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

Author(s):  
M. Harazawa ◽  
T. Yamaguchi

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.

1999 ◽  
Vol 23 (1) ◽  
pp. 59-66
Author(s):  
Khalid Kamil Kadhum

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. 


2021 ◽  
Vol 1 (4) ◽  
pp. 13-18
Author(s):  
Vladislav Nikolaevich Nikitin ◽  
◽  
Ekaterina Valerevna Kozhemyakina ◽  

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.


NeuroImage ◽  
2004 ◽  
Vol 23 (4) ◽  
pp. 1422-1431 ◽  
Author(s):  
Jae Sung Lee ◽  
Dong Soo Lee ◽  
Yu Kyeong Kim ◽  
Jinsu Kim ◽  
Ho Young Lee ◽  
...  

1983 ◽  
Vol 244 (1) ◽  
pp. H142-H149 ◽  
Author(s):  
J. A. Orr ◽  
L. C. Wagerle ◽  
A. L. Kiorpes ◽  
H. W. Shirer ◽  
B. S. Friesen

This study determined whether blood flow through the internal carotid artery (ICA) could be used to sample total cerebral blood flow in the pony. To answer this question we considered both the anatomic arrangement of the ICA in cadavers and the relative distribution of ICA blood flow to cerebral and extracerebral tissue using radioactive microspheres. Acrylic corrosion casts of the ICA indicated that this vessel traveled directly to the base of the brain, contributing to the formation of the circle of Willis, and did not send any significant branches to other tissues. Two vessels (internal ethmoidal artery and internal ophthalamic artery) did arise anteriorly from the circle of Willis and were, therefore, indirectly supplied by the ICA. Injection of radioactive microspheres of 15 microns diameter indicated that blood flow to extracerebral structures supplied by the internal ethmoidal and internal ophthalamic arteries was less than 5% of total ICA blood flow. Increases in ICA blood flow as measured with an electromagnetic flowmeter during isocapnic hypoxia (arterial PO2 near 40 Torr) in the awake pony (n = 6) were compared with increases in total brain flow as measured with radioactive microspheres (n = 6). ICA blood flow increased 40% compared with a 38% increase in total brain blood flow as measured with microspheres. We conclude that the ICA supplies predominantly brain tissue (approximately 95%) and that changes in ICA blood flow are representative of changes in total brain blood flow in the awake pony.


2017 ◽  
Vol 3 (4) ◽  
pp. 229-236
Author(s):  
Hiroshi Ujiie ◽  
Chie Shinohara ◽  
Yoshinori Tamano ◽  
Kouichi Katou ◽  
Akira Teramoto

We reviewed basic considerations in fluid dynamics of cerebral aneurysms and applied these in surgery on the three most common types: internal carotid-posterior communicating artery, middle cerebral artery, and anterior communicating artery. It was found that aneurysmal initiation and growth do not occur at symmetric bifurcations. As blood flow always obeys the law of inertia, jet flow into the aneurysm will disperse along the wall; assuming the aneurysmal wall strength is even, the shape of the aneurysm becomes round or oval. When neurosurgeons encounter an aneurysm that is not round or oval, the wall may be fragile and requires great care during surgical manipulation.


Neurosurgery ◽  
2011 ◽  
Vol 69 (3) ◽  
pp. 677-688 ◽  
Author(s):  
Hiroaki Shimizu ◽  
Takashi Inoue ◽  
Miki Fujimura ◽  
Atsushi Saito ◽  
Teiji Tominaga

Abstract BACKGROUND: Cerebral blood flow (CBF) is important in the management of cerebrovascular diseases. Surgical manipulation may compromise the appropriate interpretation of postoperative CBF changes, but the effects are not well understood. Objective: To investigate the effect of surgical manipulation on postoperative CBF in a setting of prospective randomized comparison of 2 irrigation fluids during surgery. Methods: Twenty patients undergoing the clipping of unruptured cerebral aneurysms through the pterional approach were randomly assigned to use of Artcereb, an artificial cerebrospinal fluid, or physiological saline as irrigation fluid. Postoperative CBF and clinical conditions were evaluated 3 times in the first 7 to 10 postoperative days. Results: Postoperative CBF decreased by 10 to 15% on the first postoperative day in the ipsilateral inferior frontal gyrus, where surgical manipulation may be greatest. CBF reduction was less in regions remote from the surgical site and later in the follow-up periods. Selection of irrigation fluid did not influence postoperative CBF significantly, although postoperative clinical conditions may be better using Artcereb. Conclusion: Postoperative CBF changes due to surgical manipulation should be considered in patients whose hemodynamic conditions are important for appropriate management.


