fitzpatrick M. ◽  
O'Sullivan J. ◽  
Snow H.
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Kap-Soo Han ◽  
Sang Hyuk Lee ◽  
Han Uk Ryu ◽  
Se-Hyoung Park ◽  
Gyung-Ho Chung ◽  
...  

The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p<0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (β=0.96, p<0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p<0.001 for all β values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice.


2008 ◽  
Vol 294 (2) ◽  
pp. H909-H919 ◽  
Author(s):  
Ufuk Olgac ◽  
Vartan Kurtcuoglu ◽  
Dimos Poulikakos

The work herein represents a novel approach for the modeling of low-density lipoprotein (LDL) transport from the artery lumen into the arterial wall, taking into account the effects of local wall shear stress (WSS) on the endothelial cell layer and its pathways of volume and solute flux. We have simulated LDL transport in an axisymmetric representation of a stenosed coronary artery, where the endothelium is represented by a three-pore model that takes into account the contributions of the vesicular pathway, normal junctions, and leaky junctions also employing the local WSS to yield the overall volume and solute flux. The fraction of leaky junctions is calculated as a function of the local WSS based on published experimental data and is used in conjunction with the pore theory to determine the transport properties of this pathway. We have found elevated levels of solute flux at low shear stress regions because of the presence of a larger number of leaky junctions compared with high shear stress regions. Accordingly, we were able to observe high LDL concentrations in the arterial wall in these low shear stress regions despite increased filtration velocity, indicating that the increase in filtration velocity is not sufficient for the convective removal of LDL.


Author(s):  
Ganesh Swaminathan ◽  
Suraj Thyagaraj ◽  
Francis Loth ◽  
Susan McCormick ◽  
Hisham Bassiouny

Wall shear stress (WSS) in blood vessels has been shown to play an important role in the development of atherosclerosis. In particular, regions of low and oscillating WSS have been shown to correlate with the localization of atherosclerosis. Thus, we hypothesize that increasing the WSS for patients with peripheral vascular diseases (PVD) will either reduce PVD severity or slow its progression. We analyzed WSS changes from a study by Delis et al. on 32 limbs of PVD patients [1]. Results show that intermittent pneumatic compression (IPC) increases mean WSS by 170% and 240% in PVD patients and healthy subjects, respectively. Peak WSS was found to increase by 93% and 40% in PVD patients and healthy subjects, respectively. In addition, we examined changes in NOX level with use of IPC on five limbs from PVD patients. Our study demonstrated increased NOx levels in subjects after IPC. Further research is needed to determine the benefits of IPC for PVD patients.


2001 ◽  
Vol 44 (10) ◽  
pp. 1312-1321 ◽  
Author(s):  
Zhaorong Liu ◽  
Feng He ◽  
Gang Xu ◽  
Yong Chen

2014 ◽  
Vol 41 (2) ◽  
pp. 505-516 ◽  
Author(s):  
Wouter V. Potters ◽  
Pim van Ooij ◽  
Henk Marquering ◽  
Ed vanBavel ◽  
Aart J. Nederveen

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