Hemodynamic Evaluation of Embolic Trajectory in an Arterial Bifurcation

Background and Purpose-In contrast to middle cerebral artery territory strokes, anterior cerebral artery strokes (ACAS) occur rarely. The low frequency of ACAS, in relation to middle cerebral artery territory strokes, may be explained by differences in ACA and middle cerebral artery anatomy influencing their respective flow-directed embolism rates. We aimed to determine whether variability in ACA anatomy, and in particular A1 segment diameter, is associated with embolic ACAS. Methods-Consecutive patients admitted to Boston Medical Center with embolic ACAS were reviewed. Ipsilateral and contralateral A1 diameters, M1 diameters, and terminal internal carotid artery bifurcation angles were measured from computed tomographic angiography and MRI angiography images. We compared these measurements between cases of ACAS and consecutive cases of embolic middle cerebral artery territory strokes. Results-The study comprised 55 individuals (27 ACAS, 28 middle cerebral artery territory strokes) with mean age of 69 years. In multivariate regression analysis, larger ipsilateral A1 diameters (odds ratio per 1 mm increment: 8.5; 95% confidence interval, 1.4-53.3) and ipsilateral A1/M1 diameter ratio (odds ratio per 10% increment: 1.8; 95% confidence interval, 1.2-2.9) were associated with ACAS, whereas larger ipsilateral M1 diameters was protective for ACAS (odds ratio per 1 mm increment: 0.8; 95% confidence interval, 0.0-0.9). Conclusions-Larger ipsilateral A1 diameters and A1/M1 diameter ratio are associated with embolic ACAS. These findings suggest that A1 diameters and M1 diameters are important in determining the path of emboli that reach the terminal internal carotid artery. (Stroke. 2014;45:2798-2800.)

“…7,8 Fittingly, we did note sharper angulation of the ACA in comparison with that of the MCA in our study. However, these values did not differ between cases of ACAS and MCAS.…”

Section: Strokesupporting

confidence: 69%

Section: Strokementioning

confidence: 99%

Larger A1/M1 Diameter Ratio Predicts Embolic Anterior Cerebral Artery Territorial Stroke

Shoamanesh

Masoud

Furey

et al. 2014

“…20,21 In Y-shaped bifurcations studied by Bushi et al, larger emboli were also found to exhibit a preference for wider branches. 22 Hemodynamics in the circle of Willis have been studied in glass models by Roach et al 23 and are the focus of a number of theoretical studies. 24 -28 However, we could find no reports of computational modeling of embolus trajectory.…”

Section: Discussionmentioning

confidence: 99%

“…При изучении Y-образных бифуркаций D. Bushi и соавт. также обнаруживали крупные эмболы пре-имущественно в крупных ветвях [22]. M.R.…”

Section: ■ результатыunclassified

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Chung

Hague

Chanrion

et al. 2010

Background and Purpose-The observed distribution of cerebral infarcts varies markedly from expectations based on blood-flow volume or Doppler embolus detection. In this study, we used an in vitro model of the cerebral arteries to test whether embolus microspheres encountering the circle of Willis are carried proportionally to volume flow or express a preferred trajectory related to arterial morphology or embolus size. Methods-Our model consisted of a patient-specific silicone replica of the cerebral macrocirculation featuring physiologically realistic pulsatile flow of a blood-mimicking fluid at approximately 1000 mL/min and an input pressure of approximately 150/70 mm Hg. Particles of 200, 500, and 1000 m diameter with equivalent density to thrombus were introduced to the carotid arteries and counted on exiting the model outlets. Results-The middle cerebral arteries (MCAs) of the replica attracted a disproportionate number of emboli compared with the anterior cerebral arteries; 98%Ϯ3% of 1000 m and 93%Ϯ2% of 500 m emboli entered the MCA compared with 82%Ϯ5% of the flow. The observed distribution of large emboli was consistent with the ratio of MCA:anterior cerebral artery infarcts, approximately 95% of which occur in territories supplied by the MCA. With decreasing embolus size, the distribution of emboli approaches that of the flow (approximately 89% of 200 m emboli took the MCA). Key Words: cerebral hemodynamics Ⅲ embolic stroke Ⅲ experimental Ⅲ transcranial Doppler E pidemiological evidence, 1,2 autopsy studies, 3,4 and the trajectories of "balloon emboli" in patients undergoing cerebral angiography 5 suggest that emboli incident from the common carotid artery (CCA) are more than 20 times as likely to come to rest in territories supplied by the middle cerebral artery (MCA) than the anterior cerebral artery (ACA). However, in vivo transcranial Doppler ultrasound insonation of the MCA-ACA junction performed by Wijman et al found emboli to be only 2 to 3 times more likely to enter the MCA 6 suggesting that emboli are carried roughly proportionally to flow volume. Wijman et al concluded that "cerebral embolism is unlikely to be the only cause of ACA and MCA infarcts." In this study, we clarify the relationship among blood flow, arterial topology, and embolization by implementing a physiologically realistic 3-dimensional phantom of the major cerebral arteries to investigate embolus trajectory. We hope that a better understanding of the relationship among arterial topology, blood flow, and embolus trajectory will assist in the development of patient-specific computer simulations for monitoring patients at high risk of stroke. 7 Although previous models of the circle of Willis have been developed to investigate blood flow, 8 -11 ours is the first to use a 3-dimensional in vitro model of the cerebral arteries to study embolization. Conclusions-Embolus Materials and Methods Replica AnatomyA physical model of the cerebral arteries was purchased from a company specializing in vascular replicas (Elastrat, Geneva, Switz...

“…20 There is evidence that the rate of emboli flowing to the posterior circulation is lower even when normalized by the flow ratio. A recent study 23 has shown that the tendency of large particles is to preferentially enter into the wider bifurcation branch, in a higher proportion than the flow ratio, indicating it would be better to protect the larger arteries first.…”

Section: Protection Of the Posterior Circulationmentioning

confidence: 99%

A Novel Endovascular Device for Emboli Rerouting

Grad

Sievert²,

Nishri³

et al. 2008

Self Cite

Background and Purpose-The feasibility and safety of a novel endovascularly delivered tubular mesh designed to reroute emboli away from a critical artery as a means of ischemic stroke prevention was tested in vitro and in vivo. Methods-Emboli rerouting efficacy was assessed in vitro. Perfusion through the external femoral artery that was jailed by the device, cellular proliferation rate over the jailing mesh, and the resulting tissue coverage of the orifice were assessed in the swine iliofemoral bifurcation. Device-induced embolization was assessed in a swine kidney model. Results-In vitro experiments demonstrated that particles as small as 60% of the pore dimension can be rerouted by the device, although at low efficacy, and rerouting efficacy approached 100% as the particle size approached the pore dimension. Repeat assessment of flow preimplantation and at various follow-up times by Doppler ultrasound showed no significant changes in the perfusion ratio of the jailed branch to the parent artery or the jailed branch to the naive contralateral artery either as a result of device implantation or at the follow-up times. Tissue coverage over the jailed ostium was limited to approximately 12% after stabilization. Cellular proliferation rate gradually decreased to diminishing level approximately 22 weeks postimplantation. The devices implanted across the renal arteries did not demonstrate any device-induced embolization after 1 month. Conclusions-It is proposed that this device could be used to reroute emboli away from important intracranial vessels as a means of stroke prevention.