2021 ◽  
Author(s):  
Karine Felipe Martins ◽  
Flávia Pascoal Teles ◽  
Amanda Fernandes de Sousa Oliveira Balestra ◽  
Isadora Rosa Maia

Background: Until the 70s, cerebrovascular diseases (CVDs) were neglected to the lack of resources. However, due to the advancement of technology, several imaging tests have appeared, such as magnetic resonance and computed tomography, which facilitated the diagnosis and the understanding of the pathophysiology of each disease. Objectives: The objective of this work is to identify the main CVDs signs and symptoms. Methods: An integrative literature review was carried out based on selected articles from Google Scholar, PubMed and SciELO, using the terms headache, cerebrovascular disease, neurology. Results: CVDs are characterized by causing damage to brain vessels, due to changes in blood flow momentarily or permanently in an area of the brain, allowing them to be classified as ischemic or hemorrhagic. In ischemic there is a blockage of blood flow and, consequently, of oxygen to areas of the brain, in hemorrhagic rupture of a vessel occurs and, with this, blood leakage. Therefore, it is necessary to recognize the signs and symptoms early, in order to prevent loss of neurological function, movements on one side of the body and the presence or absence of headaches in both patients, with ischemic CVD and hemorrhagic CVD prevent rapid loss of consciousness accompanied by severe headache. Such signs and symptoms associated with the patient’s family history and lifestyle can help in the diagnosis of this disease. Conclusion: Therefore, it is important to recognize the signs and symptoms of CVDs, in order to determine the treatment and advise the patient, which will guarantee a better prognosis.


2005 ◽  
Vol 3 (1) ◽  
pp. 0-0
Author(s):  
Egidijus Barkauskas ◽  
Povilas Pauliukas ◽  
Kęstutis Laurikėnas ◽  
Gytis Šustickas

