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Transcranial doppler ultrasound

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https://www.readbyqxmd.com/read/27881556/nitrite-and-s-nitrosohemoglobin-exchange-across-the-human-cerebral-and-femoral-circulation-relationship-to-basal-and-exercise-blood-flow-responses-to-hypoxia
#1
Damian M Bailey, Peter Rasmussen, Morten Overgaard, Kevin A Evans, Aske M Bohm, Thomas Seifert, Patrice Brassard, Morten Zaar, Henning B Nielsen, Peter Raven, Niels H Secher
BACKGROUND: -The mechanisms underlying red blood cell (RBC)-mediated hypoxic vasodilation remain controversial with separate roles for nitrite (NO2(-)) and S-nitrosohemoglobin (SNO-Hb) widely contested given their ability to transduce nitric oxide (NO) bioactivity within the microcirculation. To establish their relative contribution in vivo, we quantified arterial-venous (a-v) concentration gradients across the human cerebral and femoral circulation at rest and during exercise, an ideal model system characterized by physiological extremes of O2 tension and blood flow...
November 15, 2016: Circulation
https://www.readbyqxmd.com/read/27875362/relationship-between-hiv-infection-antiretroviral-therapy-inflammatory-markers-and-cerebrovascular-endothelial-function-among-adults-in-urban-china
#2
Felicia C Chow, Yanling Li, Yinghuan Hu, Joy Chan, Huanling Wang, Weihai Xu, Richard W Price, Farzaneh A Sorond, Taisheng Li
BACKGROUND: Cerebrovascular risk is increased in people living with HIV infection compared with age-matched uninfected individuals. Cerebrovascular endothelial dysfunction related to antiretroviral therapy and inflammation may contribute to higher stroke risk in HIV infection. METHODS: We compared cerebral vasoreactivity-a measure of cerebrovascular endothelial function assessed by the breath holding index (BHI) using transcranial Doppler ultrasound-between virologically suppressed Chinese HIV-infected individuals followed in an HIV clinic in Beijing, China and uninfected controls...
November 21, 2016: Journal of Acquired Immune Deficiency Syndromes: JAIDS
https://www.readbyqxmd.com/read/27843693/treatment-and-imaging-of-intracranial-atherosclerotic-stenosis-current-perspectives-and-future-directions
#3
REVIEW
Ido R van den Wijngaard, Ghislaine Holswilder, Marianne A A van Walderveen, Ale Algra, Marieke J H Wermer, Osama O Zaidat, Jelis Boiten
BACKGROUND AND PURPOSE: Intracranial atherosclerosis is a common cause of stroke worldwide. It results in ischemic stroke due to different mechanisms including artery-to-artery embolism, in situ thrombo-occlusion, occlusion of perforating arteries, and hemodynamic failure. In this review, we present an overview of current treatment and imaging modalities in intracranial atherosclerotic stenosis. METHODS: PubMed was searched for relevant articles in English that evaluated the treatment and imaging of intracranial atherosclerotic stenosis (ICAS)...
November 2016: Brain and Behavior
https://www.readbyqxmd.com/read/27837190/hyperoxia-results-in-increased-aerobic-metabolism-following-acute-brain-injury
#4
Arnab Ghosh, David Highton, Christina Kolyva, Ilias Tachtsidis, Clare E Elwell, Martin Smith
Acute brain injury is associated with depressed aerobic metabolism. Below a critical mitochondrial pO2 cytochrome c oxidase, the terminal electron acceptor in the mitochondrial respiratory chain, fails to sustain oxidative phosphorylation. After acute brain injury, this ischaemic threshold might be shifted into apparently normal levels of tissue oxygenation. We investigated the oxygen dependency of aerobic metabolism in 16 acutely brain-injured patients using a 120-min normobaric hyperoxia challenge in the acute phase (24-72 h) post-injury and multimodal neuromonitoring, including transcranial Doppler ultrasound-measured cerebral blood flow velocity, cerebral microdialysis-derived lactate-pyruvate ratio (LPR), brain tissue pO2 (pbrO2), and tissue oxygenation index and cytochrome c oxidase oxidation state (oxCCO) measured using broadband spectroscopy...
