Personalizing flow‐diverter intervention for cerebral aneurysms: from computational hemodynamics to biochemical modeling

Peach, Thomas; Ngoepe, Malebogo; Spranger, K.; Zajarias-Fainsod, Daniel; Ventikos, Yiannis

doi:10.1002/cnm.2663

Cited by 38 publications

(26 citation statements)

References 45 publications

(67 reference statements)

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“…This acceleration is possible as regions of thrombus growth are generally associated with relatively low velocities, so that growth only causes gradual changes in flow. Similar approaches have been adopted by others [13,14,36]. By neglecting convection and considering the time-averaged effects of haemodynamic parameters such as shear rates and residence time, regions of potential thrombosis can be identified, whereas interactions between blood flow and thrombus growth can also be accounted for.…”

Section: Discussionmentioning

confidence: 98%

Predicting false lumen thrombosis in patient-specific models of aortic dissection

Menichini

Cheng

Gibbs

et al. 2016

J. R. Soc. Interface.

116

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Aortic dissection causes splitting of the aortic wall layers, allowing blood to enter a ‘false lumen’ (FL). For type B dissection, a significant predictor of patient outcomes is patency or thrombosis of the FL. Yet, no methods are currently available to assess the chances of FL thrombosis. In this study, we present a new computational model that is capable of predicting thrombus formation, growth and its effects on blood flow under physiological conditions. Predictions of thrombus formation and growth are based on fluid shear rate, residence time and platelet distribution, which are evaluated through convection–diffusion–reaction transport equations. The model is applied to a patient-specific type B dissection for which multiple follow-up scans are available. The predicted thrombus formation and growth patterns are in good qualitative agreement with clinical data, demonstrating the potential applicability of the model in predicting FL thrombosis for individual patients. Our results show that the extent and location of thrombosis are strongly influenced by aortic dissection geometry that may change over time. The high computational efficiency of our model makes it feasible for clinical applications. By predicting which aortic dissection patient is more likely to develop FL thrombosis, the model has great potential to be used as part of a clinical decision-making tool to assess the need for early endovascular intervention for individual dissection patients.

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Section: Discussionmentioning

confidence: 98%

Predicting false lumen thrombosis in patient-specific models of aortic dissection

Menichini

Cheng

Gibbs

et al. 2016

J. R. Soc. Interface.

116

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show abstract

“…Device deployment was completed with an in-house fast-deployment algorithm based on a spring analogy and implemented in Matlab (Mathworks, Natick, MA, USA) and Blender, the details of which have been previously reported by the authors (25,30) and are not given here for the sake of brevity. Briefly, the device is first converted to a centreline representation, compressed radially, and aligned with the vessel to mimic the device sheathed by a catheter.…”

Section: Device Deploymentmentioning

confidence: 99%

“…(2,5,23,24) However, a number of bio-chemical models correlate an overall reduction in WSS with platelet deposition and thrombosis growth. (25,26) But, such heuristics should be viewed cautiously with studies in the literature also suggesting that both spatial and temporal variations 6 in WSS distribution, including local jetting and harmonic frequencies, may also play a significant role in thrombus initiation and growth. (27)(28)(29) In this study, three Basilar artery bifurcation aneurysms are examined with CFD models, and the effects of different FD configurations on aneurysm inflow reduction and changes in mean and peak WSS are evaluated.…”