Egidijus Barkauskas, Povilas Pauliukas, Kęstutis Laurikėnas, Gytis ŠustickasVšĮ Vilniaus greitosios pagalbos universitetinė ligoninė,Šiltnamių g. 29, LT-04130 VilniusEl paštas: [email protected] Įvadas Straipsnyje aprašomos palyginti retų arterijos didelių ir gigantiškų vidinės miego aneurizmų atsiradimo priežastys. Skirtingai nuo kitų straipsnių, čia kartu apžvelgiamos vidinės miego arterijos ekstrakranijinės ir intrakranijinės dalių aneurizmos. Aprašomos įvairios aneurizmų diagnostikos ir gydymo perrišant kaklo vidinę miego arteriją galimybės. Šio straipsnio tikslas – apžvelgti ir įvertinti Vilniaus neuroangiochirurgijos centre atliktų vidinės miego arterijos gigantiškų aneurizmų operacijų rezultatus, parodyti šių operacijų efektyvumą ir jų atlikimo metodus. Ligoniai ir metodai Straipsnyje nagrinėjami 12 ligonių, kuriems buvo vidinės miego arterijos aneurizmos, tyrimo ir gydymo duomenys. Ligonių amžius svyravo nuo 42 iki 80 metų. Visi ligoniai operuoti. Operacijos atliktos per 35 metų laikotarpį. Keturi ligoniai operuoti nuo didelių ir gigantiškų intrakranijinių aneurizmų, septyni – nuo ekstrakranijinių vidinės miego arterijos ir vienas – išorinės miego arterijos aneurizmų. Didelėmis vadinome tokias aneurizmas, kai intrakranijinių aneurizmų vidinis skersmuo didesnis negu 3 mm, o ekstrakranijinių – 3–4 ir daugiau kartų viršijo normalų tos pačios arterijos spindį. Aptariami įvairūs chirurginio gydymo metodai, daugiausia dėmesio kreipiant į aneurizmos užtrombavimo arba rezekcijos būdus ir smegenų kraujotakos atkūrimo sąlygas. Rezultatai Mūsų klinikoje iš 12 ligonių, operuotų nuo vidinės miego arterijos aneurizmos, nė vienas nemirė, naujų insultų neįvyko, ir tik 2 ligoniams iš keturių po intrakranijinių aneurizmų užtrombavimo liko neženkli hemiparezė, kuri vienai ligonei buvo nustatyta atvykus į ligoninę, o kitai hemiparezė pasireiškė dar prieš operaciją, po nepavykusio aneurizmos užkimšimo balionu. Prieš operaciją 3 ligonius varginę stiprūs galvos skausmai, plintantys į akiduobę, išnyko. Visi 12 ligonių išrašyti į namus. Išvados Pasitelkiant šiuolaikinę diagnostinę aparatūrą daugumą intrakranijinių ir ekstrakranijinių vidinės miego arterijos aneurizmų galima diagnozuoti prieš joms plyštant. Aneurizmų gydymui gali būti naudojami įvairūs metodai. Nepavykus tiesiogiai atkurti kraujotakos ir esant blogai smegenų kolateralinei apytakai galima taikyti vieną iš alternatyvių gydymo metodų, kai vidinė miego arterija perrišama, aneurizma užtrombuojama, atliekama ekstraintrakranijinio nuosruvio operacija. Mums prieinamomis operacijų metodikomis gauname gerus aneurizmų gydymo rezultatus. Reikšminiai žodžiai: vidinė miego arterija, aneurizma, vidinės miego arterijos perrišimas, ekstraintrakranijinio nuosruvio operacija Results of treatment of internal carotid artery aneurysms Egidijus Barkauskas, Povilas Pauliukas, Kęstutis Laurikėnas, Gytis ŠustickasVilnius University Emergency Hospital,Šiltnamių str. 29, LT-04130 Vilnius, LithuaniaE-mail: [email protected] Background/objective The causes of development of big and giant aneurysms of internal carotid artery are described in this paper. Differently from other papers, the intracranial and extracranial aneurysms are analyzed together in this article. Various diagnostic and treatment procedures, including ligation of internal carotid artery in the neck, are described. The main purpose of this paper is to describe and evaluate the results of operations of giant aneurysms of the internal carotid artery performed at Vilnius Neurovascular Surgery Center as well as to show the effectiveness of these operations and the methods of performing these procedures. Patients and methods Twelve patients were investigated and operated on for internal carotid artery aneurysm during a 35-year period. The age of patients was between 42 and 80 years. Four patients were operated on for big and giant intracranial aneurysms, 7 for extracranial internal carotid artery aneurysms and 1 for external carotid artery aneurysm. As big aneurysms were interpreted intracranial aneurysms with the internal diameter exceeding 3 mm and extracranial aneurysms exceeding in diameter the normal lumen of the internal carotid artery 3–4 times or more. Different methods of surgical treatment are analyzed; special attention is paid to exclusion and resection of the aneurysm as well as to the restoration of blood flow to the brain. Results Twelve patients were operated on in our center for aneurysm of the internal carotid artery. There were no deaths and strokes. Two patients had light hemiparesis after the induced thrombosis of the intracranial aneurysm. Both of them had it prior to the operation; one of them after the attempted unsuccessful balloon occlusion of the aneurysm. Three patients have had severe headache irradiating into the orbit before treatment. After the operation the headache disappeared. All patients were discharged from the hospital. Conclusions The modern diagnostic equipment allows to diagnose most of the intracranial and ectracranial internal carotid artery aneurysms before they rupture. Different methods can be applied for the treatment of these aneurysms. The extra-intracranial shunting procedure can be used as an alternative revascularization method in cases when direct blood flow to the brain cannot be restored and collateral brain blood flow is insufficient. Good results of surgical treatment of internal carotid artery aneurysms were achieved using the techniques described in this article. Keywords: internal carotid artery aneurysm, ligation of the internal carotid artery, extra-intracranial shunting operation


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