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cerebral blood flow velocity

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https://www.readbyqxmd.com/read/28642293/random-squat-stand-maneuvers-a-novel-approach-for-assessment-of-dynamic-cerebral-autoregulation
#1
Sam C Barnes, Naomi Ball, Victoria Joanna Haunton, Ronney B Panerai, Thompson G Robinson
BACKGROUND: Squat-stand maneuvers (SSM) have been used to assess dynamic cerebral autoregulation (dCA), but always at a fixed-frequency (FF). This study aimed to assess the use of random-frequency (RF) SSMs as a stimulus for measuring dCA, and to determine the reproducibility of FF and RFSSMs. METHOD: 29 healthy volunteers (19 male, mean age 23.0 [4.9] years) completed the study; 11 returned for a repeat visit (median 45 days). Heart rate, beat-to-beat blood pressure, middle cerebral artery (MCA) blood flow velocity, end-tidal CO2 and angle of the squat movement were measured...
June 22, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28627999/heritability-and-genome-wide-associations-studies-of-cerebral-blood-flow-in-the-general-population
#2
M Arfan Ikram, Hazel I Zonneveld, Gennady Roshchupkin, Albert V Smith, Oscar H Franco, Sigurdur Sigurdsson, Cornelia van Duijn, André G Uitterlinden, Lenore J Launer, Meike W Vernooij, Vilmundur Gudnason, Hieab Hh Adams
Cerebral blood flow is an important process for brain functioning and its dysregulation is implicated in multiple neurological disorders. While environmental risk factors have been identified, it remains unclear to what extent the flow is regulated by genetics. Here we performed heritability and genome-wide association analyses of cerebral blood flow in a population-based cohort study. We included 4472 persons free of cortical infarcts who underwent genotyping and phase-contrast magnetic resonance flow imaging (mean age 64...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28627298/a-prospective-transcranial-doppler-ultrasound-based-evaluation-of-the-acute-and-cumulative-effects-of-sport-related-concussion-on-neurovascular-coupling-response-dynamics
#3
Alexander D Wright, Jonathan D Smirl, Kelsey Bryk, Paul van Donkelaar
Sport-related concussion has been shown to alter cerebral blood flow (CBF) both acutely and chronically, and may exert cumulative effects across multiple injuries. Such dysfunction may be mediated by trauma-induced deficits to CBF control mechanisms, though our understanding of these effects is limited, including dynamics of neurovascular coupling (NVC) responses (i.e. CBF responses to neurologic demand). 179 junior-level contact sport athletes completed preseason testing - 42 reported never having experienced a concussion (Hx-) while 31 had endured three or more (Hx3+)...
June 18, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28618187/physically-consistent-data-assimilation-method-based-on-feedback-control-for-patient-specific-blood-flow-analysis
#4
Satoshi Ii, Mohd Azrul Hisham Mohd Adib, Yoshiyuki Watanabe, Shigeo Wada
This paper presents a novel data assimilation method for patient-specific blood flow analysis based on feedback control theory called the physically consistent feedback control-based data assimilation (PFC-DA) method. In the PFC-DA method, the signal, which is the residual error term of the velocity when comparing the numerical and reference measurement data, is cast as a source term in a Poisson equation for the scalar potential field that induces flow in a closed system. The pressure values at the inlet and outlet boundaries are recursively calculated by this scalar potential field...
June 15, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28597991/lack-of-linear-correlation-between-dynamic-and-steady-state-cerebral-autoregulation
#5
Daan L K de Jong, Takashi Tarumi, Jie Liu, Rong Zhang, Jurgen A H R Claassen
The purpose of this study was to investigate the relationship between dynamic (dCA) and steady-state cerebral autoregulation (sCA). In 28 healthy older adults, sCA was quantified by a linear regression slope of proportionate (%) changes in cerebrovascular resistance (CVR) in response to proportionate (%) changes in mean blood pressure (BP) induced by stepwise sodium nitroprusside (SNP) and phenylephrine (PhE) infusion. Cerebral blood flow (CBF) was measured at the internal carotid (ICA) and vertebral (VA) artery and cerebral blood flow velocity (CBFV) at the middle cerebral artery (MCA)...
