THE FUNCTION OF THE CIRCULUS ARTERIOSUS OF WILLIS<sup>1</sup>

Rogers, Lambert

doi:10.1093/brain/70.2.171

Cited by 44 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Мы надеем-ся, что более глубокое понимание взаимосвязи между топологией артерий, показателями кровотока и тра-екторией движения эмболов поможет в разработке индивидуального компьютерного моделирования для мониторинга пациентов с высоким риском развития инсульта [7]. Хотя ранее уже были разработаны модели Виллизиева круга для исследования кровотока [8][9][10][11], мы впервые использовали 3D модель артерий головно-го мозга in vitro для изучения движения эмболов.…”

Section: (18)'2010unclassified

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Chung

Hague

Chanrion

et al. 2010

Stroke

View full text Add to dashboard Cite

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...

show abstract

Section: (18)'2010unclassified

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Chung

Hague

Chanrion

et al. 2010

Stroke

View full text Add to dashboard Cite

show abstract

“…O circuito arterial da base do encéfalo, interpretado por alguns autores (KRAMER, 1912;SHELLSHEAR, 1927;ROGERS, 1947) como uma anastomose de irrigação, foi analisado em alguns vertebrados, como o cavalo (SANTOS, 1987), fetos de bovinos azebuados (MELO, 1996); búfalos (DING et al, 2007); cães (ALCÂNTARA & PRADA, 1992) raposas (DEPEDRINI & CAMPOS, 2003); em ratos (ANDRADE, 1983) capivaras (RECKZIEGEL et al, 2004), marsupiais (LINDEMANN et al, 2000) e em perus (CARVALHO & CAMPOS, 2011).…”

Section: Introductionunclassified

Anatomia do circuito arterial do encéfalo em Tamanduá-mirim

2013

View full text Add to dashboard Cite

Recebido para publicação 12.09. Palavras-chave: anatomia, artérias da base do encéfalo,Tamandua tetradactyla. ABSTRACT The arterial circuit of the brain is of great importance because it is responsible for vascularization of the brain and this is the main organ of the central nervous system and responsible for receiving and processing information. The species was chosen because it is a mammal belonging to the

show abstract

“…In these models, the ratio of the vascular resistance of the six major cerebral arteries is an important parameter, 6 -11 yet the literature provides no accurate data on the in vivo peripheral resistance of these vessels. Thus, the ratio of resistance is estimated, based on the assumption that the peripheral resistance of the six major cerebral arteries is inversely proportional to the brain mass irrigated by each vessel.…”

mentioning

confidence: 99%

Review of the variability of the territories of the major cerebral arteries.

Zwan

Hillen

1991

Stroke

104

View full text Add to dashboard Cite

The results of recent model studies indicate that the variability in territorial distribution of the major cerebral arteries may be much greater than has been previously recognized. We review the literature on the cortical and intracerebral territories of the anterior, middle, and posterior cerebral arteries. Although most authors claim that these territories are relatively consistent, the results of their studies show many and considerable discrepancies. The variability described by Beevor has been neither excluded nor completely confirmed, yet somehow the concept of a relatively unchanging pattern of the peripheral cerebral vascularization has gradually settled into the literature. We discuss the considerable variability of the cerebral territories, as well as the discrepancies in investigation techniques, injection materials, and specimen conditions that could be factors producing these dissimilar results. Our study shows that there are no arguments in the literature to negate the variability of the cerebral territories. (Stroke 1991;22:1078-1084) S ince the introduction of computed tomography into neuroradiologic practice, the differential diagnosis of hemodynamic watershed infarction and thromboembolic ischemia is largely based on the location of the visualized infarct. Although a wedgeshaped infarction on empirical grounds suggests a hemodynamic pathogenesis, the primary cause is indicated as thromboembolic when the infarct is not located in one of the well-known border zones. Many templates and diagrams of the territories of the six major cerebral arteries-the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries on both sides-provide a guide in making this diagnosis 1 " 5 and are based on the concept of a symmetrical and negligibly variable territorial distribution.This concept is also used in experimental models designed to investigate the hemodynamic behavior of the circle of Willis. In these models, the ratio of the vascular resistance of the six major cerebral arteries is an important parameter, 6 -11 yet the literature provides no accurate data on the in vivo peripheral resistance of these vessels. Thus, the ratio of resistance is estimated, based on the assumption that the peripheral resistance of the six major cerebral arteries is inversely proportional to the brain mass irrigated by each vessel.10 Because the variability of the territorial distribution is described in the literature as Received October 17, 1990; accepted April 23, 1991. relatively small in contrast to the large variability of the circle of Willis, the ratio of the peripheral resistance of the six major cerebral arteries is considered to be invariant in all models. However, the mathematical model of Hillen et al 11 and statistical analysis of the diameters of various segments of the circle of Willis 12 -13 indicate that within the circle a significant relationship exists between blood flow and vessel size. Considering the large variability of the proximal diameters of the major cerebral arteries (coefficients of v...

show abstract

THE FUNCTION OF THE CIRCULUS ARTERIOSUS OF WILLIS¹

Cited by 44 publications

References 0 publications

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Anatomia do circuito arterial do encéfalo em Tamanduá-mirim

Review of the variability of the territories of the major cerebral arteries.

Contact Info

Product

Resources

About

THE FUNCTION OF THE CIRCULUS ARTERIOSUS OF WILLIS1

Cited by 44 publications

References 0 publications

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Embolus Trajectory Through a Physical Replica of the Major Cerebral Arteries

Anatomia do circuito arterial do encéfalo em Tamanduá-mirim

Review of the variability of the territories of the major cerebral arteries.

Contact Info

Product

Resources

About

THE FUNCTION OF THE CIRCULUS ARTERIOSUS OF WILLIS¹