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cerebral vascular autoregulation

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https://www.readbyqxmd.com/read/29104807/neural-vascular-mechanism-for-the-cerebral-blood-flow-autoregulation-after-hemorrhagic-stroke
#1
REVIEW
Ming Xiao, Qiang Li, Hua Feng, Le Zhang, Yujie Chen
During the initial stages of hemorrhagic stroke, including intracerebral hemorrhage and subarachnoid hemorrhage, the reflex mechanisms are activated to protect cerebral perfusion, but secondary dysfunction of cerebral flow autoregulation will eventually reduce global cerebral blood flow and the delivery of metabolic substrates, leading to generalized cerebral ischemia, hypoxia, and ultimately, neuronal cell death. Cerebral blood flow is controlled by various regulatory mechanisms, including prevailing arterial pressure, intracranial pressure, arterial blood gases, neural activity, and metabolic demand...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/29043544/icp-versus-laser-doppler-cerebrovascular-reactivity-indices-to-assess-brain-autoregulatory-capacity
#2
F A Zeiler, J Donnelly, D Cardim, D K Menon, P Smielewski, M Czosnyka
BACKGROUND: To explore the relationship between various autoregulatory indices in order to determine which approximate small vessel/microvascular (MV) autoregulatory capacity most accurately. METHODS: Utilizing a retrospective cohort of traumatic brain injury patients (N = 41) with: transcranial Doppler (TCD), intracranial pressure (ICP) and cortical laser Doppler flowmetry (LDF), we calculated various continuous indices of autoregulation and cerebrovascular responsiveness: A...
October 17, 2017: Neurocritical Care
https://www.readbyqxmd.com/read/28991702/cerebral-autoregulation-is-preserved-in-multiple-sclerosis-patients
#3
Daniel Ferreira, Pedro Castro, Gonçalo Videira, João Pedro Filipe, Rosa Santos, Maria José Sá, Elsa Azevedo, Pedro Abreu
Multiple sclerosis (MS) is an inflammatory disease that may also be associated with vascular dysfunction. One master component of vascular regulation is cerebral autoregulation (CA). We aimed to investigate the integrity of CA in MS patients and study its relationship with autonomic dysfunction (AD), magnetic-resonance-imaging (MRI) lesion load and hemodynamic parameters. We enrolled 20 relapsing-remitting MS and 20 healthy subjects. CA was assessed by transfer function analysis parameters (coherence, gain and phase), as obtained in the very low, low and high-frequency domains (VLF, LF, HF, respectively)...
October 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28925890/the-use-of-hemodynamic-and-cerebral-monitoring-to-study-pharmacodynamics-in-neonates
#4
A Smits, L Thewissen, A Dereymaeker, E Dempsey, A Caicedo, Gunnar Naulaers
BACKGROUND: Drugs acting on the cardiovascular and central nervous system often display relatively fast clinical responses, which may differ in neonates compared to children and adults. Introduction of bedside monitoring tools might be of additional value in the pharmacodynamic (PD) assessment of such drugs in neonates. METHODS: We aim to provide an overview of the frequently used monitoring tools to assess drug effects on the hemodynamic status as well as the cerebral circulation, oxygenation and cerebral metabolism in neonates...
September 18, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28819737/further-controversies-about-brain-tissue-oxygenation-pressure-reactivity-after-traumatic-brain-injury
#5
Morten Andresen, Joseph Donnelly, Marcel Aries, Marianne Juhler, David Menon, Pja Hutchinson, Peter Smielewski
BACKGROUND: Continuous monitoring of cerebral autoregulation is considered clinically useful due to its ability to warn against brain ischemic insults, which may translate to a relationship with adverse outcome. It is typically performed using the pressure reactivity index (PRx) based on mean arterial pressure and intracranial pressure. A new ORx index based on brain tissue oxygenation and cerebral perfusion pressure (CPP) has been proposed that similarly allows for evaluation of cerebrovascular reactivity...
