An In Vitro Assessment of the Cerebral Hemodynamics Through Three Patient Specific Circle of Willis Geometries

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Paul Fahy ◽  
Patrick Delassus ◽  
Peter McCarthy ◽  
Sheriff Sultan ◽  
Niamh Hynes ◽  
...  
Keyword(s):  
Spin Coating ◽  
Internal Carotid ◽  
Circle Of Willis ◽  
Patient Specific ◽  
Collateral Flow ◽  
Flow Paths ◽  
Flow Rates ◽  
Vertebral Arteries ◽  
Flow Feature ◽  
The Brain

The Circle of Willis (CoW) is a complex pentagonal network comprised of fourteen cerebral vessels located at the base of the brain. The collateral flow feature within the circle of Willis allows the ability to maintain cerebral perfusion of the brain. Unfortunately, this collateral flow feature can create undesirable flow impact locations due to anatomical variations within the CoW. The interaction between hemodynamic forces and the arterial wall are believed to be involved in the formation of cerebral aneurysms, especially at irregular geometries such as tortuous segments, bends, and bifurcations. The highest propensity of aneurysm formation is known to form at the anterior communicating artery (AcoA) and at the junctions of the internal carotid and posterior communicating arteries (PcoAs). Controversy still remains as to the existence of blood flow paths through the communicating arteries for a normal CoW. This paper experimentally describes the hemodynamic conditions through three thin walled patient specific models of a complete CoW based on medical images. These models were manufactured by a horizontal dip spin coating method and positioned within a custom made cerebral testing system that simulated symmetrical physiological afferent flow conditions through the internal carotid and vertebral arteries. The dip spin coating procedure produced excellent dimensional accuracy. There was an average of less than 4% variation in diameters and wall thicknesses throughout all manufactured CoW models. Our cerebral test facility demonstrated excellent cycle to cycle repeatability, with variations of less than 2% and 1% for the time and cycle averaged flow rates, respectively. The peak systolic flow rates had less than a 4% variation. Our flow visualizations showed four independent flow sources originating from all four inlet arteries impacting at and crossing the AcoA with bidirectional cross flows. The flow paths entering the left and right vertebral arteries dissipated throughout the CoW vasculature from the posterior to anterior sides, exiting through all efferent vessels. Two of the models had five flow impact locations, while the third model had an additional two impact locations within the posterior circulation caused by an additional bidirectional cross flows along the PcoAs during the accelerating and part of the decelerating phases. For a complete CoW, bidirectional cross flows exist within the AcoA and geometrical variations within the CoW geometry can either promote uni- or bidirectional cross flows along the PcoAs.

MODELING REDISTRIBUTION CEREBRAL CIRCULATION

2021 ◽  
Vol 1 (4) ◽  
pp. 13-18
Author(s):  
Vladislav Nikolaevich Nikitin ◽  
◽  
Ekaterina Valerevna Kozhemyakina ◽  
Keyword(s):  
Blood Flow ◽  
Internal Carotid ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Entire Body ◽  
Compensatory Mechanisms ◽  
Vertebral Arteries ◽  
The Central Nervous System ◽  
Flow Through ◽  
The Brain

The brain is one of the most important organs responsible for the health and functioning of the entire body. The blood supply to the brain is carried out through 2 internal carotid and 2 vertebral arteries in norm. The brain, like other body systems, has protective (compensatory) mechanisms aimed at maintaining the necessary blood flow, one of which is the circle of Willis. The article proposes a mechanism for how blood flow is redistributed through the arteries feeding the brain, which is based on the assumption that the central nervous system controls in such a way that it minimizes flows through the connective arteries of the circle of Willis, the flows along which are normal (with symmetry of the left and right sides) practically equal to zero. Сase of the structure of the circle of Willis is considered in norm. The indicated redistribution mechanism is still only the first step towards an attempt to predict cases of changes in blood flow through the cerebral arteries, especially in stroke. In further works, it is planned to consider the inverse problem, i.e. determine the flows through the internal carotid and vertebral arteries, provided that the flows through the cerebral arteries extending from the circle of Willis have normal flow values.