June 9, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28594795/-assessing-efficacy-of-carotid-endarterectomy-by-means-of-intraoperative-flowmetry
#6
V A Luk'ianchikov, A S Tokarev, N A Polunina, O Iu Nakhabin, E V Udodov, V A Dalibaldian, A V Sytnik, V V Krylov
AIM: The study was aimed at determining volumetric blood flow velocity (VBFV) through the internal carotid artery (ICA) and assessing functional outcomes of treatment of patients, taking into consideration the dynamics of VBFV before and after the operation. PATIENTS AND METHODS: The study comprised a total of 53 patients subjected to examination of VBFV through the ICA before and after carotid endarterectomy (CEA) assessed by means of flowmetry. Neurological deficit was evaluated by means of the NIHS Scale (the M NIHSS prior to operation equalling 2...
2017: Angiologii︠a︡ i Sosudistai︠a︡ Khirurgii︠a︡, Angiology and Vascular Surgery
https://www.readbyqxmd.com/read/28583819/transcranial-doppler-identification-of-neurologic-injury-during-pediatric-extracorporeal-membrane-oxygenation-therapy
#7
Jay F Rilinger, Craig M Smith, Raye Ann O deRegnier, Joshua L Goldstein, Michele G Mills, Marleta Reynolds, Carl L Backer, Delilah M Burrowes, Priya Mehta, Juan Piantino, Mark S Wainwright
BACKGROUND: We used transcranial Doppler to examine changes in cerebral blood flow velocity in children treated with extracorporeal membrane oxygenation. We examined the association between those changes and radiologic, electroencephalographic, and clinical evidence of neurologic injury. METHODS: This was a retrospective review and prospective observational study of patients 18 years old and younger at a single university children's hospital. Transcranial Doppler studies were obtained every other day during the first 7 days of extracorporeal membrane oxygenation, and 1 additional study following decannulation, in conjunction with serial neurologic examinations, brain imaging, and 6- to 12-month follow-up...
June 2, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28581366/flat-head-positioning-increases-cerebral-blood-flow-in-anterior-circulation-acute-ischemic-stroke-a-cluster-randomized-phase-iib-trial
#8
Verónica V Olavarría, Pablo M Lavados, Paula Muñoz-Venturelli, Francisca González, Javier Gaete, Sheila Martins, Hisatomi Arima, Craig S Anderson, Alejandro M Brunser
Background Whether lying-flat improves blood flow in patients with acute ischemic stroke is unknown. Our aim was to investigate if lying-flat "changes" cerebral blood flow velocities assessed by transcranial Doppler in acute ischemic stroke patients. Methods In a multicenter cluster clinical trial, we randomly assigned patients within 12 h from onset of a neurological deficit due to cerebral ischemia of the anterior circulation to lying-flat or upright head positioning. The primary outcome was a change of 8 cm/s or more in mean cerebral blood flow velocities on transcranial Doppler to the middle cerebral artery at 1 and 24 h post-randomization, adjusted for imbalance in baseline variables...
January 1, 2017: International Journal of Stroke: Official Journal of the International Stroke Society
https://www.readbyqxmd.com/read/28577904/merging-computational-fluid-dynamics-and-4d-flow-mri-using-proper-orthogonal-decomposition-and-ridge-regression
#9
Ali Bakhshinejad, Ahmadreza Baghaie, Alireza Vali, David Saloner, Vitaliy L Rayz, Roshan M D'Souza
Time resolved phase-contrast magnetic resonance imaging 4D-PCMR (also called 4D Flow MRI) data while capable of non-invasively measuring blood velocities, can be affected by acquisition noise, flow artifacts, and resolution limits. In this paper, we present a novel method for merging 4D Flow MRI with computational fluid dynamics (CFD) to address these limitations and to reconstruct de-noised, divergence-free high-resolution flow-fields. Proper orthogonal decomposition (POD) is used to construct the orthonormal basis of the local sampling of the space of all possible solutions to the flow equations both at the low-resolution level of the 4D Flow MRI grid and the high-level resolution of the CFD mesh...
June 14, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28577164/internal-jugular-vein-blood-flow-in-the-upright-position-during-external-compression-and-increased-central-venous-pressure-an-ultrasound-study-in-healthy-volunteers
#10
Tze Yeng Yeoh, Lashmi Venkatraghavan, Joseph A Fisher, Massimiliano Meineri
BACKGROUND: External compression of the jugular veins is an effective method to increase intracranial blood volume and brain stiffness in rats and healthy volunteers. It has been reported that, on assuming an upright posture, cerebral venous drainage is distributed away from the internal jugular veins (IJVs) to the cervical venous plexus, causing complete collapse of the IJV. If so, it is not clear why external IJV compression would increase intracranial blood volume, but the latter is frequently observed in neurosurgery in the sitting position...
