Benchmark for Numerical Models of Stented Coronary Bifurcation Flow

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
P. García Carrascal ◽  
J. García García ◽  
J. Sierra Pallares ◽  
F. Castro Ruiz ◽  
F. J. Manuel Martín
Keyword(s):  
Blood Flow ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Velocity Fields ◽  
Cfd Modeling ◽  
Coronary Bifurcation ◽  
Stent Restenosis ◽  
Cfd Models ◽  
In Stent Restenosis

In-stent restenosis ails many patients who have undergone stenting. When the stented artery is a bifurcation, the intervention is particularly critical because of the complex stent geometry involved in these structures. Computational fluid dynamics (CFD) has been shown to be an effective approach when modeling blood flow behavior and understanding the mechanisms that underlie in-stent restenosis. However, these CFD models require validation through experimental data in order to be reliable. It is with this purpose in mind that we performed particle image velocimetry (PIV) measurements of velocity fields within flows through a simplified coronary bifurcation. Although the flow in this simplified bifurcation differs from the actual blood flow, it emulates the main fluid dynamic mechanisms found in hemodynamic flow. Experimental measurements were performed for several stenting techniques in both steady and unsteady flow conditions. The test conditions were strictly controlled, and uncertainty was accurately predicted. The results obtained in this research represent readily accessible, easy to emulate, detailed velocity fields and geometry, and they have been successfully used to validate our numerical model. These data can be used as a benchmark for further development of numerical CFD modeling in terms of comparison of the main flow pattern characteristics.

scholarly journals Computational fluid dynamic simulations of image-based stented coronary bifurcation models

2013 ◽  
Vol 10 (84) ◽  
pp. 20130193 ◽  
Author(s):  
Claudio Chiastra ◽  
Stefano Morlacchi ◽  
Diego Gallo ◽  
Umberto Morbiducci ◽  
Rubén Cárdenes ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Coronary Arteries ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Conventional Coronary Angiography ◽  
Coronary Bifurcation ◽  
Dynamic Simulations ◽  
Stent Restenosis ◽  
Relative Residence Time ◽  
In Stent Restenosis

One of the relevant phenomenon associated with in-stent restenosis in coronary arteries is an altered haemodynamics in the stented region. Computational fluid dynamics (CFD) offers the possibility to investigate the haemodynamics at a level of detail not always accessible within experimental techniques. CFD can quantify and correlate the local haemodynamics structures which might lead to in-stent restenosis. The aim of this work is to study the fluid dynamics of realistic stented coronary artery models which replicate the complete clinical procedure of stent implantation. Two cases of pathologic left anterior descending coronary arteries with their bifurcations are reconstructed from computed tomography angiography and conventional coronary angiography images. Results of wall shear stress and relative residence time show that the wall regions more prone to the risk of restenosis are located next to stent struts, to the bifurcations and to the stent overlapping zone for both investigated cases. Considering a bulk flow analysis, helical flow structures are generated by the curvature of the zone upstream from the stent and by the bifurcation regions. Helical recirculating microstructures are also visible downstream from the stent struts. This study demonstrates the feasibility to virtually investigate the haemodynamics of patient-specific coronary bifurcation geometries.

scholarly journals Challenging treatment of in-stent restenosis in a coronary bifurcation by implantation of a bioresorbable scaffold under optical coherence tomography guidance

2019 ◽  
Vol 26 (3) ◽  
pp. 304-306
Author(s):  
Grzegorz Zuk ◽  
Dariusz Ciecwierz ◽  
Piotr Drewla ◽  
Marcin Gruchała ◽  
Juan Luis Gutiérrez-Chico ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Optical Coherence ◽  
Coronary Bifurcation ◽  
Bioresorbable Scaffold ◽  
Stent Restenosis ◽  
In Stent Restenosis

Patient-Specific Stented Coronary Bifurcations: Numerical Analysis of Near-Wall Quantities and the Bulk Flow

2013 ◽  
Author(s):  
Claudio Chiastra ◽  
Stefano Morlacchi ◽  
Diego Gallo ◽  
Umberto Morbiducci ◽  
Rubén Cárdenes ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Shear Stress ◽  
Coronary Arteries ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Wall Region ◽  
Stent Restenosis ◽  
Local Measurements ◽  
In Stent Restenosis

The mechanisms and the causes of the in-stent restenosis process in coronary arteries are not fully understood. One of the most relevant phenomena, which seems to be associated to this process, is an altered hemodynamics in the stented wall region [1]. In vivo local measurements of velocities and their gradients in human coronary arteries are very difficult and can hardly be applied to successfully investigate the fluid dynamic field [1]. Alternatively, virtual models of blood flow in patient-specific coronary arteries allow the study of local fluid dynamics and the computation of the wall shear stress (WSS) and other quantities which can be related to the risk of restenosis.

