Fluid Structure Interaction With Contact Surface Methodology for Evaluation of Endovascular Carotid Implants for Drug-Resistant Hypertension Treatment

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Dinesh A. Peter ◽  
Yared Alemu ◽  
Michalis Xenos ◽  
Ori Weisberg ◽  
Itzhak Avneri ◽  
...  
Keyword(s):  
Contact Surface ◽  
Carotid Arteries ◽  
Carotid Sinus ◽  
Drug Resistant ◽  
Hypertensive Patients ◽  
Structure Interaction ◽  
Sinus Wall ◽  
Device Deployment ◽  
Von Mises ◽  
Physiologic Model

Drug-resistant hypertensive patients may be treated by mechanical stimulation of stretch-sensitive baroreceptors located in the sinus of carotid arteries. To evaluate the efficacy of endovascular devices to stretch the carotid sinus such that the induced strain might trigger baroreceptors to increase action potential firing rate and thereby reduce systemic blood pressure, numerical simulations were conducted of devices deployed in subject-specific carotid models. Two models were chosen—a typical physiologic carotid and a diminutive atypical physiologic model representing a clinically worst case scenario—to evaluate the effects of device deployment in normal and extreme cases, respectively. Based on the anatomical dimensions of the carotids, two different device sizes were chosen out of five total device sizes available. A fluid structure interaction (FSI) simulation methodology with contact surface between the device and the arterial wall was implemented for resolving the stresses and strains induced by device deployment. Results indicate that device deployment in the carotid sinus of the physiologic model induces an increase of 2.5% and 7.5% in circumferential and longitudinal wall stretch, respectively, and a maximum of 54% increase in von Mises arterial stress at the sinus wall baroreceptor region. The second device, deployed in the diminutive carotid model, induces an increase of 6% in both circumferential and longitudinal stretch and a 50% maximum increase in von Mises stress at the sinus wall baroreceptor region. Device deployment has a minimal effect on blood-flow patterns, indicating that it does not adversely affect carotid bifurcation hemodynamics in the physiologic model. In the smaller carotid model, deployment of the device lowers wall shear stress at sinus by 16% while accelerating flow entering the external carotid artery branch. Our FSI simulations of carotid arteries with deployed device show that the device induces localized increase in wall stretch at the sinus, suggesting that this will activate baroreceptors and subsequently may control hypertension in drug-resistant hypertensive patients, with no consequential deleterious effects on the carotid sinus hemodynamics.

MRI-based detection of renal artery abnormalities related to renal denervation by catheter-based radiofrequency ablation in drug resistant hypertensive patients

2018 ◽  
Vol 28 (8) ◽  
pp. 3355-3361 ◽  
Author(s):  
Monica Sigovan ◽  
Salim Si-Mohamed ◽  
Pierre-Yves Courand ◽  
Brahim Harbaoui ◽  
Marc Sapoval ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Renal Artery ◽  
Renal Denervation ◽  
Drug Resistant ◽  
Hypertensive Patients

3D fluid-structure interaction (FSI) simulation of new type vortex generators in smooth wavy fin-and-elliptical tube heat exchanger

2016 ◽  
Vol 33 (8) ◽  
pp. 2504-2529 ◽  
Author(s):  
Babak Lotfi ◽  
Bengt Sunden ◽  
Qiu-Wang Wang
Keyword(s):  
Heat Exchanger ◽  
Mechanical Behavior ◽  
Elastic Strain ◽  
Fluid Structure Interaction ◽  
Vortex Generators ◽  
Von Mises Stress ◽  
Fluid Structure ◽  
Content Type ◽  
Structure Interaction ◽  
Von Mises

Purpose The purpose of this paper is to investigate the numerical fluid-structure interaction (FSI) framework for the simulations of mechanical behavior of new vortex generators (VGs) in smooth wavy fin-and-elliptical tube (SWFET) heat exchanger using the ANSYS MFX Multi-field® solver. Design/methodology/approach A three-dimensional FSI approach is proposed in this paper to provide better understanding of the performance of the VG structures in SWFET heat exchangers associated with the alloy material properties and geometric factors. The Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are applied for modeling of the turbulent flow in SWFET heat exchanger and the linear elastic Cauchy-Navier model is solved for the structural von Mises stress and elastic strain analysis in the VGs region. Findings Parametric studies conducted in the course of this research successfully identified illustrate that the maximum magnitude of von Mises stress and elastic strain occurs at the root of the VGs and depends on geometrical parameters and material types. These results reveal that the titanium alloy VGs shows a slightly higher strength and lower elastic strain compared to the aluminum alloy VGs. Originality/value This paper is one of the first in the literature that provides original information mechanical behavior of a SWFET heat exchanger model with new VGs in the field of FSI coupling technique.

