scholarly journals Underlying mechanism of hemodynamics and intracranial aneurysm

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Haishuang Tang ◽  
Qingsong Wang ◽  
Fengfeng Xu ◽  
Xiaoxi Zhang ◽  
Zhangwei Zeng ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysm ◽  
Blood Vessels ◽  
Intracranial Aneurysms ◽  
Physiological Condition ◽  
Modern Society ◽  
Underlying Mechanism ◽  
Aneurysm Rupture ◽  
New Perspective ◽  
The Relationship

AbstractIn modern society, subarachnoid hemorrhage, mostly caused by intracranial aneurysm rupture, is accompanied by high disability and mortality rate, which has become a major threat to human health. Till now, the etiology of intracranial aneurysm has not been entirely clarified. In recent years, more and more studies focus on the relationship between hemodynamics and intracranial aneurysm. Under the physiological condition, the mechanical force produced by the stable blood flow in the blood vessels keeps balance with the structure of the blood vessels. When the blood vessels are stimulated by the continuous abnormal blood flow, the functional structure of the blood vessels changes, which becomes the pathophysiological basis of the inflammation and atherosclerosis of the blood vessels and further promotes the occurrence and development of the intracranial aneurysm. This review will focus on the relationship between hemodynamics and intracranial aneurysms, will discuss the mechanism of occurrence and development of intracranial aneurysms, and will provide a new perspective for the research and treatment of intracranial aneurysms.

Abstract 147: Role of Nicotine in the Development of Intracranial Aneurysm Rupture

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Yoshinobu Kamio ◽  
Hajime Furukawa ◽  
Kimihiko Yokosuka ◽  
Masaaki Korai ◽  
Kazuha Mitsui ◽  
...  
Keyword(s):  
Intracranial Aneurysm ◽  
Tobacco Smoke ◽  
Intracranial Aneurysms ◽  
Aneurysm Rupture ◽  
Alpha7 Nicotinic Acetylcholine Receptor ◽  
Acetate Salt ◽  
Nicotine Receptors ◽  
Aneurysm Wall ◽  
Salt Hypertension

Background: Nicotine is one of main chemicals of tobacco smoke and promotes atherosclerosis and stroke. Tobacco smoke is considered an independent risk factor for intracranial aneurysm formation, growth, and rupture. There are mainly 5 subtypes of nicotine receptors. Roles of alpha7 nicotinic acetylcholine receptor (α7nAChR) in inflammation and vascular remodeling are diverse and context-dependent. Notably, endothelial α7nAChR is considered to mediate nicotine-induced inflammation. Activation of endothelial α7nAChR by nicotine may promote aneurysm rupture by increasing the aneurysm wall inflammation. Using a mouse model of intracranial aneurysm, we examined effects of nicotine in aneurysm rupture. Moreover we investigated potential roles of α7nAChR stimulation by nicotine in the pathophysiology of intracranial aneurysms. Methods: Intracranial aneurysms were induced by a combination of elastase injection into the cerebrospinal fluid and deoxycorticosteron acetate-salt (DOCA-salt) hypertension in male mice. Mice were treated with (1) nicotine (5 mg/kg/day, n=25); (2) saline sc (n=22) for three weeks after aneurysm induction. To investigate the effect of α7nAChR, mice were treated with (1) saline sc + saline ip (n=11); (2) saline sc + α7nAChR antagonist (Methyllycaconitine, MLA 5mg/kg/day) ip (n=13); (3) nicotine (5 mg/kg/day, sc, 28 days) + saline ip (n=18); (4) nicotine sc + MLA ip (n=18). Results: Nicotine alone significantly increased aneurysmal rupture compared with saline treatment (89% vs 46%, p=0.009). While α7nAChR antagonist did not affect the incidence of aneurysm or rupture rates, the α7nAChR antagonist significantly reduced the deleterious effect of nicotine as indicated by the reduction of the rupture rates (41% vs 100%: nicotine sc + MLA ip group vs nicotine sc + saline ip group, p=0.027). Conclusion: Our data indicate the promotion of aneurysm rupture by nicotine may be mediated by its stimulation of alpha7nAChR.

