scholarly journals The Role of Wall Shear Stress in the Assessment of Right Ventricle Hydraulic Workload

2015 ◽  
Vol 5 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Vitaly Kheyfets ◽  
Mirunalini Thirugnanasambandam ◽  
Lourdes Rios ◽  
Daniel Evans ◽  
Triston Smith ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Right Ventricle ◽  
Wall Shear

scholarly journals Piezo1 mediates angiogenesis through activation of MT1-MMP signaling

2019 ◽  
Vol 316 (1) ◽  
pp. C92-C103 ◽  
Author(s):  
Hojin Kang ◽  
Zhigang Hong ◽  
Ming Zhong ◽  
Jennifer Klomp ◽  
Kayla J. Bayless ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Matrix Metalloproteinase ◽  
Matrix Metalloproteinase 2 ◽  
Sprouting Angiogenesis ◽  
Sphingosine 1 Phosphate ◽  
Wall Shear ◽  
Membrane Type

Angiogenesis is initiated in response to a variety of external cues, including mechanical and biochemical stimuli; however, the underlying signaling mechanisms remain unclear. Here, we investigated the proangiogenic role of the endothelial mechanosensor Piezo1. Genetic deletion and pharmacological inhibition of Piezo1 reduced endothelial sprouting and lumen formation induced by wall shear stress and proangiogenic mediator sphingosine 1-phosphate, whereas Piezo1 activation by selective Piezo1 activator Yoda1 enhanced sprouting angiogenesis. Similarly to wall shear stress, sphingosine 1-phosphate functioned by activating the Ca2+ gating function of Piezo1, which in turn signaled the activation of the matrix metalloproteinase-2 and membrane type 1 matrix metalloproteinase during sprouting angiogenesis. Studies in mice in which Piezo1 was conditionally deleted in endothelial cells demonstrated the requisite role of sphingosine 1-phosphate-dependent activation of Piezo1 in mediating angiogenesis in vivo. These results taken together suggest that both mechanical and biochemical stimuli trigger Piezo1-mediated Ca2+ influx and thereby activate matrix metalloproteinase-2 and membrane type 1 matrix metalloproteinase and synergistically facilitate sprouting angiogenesis.

Role of Hemodynamics in Initiation of Aneurysmal Remodeling

2010 ◽  
Author(s):  
Hui Meng ◽  
Sabareesh K. Natarajan ◽  
Eleni Metaxa ◽  
Markus Tremmel ◽  
Ling Gao ◽  
...  
Keyword(s):  
Risk Factors ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Intracranial Aneurysm ◽  
Hemodynamic Stress ◽  
Key Factor ◽  
Aneurysm Development ◽  
Wall Shear

Hemodynamic insult has long been speculated to be a key factor in intracranial aneurysm (IA) formation,1 but the specifics of hemodynamic insult contributing to this process are not understood. Despite other risk factors, IAs are predominantly found at locations associated with unique hemodynamic stress such as at the apices of arterial bifurcations or outer curves, prominent in high wall shear stress (WSS) and wall shear stress gradients (WSSG).2 Furthermore, it appears that increased flow at these locations is required to trigger the initiation of aneurysmal remodeling.3 We have previously shown that increasing flow in the rabbit basilar artery (BA), secondary to common carotid artery (CCA) ligation, resulted in nascent aneurysm development at the basilar terminus (BT).4 However, it is unclear if certain hemodynamic stress thresholds must be exceeded to trigger aneurysmal remodeling, and whether sustained insult is necessary.

scholarly journals Hemodynamics of Cerebral Aneurysm Initiation: The Role of Wall Shear Stress and Spatial Wall Shear Stress Gradient