November 11, 2016: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/27796172/risk-factors-between-intracranial-extracranial-atherosclerosis-and-anterior-posterior-circulation-stroke-in-ischaemic-stroke
#5
Yan Li, Yefeng Cai, Min Zhao, Jingbo Sun
OBJECTIVES: Atherosclerosis is an important cause of stroke and remains a challenge for stroke prevention. Risk factors involved in atherosclerotic stroke and anterior and posterior circulation strokes (ACS and PCS, respectively) are different. The purpose of this study is to investigate differences in risk factors between intracranial and extracranial atherosclerosis (ICAS and ECAS), ACS and PCS, and ICAS/ECAS with ACS/PCS in a Chinese acute ischaemic stroke population. METHODS: We analysed 551 ischaemic stroke patients who had been enrolled between August 2005 and July 2008...
October 31, 2016: Neurological Research
https://www.readbyqxmd.com/read/27757739/cerebral-hemodynamics-in-sepsis-assessed-by-transcranial-doppler-a-systematic-review-and-meta-analysis
#6
Daniel Silva de Azevedo, Angela Salomao Macedo Salinet, Marcelo de Lima Oliveira, Manoel Jacobsen Teixeira, Edson Bor-Seng-Shu, Ricardo de Carvalho Nogueira
Cerebral microcirculation is gradually compromised during sepsis, with significant reductions in the function of capillaries and blood perfusion in small vessels. Transcranial Doppler ultrasound (TCD) has been used to assess cerebral circulation in a typical clinical setting. This study was to systematically review TCD studies, assess their methodological quality, and identify trends that can be associated with the temporal evolution of sepsis and its clinical outcome. A meta-analysis of systematic reviews was conducted according to the PRISMA statement...
October 18, 2016: Journal of Clinical Monitoring and Computing
https://www.readbyqxmd.com/read/27754235/os-34-02-concentration-dependent-effect-of-plasma-resveratrol-on-cerebral-vasodilator-responsiveness-cvr-in-adults-with-type-2-diabetes-mellitus-t2dm
#7
Rachel Wong, Rhenan Nealon, Daniel Raederstorff, Peter Howe
OBJECTIVE: Having shown that resveratrol consumption can improve flow mediated dilation of the brachial artery, we tested its effects on CVR to hypercapnia in adults with T2DM, a risk population for cerebrovascular disease and cognitive impairments. DESIGN AND METHOD: In a double-blind crossover trial, 34 adults with T2DM consumed 0, 75, 150 and 300 mg of synthetic trans-resveratrol (one dose per week in random order). Before and 1-2 hr after dosing, transcranial Doppler ultrasound was used to assess CVR to a hypercapnic stimulus (breathing Carbogen gas for 3 min) in the middle (MCA) and posterior (PCA) cerebral arteries...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27721780/the-need-for-a-rational-approach-to-vasoconstrictive-syndromes-transcranial-doppler-and-calcium-channel-blockade-in-reversible-cerebral-vasoconstriction-syndrome
#8
Elisabeth B Marsh, Wendy C Ziai, Rafael H Llinas
INTRODUCTION: Reversible cerebral vasoconstriction syndrome (RCVS) typically affects young patients and left untreated can result in hemorrhage or ischemic stroke. Though the disorder has been well characterized in the literature, the most appropriate way to diagnose, treat, and evaluate therapeutic response remains unclear. In previous studies, transcranial Doppler ultrasound (TCD) has shown elevated velocities indicative of vasospasm. This imaging modality is noninvasive and inexpensive; an attractive option for diagnosis and therapeutic monitoring if it is sensitive enough to detect changes in the acute setting given that RCVS often affects the distal vessels early in the course of disease...