Section: Introductionmentioning

confidence: 99%

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Peach

Spranger

Ventikos

2016

Proc Inst Mech Eng H

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Bifurcation aneurysms account for a large fraction of cerebral aneurysms and often present morphologies that render traditional endovascular treatments, such as coiling, challenging and problematic. Flow-diverter stents offer a potentially elegant treatment option for such aneurysms, but clinical use of these devices remains controversial. Specifically, the deployment of a flow-diverter device in a bifurcation entails jailing one or more potentially vital vessels with a low-porosity mesh designed to restrict the flow. When multiple device placement configurations exist, the most appropriate clinical decision becomes increasingly opaque. In this study, three bifurcation aneurysm geometries were virtually treated by flow-diverter device. Each aneurysm was selected to offer two possible device deployment positions. Flow-diverters similar to commercially available designs were deployed with a fast-deployment algorithm before transient and steady state computational fluid dynamics simulations were performed. Reductions in aneurysm inflow, mean wall shear stress and maximum wall shear stress, all factors often linked with aneurysm treatment outcome, were compared for different device configurations in each aneurysm. In each of the three aneurysms modelled, a particular preferential device placement was shown to offer superior performance with the greatest reduction in the flow metrics considered. In all the three aneurysm geometries, substantial variations in inflow reduction (up to 25.3%), mean wall shear stress reduction (up to 14.6%) and maximum wall shear stress reduction (up to 12.1%) were seen, which were all attributed to device placement alone. Optimal device placement was found to be non-trivial and highly aneurysm specific; in only one-third of the simulated geometries, the best overall performance was achieved by deploying a device in the daughter vessel with the highest flow rate. Good correspondence was seen between transient results and steady state computations that offered a significant reduction in simulation run time. If accurate steady state computations are combined with the fast-deployment algorithm used, the modest run time and corresponding hardware make a virtual treatment pipeline in the clinical setting a meaningful possibility.

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“…The chaotic flow field in AAAs [3] leads to complex WSS distributions [4] and interesting near-wall flow structures [1]. Thrombosis in the left ventricle [49], aortic dissection [41], stented arteries [28], and flow diverter treated cerebral aneurysms [43] represent other applications of complex transport potentially affecting local thrombosis.…”

Section: Introductionmentioning

confidence: 99%

Wall shear stress exposure time: a Lagrangian measure of near-wall stagnation and concentration in cardiovascular flows

Arzani

Gambaruto

Chen

et al. 2016

Biomech Model Mechanobiol

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms suitable in regions of complex hemodynamics that are traditionally difficult to quantify, yet encountered in many disease scenarios. Keywords: advection-diffusion; blood flow; hemodynamics; near-wall transport; residence time; shear stress; p. 2 IntroductionBiomechanical interactions between blood flow and the vessel wall are central to the initiation and progression of most cardiovascular diseases. Indeed, the majority of computational and experimental investigations into blood flow seek to understand how local flow mechanics relates to disease progression in or on the vessel wall. Blood flow conditions in diseased vessels are usually spatially and temporally complex and are challenging to characterize [51,50], even without reference to the coupled biochemical or biophysical processes driving disease progression. Nonetheless, the role of blood flow mechanics in the "near-wall" region is of utmost importance since this is where such couplings are most profound. In the near-wall region, blood flow serves to impart mechanical stresses on the vessel wall, as well as regulate the local transport of reactive material between the tissue and fluid domains. It is this latter mechanism that motivates the work presented herein.A compelling scenario involving the interaction between blood flow and the vessel wall is atherosclerosis, which is a leading cause of death worldwide. Atherosclerosis occurs mainly in locations of disturbed blood flow patterns [9,47]. The local transport of several substances near and at the vessel wall are known to influence atherosclerosis progression [56]. For example, previous studies have looked into transport of low density lipoproteins (LDL) [17,20,30,14], high density lipoproteins (HDL) [40,24], oxygen [16,27], nitric oxide (NO) [45,35], monocytes [12,14], and adenine triphosphate ATP and adenine diphosphate ADP [13,15,8] as important mass transport processes involved in atherosclerosis.Intravascular thrombosis is another compelling pathology associated with most cardiovascular diseases where near-wall transport becomes important [7,25]. The trajectories of individual platelets and the accumulation and residence time of chemical solutes including ADP, thrombin, and various blood factors control clot formation. These solutes, and especially in activated form, are generated at the vessel wall or from bound platelets. Complex hemodynamics and flow stagnation are often associated with prothrombotic conditions. For example, intraluminal thrombus in abdominal aortic aneurysm (AAA) [57,54] complicates disease progression, and is thought to be strongly coupled to flow stagnation and recirculation. The chaotic flow field in AAAs [3] Near-wall transport can either be (i) explicitly modeled for a specific transport problem, or (ii) inferred from appropriate hemodynamics meas...

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Personalizing flow‐diverter intervention for cerebral aneurysms: from computational hemodynamics to biochemical modeling

Cited by 38 publications

References 45 publications

Predicting false lumen thrombosis in patient-specific models of aortic dissection

Predicting false lumen thrombosis in patient-specific models of aortic dissection

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Wall shear stress exposure time: a Lagrangian measure of near-wall stagnation and concentration in cardiovascular flows

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