Fluid Structure Interaction Analysis of Stentless Bio-Prosthetic Aortic Heart Valve in Sinus of Valsalva

2010 ◽  
Author(s):  
Esfandyar Kouhi ◽  
Yos Morsi
Keyword(s):  
Blood Flow ◽  
Heart Valve ◽  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
Fluid Pressure ◽  
Von Mises Stress ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Aortic Heart Valve ◽  
Von Mises

In this paper the fluid structure interaction in stentless aortic heart valve during acceleration phase was performed successfully using the commercial ANSYS/CFX package. The aim is to provide unidirectional coupling FSI analysis of physiological blood flow within an anatomically corrected numerical model of stentless aortic valve. Pulsatile, Newtonian, and turbulent blood flow rheology at aortic level was applied to fluid domain. The proposed structural prosthesis had a novel multi thickness leaflet design decreased from aortic root down to free age surface. An appropriate interpolation scheme used to import the fluid pressure on the structure at their interface. The prosthesis deformations over the acceleration time showed bending dominant characteristic at early stages of the cardiac cycle. More stretching and flattening observed in the rest of the times steps. The multi axial Von Mises stress data analysis was validated with experimental data which confirmed the initial design of the prosthesis.

Acute Device-Based Blood Pressure Reduction: Electrical Activation of the Carotid Baroreflex in Patients Undergoing Elective Carotid Surgery

Vascular ◽  
2007 ◽  
Vol 15 (2) ◽  
pp. 63-69 ◽  
Author(s):  
Jürg Schmidli ◽  
Hannu Savolainen ◽  
Friedrich Eckstein ◽  
Eric Irwin ◽  
Tim K. Peters ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Carotid Sinus ◽  
Blood Pressure Reduction ◽  
Acute Effect ◽  
Carotid Surgery ◽  
Proof Of Concept ◽  
Sinus Wall ◽  
Carotid Baroreflex ◽  
Voltage Dependent ◽  
Stimulation Of

Carotid sinus baroreceptors are involved in controlling blood pressure (BP) by providing input to the cardiovascular regulatory centers of the medulla. The acute effect of temporarily placing an electrode on the carotid sinus wall to electrically activate the baroreflex was investigated. We studied 11 patients undergoing elective carotid surgery. Baseline BP was 146+30/66±17 mm Hg and heart rate (HR) 72±7 bpm (mean ± standard deviation). An electrode was placed upon the carotid sinus and after obtaining a steady state baseline of BP and HR, an electric current was applied and increased in 1-volt increments. A voltage dependent and highly significant reduction in BP was observed which averaged 18±26* and 8.0±12 mm Hg for systolic BP and diastolic BP, respectively. Maximal reductions occurred at 4.4±1.2 V: 23±24 mm Hg*, 16±10 mm Hg* and 7±12 bpm* for systolic BP, diastolic BP and HR, respectively (= p <.05). Thus, electrical stimulation of the carotid sinus activates the carotid baroreflex resulting in a reduction in BP and HR. This presents a proof of concept for device based baroreflex modulation in acute BP regulation and adds to the available data which provide a rationale for evaluating this system in the context of chronic BP reduction in hypertensive patients.