An Experimental Study of the Effects Anatomical Variations Have on Collateral Flows Within the Circle of Willis

2011 ◽  
Author(s):  
Paul Fahy ◽  
Patrick Delassus ◽  
Padraig O’Flynn ◽  
Liam Morris
Keyword(s):  
Experimental Study ◽  
Blood Flow ◽  
Cerebral Arteries ◽  
Anatomical Variations ◽  
Flow Patterns ◽  
Circle Of Willis ◽  
Collateral Flow ◽  
Arterial Network ◽  
Flow Feature ◽  
The Brain

The circle of Willis (CoW) is a complex arterial network comprising of major cerebral arteries that converge to form a pentagonal arrangement as shown in Figure 1(A). This arterial network supplies oxygen-enriched blood to the brain. An incomplete CoW can exist in up to 50% of cases [1]. These missing vessels can be accommodated by the collateral flow feature within the CoW configuration. In certain circumstances, anatomical variations within the CoW can result in undesirable flow patterns [2–3]. It is unclear from the literature what effects these variations can have on blood flow collision paths within a complete CoW.

Computational Fluid Dynamics Simulation of the Blood Flow in the Circle of Willis

2002 ◽  
Author(s):  
M. Harazawa ◽  
T. Yamaguchi
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Internal Carotid ◽  
Complex Geometry ◽  
Cerebral Aneurysms ◽  
Cerebrovascular Diseases ◽  
Circle Of Willis ◽  
Dynamics Simulation ◽  
The Brain ◽  
Internal Carotid Arteries

The blood supply for the brain is born by four arteries, that is, two internal carotid arteries and two vertebral arteries. They are mutually connected at the cerebral base, and form a closed arterial circle, called the circle of Willis, so that the safety of the brain blood supply is increased. However their anastomoses show a very wide variety of atypism. If some of anastomses are very thin, or even do not exist, the safety of the blood supply is not secured. This is particularly important when some diseases such as cerebral thrombosis occurs and the blood flow supply stops unilaterally. Redistribution of the blood supply in such cases is thought to be strongly affected by geometrical configuration of the anastomoses. It is also known that cerebral aneurysms, which may induce serious cerebrovascular diseases, preferentially occur at the circle of Willis. Complex blood flow pattern has been suspected of having an influence on this preference. This is again dependent on complex geometry of the circle.

scholarly journals Study of the blood supply of the brain in sheep

1999 ◽  
Vol 23 (1) ◽  
pp. 59-66
Author(s):  
Khalid Kamil Kadhum
Keyword(s):  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Blood Supply ◽  
Basilar Artery ◽  
Internal Carotid ◽  
Ventral Surface ◽  
Circle Of Willis ◽  
Maxillary Artery ◽  
Cerebellar Artery ◽  
The Brain

The brain of the sheep receives its blood supply through the carotid rete and the basilar artery. The carotid rete formed of contribution of internal carotid artery and branches from maxillary artery. The internal carotid artery courses on the ventral surface of the cerebal crus to give the rostral cerebal artery and the caudal communicating artery . Thus , arteries excepted the middle cerebal artery forming with the same arteries of the opposite side , the cerebal arterial circle or circle of Willis. The internal caroted artery also gives off hypophysialartery to the  1999 ind, (1) swell, ügymielly wel dati', il pellilendiambell ileti  hypophysis. The caudal communicating artery give off the caudal cerebal artery and the rostral cerebellar artery and unite with the corresponding artery of the opposite side to form the basilar artery rostral to the pone . The basilar artery gives off the pontine artery , caudal cerebellar artery and the medullary branch. 