scholarly journals How Intracranial Aneurysm Rupture Damages the Brain

2008 ◽  
Vol 14 (1_suppl) ◽  
pp. 9-12 ◽  
Author(s):  
T. Trojanowski
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysm ◽  
Brain Dysfunction ◽  
Aneurysm Rupture ◽  
Acute Stage ◽  
Neurological Deficits ◽  
Arterial Bleeding ◽  
Secondary Haemorrhage ◽  
Global Brain ◽  
The Brain

Intracranial aneurysm rupture causes arterial bleeding into the subarachnoid space (SAH). In the acute stage lasting around 5 minutes intracranial pressure (ICP) rises rapidly up to the level between systolic and diastolic blood pressures, which slows down the outflow of blood, facilitates clot formation in the site of rupture and leads to arrest of bleeding. Increased ICP lowers cerebral perfusion pressure, causing brain ischemia, which is unevenly distributed throughout the brain as a result of interhemispheric pressure gradients, arterial spasms and other factors. No-reflow phenomenon in the capillaries following temporary arrest or considerable slowing of circulation produces areas of hypoperfusion and reduced capacity of blood flow autoregulation scattered irregularly in the brain in the subacute stage up to 30 minutes following haemorrhage. Disturbed regional cerebral blood flow is accompanied by spots of damaged blood brain barrier resulting in brain oedema. After SAH the brain remains vulnerable to reduction of blood flow and hypoxaemia, which explains greater brain damage after secondary haemorrhage, and in some cases persistent neurological deficits or global brain dysfunction.

scholarly journals Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

2021 ◽  
Author(s):  
Barry Vuong
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Optical Coherence ◽  
Specific Flow ◽  
Arterial Lumen ◽  
Risk Of Rupture

The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

Embarrassed customers: the dark side of receiving help from others

2017 ◽  
Vol 28 (4) ◽  
pp. 788-806 ◽  
Author(s):  
Seo Young Kim ◽  
Youjae Yi
Keyword(s):  
Customer Satisfaction ◽  
Underlying Mechanism ◽  
Customer Engagement ◽  
Dark Side ◽  
Service Encounters ◽  
Content Type ◽  
Altruistic Motivation ◽  
Engagement Behavior ◽  
New Perspective ◽  
The Relationship

Purpose The purpose of this paper is to demonstrate that customer engagement behavior may not always be a positive experience for customers. Specifically, the paper examines the effect of sources of help (employee vs customer) on customer satisfaction, and the underlying mechanism behind such an effect. Design/methodology/approach Three studies were conducted to test the hypotheses, and bootstrapping was used to analyze the proposed mediation and moderation models. Findings The results from the studies demonstrated the effect of sources of help (employee vs customer) on customer satisfaction. Specifically, compared to those who have received help from employees, customers who have received help from other customers showed lower satisfaction toward the firm. The relationship between sources of help and satisfaction was mediated by an affective factor, embarrassment, and a cognitive factor, altruistic motivation. In addition, the relationship between embarrassment and satisfaction was moderated by concern for face. Practical implications Firms should devote more resources toward minimizing customers’ embarrassment during service encounters and demonstrate altruistic motivation to provide voluntary help to lead customers to reciprocate helping. Originality/value The current research provides a new perspective on customer engagement behavior during service encounters. This research highlights the negative outcomes of receiving help from other customers.

scholarly journals The Relationship Between Smoking and Delayed Cerebral Ischemia After Intracranial Aneurysm Rupture: A Systematic Review and Meta-Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaolong Ya ◽  
Chaoqi Zhang ◽  
Shuo Zhang ◽  
Qian Zhang ◽  
Yong Cao ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Intracranial Aneurysm ◽  
Meta Analysis ◽  
Delayed Cerebral Ischemia ◽  
Aneurysm Rupture ◽  
Cochrane Library ◽  
Significant Difference ◽  
Smoking Group ◽  
Main Component ◽  
The Relationship