June 2, 2017: Canadian Journal of Anaesthesia, Journal Canadien D'anesthésie
https://www.readbyqxmd.com/read/28573981/at-what-data-length-do-cerebral-autoregulation-measures-stabilise
#11
Adam Mahdi, Dragana Nikolic, Antony Birch, Stephen Payne
Cerebral autoregulation is commonly assessed through mathematical models that use non-invasive measurements of arterial blood pressure and cerebral blood flow velocity. There is no agreement in the literature as to what is the minimum length of data needed for the cerebral autoregulation coefficients to stabilise. We introduce a simple empirical tool for studying the minimum length of time series needed to parameterise three popular cerebral autoregulation coefficients ARI, Mx and Phase (in the low frequency range [0...
June 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28572497/ubc-nepal-expedition-markedly-lower-cerebral-blood-flow-in-high-altitude-sherpa-children-compared-to-children-residing-at-sea-level
#12
Daniela Flück, Laura Emily Morris, Shailesh Niroula, Christine M Tallon, Kami T Sherpa, Mike Stembridge, Philip N Ainslie, Ali Mary McManus
Developmental cerebral hemodynamic adaptations to chronic high altitude exposure, such as in the Sherpa population, are largely unknown. To examine hemodynamic adaptations in the developing human brain, we assessed common carotid (CCA), internal carotid (ICA) and vertebral artery (VA) flow and middle cerebral artery (MCA) velocity in 25 (9.6±1.0 y, 129±9 cm, 27±8 kg, 14 girls) Sherpa children (3800m, Nepal) and 25 (9.9±0.7 y, 143±7 cm, 34±6 kg, 14 girls) age-matched sea-level children (344m, Canada) during supine rest...
June 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28567105/cerebral-haemodynamics-in-early-puerperium-a-prospective-study
#13
G P Anzola, R Brighenti, M Cobelli, A Giossi, S Mazzucco, S Olivato, E Pari, M P Piras, A Padovani, F Rinaldi, G Turri
AIM: Prospective study on 900 consecutive puerperae to assess normal values and range of the blood flow velocity in the middle cerebral artery in both hemispheres. MATERIAL AND METHOD: M1 and M2 segments of both middle cerebral arteries were assessed in all subjects within 96 hours of delivery. Mean flow velocity was recorded after adjusting for insonation angle. Lindegaard index (LI = middle cerebral artery-Internal Carotid Artery mean flow velocity ratio) was calculated whenever the mean flow velocity exceeded 100 cm/second...
May 2017: Ultrasound: Journal of the British Medical Ultrasound Society
https://www.readbyqxmd.com/read/28554964/decreasing-cerebral-oxygen-consumption-during-upright-tilt-in-vasovagal-syncope
#14
Marvin S Medow, Mira L Kothari, Amanda M Goetz, Mary Breige O'Donnell-Smith, Courtney Terilli, Julian M Stewart
We measured changes in transcranial Doppler ultrasound (TCD) and near infrared spectroscopy (NIRS) during 70° upright tilt in patients with recurrent vasovagal syncope (VVS, N = 20), postural tachycardia syndrome (POTS, N = 20), and healthy controls (N = 12) aged 15-27 years old. VVS was included if they fainted during testing within 5-15 min of upright tilt. We combined TCD and NIRS to obtain estimates of percent change in the cerebral metabolic rate of oxygen consumption (CMRO2), cerebral blood flow velocity (CBFv), and oxygen extraction fraction (OEF)...
May 2017: Physiological Reports
https://www.readbyqxmd.com/read/28541891/critical-closing-pressure-during-controlled-increase-in-intracranial-pressure-comparison-of-three-methods
#15
Katarzyna Kaczmarska, Magdalena Kasprowicz, Agnieszka Uryga, Leanne Calviello, Georgios Varsos, Zofia Czosnyka, Marek Czosnyka
Critical closing pressure (CrCP) is the arterial blood pressure (ABP) threshold, below which small arterial vessels collapse and cerebral blood flow ceases. Here we aim to compare three methods for CrCPestimation in scenario of a controlled increase in intracranial pressure (ICP), induced by infusion tests performed in patients with suspected normal pressure hydrocephalus (NPH). METHODS: Computer recordings of directly-measured ICP, ABP and transcranial Doppler cerebral blood flow velocity (CBFV), from 37 NPH patients undergoing infusion tests, were retrospectively analyzed...
