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cerebral blood flow velocity

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https://www.readbyqxmd.com/read/28209740/quantitative-mri-volumetry-diffusivity-cerebrovascular-flow-and-cranial-hydrodynamics-during-head-down-tilt-and-hypercapnia-the-spacecot-study
#1
Larry Allen Kramer, Khader M Hasan, Ashot E Sargsyan, Karina Marshall-Goebel, Jörn Rittweger, Dorit Donoviel, Saki Higashi, Benson Mwangi, Darius A Gerlach, Eric M Bershad
PURPOSE: In order to improve the pathophysiologic understanding of visual changes observed in astronauts, we aimed to use quantitative MRI to measure anatomic and physiologic responses during a ground-based spaceflight analogue (head down tilt, HDT) combined with increased ambient carbon dioxide (CO2). METHODS: Six healthy, male subjects participated in the double-blinded, randomized cross-over design study with two conditions: 26.5 h of -12° HDT with ambient air and with 0...
February 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28207907/argon-does-not-affect-cerebral-circulation-or-metabolism-in-male-humans
#2
Frank Grüne, Stephan Kazmaier, Sanne Elisabeth Hoeks, Robert Jan Stolker, Marc Coburn, Andreas Weyland
OBJECTIVE: Accumulating data have recently underlined argon´s neuroprotective potential. However, to the best of our knowledge, no data are available on the cerebrovascular effects of argon (Ar) in humans. We hypothesized that argon inhalation does not affect mean blood flow velocity of the middle cerebral artery (Vmca), cerebral flow index (FI), zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe), resistance area product (RAP) and the arterio-jugular venous content differences of oxygen (AJVDO2), glucose (AJVDG), and lactate (AJVDL) in anesthetized patients...
2017: PloS One
https://www.readbyqxmd.com/read/28196095/depth-dependent-flow-and-pressure-characteristics-in-cortical-microvascular-networks
#3
Franca Schmid, Philbert S Tsai, David Kleinfeld, Patrick Jenny, Bruno Weber
A better knowledge of the flow and pressure distribution in realistic microvascular networks is needed for improving our understanding of neurovascular coupling mechanisms and the related measurement techniques. Here, numerical simulations with discrete tracking of red blood cells (RBCs) are performed in three realistic microvascular networks from the mouse cerebral cortex. Our analysis is based on trajectories of individual RBCs and focuses on layer-specific flow phenomena until a cortical depth of 1 mm. The individual RBC trajectories reveal that in the capillary bed RBCs preferentially move in plane...
February 14, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28193707/arterial-pressure-heart-rate-and-cerebral-hemodynamics-across-the-adult-life-span
#4
Chang-Yang Xing, Takashi Tarumi, Rutger L Meijers, Marcel Turner, Justin Repshas, Li Xiong, Kan Ding, Wanpen Vongpatanasin, Li-Jun Yuan, Rong Zhang
Age-related alterations in systemic and cerebral hemodynamics are not well understood. The purpose of this study is to characterize age-related alterations in beat-to-beat oscillations in arterial blood pressure (BP), heart rate (HR), cerebral blood flow (CBF), cardiac baroreflex sensitivity, and dynamic cerebral autoregulation across the adult life span. We studied 136 healthy adults aged 21 to 80 years (60% women). Beat-to-beat BP, HR, and CBF velocity were measured at rest and during sit-stand maneuvers to mimic effects of postural changes on BP and CBF...
February 13, 2017: Hypertension
https://www.readbyqxmd.com/read/28192264/balloon-angioplasty-for-in-stent-restenosis-resulting-in-carotid-stent-fracture-with-literature-review-of-stent-in-stent-technique-as-a-viable-therapeutic-option
#5
Abdul-Haseeb Naeem, Ghaya Al-Rumaihi, Amirpouyan Namavarian, Manas Sharma, Melfort Boulton
BACKGROUND: Carotid stent fractures are rare and multiple etiologies have been proposed to explain their occurrence. We present a patient with a internal carotid artery (ICA) stent who developed in-stent restenosis. We performed balloon angioplasty to address in-stent restenosis but post-procedure he developed a carotid stent fracture. To our knowledge, balloon angioplasty has not been reported to cause stent fractures and we report the first case report. CASE DESCRIPTION: 72-year-old male underwent stenting for symptomatic left ICA stenosis with post-stenting residual stenosis of 55%...