May 2016: Case Reports in Neurology
https://www.readbyqxmd.com/read/27643195/os-34-02-concentration-dependent-effect-of-plasma-resveratrol-on-cerebral-vasodilator-responsiveness-cvr-in-adults-with-type-2-diabetes-mellitus-t2dm
#9
Rachel Wong, Rhenan Nealon, Daniel Raederstorff, Peter Howe
OBJECTIVE: Having shown that resveratrol consumption can improve flow mediated dilation of the brachial artery, we tested its effects on CVR to hypercapnia in adults with T2DM, a risk population for cerebrovascular disease and cognitive impairments. DESIGN AND METHOD: In a double-blind crossover trial, 34 adults with T2DM consumed 0, 75, 150 and 300 mg of synthetic trans-resveratrol (one dose per week in random order). Before and 1-2 hr after dosing, transcranial Doppler ultrasound was used to assess CVR to a hypercapnic stimulus (breathing Carbogen gas for 3 min) in the middle (MCA) and posterior (PCA) cerebral arteries...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27634602/brain-perfusion-and-arterial-blood-flow-velocity-during-prolonged-body-tilting
#10
David Montero, Sven Rauber
BACKGROUND: It remains unknown whether brain perfusion is preserved and mirrored by middle cerebral blood flow velocity (MCA BFV) during prolonged changes in body posture. Herein, we examined the impact of sustained (180 min) 30° head-up (HUT) and head-down (HDT) tilt on brain perfusion, as determined by MCA BFV and blood flow in the extracranial arteries. METHODS: In 10 healthy male subjects, arterial diameters, BFVs, and blood flows were determined in the left internal carotid (ICA) and vertebral (VA) arteries using duplex Doppler ultrasound in supine rest, and 5, 20, 60, 120, and 180 min following 30° HUT and HDT...
August 2016: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/27634108/the-effects-of-superimposed-tilt-and-lower-body-negative-pressure-on-anterior-and-posterior-cerebral-circulations
#11
Michael M Tymko, Caroline A Rickards, Rachel J Skow, Nathan C Ingram-Cotton, Michael K Howatt, Trevor A Day
Steady-state tilt has no effect on cerebrovascular reactivity to increases in the partial pressure of end-tidal carbon dioxide (PETCO2). However, the anterior and posterior cerebral circulations may respond differently to a variety of stimuli that alter central blood volume, including lower body negative pressure (LBNP). Little is known about the superimposed effects of head-up tilt (HUT; decreased central blood volume and intracranial pressure) and head-down tilt (HDT; increased central blood volume and intracranial pressure), and LBNP on cerebral blood flow (CBF) responses...
September 2016: Physiological Reports
https://www.readbyqxmd.com/read/27623561/transcranial-doppler-re-screening-of-subjects-who-participated-in-stop-and-stop-ii
#12
Robert J Adams, Dan T Lackland, Lynette Brown, David Brown, Jenifer Voeks, Heather J Fullerton, Julie Kanter, Janet L Kwiatkowski
In children with Sickle Cell Disease, the combination of risk stratification with Transcranial Doppler Ultrasound (TCD) and selective chronic red cell transfusion (CRCT-the STOP Protocol) is one of the most effective stroke prevention strategies in medicine. How fully it is being implemented is unclear. Nineteen of 26 sites that conducted the two pivotal clinical trials (STOP and STOP II) participated in Post STOP, a comprehensive medical records review assessing protocol implementation in the 10-15 years since the trials ended...