Relation between histological age-changes in the carotid body and atherosclerosis in the carotid arteries

1987 ◽  
Vol 101 (12) ◽  
pp. 1271-1275 ◽  
Author(s):  
Patrick Lowe ◽  
Donald Heath ◽  
Paul Smith
Keyword(s):  
Blood Flow ◽  
Carotid Body ◽  
Carotid Arteries ◽  
Carotid Sinus ◽  
Carotid Bifurcation ◽  
Age Changes ◽  
Histological Changes ◽  
Atherosclerotic Lesions ◽  
Flow Through ◽  
Human Carotid

Abstract Histological changes in the human carotid body associated with increasing age are accompanied by occlusive atherosclerotic lesions in the arteries of the carotid bifurcation, and are probably ischaemic in origin. The carotid sinus, however, is unusually susceptible to the development of atheroma and its occlusion appears to have little influence in compromising blood flow through the glomic arteries.

Age-Dependent Morphological Changes of the Human Carotid Bifurcation

1999 ◽  
Author(s):  
Baruch B. Lieber ◽  
Ajay K. Wakhloo ◽  
Andreas R. Luft ◽  
Afshin A. Divani
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Carotid Sinus ◽  
Subsequent Development ◽  
Carotid Bifurcation ◽  
Support Pressure ◽  
Morphological Development ◽  
Sinus Wall ◽  
The Brain ◽  
Human Carotid

Abstract The development, significance and function of the human carotid sinus is not yet well understood. The arterial wall within the carotid sinus is well enervated and it contains baroreceptive neural terminals. One hypothesis that was put forward is that the dilation, which may involve all vessels of the carotid bifurcation, exists to support pressure sensing1. Another hypothesis that is supported only by phenomenological observations assume that the function of the sinus is to protect the brain by slowing blood flow and reducing pulsatility2. Yet another hypothesis interprets the sinus as an ontogenetic or phylogenic residual3. More recently, carotid hemodynamics has been investigated using in vitro and computational models. Flow patterns in the carotid sinus were found to be complex and as such have been implicated in the hetrogenesis and subsequent development of atherosclerosis at this site. However, the development of this unique sinus morphology, the role of hemodynamics in such development, and the physiological implications created by this unique morphology have not been investigated. Understanding the hemodynamic and developmental forces that play a role in remodeling of the carotid bifurcation and development of the sinus is of both fundamental and clinical interest and can lead to better prognostication and therapy of carotid disease. Therefore, we initiated a study of the morphological development of the human carotid bulb using different age groups under the hypothesis that sinus morphology reflects an adaptive change in response to alterations in cerebral blood supply during the developmental years of the brain. This adaptation attempts to reduce hydraulic losses in the carotid bifurcation through reduced flow disturbances and maintain high level of blood supply to the brain than consumes about 15% of cardiac output under basal conditions. In addition, it may protect the sinus wall from high shear stress and/or the brain from highly pulsatile blood flow conditions. Initially, we analyzed the angle and sinus morphology of the carotid bifurcation in pediatric and adult patients using biplane digital subtraction angiograms to characterize changes that occur as the brain matures.

Fluid-Structure Interaction Analysis of Flow-Induced Deformation in a Two-Phase, Neo-Hookean Marine Egg

2006 ◽  
Vol 128 (4) ◽  
pp. 519-526 ◽  
Author(s):  
T. Kim ◽  
C W. Wang ◽  
F. I. M. Thomas ◽  
A. M. Sastry
Keyword(s):  
Interaction Analysis ◽  
Von Mises Stress ◽  
Finite Element Analyses ◽  
Two Phase ◽  
Shear Moduli ◽  
Arbacia Punctulata ◽  
Structure Interaction ◽  
Material Parameters ◽  
Von Mises ◽  
Von Mises Stresses

Coupled computational fluid dynamics and finite element analyses were used to determine the material properties of the egg and jelly layer of the sea urchin Arbacia punctulata. Prior experimental shear flow results were used to provide material parameters for these simulations. A Neo-Hookean model was used to model the hyperelastic behaviors of the jelly layer and egg. A simple compressive simulation was then performed, to compare the maximum von Mises stresses within eggs, with and without jelly layers. Results of this study showed that (1) shear moduli range from ∼100to160Pa, and ∼40to140Pa for an egg without a jelly layer, and jelly layer itself, respectively; and (2) the presence of the jelly layer significantly reduces maximum von Mises stress in an egg undergoing compression.

Sign in / Sign up

Export Citation Format

Share Document