February 9, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28188214/transcranial-doppler-determined-change-in-posterior-cerebral-artery-blood-flow-velocity-does-not-reflect-vertebral-artery-blood-flow-during-exercise
#6
Takuro Washio, Hiroyuki Sasaki, Shigehiko Ogoh
We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow, in healthy subjects, during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior blood flow, were continuously measured during an exercise trial, using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level...
February 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28186430/cerebral-blood-flow-frontal-lobe-oxygenation-and-intra-arterial-blood-pressure-during-sprint-exercise-in-normoxia-and-severe-acute-hypoxia-in-humans
#7
David Curtelin, David Morales-Alamo, Rafael Torres-Peralta, Peter Rasmussen, Marcos Martin-Rincon, Mario Perez-Valera, Christoph Siebenmann, Ismael Pérez-Suárez, Evgenia Cherouveim, A William Sheel, Carsten Lundby, José Al Calbet
Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min(-1), mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28181956/extrapyramidal-symptoms-in-schizophrenia-evidence-of-blunted-cerebral-hemodynamics-during-a-planning-task
#8
Daniel Schuepbach, Matthias Michel, Gert Wagner, Stefan Duschek, Sabine C Herpertz
Acute extrapyramidal symptoms (EPS) occur frequently in schizophrenia, mostly caused by antidopaminergic substances. There have been no published reports on the impact of acute EPS on cerebral blood flow (CBF) or related measures. In the following study, we examined schizophrenic patients with and without EPS during a planning task and measurements of CBF velocity. Sixteen patients with chronic schizophrenia and 16 healthy participants performed a planning paradigm during bilateral functional transcranial Doppler sonography of the middle cerebral arteries...
February 8, 2017: International Clinical Psychopharmacology
https://www.readbyqxmd.com/read/28179559/acute-cerebral-venous-thrombosis-three-dimensional-visualization-and-quantification-of-hemodynamic-alterations-using-4-dimensional-flow-magnetic-resonance-imaging
#9
Florian Schuchardt, Anja Hennemuth, Laure Schroeder, Stephan Meckel, Michael Markl, Thomas Wehrum, Andreas Harloff
BACKGROUND AND PURPOSE: Cerebral venous thrombosis (CVT) affects venous hemodynamics and can provoke severe stroke and chronic intracranial hypertension. We sought to comprehensively analyze 3-dimensional blood flow and hemodynamic alterations during acute CVT including collateral recruitment and at follow-up. METHODS: Twenty-two consecutive patients with acute CVT were prospectively included and underwent routine brain magnetic resonance imaging (MRI) and 4-dimensional flow MRI at 3 T for the in vivo assessment of cerebral blood flow...
February 8, 2017: Stroke; a Journal of Cerebral Circulation
https://www.readbyqxmd.com/read/28166116/cerebral-blood-flow-responses-to-aquatic-treadmill-exercise
#10
Rhodri Parfitt, Marianne Y Hensman, Samuel J E Lucas
INTRODUCTION: Aquatic treadmills are used as a rehabilitation method for conditions such as spinal cord injury, osteoarthritis and stroke, and can facilitate an earlier return to exercise training for athletes. However, their effect on cerebral blood flow (CBF) responses has not been examined. We tested the hypothesis that aquatic treadmill exercise would augment CBF and lower heart rate compared to land-based treadmill exercise. METHODS: Eleven participants completed incremental exercise (crossover design) starting from walking pace [4 km/h, immersed to iliac crest (aquatic), 6 km/h (land)] and increasing 1 km/h every 2 min up to 10 km/h for aquatic (maximum belt speed) or 12 km/h for land...