August 17, 2017: Neurocritical Care
https://www.readbyqxmd.com/read/28782872/the-role-of-vascular-resistance-in-bold-responses-to-progressive-hypercapnia
#6
James Duffin, Olivia Sobczyk, Adrian Crawley, Julien Poublanc, Lashmi Venkatraghavan, Kevin Sam, Alan Mutch, David Mikulis, Joseph Fisher
The ability of the cerebral vasculature to regulate vascular diameter, hence resistance and cerebral blood flow (CBF), in response to metabolic demands (neurovascular coupling), and perfusion pressure changes (autoregulation) may be assessed by measuring the CBF response to carbon dioxide (CO2 ). In healthy individuals, the CBF response to a ramp CO2 stimulus from hypocapnia to hypercapnia is assumed sigmoidal or linear. However, other response patterns commonly occur, especially in individuals with cerebrovascular disease, and these remain unexplained...
August 7, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28668343/changes-in-arterial-cerebral-blood-volume-during-lower-body-negative-pressure-measured-with-mri
#7
Joseph R Whittaker, Molly G Bright, Ian D Driver, Adele Babic, Sharmila Khot, Kevin Murphy
Cerebral Autoregulation (CA), defined as the ability of the cerebral vasculature to maintain stable levels of blood flow despite changes in systemic blood pressure, is a critical factor in neurophysiological health. Magnetic resonance imaging (MRI) is a powerful technique for investigating cerebrovascular function, offering high spatial resolution and wide fields of view (FOV), yet it is relatively underutilized as a tool for assessment of CA. The aim of this study was to demonstrate the potential of using MRI to measure changes in cerebrovascular resistance in response to lower body negative pressure (LBNP)...
June 28, 2017: NeuroImage
https://www.readbyqxmd.com/read/28657491/novel-noninvasive-method-of-cerebrovascular-blood-volume-assessment-using-brain-bioimpedance
#8
Mohamad H Tiba, Brendan M McCracken, Sardar Ansari, Ashwin Belle, Brandon C Cummings, Venkatakrishna Rajajee, Parag G Patil, Hasan B Alam, Kevin R Ward
Cerebrovascular autoregulation (CAR) is the ability of vessels to modulate their tone in response to changes in pressure. As an auto-protective mechanism, CAR is critical in preventing secondary brain injury post-trauma. Monitoring of changes in cerebral blood volume might be valuable in evaluating CAR and response to various therapies. In this study, we utilized an ocular-brain bioimpedance interface to assess real time changes in cerebral blood volume in response to a number of physiological challenges. We hypothesize that changes in brain bioimpedance (dz) would track changes in cerebral blood volume...
November 15, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28656320/rho-kinase-and-the-nitric-oxide-pathway-modulate-basilar-arterial-reactivity-to-acetylcholine-and-angiotensin-ii-in-streptozotocin-induced-diabetic-mice
#9
Md Zahorul Islam, Cuong Van Dao, Atsushi Miyamoto, Mitsuya Shiraishi
Diabetes mellitus comprises a heterogeneous group of metabolic disorders with underlying hyperglycemia and secondary cardiovascular complications. Growing evidence suggests that vascular dysfunction is among the most important causes of diabetic cardiovascular disease. Therefore, we determined whether streptozotocin (STZ)-induced diabetes in mice affects blood pressure and cerebral arterial responsiveness to angiotensin (Ang) II and acetylcholine (ACh), which are important modulators of cerebrovascular autoregulation...
June 27, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28497934/cerebral-autoregulation-monitoring-in-acute-traumatic-brain-injury-what-s-the-evidence
#10
Leanne A Calviello, Joseph Donnelly, Frederick A Zeiler, Eric P Thelin, Peter Smielewski, Marek Czosnyka
Cerebral autoregulation is conceptualized as a vascular self-regulatory mechanism within the brain. Controlled by elusive relationships between various biophysical processes, it functions to protect the brain against potential damages caused by sudden changes in cerebral perfusion pressures and flow. Following events such as traumatic brain injuries (TBI), autoregulation may be compromised, potentially leading to an unfavorable outcome. In spite of its complexity, autoregulation has been able to be quantified non-invasively within the neuro-critical care setting with the aid of transcranial Doppler...
