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cerebral vascular autoregulation

Pedro Castro, Elsa Azevedo, Isabel Rocha, Farzaneh Sorond, Jorge M Serrador
BACKGROUND: Chronic kidney disease increases stroke incidence and severity but the mechanisms behind this cerebro-renal interaction are mostly unexplored. Since both vascular beds share similar features, microvascular dysfunction could be the possible missing link. Therefore, we examined the relationship between renal function and cerebral autoregulation in the early hours post ischemia and its impact on outcome. METHODS: We enrolled 46 ischemic strokes (middle cerebral artery)...
March 2, 2018: BMC Neurology
Flora A Kennedy McConnell, Stephen J Payne
OBJECTIVE: Ischemic 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. A steady-state model of the cerebral arterial network was used to investigate the interaction of these mechanisms when autoregulation is impaired ipsilateral to an occluded artery. MATERIALS AND METHODS: Twelve structural variants of the circle of Willis were modelled with left internal carotid artery occlusion and coupled with (1) a passive model of the cerebral vascular bed, (2) a steady-state model of an autoregulating cerebral vascular bed, and (3) a model in which the contralateral hemisphere autoregulates and the ipsilateral hemisphere does not...
2018: Acta Neurochirurgica. Supplement
Erin D Ozturk, Can Ozan Tan
BACKGROUND: The marked increase in the size of the brain, and consequently, in neural processing capability, throughout human evolution is the basis of the higher cognitive function in humans. However, greater neural, and thus information processing capability, comes at a significant metabolic cost; despite its relatively small size, the modern human brain consumes almost a quarter of the glucose and oxygen supply in the human body. Fortunately, several vascular mechanisms ensure sufficient delivery of glucose and oxygen to the active neural tissue (neurovascular coupling), prompt removal of neural metabolic by-products (cerebral vasoreactivity), and constant global blood supply despite daily variations in perfusion pressure (cerebral autoregulation)...
February 17, 2018: Journal of Physiological Anthropology
Yurie Obata, Viachaslau Barodka, Dan E Berkowitz, Allan Gottschalk, Charles W Hogue, Jochen Steppan
BACKGROUND: Pulse pressure, the ambulatory arterial stiffness index (AASI), and the symmetric AASI are established predictors of adverse cardiovascular outcomes. However, little is known about their relationship to cerebral autoregulation. This study evaluated whether these markers of vascular properties relate to the lower limit of cerebral autoregulation (LLA). METHODS AND RESULTS: The LLA was determined during cardiac surgery with transcranial Doppler ultrasonography in 181 patients...
February 8, 2018: Journal of the American Heart Association
Dipali Goyal, Ravi Goyal
The Alpha Adrenergic Signaling Pathway is one of the chief regulators of cerebrovascular tone and cerebral blood flow (CBF), mediating its effects in the arteries through alpha1-adrenergic receptors (Alpha1AR). In the ovine middle cerebral artery (MCA), with development from a fetus to an adult, others and we have shown that Alpha1AR play a key role in contractile responses, vascular development, remodeling, and angiogenesis. Importantly, Alpha1AR play a significant role in CBF autoregulation, which is incompletely developed in a premature fetus as compared to a near-term fetus...
January 29, 2018: Scientific Reports
Kevin S King, Min Sheng, Peiying Liu, Christopher D Maroules, Craig D Rubin, Ron M Peshock, Roderick W McColl, Hanzhang Lu
Background and purpose Vascular risk factors have been associated with decreased cerebral blood flow (CBF) but this is etiologically nonspecific and may result from vascular insufficiency or a response to decreased brain metabolic activity. We apply new MRI techniques to measure oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen consumption (CMRO2), hypothesizing that decreased CBF related to these vascular risk factors will be associated with increased OEF, confirming a primary vascular insufficiency...
January 1, 2018: Neuroradiology Journal
A Ruesch, M A Smith, G Wollstein, I A Sigal, S Nelson, J M Kainerstorfer
The mechanism that maintains a stable blood flow in the brain despite changes in cerebral perfusion pressure (CPP), and therefore guaranties a constant supply of oxygen and nutrients to the neurons, is known as cerebral autoregulation (CA). In a certain range of CPP, blood flow is mediated by a vasomotor adjustment in vascular resistance through dilation of blood vessels. CA is known to be impaired in diseases like traumatic brain injury, Parkinson's disease, stroke, hydrocephalus and others. If CA is impaired, blood flow and pressure changes are coupled and the oxygen supply might be unstable...
February 2017: Proceedings of SPIE
Nikolett Szarka, Mallikarjuna R Pabbidi, Krisztina Amrein, Endre Czeiter, Gergely Berta, Krisztina Pohoczky, Zsuzsanna Helyes, Zoltan Ungvari, Akos Koller, Andras Buki, Peter Toth
Traumatic brain injury (TBI) impairs autoregulation of cerebral blood flow, which contributes to the development of secondary brain injury, increasing mortality of patients. Impairment of pressure-induced myogenic constriction of cerebral arteries plays a critical role in autoregulatory dysfunction; however, the underlying cellular and molecular mechanisms are not well understood. To determine the role of mitochondria-derived H2 O2 and large-conductance calcium-activated potassium channels (BKCa ) in myogenic autoregulatory dysfunction, middle cerebral arteries (MCAs) were isolated from rats with severe weight drop-impact acceleration brain injury...
January 12, 2018: Journal of Neurotrauma
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
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
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
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
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
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
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
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
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...
September 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
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
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
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
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