February 4, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28161877/minimizing-the-blood-velocity-differences-between-phase-contrast-magnetic-resonance-imaging-and-computational-fluid-dynamics-simulation-in-cerebral-arteries-and-aneurysms
#11
Mohd Azrul Hisham Mohd Adib, Satoshi Ii, Yoshiyuki Watanabe, Shigeo Wada
The integration of phase-contrast magnetic resonance images (PC-MRI) and computational fluid dynamics (CFD) is a way to obtain detailed information of patient-specific hemodynamics. This study proposes a novel strategy for imposing a pressure condition on the outlet boundary (called the outlet pressure) in CFD to minimize velocity differences between the PC-MRI measurement and the CFD simulation, and to investigate the effects of outlet pressure on the numerical solution. The investigation involved ten patient-specific aneurysms reconstructed from a digital subtraction angiography image, specifically on aneurysms located at the bifurcation region...
February 4, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28159806/oscillatory-lower-body-negative-pressure-impairs-working-memory-task-related-functional-hyperemia-in-healthy-volunteers
#12
Sana Merchant, Marvin S Medow, Paul Visintainer, Courtney Terilli, Julian M Stewart
Neurovascular coupling (NVC) describes the link between an increase in task related neural activity and increased cerebral blood flow denoted "functional hyperemia". We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-Back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow (OCBF) can reduce functional hyperemia and NVC produced by a working memory task, and can interfere with working memory...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28155701/exploring-potential-association-between-flow-instability-and-rupture-in-patients-with-matched-pairs-of-ruptured-unruptured-intracranial-aneurysms
#13
Lijian Xu, Lixu Gu, Hao Liu
BACKGROUND: Patients with multiple intracranial aneurysms present a great challenge to the neurosurgeon, particularly when presenting with subarachnoid hemorrhage. Misjudgment may result in disastrous postoperative rebleeding from the untreated but true-ruptured lesion. METHODS: In this study, computational fluid dynamic simulations of two matched-pairs of ruptured-unruptured cerebral aneurysms were performed to investigate the potential association between flow instability and aneurysm rupture...
December 28, 2016: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28146671/the-neuroergonomics-of-vigilance
#14
Matthew E Funke, Joel S Warm, Gerald Matthews, Gregory J Funke, Peter Y Chiu, Tyler H Shaw, Eric T Greenlee
OBJECTIVE: The aim of this study was to examine the effects of uncertainty about where in the field of view critical signals for detection appear during a vigilance task (spatial uncertainty) on cerebral blood flow velocity (CBFV) and oculomotor fatigue. BACKGROUND: Neuroergonomics is a dimension of human factors founded by Raja Parasuraman that studies brain functions underlying performance at work. Neuroergonomic studies have shown that observers in vigilance tasks lose information-processing resources over time and experience oculomotor fatigue as indexed by a temporal decline in CBFV and elevation in eye closure as reflected in the PERCLOS metric...
February 2017: Human Factors
https://www.readbyqxmd.com/read/28140493/cerebral-high-intensity-transient-signals-during-pediatric-cardiac-catheterization-a-pilot-study-using-transcranial-doppler-ultrasonography
#15
Kerri L LaRovere, Kush Kapur, Doff B McElhinney, Alexander Razumovsky, Barry D Kussman
BACKGROUND AND PURPOSE: Cerebral emboli are one potential cause of acute brain injury in children with congenital heart disease (CHD) undergoing cardiac catheterization. In this pilot study using transcranial Doppler (TCD) ultrasonography, we sought to evaluate the incidence, burden, and circumstances of cerebral high-intensity transient signals (HITS), presumably representing emboli, during pediatric cardiac catheterization. METHODS: Emboli monitoring of the right middle cerebral artery was performed in five children...
