scholarly journals Ascending Aorta Resection and End-to-End Anastomosis: Redistribution of Wall Shear Stress Induced by a Bioprosthetic Heart Valve

Prosthesis ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 297-303
Author(s):  
Giuseppe M. Raffa ◽  
Salvatore Pasta
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Heart Valve ◽  
Ascending Aorta ◽  
Bioprosthetic Heart Valve ◽  
Ascending Aortic Aneurysm ◽  
Hemodynamic Forces ◽  
Lack Of Information ◽  
End To End ◽  
Wall Shear

Although aortic resection and end-to-end anastomosis are applied to repair ascending aortic aneurysm, there is a lack of information on the late risk of post-operative complications, such as aortic dissection and aneurysmal re-dilatation. It is recognized that altered hemodynamic forces exerted on an aortic wall play an important role on dissection and aneurysm formation. We present a case in which the hemodynamic forces were investigated prior and after repair of an ascending aorta treated by resection with end-to-end anastomosis and a bioprosthetic heart valve. Post-operative wall shear stress was redistributed uniformly along the vessel circumference, and this may suggest a reduced risk of complications near aortic root, but not exclude the re-dilatation of the ascending aorta.

scholarly journals Comparative Study of Wall-Shear Stress at the Ascending Aorta for Different Mechanical Heart Valve Prostheses

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Qianhui Li ◽  
Franziska Hegner ◽  
Christoph H. Bruecker
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Heart Valve ◽  
Aortic Wall ◽  
Mechanical Heart Valve ◽  
Ascending Aorta ◽  
Field Analysis ◽  
Human Aorta ◽  
Wall Shear ◽  
The Impact

AbstractAn experimental study is reported which investigates the wall shear stress (WSS) distribution in a transparent model of the human aorta comparing an St. Jude Medical (SJM) Regent bileaflet mechanical heart valve (BMHV) with the Lapeyre-Triflo FURTIVA trileaflet mechanical heart valve (TMHV) in physiological pulsatile flow. Elastic microcantilever structures, calibrated as micropillar WSS sensors by microparticle-image-velocimetry measurements, are applied to the wall along the ascending aorta (AAo). The peak WSS values in the BMHV are observed to be almost twice that of the values seen in the TMHV. Flow field analysis illuminates that these peaks are linked to the jet-like flows generated in the valves interacting with the aortic wall. Not only the magnitude but also the impact regions are specific for different valve designs. The side-orifice jets generated by the BMHV travel along the aortic wall in the AAo, impacting the wall throughout the AAo. However, the jets generated by TMHV impact further downstream in the AAo and results in a reduced WSS.

Multi-Axial Mechanical Stimulation of HUVECs Demonstrates That Combined Loading is not Equivalent to the Superposition of Individual Wall Shear Stress and Tensile Hoop Stress Components

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Liam T. Breen ◽  
Peter E. McHugh ◽  
Bruce P. Murphy
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cellular Response ◽  
Umbilical Vein ◽  
Combined Loading ◽  
Hoop Strain ◽  
Hemodynamic Forces ◽  
Testing Period ◽  
Wall Shear

Over the past 25 years, many laboratory based bioreactors have been used to study the cellular response to hemodynamic forces. The vast majority of these studies have focused on the effect of a single isolated hemodynamic force, generally consisting of a wall shear stress (WSS) or a tensile hoop strain (THS). However, investigating the cellular response to a single isolated force does not accurately represent the true in vivo situation, where a number of forces are acting simultaneously. This study used a novel bioreactor to investigate the cellular response of human umbilical vein endothelial cells (HUVECs) exposed to a combination of steady WSS and a range of cyclic THS. HUVECs exposed to a range of cyclic THS (0–12%), over a 12 h testing period, expressed an upregulation of both ICAM-1 and VCAM-1. HUVECs exposed to a steady WSS (0 dynes/cm2 and 25 dynes/cm2), over a 12 h testing period, also exhibited an ICAM-1 upregulation but a VCAM-1 downregulation, where the greatest level of WSS stimulus resulted in the largest upregulation and downregulation of ICAM-1 and VCAM-1, respectively. A number of HUVEC samples were exposed to a high steady WSS (25 dynes/cm2) combined with a range of cyclic THS (0–4%, 0–8%, and 0–12%) for a 12 h testing period. The initial ICAM-1 upregulation, due to the WSS alone, was downregulated with the addition of a cyclic THS. It was observed that the largest THS (0–12%) had the greatest reducing effect on the ICAM-1 upregulation. Similarly, the initial VCAM-1 downregulation, due to the high steady WSS alone, was further downregulated with the addition of a cyclic THS. A similar outcome was observed when HUVEC samples were exposed to a low steady WSS combined with a range of cyclic THS. However, the addition of a THS to the low WSS did not result in an expected ICAM-1 downregulation. In fact, it resulted in a trend of unexpected ICAM-1 upregulation. The unexpected cellular response to the combination of a steady WSS and a cyclic THS demonstrates that such a response could not be determined by simply superimposing the cellular responses exhibited by ECs exposed to a steady WSS and a cyclic THS that were applied in isolation.