Incompetent Circle of Willis and Vertebrobasilar Insufficiency

2003 ◽  
Vol 112 (8) ◽  
pp. 657-664 ◽  
Author(s):  
Louis W. Welsh ◽  
Bernard Lewin ◽  
John J. Welsh ◽  
Joseph E. Dragonette
Keyword(s):  
Internal Carotid ◽  
Circle Of Willis ◽  
Structural Defects ◽  
Vertebrobasilar Insufficiency ◽  
Resonance Imaging ◽  
Vertebral Arteries ◽  
Significant Difference ◽  
Asymptomatic Individuals ◽  
The Relationship ◽  
Carotid And Vertebral Arteries

An analysis of the vascular basis of vertebrobasilar insufficiency was derived from the examination of 135 subjects by magnetic resonance imaging and angiography. The data from this cohort were compared to those from normal, ie, asymptomatic, individuals. We concluded that there is a significant difference in the potential for intracerebral collateralization and regional perfusion due to structural defects such as stenosis or developmental absence of the posterior communicating arteries in this symptomatic group. In addition, an occlusion of one or more of the source vessels, the internal carotid and vertebral arteries, in conjunction with an incomplete circle of Willis increased the potential for hindbrain perfusion deficits. Clinical cases illustrate the relationship between failure of internal shunting and the myriad symptoms of hindbrain dysfunction.

scholarly journals Vascularization of the Alouatta belzebul brain base

2020 ◽  
Vol 40 (4) ◽  
pp. 315-323
Author(s):  
Dayane Kelly Sabec-Pereira ◽  
Fabiano C. Lima ◽  
Fabiano R. Melo ◽  
Fabiana Cristina S.A. Melo ◽  
Kleber Fernando Pereira ◽  
...  
Keyword(s):  
Cerebral Artery ◽  
Internal Carotid ◽  
Cerebral Arteries ◽  
Terminal Branch ◽  
Vertebral Arteries ◽  
Caudal Portion ◽  
Cerebellar Artery ◽  
The Right ◽  
The Brain ◽  
Left Middle

ABSTRACT: We studied the arterial circle in the brain of five specimens of the Alouatta belzebul primate. The material had the arterial system perfused (water at 40°C), injected with stained latex (Neoprene 650), fixed in aqueous formaldehyde solution (10%) and dissected for vessel verification. The arterial circle of this primate is composed of two vascular systems: the vertebra-basilar and the carotid ones, which anastomose to close the arterial circuit. In the caudal portion of the arterial circle, there are the vertebral arteries and their branches: the rostral spinal artery and the caudal inferior cerebellar artery. The anastomosis of the vertebral arteries gives rise to the basilar artery. It presented an anatomical variation at the beginning of its path, forming a double basilar artery, called arterial island. In its course, it emitted branches giving rise to the rostral inferior cerebellar artery, the pontine arteries, the rostral cerebellar arteries, the satellite rostral cerebellar arteries and its terminal branch, the caudal cerebral artery, which presented itself in two segments: the pre-communicating one and post-communicating, joining the internal carotid artery and originating the caudal communicating artery. This group of arteries and anastomoses enclose the caudal portion of the arterial circle. From the right and left internal carotid arteries begins the rostral portion of the arterial circle, which consists of the right and left rostral cerebral arteries and the right and left middle cerebral arteries. The rostral cerebral arteries anastomose into a single trunk, giving rise to the interhemispheric artery, and in A. belzebul and Sapajus libidinosus, the rostral communicating artery is absent. The interhemispheric artery goes to the midbrain region and the corpus callosum knee divides into pericalous artery and callosarginal artery, which will supply the pre and post-central regions of the cerebral hemispheres of this species, as well as other non-human and human primates. It is noted that in the first part of the left rostral cerebral artery, there is a direct inosculation between the recurrent branch of the rostral cerebral artery and left middle cerebral artery to supply the entorhinal region. This fact also occurs in Pongo spp. The middle cerebral artery travels along the lateral sulcus where it emits several superficial branches to irrigate the superior and inferior lateral cortical regions of the frontal, parietal and temporal lobes. It is not part of the arterial circle but is the terminal branch of the internal carotid artery. A. belzebul can be considered to depend on two sources of supply to the brain: the vertebra-basilar and carotid systems, contributing to the intervention of veterinarians during clinical and surgical procedures in other primates, as well as the preservation of wild animals.