2011 ◽  
Vol 32 (3) ◽  
pp. 587-594 ◽  
Author(s):  
Z. Kulcsár ◽  
Á. Ugron ◽  
M. Marosfői ◽  
Z. Berentei ◽  
G. Paál ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Aneurysm ◽  
Stress Gradient ◽  
Wall Shear Stress Gradient ◽  
Shear Stress Gradient ◽  
Wall Shear

scholarly journals Effects of Disturbed Flow on Vascular Endothelium: Pathophysiological Basis and Clinical Perspectives

2011 ◽  
Vol 91 (1) ◽  
pp. 327-387 ◽  
Author(s):  
Jeng-Jiann Chiu ◽  
Shu Chien
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Patterns ◽  
Arterial Tree ◽  
Disturbed Flow ◽  
Hemodynamic Forces ◽  
Venous Diseases ◽  
Wall Shear

Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.

scholarly journals Biomechanical impact of provisional stenting and balloon dilatation on coronary bifurcation: clinical implications

2017 ◽  
Vol 123 (1) ◽  
pp. 221-226 ◽  
Author(s):  
Henry Y. Chen ◽  
Khalid Al-Saadon ◽  
Yves Louvard ◽  
Ghassan S. Kassab
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Balloon Dilatation ◽  
Computational Models ◽  
Stress Ratio ◽  
Solid Mechanics ◽  
Side Branch ◽  
Wall Shear ◽  
Provisional Stenting

In-stent restenosis (ISR) and stent thrombosis remain clinically significant problems for bifurcations. Although the role of wall shear stress (WSS) has been well investigated, the role of circumferential wall stresses (CWS) has not been well studied in provisional stenting with and without final kissing balloon (FKB). We hypothesized that the perturbation of CWS at the SB in provisional stenting and balloon dilatation is an important factor in addition to WSS, and, hence, may affect restenosis rates (i.e., higher CWS correlates with higher restenosis). To test this hypothesis, we developed computational models of stent, FKB at bifurcation, and finite element simulations that considered both fluid and solid mechanics of the vessel wall. We computed the stress ratio (CWS/WSS) to show potential correlation with restenosis in clinical studies (i.e., higher stress ratio correlates with higher restenosis). Our simulation results show that stenting in the main branch (MB) increases the maximum CWS in the side branch (SB) and, hence, yields a higher stress ratio in the SB, as compared with the MB. FKB dilatation decreases the CWS and increases WSS, which collectively lowers the stress ratio in the SB. The changes of stress ratio were correlated positively with clinical data in provisional stenting and FKB. Both fluid and solid mechanics need to be evaluated when considering various stenting techniques at bifurcations, as solid stresses also play an important role in clinical outcome. An integrative index of bifurcation mechanics is the stress ratio that considers both CWS and WSS. NEW & NOTEWORTHY Although the role of wall shear stress (WSS) has been well investigated, the role of circumferential wall stresses (CWS) has not been well studied in provisional stenting with and without final kissing balloon. Both fluid and solid mechanics need to be evaluated when considering various stenting techniques at bifurcations. An integrative index of bifurcation mechanics is the stress ratio that considers both CWS and WSS.

Non-Newtonian Models for Blood Flow Through an Arterial Stenosis

2011 ◽  
Author(s):  
F. Kh. Tazyukov ◽  
H. A. Khalaf ◽  
Jafar M. Hassan
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Arterial Stenosis ◽  
Stenosed Artery ◽  
Two Dimensional Flow ◽  
Flow Through ◽  
Wall Shear ◽  
Volume Method

The problems of non-Newtonian blood flow through a stenosed artery are solved numerically using Finite Volume Method where the non-Newtonian rheology of the flowing blood is characterised by the Generalised Power-law, Carreau-Yasuda and Cross models. In view of the haemodynamical mechanisms related to atherosclerosis formation and the role of the wall shear stress in initiating and further developing of the disease, the investigation is focused on the two-dimensional flow field and in particular on the distribution of the wall shear stress in the vicinity of the stenosis. A comparison is made between the effects of each rheological model on the aforementioned parameters for different Re number.

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