Determination of Wall Tension in Cerebral Artery Aneurysms by Numerical Simulation

The Fontan procedure is a surgery that is performed on single-ventricle heart patients, and, due to the wide range of anatomies and variations among patients, lends itself nicely to study by advanced numerical methods. We focus on a patient-specific Fontan configuration, and perform a fully coupled fluid-structure interaction (FSI) analysis of hemodynamics and vessel wall motion. To enable physiologically realistic simulations, a simple approach to constructing a variable-thickness blood vessel wall description is proposed. Rest and exercise conditions are simulated and rigid versus flexible vessel wall simulation results are compared. We conclude that flexible wall modeling plays an important role in predicting quantities of hemodynamic interest in the Fontan connection. To the best of our knowledge, this paper presents the first three-dimensional patientspecific fully coupled FSI analysis of a total cavopulmonary connection that also includes large portions of the pulmonary circulation.

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“…Alternatively, this issue may also be circumvented by using thee-dimensional solid modeling as in [3,19,42,48,51].…”

Section: Stage 3-finalizationmentioning

confidence: 99%

Computational fluid–structure interaction: methods and application to a total cavopulmonary connection

et al. 2009

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“…The topics investigated range from heart 2 J. Lantz et al valves [Cheng et al, 2003[Cheng et al, , 2004Dahl et al, 2010;Simon et al, 2010], to estimation of wall stresses and strains in either healthy subjects [Gao et al, 2006b;McGregor et al, 2007] or in pathological cases such as aneurysms [Isaksen et al, 2008;Li and Kleinstreuer, 2005a,b;Scotti et al, 2008;Kelly and O'Rourke, 2010;Xenos et al, 2010;Tan et al, 2009]. There have also been attempts to estimate the WSS on the arterial surface [Jin et al, 2003;Gao et al, 2006a;Shahcheraghi et al, 2002].…”

Section: Introductionmentioning

confidence: 99%

Wall Shear Stress in a Subject Specific Human Aorta — Influence of Fluid-Structure Interaction

Lantz

Renner

Karlsson

2011

Int. J. Appl. Mechanics

132

106

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shear stress (WSS) has been correlated to the development of atherosclerosis in arteries. As WSS depends on the blood flow dynamics, it is sensitive to pulsatile effects and local changes in geometry. The aim of this study is therefore to investigate if the effect of wall motion changes the WSS or if a rigid wall assumption is sufficient. Magnetic resonance imaging (MRI) was used to acquire subject specific geometry and flow rates in a human aorta, which were used as inputs in numerical models. Both rigid wall models and fluid-structure interaction (FSI) models were considered, and used to calculate the WSS on the aortic wall. A physiological range of different wall stiffnesses in the FSI simulations was used in order to investigate its effect on the flow dynamics. MRI measurements of velocity in the descending aorta were used as validation of the numerical models, and good agreement was achieved. It was found that the influence of wall motion was low on time-averaged WSS and oscillating shear index, but when regarding instantaneous WSS values the effect from the wall motion was clearly visible. Therefore, if instantaneous WSS is to be investigated, a FSI simulation should be considered.

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“…Anevrizmanın damar üzerinde bulunduğu bölge, boy-en oranı rüptür riski üzerinde etkiye sahiptir, ancak bu parametreler belirli bir risk analizi için yeterli değildir [9]. Araştırmalar göstermektedir ki, anevrizmanın oluşumu ve sonrasında rüptürüne kadar geçen süreç doğrudan anevrizma bölgesindeki hemodinamik faktörler ile ilişkilidir [10].…”

Section: Introductionunclassified

“…Bunların ışığında hemodinamik faktörler arasında, anevrizmasının büyümesine ve rüptüre sebep olan damar yüzeyinde oluşan duvar kayma gerilimi (WSS, wall shear stress) gösterilmektedir. Zira WSS değeri damar duvarında belli bir seviyeye ulaştığında rüptür oluşmaktadır [9,11]. Ayrıca WSS kanın hızına, debisine, basınç farklılıklarına ve viskozitesine doğrudan bağlı olduğu için, anevrizmada meydana gelen değişikliklerle ilişkilendirilebilir [12,13].…”