scholarly journals Comparison of Newtonian and Non-newtonian Fluid Models in Blood Flow Simulation in Patients With Intracranial Arterial Stenosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Haipeng Liu ◽  
Linfang Lan ◽  
Jill Abrigo ◽  
Hing Lung Ip ◽  
Yannie Soo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Newtonian Fluid ◽  
Fluid Model ◽  
Arterial Stenosis ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Fluid Models ◽  
Cfd Models ◽  
Atherosclerotic Stenosis ◽  
Transient Simulations

BackgroundNewtonian fluid model has been commonly applied in simulating cerebral blood flow in intracranial atherosclerotic stenosis (ICAS) cases using computational fluid dynamics (CFD) modeling, while blood is a shear-thinning non-Newtonian fluid. We aimed to investigate the differences of cerebral hemodynamic metrics quantified in CFD models built with Newtonian and non-Newtonian fluid assumptions, in patients with ICAS.MethodsWe built a virtual artery model with an eccentric 75% stenosis and performed static CFD simulation. We also constructed CFD models in three patients with ICAS of different severities in the luminal stenosis. We performed static simulations on these models with Newtonian and two non-Newtonian (Casson and Carreau-Yasuda) fluid models. We also performed transient simulations on another patient-specific model. We measured translesional pressure ratio (PR) and wall shear stress (WSS) values in all CFD models, to reflect the changes in pressure and WSS across a stenotic lesion. In all the simulations, we compared the PR and WSS values in CFD models derived with Newtonian, Casson, and Carreau-Yasuda fluid assumptions.ResultsIn all the static and transient simulations, the Newtonian/non-Newtonian difference on PR value was negligible. As to WSS, in static models (virtual and patient-specific), the rheological difference was not obvious in areas with high WSS, but observable in low WSS areas. In the transient model, the rheological difference of WSS areas with low WSS was enhanced, especially during diastolic period.ConclusionNewtonian fluid model could be applicable for PR calculation, but caution needs to be taken when using the Newtonian assumption in simulating WSS especially in severe ICAS cases.

scholarly journals Novel CFD modeling approaches to assessing urine flow in prostatic urethra after transurethral surgery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bin Zhang ◽  
Shuang Liu ◽  
Yinxia Liu ◽  
Bo Wu ◽  
Xuhui Zhang ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Urine Flow ◽  
Prostatic Urethra ◽  
Dynamics Simulation ◽  
Cfd Modeling ◽  
Transverse Diameter ◽  
Cfd Models ◽  
Post Surgery ◽  
Through Flow ◽  
Urethral Orifice

AbstractAssessment of the pressure and velocity of urine flow for different diameter ratios of prostatic urethra (RPU) after transurethral surgery using computational fluid dynamics (CFD). A standardized and idealized two-dimensional CFD model after transurethral surgery (CATS-1st) was developed for post-surgery mid-voiding. Using CATS-1st, 210 examples were amplified according to an array of size [3][5][14], which contained three groups of longitudinal diameters of prostatic urethra (LD-PU). Each of these groups contained five subgroups of transverse diameters of the bladder neck (TD-BN), each with 14 examples of transverse diameters of PU (TD-PU). The pressure and velocity of urine flow were monitored through flow dynamics simulation, and the relationship among RPU-1 (TD-PU/TD-BN), RPU-2 (RPU-1/LD-PU), the transverse diameter of the vortex, and the midpoint velocity of the external urethral orifice (MV-EUO) was determined. A total of 210 CATS examples, including CATS-1st examples, were analyzed. High (bladder and PU) and medium/low (the rest of the urethra) pressure zones, and low (bladder), medium (PU), and high (the rest of the urethra) velocity zones were determined. The rapid changes in the velocity were concentrated in and around the PU. Laminar flow was present in all the examples. The vortices appeared and then gradually shrank with reducing RPU on both the sides of PU in 182 examples. In the vortex examples, minimum RPU-1 and RPU-2 reached close to the values of 0.79 and 0.02, respectively. MV-EUO increased gradually with decreasing RPU. In comparison to the vortex examples, the non-vortex examples exhibited a significantly higher (p < 0.01) MV-EUO. The developed CFD models (CATS) presented an effective simulation of urine flow behavior within the PU after transurethral surgery for benign prostatic hyperplasia (BPH). These models could prove to be useful for morphological repair in PU after transurethral surgery.

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