Association of Regional Wall Shear Stress and Progressive Ascending Aorta Dilation in Bicuspid Aortic Valve

2021 ◽  
Author(s):  
Gilles Soulat ◽  
Michael B. Scott ◽  
Bradley D. Allen ◽  
Ryan Avery ◽  
Robert O. Bonow ◽  
...  
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Wall Shear Stress ◽  
Bicuspid Aortic Valve ◽  
Ascending Aorta ◽  
Regional Wall ◽  
Wall Shear

scholarly journals Low and Oscillatory Wall Shear Stress Is Not Related to Aortic Dilation in Patients With Bicuspid Aortic Valve

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Lydia Dux-Santoy ◽  
Andrea Guala ◽  
Julio Sotelo ◽  
Sergio Uribe ◽  
Gisela Teixidó-Turà ◽  
...  
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Wall Shear Stress ◽  
Healthy Volunteers ◽  
Aortic Arch ◽  
Bicuspid Aortic Valve ◽  
Ascending Aorta ◽  
Oscillatory Shear ◽  
Aortic Dilation ◽  
Wall Shear

Objective: To assess the relationship between regional wall shear stress (WSS) and oscillatory shear index (OSI) and aortic dilation in patients with bicuspid aortic valve (BAV). Approach and Results: Forty-six consecutive patients with BAV (63% with right-left-coronary-cusp fusion, aortic diameter ≤ 45 mm and no severe valvular disease) and 44 healthy volunteers were studied by time-resolved 3-dimensional phase-contrast magnetic resonance imaging. WSS and OSI were quantified at different levels of the ascending aorta and the aortic arch, and regional WSS and OSI maps were obtained. Seventy percent of BAV had ascending aorta dilation. Compared with healthy volunteers, patients with BAV had increased WSS and decreased OSI in most of the ascending aorta and the aortic arch. In both BAV and healthy volunteers, regions of high WSS matched regions of low OSI and vice versa. No regions of both low WSS and high OSI were identified in BAV compared with healthy volunteers. Patients with BAV with dilated compared with nondilated aorta presented low and oscillatory WSS in the aortic arch, but not in the ascending aorta where dilation is more prevalent. Furthermore, no regions of concomitant low WSS and high OSI were identified when BAV were compared according to leaflet fusion pattern, despite the well-known differences in regional dilation prevalence. Conclusions: Regions with low WSS and high OSI do not match those with the highest prevalence of dilation in patients with BAV, thus providing no evidence to support the low and oscillatory shear stress theory in the pathogenesis of proximal aorta dilation in the presence of BAV.

Measurement of systolic and diastolic arterial wall shear stress in the ascending aorta

2008 ◽  
Vol 24 (4) ◽  
pp. 196-203 ◽  
Author(s):  
Efstathios P. Efstathopoulos ◽  
George Patatoukas ◽  
Ioannis Pantos ◽  
Odysseas Benekos ◽  
Demosthenes Katritsis ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Arterial Wall ◽  
Ascending Aorta ◽  
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 NUMERICAL ANALYSIS OF HEMODYNAMIC FORCES THROUGH STENOTIC ARTERY

2013 ◽  
Vol 43 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Syeda Reham Shahed ◽  
Mohammad Ali ◽  
Md. Quamrul Islam
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Numerical Analysis ◽  
Wall Shear Stress ◽  
Peak Flow ◽  
Hemodynamic Forces ◽  
Time Period ◽  
Stenosis Severity ◽  
Wall Shear ◽  
Inlet Boundary Condition

A numerical analysis is carried out to demonstrate the variation of two hemodynamic forces: wallshear stress and pressure in the flow field of stenotic artery. The artery has 75% stenosis severity withaxisymmetric cosine shaped stenosis. The wall of the vessel is considered to be rigid. A sinusoidal pulsatile flowis assumed as inlet boundary condition. During the simulation both standard k-? model of low Reynoldscorrection and standard k-? model are used. Some analysis with standard k-? model with low Reynoldscorrection show better agreement with previous experimental results. The peak wall shear stress is found to belocated proximal to the stenosis throat. The results from the standard k-? turbulence model illustratesoscillating wall shear stress downstream the stenosis throat throughout the time period. The pressure gradientat the throat is highest at peak flow condition. These factors contribute to further growth and rupture ofplaques.DOI: http://dx.doi.org/10.3329/jme.v43i1.15780

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