scholarly journals Computational Fluid Dynamics of Blood Flow in the Abdominal Aorta Post “Chimney” Endovascular Aneurysm Repair (ChEVAR)

10.5772/67011 ◽  
2017 ◽  
Author(s):  
Hila Ben Gur ◽  
Moses Brand ◽  
Gábor Kósa ◽  
Saar Golan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Abdominal Aorta ◽  
Endovascular Aneurysm Repair ◽  
Aneurysm Repair

scholarly journals Computational Fluid Dynamics Modeling of Redundant Stent-Graft Configurations in Endovascular Aneurysm Repair

2010 ◽  
Author(s):  
Leonard W. Tse ◽  
Tina L. T. Shek ◽  
Aydin Nabovati ◽  
Cristina H. Amon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Steady State ◽  
Stent Graft ◽  
Endovascular Aneurysm Repair ◽  
Clinical Consequence ◽  
Dynamics Modeling ◽  
Aneurysm Wall ◽  
Aneurysm Repair

An aneurysm is a bulge or localized dilation of an artery that can result in rupture, rapid blood loss, and death. Endovascular aneurysm repair (EVAR) is a minimally-invasive surgical technique that involves delivery of a stent-graft from within the blood vessels. The metallic stents anchor and support the graft (fabric tube), through which blood flow is contained and directed. This relieves the pressure on the weakened aneurysm wall. When the stent-graft is too long for a given patient, the redundant (extra) length adopts a convex configuration in the aneurysm. Based on clinical experience, we hypothesize that redundant stent-graft configurations increase the downward force acting on the device thereby increasing the risk of device dislodgement and failure. This work numerically studies both steady-state and physiologic pulsatile blood flow in redundant stent-graft configurations. Computational fluid dynamics simulations predicted peak downward displacement force for the zero-, moderate- and severe-redundancy configurations of 7.49, 7.65 and 8.04 N, respectively for steady-state flow; and 7.55, 7.70 and 8.31 N, respectively for physiologic pulsatile flow. These results suggest that redundant stent-graft configurations in EVAR do increase the downward force acting on the device, but the clinical consequence depends significantly on device-specific resistance to dislodgement.

Computational Fluid Dynamics Evaluation of the Cross-Limb Stent Graft Configuration for Endovascular Aneurysm Repair

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Tina L. T. Shek ◽  
Leonard W. Tse ◽  
Aydin Nabovati ◽  
Cristina H. Amon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Stent Graft ◽  
Endovascular Aneurysm Repair ◽  
Planar Geometry ◽  
Short Term ◽  
Out Of Plane ◽  
Transient Simulations ◽  
The Cross ◽  
Aneurysm Repair

The technique of crossing the limbs of bifurcated modular stent grafts for endovascular aneurysm repair (EVAR) is often employed in the face of splayed aortic bifurcations to facilitate cannulation and prevent device kinking. However, little has been reported about the implications of cross-limb EVAR, especially in comparison to conventional EVAR. Previous computational fluid dynamics studies of conventional EVAR grafts have mostly utilized simplified planar stent graft geometries. We herein examined the differences between conventional and cross-limb EVAR by comparing their hemodynamic flow fields (i.e., in the “direct” and “cross” configurations, respectively). We also added a “planar” configuration, which is commonly found in the literature, to identify how well this configuration compares to out-of-plane stent graft configurations from a hemodynamic perspective. A representative patient’s cross-limb stent graft geometry was segmented using computed tomography imaging in Mimics software. The cross-limb graft geometry was used to build its direct and planar counterparts in SolidWorks. Physiologic velocity and mass flow boundary conditions and blood properties were implemented for steady-state and pulsatile transient simulations in ANSYS CFX. Displacement forces, wall shear stress (WSS), and oscillatory shear index (OSI) were all comparable between the direct and cross configurations, whereas the planar geometry yielded very different predictions of hemodynamics compared to the out-of-plane stent graft configurations, particularly for displacement forces. This single-patient study suggests that the short-term hemodynamics involved in crossing the limbs is as safe as conventional EVAR. Higher helicity and improved WSS distribution of the cross-limb configuration suggest improved flow-related thrombosis resistance in the short term. However, there may be long-term fatigue implications to stent graft use in the cross configuration when compared to the direct configuration.

Computational fluid dynamics in abdominal aorta bifurcation: non-Newtonian versus Newtonian blood flow in a real case study

2017 ◽  
Vol 20 (8) ◽  
pp. 822-831 ◽  
Author(s):  
Armando A. Soares ◽  
Sílvia Gonzaga ◽  
Carlos Oliveira ◽  
André Simões ◽  
Abel I. Rouboa
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Abdominal Aorta ◽  
Real Case

scholarly journals A Simple Transient Poiseuille-Based Approach to Mimic the Womersley Function and to Model Pulsatile Blood Flow

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 9-17
Author(s):  
Andrea Natale Impiombato ◽  
Giorgio La Civita ◽  
Francesco Orlandi ◽  
Flavia Schwarz Franceschini Zinani ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Quadratic Function ◽  
Pulsatile Blood Flow ◽  
Flow Through ◽  
Simplified Analysis ◽  
Function Models ◽  
Flow Reversals

As it is known, the Womersley function models velocity as a function of radius and time. It has been widely used to simulate the pulsatile blood flow through circular ducts. In this context, the present study is focused on the introduction of a simple function as an approximation of the Womersley function in order to evaluate its accuracy. This approximation consists of a simple quadratic function, suitable to be implemented in most commercial and non-commercial computational fluid dynamics codes, without the aid of external mathematical libraries. The Womersley function and the new function have been implemented here as boundary conditions in OpenFOAM ESI software (v.1906). The discrepancy between the obtained results proved to be within 0.7%, which fully validates the calculation approach implemented here. This approach is valid when a simplified analysis of the system is pointed out, in which flow reversals are not contemplated.

Computational Fluid Dynamics (CFD) Study of the 4th Generation Prototype of a Continuous Flow Ventricular Assist Device (VAD)

2004 ◽  
Vol 126 (2) ◽  
pp. 180-187 ◽  
Author(s):  
Xinwei Song ◽  
Houston G. Wood ◽  
Don Olsen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Ventricular Assist Device ◽  
Continuous Flow ◽  
Surrounding Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

The continuous flow ventricular assist device (VAD) is a miniature centrifugal pump, fully suspended by magnetic bearings, which is being developed for implantation in humans. The CF4 model is the first actual prototype of the final design product. The overall performances of blood flow in CF4 have been simulated using computational fluid dynamics (CFD) software: CFX, which is commercially available from ANSYS Inc. The flow regions modeled in CF4 include the inlet elbow, the five-blade impeller, the clearance gap below the impeller, and the exit volute. According to different needs from patients, a wide range of flow rates and revolutions per minute (RPM) have been studied. The flow rate-pressure curves are given. The streamlines in the flow field are drawn to detect stagnation points and vortices that could lead to thrombosis. The stress is calculated in the fluid field to estimate potential hemolysis. The stress is elevated to the decreased size of the blood flow paths through the smaller pump, but is still within the safe range. The thermal study on the pump, the blood and the surrounding tissue shows the temperature rise due to magnetoelectric heat sources and thermal dissipation is insignificant. CFD simulation proved valuable to demonstrate and to improve the performance of fluid flow in the design of a small size pump.

Sign in / Sign up

Export Citation Format

Share Document