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Computational Fluid Dynamics Study of Bifurcation Aneurysms Treated with Pipeline Embolization Device: Side Branch Diameter Study.

Tang AY, Chung WC, Liu ET, Qu JQ, Tsang AC, Leung GK, Leung KM, Yu AC, Chow KW - J Med Biol Eng (2015)

Bottom Line: This may result in side-branch hypoperfusion subsequent to stenting.Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions.This quantitative analysis can assist in treatment planning and therapeutic decision-making.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China.

ABSTRACT

An intracranial aneurysm, abnormal swelling of the cerebral artery, may lead to undesirable rates of mortality and morbidity upon rupture. Endovascular treatment involves the deployment of a flow-diverting stent that covers the aneurysm orifice, thereby reducing the blood flow into the aneurysm and mitigating the risk of rupture. In this study, computational fluid dynamics analysis is performed on a bifurcation model to investigate the change in hemodynamics with various side branch diameters. The condition after the deployment of a pipeline embolization device is also simulated. Hemodynamic factors such as flow velocity, pressure, and wall shear stress are studied. Aneurysms with a larger side branch vessel might have greater risk after treatment in terms of hemodynamics. Although a stent could lead to flow reduction entering the aneurysm, it would drastically alter the flow rate inside the side branch vessel. This may result in side-branch hypoperfusion subsequent to stenting. In addition, two patient-specific bifurcation aneurysms are tested, and the results show good agreement with the idealized models. Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions. This quantitative analysis can assist in treatment planning and therapeutic decision-making.

No MeSH data available.


Related in: MedlinePlus

a Absolute axial velocity of blood flow at orifice throughout complete cardiac cycle (normalized with respect to cardiac period T). Velocity is generally higher when side branch diameter is large. b CFD-derived mean volume flow rate into intracranial aneurysm as function of side branch diameter. A large side branch diameter (d = 2.0 mm) shows a greater flow rate into aneurysm before stent deployment. c Corresponding results for side branch vessel and distal parent artery; at small side branch diameter, alteration of mean volume flow rate due to stenting, however, is minimal
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Fig7: a Absolute axial velocity of blood flow at orifice throughout complete cardiac cycle (normalized with respect to cardiac period T). Velocity is generally higher when side branch diameter is large. b CFD-derived mean volume flow rate into intracranial aneurysm as function of side branch diameter. A large side branch diameter (d = 2.0 mm) shows a greater flow rate into aneurysm before stent deployment. c Corresponding results for side branch vessel and distal parent artery; at small side branch diameter, alteration of mean volume flow rate due to stenting, however, is minimal

Mentions: Ideally, a flow-diverting stent should hinder the volume flux into the aneurysm with minimal disruption to the blood supply in the side branch vessel. The flow rate into the aneurysm can be measured by creating a control interior surface at the neck connecting the aneurysm and the distal parent vessel. As the aneurysm is a blind sac, the mass of fluid flowing in must be equal to that flowing out. The mean volume flow rate into the aneurysm (Q) can be determined by evaluating the following integral [20]:4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q = \frac{1}{T}\int_{T}^{t + T} {\frac{\left/ V \right/A}{2}dt} = \frac{A}{2T}\int_{T}^{t + T} {\left/ V \right/dt} $$\end{document}Q=1T∫Tt+TVA2dt=A2T∫Tt+TVdtwhere T is the cardiac cycle, /V/ is the spatial-averaged absolute axial velocity (the component perpendicular to the control surface) at the neck region, A is the cross-sectional area of the neck, and t is an arbitrary time instant. Simpson’s rule is employed. The absolute axial velocity /V/ is substantially reduced after stenting (Fig. 7a).Fig. 7


Computational Fluid Dynamics Study of Bifurcation Aneurysms Treated with Pipeline Embolization Device: Side Branch Diameter Study.

Tang AY, Chung WC, Liu ET, Qu JQ, Tsang AC, Leung GK, Leung KM, Yu AC, Chow KW - J Med Biol Eng (2015)

a Absolute axial velocity of blood flow at orifice throughout complete cardiac cycle (normalized with respect to cardiac period T). Velocity is generally higher when side branch diameter is large. b CFD-derived mean volume flow rate into intracranial aneurysm as function of side branch diameter. A large side branch diameter (d = 2.0 mm) shows a greater flow rate into aneurysm before stent deployment. c Corresponding results for side branch vessel and distal parent artery; at small side branch diameter, alteration of mean volume flow rate due to stenting, however, is minimal
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig7: a Absolute axial velocity of blood flow at orifice throughout complete cardiac cycle (normalized with respect to cardiac period T). Velocity is generally higher when side branch diameter is large. b CFD-derived mean volume flow rate into intracranial aneurysm as function of side branch diameter. A large side branch diameter (d = 2.0 mm) shows a greater flow rate into aneurysm before stent deployment. c Corresponding results for side branch vessel and distal parent artery; at small side branch diameter, alteration of mean volume flow rate due to stenting, however, is minimal
Mentions: Ideally, a flow-diverting stent should hinder the volume flux into the aneurysm with minimal disruption to the blood supply in the side branch vessel. The flow rate into the aneurysm can be measured by creating a control interior surface at the neck connecting the aneurysm and the distal parent vessel. As the aneurysm is a blind sac, the mass of fluid flowing in must be equal to that flowing out. The mean volume flow rate into the aneurysm (Q) can be determined by evaluating the following integral [20]:4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q = \frac{1}{T}\int_{T}^{t + T} {\frac{\left/ V \right/A}{2}dt} = \frac{A}{2T}\int_{T}^{t + T} {\left/ V \right/dt} $$\end{document}Q=1T∫Tt+TVA2dt=A2T∫Tt+TVdtwhere T is the cardiac cycle, /V/ is the spatial-averaged absolute axial velocity (the component perpendicular to the control surface) at the neck region, A is the cross-sectional area of the neck, and t is an arbitrary time instant. Simpson’s rule is employed. The absolute axial velocity /V/ is substantially reduced after stenting (Fig. 7a).Fig. 7

Bottom Line: This may result in side-branch hypoperfusion subsequent to stenting.Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions.This quantitative analysis can assist in treatment planning and therapeutic decision-making.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077 China.

ABSTRACT

An intracranial aneurysm, abnormal swelling of the cerebral artery, may lead to undesirable rates of mortality and morbidity upon rupture. Endovascular treatment involves the deployment of a flow-diverting stent that covers the aneurysm orifice, thereby reducing the blood flow into the aneurysm and mitigating the risk of rupture. In this study, computational fluid dynamics analysis is performed on a bifurcation model to investigate the change in hemodynamics with various side branch diameters. The condition after the deployment of a pipeline embolization device is also simulated. Hemodynamic factors such as flow velocity, pressure, and wall shear stress are studied. Aneurysms with a larger side branch vessel might have greater risk after treatment in terms of hemodynamics. Although a stent could lead to flow reduction entering the aneurysm, it would drastically alter the flow rate inside the side branch vessel. This may result in side-branch hypoperfusion subsequent to stenting. In addition, two patient-specific bifurcation aneurysms are tested, and the results show good agreement with the idealized models. Furthermore, the peripheral resistance of downstream vessels is investigated by varying the outlet pressure conditions. This quantitative analysis can assist in treatment planning and therapeutic decision-making.

No MeSH data available.


Related in: MedlinePlus