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.

scholarly journals Impact of main branch stenting on endothelial shear stress: role of side branch diameter, angle and lesion

2011 ◽  
Vol 9 (71) ◽  
pp. 1187-1193 ◽  
Author(s):  
Henry Y. Chen ◽  
Issam D. Moussa ◽  
Charles Davidson ◽  
Ghassan S. Kassab
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Computational Models ◽  
Stress Gradient ◽  
Haemodynamic Effect ◽  
Side Branch ◽  
Negative Effects ◽  
Stent Restenosis ◽  
Negative Effect ◽  
Wall Shear

In-stent restenosis and stent thrombosis remain clinically significant problems for bifurcation lesions. The objective of this study is to determine the haemodynamic effect of the side branch (SB) on main branch (MB) stenting. We hypothesize that the presence of a SB has a negative effect on MB wall shear stress (WSS), wall shear stress gradient (WSSG) and oscillatory shear index (OSI); and that the bifurcation diameter ratio (SB diameter/MB diameter) and angle are important contributors. We further hypothesized that stent undersizing exaggerates the negative effects on WSS, WSSG and OSI. To test these hypotheses, we developed computational models of stents and non-Newtonian blood. The models were then interfaced, meshed and solved in a validated finite-element package. Stents at bifurcation models were created with 30° and 70° bifurcation angles and bifurcations with diameter ratios of SB/MB = 1/2 and 3/4. It was found that stents placed in the MB at a bifurcation lowered WSS dramatically, while elevating WSSG and OSI. Undersizing the stent exaggerated the decrease in WSS, increase in WSSG and OSI, and disturbed the flow between the struts and the vessel wall. Stenting the MB at bifurcations with larger SB/MB ratios or smaller SB angles (30°) resulted in lower WSS, higher WSSG and OSI. Stenosis at the SB lowered WSS and elevated WSSG and OSI. These findings highlight the effects of major biomechanical factors in MB stenting on endothelial WSS, WSSG, OSI and suggests potential mechanisms for the potentially higher adverse clinical events associated with bifurcation stenting.

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.

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

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 Mis-sizing of stent promotes intimal hyperplasia: impact of endothelial shear and intramural stress

2011 ◽  
Vol 301 (6) ◽  
pp. H2254-H2263 ◽  
Author(s):  
Henry Y. Chen ◽  
Anjan K. Sinha ◽  
Jenny S. Choy ◽  
Hai Zheng ◽  
Michael Sturek ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Coronary Arteries ◽  
Vessel Wall ◽  
Solid Mechanics ◽  
Linear Regression Analysis ◽  
Wall Stress ◽  
Linear Relations ◽  
Flow Disturbances ◽  
Wall Shear

Stent can cause flow disturbances on the endothelium and compliance mismatch and increased stress on the vessel wall. These effects can cause low wall shear stress (WSS), high wall shear stress gradient (WSSG), oscillatory shear index (OSI), and circumferential wall stress (CWS), which may promote neointimal hyperplasia (IH). The hypothesis is that stent-induced abnormal fluid and solid mechanics contribute to IH. To vary the range of WSS, WSSG, OSI, and CWS, we intentionally mismatched the size of stents to that of the vessel lumen. Stents were implanted in coronary arteries of 10 swine. Intravascular ultrasound (IVUS) was used to size the coronary arteries and stents. After 4 wk of stent implantation, IVUS was performed again to determine the extent of IH. In conjunction, computational models of actual stents, the artery, and non-Newtonian blood were created in a computer simulation to yield the distribution of WSS, WSSG, OSI, and CWS in the stented vessel wall. An inverse relation ( R2 = 0.59, P < 0.005) between WSS and IH was found based on a linear regression analysis. Linear relations between WSSG, OSI, and IH were observed ( R2 = 0.48 and 0.50, respectively, P < 0.005). A linear relation ( R2 = 0.58, P < 0.005) between CWS and IH was also found. More statistically significant linear relations between the ratio of CWS to WSS (CWS/WSS), the products CWS × WSSG and CWS × OSI, and IH were observed ( R2 = 0.67, 0.54, and 0.56, respectively, P < 0.005), suggesting that both fluid and solid mechanics influence the extent of IH. Stents create endothelial flow disturbances and intramural wall stress concentrations, which correlate with the extent of IH formation, and these effects were exaggerated with mismatch of stent/vessel size. These findings reveal the importance of reliable vessel and stent sizing to improve the mechanics on the vessel wall and minimize IH.

scholarly journals Effect of reverse flow on the pattern of wall shear stress near arterial branches

2011 ◽  
Vol 8 (64) ◽  
pp. 1594-1603 ◽  
Author(s):  
A. Kazakidi ◽  
A. M. Plata ◽  
S. J. Sherwin ◽  
P. D. Weinberg
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Steady Flow ◽  
Stokes Equations ◽  
Reverse Flow ◽  
Side Branch ◽  
Navier Stokes ◽  
Wall Region ◽  
Wall Shear ◽  
Near Wall

Atherosclerotic lesions have a patchy distribution within arteries that suggests a controlling influence of haemodynamic stresses on their development. The distribution near aortic branches varies with age and species, perhaps reflecting differences in these stresses. Our previous work, which assumed steady flow, revealed a dependence of wall shear stress (WSS) patterns on Reynolds number and side-branch flow rate. Here, we examine effects of pulsatile flow. Flow and WSS patterns were computed by applying high-order unstructured spectral/hp element methods to the Newtonian incompressible Navier–Stokes equations in a geometrically simplified model of an aorto-intercostal junction. The effect of pulsatile but non-reversing side-branch flow was small; the aortic WSS pattern resembled that obtained under steady flow conditions, with high WSS upstream and downstream of the branch. When flow in the side branch or in the aortic near-wall region reversed during part of the cycle, significantly different instantaneous patterns were generated, with low WSS appearing upstream and downstream. Time-averaged WSS was similar to the steady flow case, reflecting the short duration of these events, but patterns of the oscillatory shear index for reversing aortic near-wall flow were profoundly altered. Effects of reverse flow may help explain the different distributions of lesions.

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