The Pathological Significance of False Membranes under the Dura Mater in Insanity

1877 ◽  
Vol 23 (103) ◽  
pp. 349-355 ◽  
Author(s):  
T. S. Clouston
Keyword(s):  
Internal Carotid ◽  
Nerve Tissue ◽  
Pia Mater ◽  
Vertebral Arteries ◽  
The Tempest ◽  
Morbid Action ◽  
Supply Pipe ◽  
Previous Condition ◽  
The Brain ◽  
Carotid And Vertebral Arteries

Many of the well-known pathological appearances found in the brain in insanity will, I doubt not, be found to have much more significance than they are thought to have at present, when the general physiology and pathology of the organ is better understood. It cannot be that such serious and enduring marks of morbid action in the parts supplied by the internal carotid and vertebral arteries as thickened and condensed cranial bones, adherent and thickened membranes, congested and toughened vessels, pia mater adherent to convolutions, and atrophied convolutions; all appearances, one or other of which are found in the majority of the insane, and treated almost as matters of course in the asylum dead house—could have arisen without intense disturbance in the working of the delicate neurine that those structures envelop and subserve. We as yet don't fully know what those things mean, as regards the previous condition of the brain. We talk of over-action, congestions, and brain excitement, but such terms are but vague expressions when we closely analyse what they mean. I think we are entitled to conclude that if such things are the accompaniments and effects of the storm on the bulwarks and sails of the vessel, the state of matters in the ship itself, while the tempest was at its height, must have been disturbed enough, could we only have had the means to see it. I have scarcely any patience in arguing with those who will say that there are no pathological changes left in the brains of those who have died insane, when such things are commonly met with, and can be seen by any tyro. It is our capacity to draw conclusions from such things that is at fault; and our means of observation as to the real condition of the minute brain structure. Conceive what dynamical disturbances must have occurred in the working during life of a most highly organised, yet infinitely delicate, jelly-like convolution supplied by a twig of a meningeal artery, during the long period when that twig was becoming thickened in its coats, overstrained at one time by intense congestion, its perivascular space alternately blocked up by débris, and by the overloaded vessel, its blood current now rushing at twice its usual speed, and then in a state almost of stasis. It is vain for anyone to say that such conditions can lead to an organic alteration in the coats of the vessel, and yet that the neurine may be left normal. The fact that all those vascular disturbances and changes were, probably, the result of the morbid vital action in the nerve tissue, and not its cause, were the result of the mere straining of the supply pipe from the irregular demands of the part supplied, should make us realize very vividly the intensity of the pathological disturbance that goes on in the convolutions of a brain that is acutely maniacal.

scholarly journals Analyzing Circle of Willis blood flow in ischemic stroke patients through 3D Stroke Arterial Flow Estimation

2017 ◽  
Vol 23 (4) ◽  
pp. 427-432 ◽  
Author(s):  
Aichi Chien ◽  
Fernando Viñuela
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Flow Patterns ◽  
Circle Of Willis ◽  
Arterial Flow ◽  
Patient Specific ◽  
Collateral Flow ◽  
Flow Data ◽  
Time Resolved ◽  
Flow Estimation

Background The objective of ischemic stroke (IS) treatment is to achieve revascularization in cerebral arteries to restore blood flow. However, there is no available method to extract arterial flow data from clinical CTA images. We developed 3D Stroke Arterial Flow Estimation (SAFE), which provides blood flow data throughout the Circle of Willis based on 3D CTA and allows comparison of arterial flow distribution in the brain. Methods We implemented a newly developed 3D vascular reconstruction algorithm for clinical stroke CTA images. Based on the patient-specific vascular structure, SAFE calculates time-resolved blood flow information for the entire Circle of Willis and allows quantitative flow study of IS cases. Clinical IS cases are presented to demonstrate the feasibility. Four patients with CTA images and CT perfusion data were studied. To validate the SAFE analysis, correlation analysis comparing blood flow at the MCA, ICA, and BA was performed. Results Different blood flow patterns were found in individual IS patients. Altered flow patterns and high collateral flow rates were found near occlusions in all cases. Quantitative comparison of blood flow data showed that SAFE obtained flow data and CTP were significantly correlated and provide complementary information about cerebral blood flow for individual patients. Conclusions We present SAFE analysis for collecting detailed time-resolved cerebral arterial flow data in the entire Circle of Willis for IS. Further study with more cases may be important to test the clinical utilization of SAFE and helpful to the study of the underlying hemodynamics of stroke.