August 2017: Minerva Anestesiologica
https://www.readbyqxmd.com/read/28416148/alterations-in-autonomic-cerebrovascular-control-after-spinal-cord-injury
#11
Dong-Il Kim, Can Ozan Tan
Among chronic cardiovascular and metabolic sequelae of spinal cord injury (SCI) is an up-to four-fold increase in the risk of ischemic and hemorrhagic stroke, suggesting that individuals with SCI cannot maintain stable cerebral perfusion. In able-bodied individuals, the cerebral vasculature is able to regulate cerebral perfusion in response to swings in arterial pressure (cerebral autoregulation), blood gases (cerebral vasoreactivity), and neural metabolic demand (neurovascular coupling). This ability depends, at least partly, on intact autonomic function, but high thoracic and cervical spinal cord injuries result in disruption of sympathetic and parasympathetic cerebrovascular control...
April 4, 2017: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/28384837/the-impact-of-integrated-evaluation-of-hemodynamics-on-management-of-preterm-infants-with-late-onset-compromised-systemic-circulation
#12
Reem Amer, Reem Kalash, Mary M Seshia, Yasser N Elsayed
Objectives To study the impact of integrated evaluation of hemodynamics (IEH), using targeted neonatal echocardiography (TNE), cerebral regional tissue oxygenation (crRTO), and fractional oxygen extraction (FOE), using near-infrared spectroscopy (NIRS) on the management of infants with late-onset compromised systemic circulation (LCSC), and evaluation of the hemodynamic characteristics. Study Design Retrospective cohort study comparing infants with LCSC who underwent IEH (April 2014 to May 2016) with an earlier EPOCH who did not undergo IEH (January 2012 to March 2014)...
August 2017: American Journal of Perinatology
https://www.readbyqxmd.com/read/28302914/new-insights-into-mechanisms-of-small-vessel-disease-stroke-from-genetics
#13
REVIEW
Rhea Tan, Matthew Traylor, Loes Rutten-Jacobs, Hugh Markus
Cerebral small vessel disease (SVD) is a common cause of lacunar strokes, vascular cognitive impairment (VCI) and vascular dementia. SVD is thought to result in reduced cerebral blood flow, impaired cerebral autoregulation and increased blood-brain barrier (BBB) permeability. However, the molecular mechanisms underlying SVD are incompletely understood. Recent studies in monogenic forms of SVD, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), and 'sporadic' SVD have shed light on possible disease mechanisms in SVD...
April 1, 2017: Clinical Science (1979-)
https://www.readbyqxmd.com/read/28268070/post-carotid-endarterectomy-hypertension-part-1-association-with-pre-operative-clinical-imaging-and-physiological-parameters
#14
J E Newman, M J Bown, R D Sayers, J P Thompson, T G Robinson, B Williams, R Panerai, P Lacy, A R Naylor
OBJECTIVE/BACKGROUND: Post-endarterectomy hypertension (PEH) is a well recognised, but poorly understood, phenomenon after carotid endarterectomy (CEA) that is associated with post-operative intracranial haemorrhage, hyperperfusion syndrome, and cardiac complications. The aim of the current study was to identify pre-operative clinical, imaging, and physiological parameters associated with PEH. METHODS: In total, 106 CEA patients undergoing CEA under general anaesthesia underwent pre-operative evaluation of 24 hour ambulatory arterial blood pressure (BP), baroreceptor sensitivity, cerebral autoregulation, and transcranial Doppler measurement of cerebral blood flow velocity (CBFv) and pulsatility index...
November 2017: European Journal of Vascular and Endovascular Surgery
https://www.readbyqxmd.com/read/28055302/t-type-ca-2-channels-and-autoregulation-of-local-blood-flow
#15
Lars Jørn Jensen, Morten Schak Nielsen, Max Salomonsson, Charlotte Mehlin Sørensen
L-type voltage gated Ca(2+) channels are considered to be the primary source of calcium influx during the myogenic response. However, many vascular beds also express T-type voltage gated Ca(2+) channels. Recent studies suggest that these channels may also play a role in autoregulation. At low pressures (40-80 mmHg) T-type channels affect myogenic responses in cerebral and mesenteric vascular beds. T-type channels also seem to be involved in skeletal muscle autoregulation. This review discusses the expression and role of T-type voltage gated Ca(2+) channels in the autoregulation of several different vascular beds...