May 24, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28539354/cerebral-oxygenation-and-regional-cerebral-perfusion-responses-with-resistance-breathing-during-central-hypovolemia
#16
Victoria L Kay, Justin Daniel Sprick, Caroline A Rickards
Resistance breathing improves tolerance to central hypovolemia induced by lower body negative pressure (LBNP), but this is not related to protection of anterior cerebral blood flow (indexed by mean middle cerebral artery velocity, MCAv). We hypothesized that inspiratory resistance breathing improves tolerance to central hypovolemia by maintaining cerebral oxygenation (ScO2), and protecting cerebral blood flow in the posterior cerebral circulation (indexed by posterior cerebral artery velocity, PCAv). Eight subjects (4M/4F) completed two experimental sessions of a presyncopal-limited LBNP protocol (3 mmHg/min onset rate) with and without (Control) resistance breathing via an impedance threshold device (ITD)...
May 24, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28537493/the-relationship-between-cerebral-vasoreactivity-and-post-concussive-symptom-severity
#17
Tamadher Albalawi, Jason W Hamner, Matthew Lapointe, William Meehan, Can Ozan Tan
While pathophysiology underlying post-concussion symptom burden is unknown, data suggest that cerebrovascular dysfunction may be among the culprits. We sought to determine whether the degree of impairment in the ability of cerebrovasculature to buffer against changes in arterial gases (vasoreactivity) is associated with concussion symptoms. In 15 participants (19±5 years, 1 week to 1 year post-injury) diagnosed with concussion, we assessed vasoreactivity from the slope of the linear relationship of beat-by-beat middle cerebral artery blood flow velocity (transcranial Doppler ultrasound) to end-tidal CO<sub>2</sub> during progressive increases in end-tidal CO<sub>2</sub> (air rebreathing)...
May 24, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28526782/acute-impact-of-drinking-coffee-on-the-cerebral-and-systemic-vasculature
#18
Takuro Washio, Hiroyuki Sasaki, Shigehiko Ogoh
Previous studies have suggested that the risk of ischemic stroke increases immediately after drinking coffee. Indeed, drinking coffee, that is, caffeine, acutely increases arterial stiffness as well as blood pressure and peripheral vascular resistance. On the other hand, it has been reported that arterial stiffening is associated with elevation in the pulsatility index (PI) of cerebral blood flow (CBF), which increases the risk of brain disease. However, the effect of drinking coffee on the PI of the CBF and its interaction with arterial stiffness remain unknown...
May 2017: Physiological Reports
https://www.readbyqxmd.com/read/28505975/reduced-cardiovascular-functions-in%C3%A2-patients-with-alzheimer-s-disease
#19
Wang-Sheng Jin, Xian-Le Bu, Ye-Ran Wang, Ling Li, Wei-Wei Li, Yu-Hui Liu, Chi Zhu, Xiu-Qing Yao, Yang Chen, Chang-Yue Gao, Tao Zhang, Hua-Dong Zhou, Fan Zeng, Yan-Jiang Wang
Previous studies have suggested that cardiovascular functions might play a critical role in Alzheimer's disease (AD) pathogenesis. However, the relationship among heart function, blood flow of cerebral vessels, and AD remains unclear. In the present study, AD patients (n = 34) and age- and gender-matched cognitively normal controls (n = 34) were recruited. Demographic and comorbidity information was collected. The ejection fraction was measured using echocardiography, and the mean velocity, pulsatility index (PI), and resistance index (RI) of the basilar artery (BA), left terminal internal carotid artery (LTICA), and right terminal internal carotid artery (RTICA) were measured using transcranial Doppler...
2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28490201/a-comparison-of-haemodynamics-between-subcranial-intracranial-bypass-and-the-traditional-extracranial-intracranial-bypass
#20
Zaitao Yu, Yang Yang, Xiang'en Shi, Hai Qian, Fangjun Liu
BACKGROUND: Ischemic cerebrovascular diseases are traditionally treated using an extracranial-intracranial (EC-IC) bypass. The use of the internal maxillary artery (IMA) in the subcranial-intracranial (SC-IC) bypass was recently described as an alternative treatment. However, the haemodynamics of this new approach have not been defined. METHODS: The haemodynamic parameters (flow volume [FV], internal diameter [ID], time-averaged mean velocity [TAM], pulsatility index [PI] and resistance index [RI]) of the IMA-radial artery graft (RAG)-middle cerebral artery (MCA) (n = 12) bypass and superficial temporal artery (STA)-MCA bypass (n = 18) were measured using intraoperative duplex ultrasonography and compared...
May 11, 2017: British Journal of Neurosurgery
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