Spontaneous germinal matrix and intraventricular hemorrhage in prematurely born rabbits

1982 ◽  
Vol 56 (3) ◽  
pp. 404-410 ◽  
Author(s):  
Antonio V. Lorenzo ◽  
Keasley Welch ◽  
Scott Conner
Keyword(s):  
Intraventricular Hemorrhage ◽  
Internal Carotid ◽  
Germinal Matrix ◽  
Content Type ◽  
Vertebral Arteries ◽  
Rete Mirabile ◽  
Premature Babies ◽  
Near Term ◽  
The Brain ◽  
Carotid And Vertebral Arteries

✓ Spontaneous hemorrhage into the ventricles in premature babies is a major problem, and neither its cause nor its pathogenesis is understood. A model is presented for the study of germinal matrix and intraventricular hemorrhage in the preterm rabbit. This animal is particularly suitable because like the human, 1) the maximal growth of the brain occurs perinatally; 2) there is an abundant germinal matrix near term, and by birth this is substantially reduced; 3) there is no rete mirabile; 4) the blood flow to the brain is via internal carotid and vertebral arteries; 5) the maturation of the lungs is completed just before term; and 6) the rabbit pup can maintain a separate existence from the dam when delivered prematurely. Eight of 64 such animals were found to have developed spontaneous germinal matrix hemorrhage with or without rupture into the ventricles. Several physiological and chemical features characteristic of the premature rabbit are presented. The hemorrhage in the lagomorph might be a paradigm of that in infants, and its study may aid in the understanding of the pathogenesis of the process.

The Pathological Significance of False Membranes under the Dura Mater in Insanity

1877 ◽  
Vol 23 (103) ◽  
pp. 349-355
Author(s):  
T. S. Clouston
Keyword(s):  
Internal Carotid ◽  
Nerve Tissue ◽  
Pia Mater ◽  
Vertebral Arteries ◽  
The Tempest ◽  
Morbid Action ◽  
Supply Pipe ◽  
Previous Condition ◽  
The Brain ◽  
Carotid And Vertebral Arteries

Many of the well-known pathological appearances found in the brain in insanity will, I doubt not, be found to have much more significance than they are thought to have at present, when the general physiology and pathology of the organ is better understood. It cannot be that such serious and enduring marks of morbid action in the parts supplied by the internal carotid and vertebral arteries as thickened and condensed cranial bones, adherent and thickened membranes, congested and toughened vessels, pia mater adherent to convolutions, and atrophied convolutions; all appearances, one or other of which are found in the majority of the insane, and treated almost as matters of course in the asylum dead house—could have arisen without intense disturbance in the working of the delicate neurine that those structures envelop and subserve. We as yet don't fully know what those things mean, as regards the previous condition of the brain. We talk of over-action, congestions, and brain excitement, but such terms are but vague expressions when we closely analyse what they mean. I think we are entitled to conclude that if such things are the accompaniments and effects of the storm on the bulwarks and sails of the vessel, the state of matters in the ship itself, while the tempest was at its height, must have been disturbed enough, could we only have had the means to see it. I have scarcely any patience in arguing with those who will say that there are no pathological changes left in the brains of those who have died insane, when such things are commonly met with, and can be seen by any tyro. It is our capacity to draw conclusions from such things that is at fault; and our means of observation as to the real condition of the minute brain structure. Conceive what dynamical disturbances must have occurred in the working during life of a most highly organised, yet infinitely delicate, jelly-like convolution supplied by a twig of a meningeal artery, during the long period when that twig was becoming thickened in its coats, overstrained at one time by intense congestion, its perivascular space alternately blocked up by débris, and by the overloaded vessel, its blood current now rushing at twice its usual speed, and then in a state almost of stasis. It is vain for anyone to say that such conditions can lead to an organic alteration in the coats of the vessel, and yet that the neurine may be left normal. The fact that all those vascular disturbances and changes were, probably, the result of the morbid vital action in the nerve tissue, and not its cause, were the result of the mere straining of the supply pipe from the irregular demands of the part supplied, should make us realize very vividly the intensity of the pathological disturbance that goes on in the convolutions of a brain that is acutely maniacal.

Sign in / Sign up

Export Citation Format

Share Document