May 4, 2017: Channels
https://www.readbyqxmd.com/read/27995510/mechanisms-of-global-cerebral-edema-formation-in-aneurysmal-subarachnoid-hemorrhage
#16
REVIEW
Erik G Hayman, Aaron Wessell, Volodymyr Gerzanich, Kevin N Sheth, J Marc Simard
A growing body of clinical literature emphasizes the impact of cerebral edema in early brain injury following aneurysmal subarachnoid hemorrhage (aSAH). Aneurysm rupture itself initiates global cerebral edema in up to two thirds of cases. Although cerebral edema is not a universal feature of aSAH, it portends a poor clinical course, with quantitative analysis revealing a direct correlation between cerebral edema and poor outcome, including mortality and cognitive deficits. Mechanistically, global cerebral edema has been linked to global ischemia at the time of aneurysm rupture, dysfunction of autoregulation, blood breakdown products, neuroinflammation, and hyponatremia/endocrine abnormalities...
April 2017: Neurocritical Care
https://www.readbyqxmd.com/read/27927653/knockdown-of-add3-impairs-the-myogenic-response-of-renal-afferent-arterioles-and-middle-cerebral-arteries
#17
Fan Fan, Mallikarjuna R Pabbidi, Ying Ge, Longyang Li, Shaoxun Wang, Paige N Mims, Richard J Roman
We have reported that the myogenic response of the renal afferent arteriole (Af-art) and middle cerebral artery (MCA) and autoregulation of renal and cerebral blood flow are impaired in Fawn-Hooded Hypertensive (FHH) rats. Transfer of a region of chromosome 1 containing γ-adducin (Add3) from the Brown Norway rat rescued the vascular dysfunction and the development of renal disease. To examine whether Add3 is a viable candidate gene altering renal and cerebral hemodynamics in FHH rats, we knocked down the expression of Add3 in rat Af-arts and MCAs cultured for 36-h using a 27-mer Dicer-substrate short interfering RNA (DsiRNA)...
June 1, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/27891584/an-observational-study-of-the-macro-and-micro-haemodynamic-implications-of-epidural-anaesthesia-in-children
#18
L Triffterer, P Marhofer, G Lechner, T C Marksz, O Kimberger, W Schmid, D Marhofer
The haemodynamic implications of epidural anaesthesia in children are poorly documented. We report macro- and micro-haemodynamic data from an observational study of 25 children ranging from neonates to six-years old, who underwent surgery conducted with a specific combination of monitoring systems. We analysed 90 min of study-related monitoring after epidural catheterisation, with skin incision taking place after around 30 min. We recorded macrohaemodynamic parameters (monitored using LiDCOrapid) including heart rate, mean arterial pressure, cardiac output, stroke volume, systemic vascular resistance and stroke volume variation...
April 2017: Anaesthesia
https://www.readbyqxmd.com/read/27862767/dynamics-of-cerebral-blood-flow-in-patients-with-mild-non-ischaemic-heart-failure
#19
Christian D Erkelens, Haye H van der Wal, Bauke M de Jong, Jan-Willem Elting, Remco Renken, Marleen Gerritsen, Peter Jan van Laar, Vincent M van Deursen, Peter van der Meer, Dirk J van Veldhuisen, Adriaan A Voors, Gert-Jan Luijckx
AIMS: Heart failure (HF) is associated with tissue hypoperfusion and congestion leading to organ dysfunction. Although cerebral blood flow (CBF) is preserved over a wide range of perfusion pressures in healthy subjects, it is impaired in end-stage HF. We aimed to compare CBF, autoregulation, and cognitive function in patients with mild non-ischaemic HF with healthy controls. METHODS AND RESULTS: Fifteen patients with mild idiopathic dilated cardiomyopathy and 15 matched healthy controls were studied...
February 2017: European Journal of Heart Failure
https://www.readbyqxmd.com/read/27831856/the-dual-role-of-cerebral-autoregulation-and-collateral-flow-in-the-circle-of-willis-after-major-vessel-occlusion
#20
Flora Kennedy McConnell, Stephen Payne
OBJECTIVE: Ischaemic stroke is a leading cause of death and disability. Autoregulation and collateral blood flow through the circle of Willis both play a role in preventing tissue infarction. To investigate the interaction of these mechanisms a one-dimensional steady-state model of the cerebral arterial network was created. METHODS: Structural variants of the circle of Willis that present particular risk of stroke were recreated by using a network model coupled with: 1) a steady-state physiological model of cerebral autoregulation; and 2) one wherein the cerebral vascular bed was modeled as a passive resistance...
August 2017: IEEE Transactions on Bio-medical Engineering
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