January 31, 2017: Journal of Neuroimaging: Official Journal of the American Society of Neuroimaging
https://www.readbyqxmd.com/read/28137972/identification-of-the-upward-movement-of-human-cerebrospinal-fluid-in-vivo-and-its-relation-to-the-brain-venous-system
#16
Steffi Dreha-Kulaczewski, Arun A Joseph, Klaus-Dietmar Merboldt, Hans-Christoph Ludwig, Jutta Gärtner, Jens Frahm
: Cerebrospinal fluid (CSF) flux is involved in the pathophysiology of neurodegenerative diseases and cognitive impairment after traumatic brain injury, all hallmarked by the accumulation of cellular metabolic waste. Its effective disposal via various CSF routes has been demonstrated in animal models. In contrast, the CSF dynamics in humans are still poorly understood. Forced Inspiration has recently been identified as a main driving force of CSF flow in the human brain using novel real-time magnetic resonance imaging (MRI)...
January 30, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28113579/functional-transcranial-doppler-ultrasound-for-measurement-of-hemispheric-lateralization-during-visual-memory-and-visual-search-cognitive-tasks
#17
Benjamin Hage, Mohammed Alwatban, Erin Barney, Mark Mills, Michael Dodd, Edward Truemper, Gregory Bashford
Functional transcranial Doppler ultrasound (fTCD) is a non-invasive sensing modality that measures blood flow velocities in cerebral arteries (CBFV) with high temporal resolution. CBFV change is correlated to changes in cerebral oxygen uptake, enabling fTCD to measure brain activity and lateralization with high accuracy. However, few studies have examined the relationship of CBFV change during visual search and visual memory tasks. Here a protocol to compare lateralization between these two similar cognitive tasks using fTCD is demonstrated...
August 26, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28104922/volumetric-doppler-angle-correction-for-ultrahigh-resolution-optical-coherence-doppler-tomography
#18
Jiang You, Ang Li, Congwu Du, Yingtian Pan
Ultrahigh-resolution optical coherence Doppler tomography (μODT) demonstrates great potential for quantitative blood flow imaging owing to its large field of view and capillary resolution. However, μODT only detects the axial flow velocity and requires Doppler angle correction to retrieve the absolute velocity. Although methods for Doppler angle tracking of single or few large vessels have been reported, a method that enables angle correction of the entire 3D microvascular networks remains a challenge. Here, we present a method based on eigenvalue analysis of 3D Hessian matrix to retrieve the orientation of each tubular vessel...
January 2, 2017: Applied Physics Letters
https://www.readbyqxmd.com/read/28099160/phase-shift-between-respiratory-oscillations-in-cerebral-blood-flow-velocity-and-arterial-blood-pressure
#19
Agnieszka Uryga, Michał M Placek, Paweł Wachel, Tomasz Szczepański, Marek Czosnyka, Magdalena Kasprowicz
We aim to investigate whether phase shift between respiratory oscillations in cerebral blood flow velocity (CBFV) and arterial blood pressure (ABP) is associated with changes in cerebral autoregulation (CA) or reflects the mechano-elastic properties of the cerebrovascular bed. The relationships between respiratory phase shift and slow wave phase shift versus cerebrovascular time constant (the product of cerebrovascular resistance and compliance) and the index of CA (Mx) were analyzed during breathing at 6, 10, and 15 breaths min(-1) in 39 volunteers...
January 18, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28057635/in-vivo-assessment-of-the-impact-of-regional-intracranial-atherosclerotic-lesions-on-brain-arterial-3d-hemodynamics
#20
C Wu, S Schnell, P Vakil, A R Honarmand, S A Ansari, J Carr, M Markl, S Prabhakaran
BACKGROUND AND PURPOSE: Intracranial atherosclerosis induces hemodynamic disturbance, which is not well-characterized, particularly in cerebral flow redistribution. We aimed to characterize the impact of regional stenotic lesions on intracranial hemodynamics by using 4D flow MR imaging. MATERIALS AND METHODS: 4D flow MR imaging was performed in 22 symptomatic patients (mean age, 68.4 ± 14.2 years) with intracranial stenosis (ICA, n = 7; MCA, n = 9; basilar artery, n = 6) and 10 age-appropriate healthy volunteers (mean age, 60...
January 5, 2017: AJNR. American Journal of Neuroradiology
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