Section: Introductionunclassified

Beyin Anevrizmalarında Hemodinamik Kuvvetlerin Kanın Newtoniyen ve Newtoniyen Olmayan Durumlarında Hesaplamalı Akışkanlar Dinamiği ile İncelenmesi

Olcay¹,

Ural²,

Süslü³

et al. 2017

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Anahtar KelimelerBeyin anevrizması, Hesaplamalı akışkanlar dinamiği, Newtoniyen olmayan kan akış modellemesi Özet: Günümüz teknolojisi sayesinde farklı teknikler ile elde edilen damar yapılarını, bilgisayar ortamına aktarmak mümkün hale gelmiştir. Bilgisayar ortamına aktarılan bu görüntüler sayesinde damarlara hesaplamalı akışkanlar dinamiği (HAD) yöntemi uygulanabilmekte ve kişilere özel çeşitli tedaviler geliştirilebilmektedir. Bu çalışmada da benzer şekilde gerçek bir hastadan alınan damar modelleri kılcal yapılardan arındırılarak kullanılmıştır. Hazırlanan HAD modeli için kanın viskozitesi; Newtoniyen ve Newtoniyen olmayan Power Law modeli ve yine Newtoniyen olmayan Carreu modeli olmak üzere üç farklı şekilde tanımlanmıştır. Böylece HAD modelleriyle anevrizma bölgesindeki hemodinamik akışı belirleyen parametreler olan hız değerleri, basınç düşüşü ve kayma gerilmeleri hesaplanmıştır. Elde edilen veriler görsel olarak sunularak gereken değerlendirmeler yapılmış, kanı Newtoniyen ya da Newtoniyen olmayan şekilde modellemenin sonuçlara etkisi belirlenmiştir. Kanın Newtoniyen olarak modellenmesi durumunda anevrizma içinde daha yüksek hız değerleri elde edilirken hem basınç hem de duvar kayma gerilimleri değişimlerinde ise Newtoniyen modellemede daha düşük değerler elde edilmiştir. Yapılan çalışmada, HAD yönteminin hastaların tedavisinde hastaya özgü bir yöntem olarak kullanılabileceği görülmüştür. Abstract: In today's technology blood vessel structures can be obtained with a variety of methods and it is possible now to import these structures into the solid modelling. With the help of imported geometries, modelling of computational fluid dynamics (CFD) can be applied and patient specific solutions can be developed. In this study, in similar manner blood vessel images were obtained from a patient and the geometry was cleaned so that only brain aneurysm region was ready to use. Viscosity of blood was defined in CFD model with three different ways: Newtonian type, Non-Newtonian Power Law and Non-Newtonian Carreu. Velocity vectors, variation in pressure drop and wall shear stresses identifying the hemodynamic structure of aneurysm region were calculated with the help of CFD models. The results were presented with pictures and necessary evaluations about the results were discussed. Besides, the effect of viscosity definition in CFD modelling on obtained results was also identified and reported. When blood was modelled with a Newtonian type fluid, the velocity vector values were appeared to be higher in the aneurysm region compared to the Non-Newtonian modelling of the blood. On the other hand, pressure variation and wall shear stress in the aneurysm region were obtained to be larger for the Non-Newtonian blood modelling compared to the Newtonian blood modelling. These study showed that CFD tool can be utilized in the treatment of patients. Investigation of Brain

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Determination of Wall Tension in Cerebral Artery Aneurysms by Numerical Simulation

Cited by 159 publications

References 42 publications

Computational fluid–structure interaction: methods and application to a total cavopulmonary connection

Computational fluid–structure interaction: methods and application to a total cavopulmonary connection

Wall Shear Stress in a Subject Specific Human Aorta — Influence of Fluid-Structure Interaction

Beyin Anevrizmalarında Hemodinamik Kuvvetlerin Kanın Newtoniyen ve Newtoniyen Olmayan Durumlarında Hesaplamalı Akışkanlar Dinamiği ile İncelenmesi

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