Background: Delayed cerebral ischemia (DCI) is the main cause of death and disability after intracranial aneurysm rupture. Previous studies have shown that smoking can lead to DCI after intracranial aneurysm rupture. However, some recent studies have shown that nicotine, as the main ingredient of tobacco, can cause cerebral vasodilation. This view has led to a debate about the relationship between smoking and DCI. This study aims to determine the relationship between smoking and DCI.Methods: A systematic literature search was performed according to PRISMA guidelines. The Cochrane Library, Web of Science, PubMed, and Embase online databases were searched for studies published up to September 2020. All studies related to smoking and DCI were included in the analysis. The R and RevMan software were used for data analysis, and random or fixed model analysis was selected depending on the degree of heterogeneity. Publication bias was examined by using the Begg–Mazumdar test and using contour-enhanced funnel plots with trim method.Results: A total of eight original articles (12 cohorts) with 10,722 patients were included in this meta-analysis. There were statistically significant higher rates of DCI in the smoking group than in the non-smoking group (RRtotal = 1.16, 95%CI: 1.05–1.27). After heterogeneity among cohorts was removed by sensitivity analysis, there was still a statistically significant difference in the incidence of DCI between the smoking and non-smoking groups (RRtotal = 1.13, 95%CI: 1.07–1.20).Conclusions: Although the effects of nicotine as the main component of tobacco are unclear in terms of cerebral vessels, the present study suggests that smoking is a risk factor for DCI in patients with ruptured aneurysm.

scholarly journals Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

2021 ◽  
Author(s):  
Barry Vuong
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Optical Coherence ◽  
Specific Flow ◽  
Arterial Lumen ◽  
Risk Of Rupture

The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

scholarly journals Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

2021 ◽  
Author(s):  
Barry Vuong
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Fluid Dynamic ◽  
Patient Specific ◽  
Optical Coherence ◽  
Specific Flow ◽  
Arterial Lumen ◽  
Risk Of Rupture

The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

Numerical simulation flow dynamics of an intracranial aneurysm

2021 ◽  
pp. 1-7
Author(s):  
Yang Zhang ◽  
Junjie Fan ◽  
Yunxia Xiu ◽  
Luyao Zhang ◽  
Guangxin Chen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Intracranial Aneurysm ◽  
Intracranial Aneurysms ◽  
Carotid Arteries ◽  
Internal Carotid ◽  
Flow Characteristics ◽  
High Particle ◽  
Internal Carotid Arteries

BACKGROUND: Computational fluid dynamics provides a new method for the study of the blood flow characteristics of the formation and development of intracranial aneurysms. OBJECTIVE: To compare blood flow characteristics between the healthy internal carotid artery and normal intracranial aneurysms. METHODS: The internal carotid arteries were simulated to obtain hemodynamic parameters in one patient. RESULTS: The internal carotid artery associated with aneurysm presents low wall shear stress, high oscillatory shear index, and high particle retention time compared with the normal internal carotid artery. CONCLUSIONS: There are differences in blood flow between the normal internal carotid artery and intracranial aneurysm. The vortex of the aneurysm will produce turbulence, indicating that it is unstable, which results in the growth and rupture of the aneurysm.

Aneurysm Rupture After Treatment With Flow Diverting Stent

2010 ◽  
Author(s):  
Juan Cebral ◽  
Fernando Mut ◽  
Esteban Scrivano ◽  
Pedro Lylyk ◽  
Christopher Putman
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysm ◽  
Intracranial Aneurysms ◽  
Aneurysm Rupture ◽  
Unruptured Aneurysms ◽  
Geometrically Complex ◽  
Hemodynamic Study ◽  
Flow Diverting Stent

Recently there has been increased interest in the use of flow diverting devices to treat intracranial aneurysms. The goal is to deviate the blood flow away from the aneurysm and promote its thrombosis and exclusion from the circulation. This therapy is mostly considered for large, geometrically complex, wide necked, unruptured aneurysms that are difficult or impossible to coil or clip. Recent trials using flow diverting stents have shown promising results [1]. However, little is known about the possible complications of these procedures. This paper presents a hemodynamic study of a cerebral aneurysm that was treated with a flow diverting stent and ruptured a few days later.

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