December 2016: American Journal of Hematology
https://www.readbyqxmd.com/read/27615115/quantifying-cerebrovascular-reactivity-in-anterior-and-posterior-cerebral-circulations-during-voluntary-breath-holding
#13
Christina D Bruce, Craig D Steinback, Uday V Chauhan, Jamie R Pfoh, Maria Abrosimova, Emily R Vanden Berg, Rachel J Skow, Margie H Davenport, Trevor A Day
What is the central question of this study? We developed and validated a 'stimulus index' (SI; ratio of end-tidal partial pressures of CO2 and O2 ) method to quantify cerebrovascular reactivity (CVR) in anterior and posterior cerebral circulations during breath holding. We aimed to determine whether the magnitude of CVR is correlated with breath-hold duration. What is the main finding and its importance? Using the SI method and transcranial Doppler ultrasound, we found that the magnitude of CVR of the anterior and posterior cerebral circulations is not positively correlated with physiological or psychological break-point during end-inspiratory breath holding...
December 1, 2016: Experimental Physiology
https://www.readbyqxmd.com/read/27598350/personalized-reminders-increase-screening-for-stroke-risk-in-children-with-sickle-cell-anemia
#14
Devin S Muntz, David G Bundy, John J Strouse
OBJECTIVES: Transcranial Doppler ultrasound (TCD) effectively identifies children with sickle cell anemia (SCA) who are at increased risk of stroke. We evaluated a low-cost quality improvement (QI) intervention to increase the proportion of children screened by TCD. METHODS: We measured the proportion of children with SCA receiving appropriate TCD screening for increased cerebral blood velocity, a marker of stroke risk, for time periods before (April 1, 2009-July 1, 2010) and after (October 1, 2010-January 1, 2012) the implementation of a QI program...
September 2016: Southern Medical Journal
https://www.readbyqxmd.com/read/27591061/assessment-of-cerebral-embolism-and-vascular-reserve-parameters-in-patients-with-carotid-artery-stenosis
#15
Przemyslaw Puz, Anetta Lasek-Bal, Tomasz Urbanek, Zofia Kazibutowska
AIM: Carotid artery stenosis can result in the brain tissue injury related to the intracranial aterial flow disturbances as well as microembolic complications. The choice of the proper therapy in patients with carotid artery stenosis, especially asymptomatic, remains still a significant clinical problem. The study aim was an assessment of the cerebral embolism and brain vascular reserve parameters in patients with carotid artery stenosis regarding the occurrence of the clinical symptoms, the degree of stenosis as well as plaque morphology...
2016: Neurologia i Neurochirurgia Polska
https://www.readbyqxmd.com/read/27579796/doppler-and-duplex-sonography-for-the-diagnosis-of-the-irreversible-cessation-of-brain-function-brain-death-current-guidelines-in-germany-and-neighboring-countries
#16
U Walter, S J Schreiber, M Kaps
Extra- and transcranial sonography of brain-supplying arteries is accepted worldwide in brain death protocols as a valid "ancillary" method of proving brain circulatory arrest. Color-coded duplex sonography and CT angiography have been newly incorporated in the fourth update of the German Medical Association's guidelines for the determination of the irreversible cessation of brain function ("brain death"), effective July 2015. The updated guidelines address in more detail the diagnostic procedures and the required qualifications of the examiners...
August 31, 2016: Ultraschall in der Medizin
https://www.readbyqxmd.com/read/27576247/functional-transcranial-doppler-ultrasound-for-measurement-of-hemispheric-lateralization-during-visual-memory-and-visual-search-cognitive-tasks
#17
Benjamin Hage, Mohammed R Alwatban, Erin Barney, Mark Mills, Michael D Dodd, Edward J Truemper, Gregory R Bashford
Functional transcranial Doppler ultrasound (fTCD) is a noninvasive sensing modality that measures cerebral blood flow velocity (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...
December 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27567295/early-predictors-of-fever-in-patients-with-aneurysmal-subarachnoid-hemorrhage
#18
Ivan Rocha Ferreira da Silva, Gabriel Rodriguez de Freitas
BACKGROUND: Fever is commonly observed in patients who have had aneurysmal subarachnoid hemorrhage (SAH), and it has been associated with the occurrence of delayed cerebral ischemia and worse outcomes in previous studies. Frequently, fever is not the result of bacterial infections, and distinction between infection-related fever and fever secondary to brain injury (also referred as central fever) can be challenging. OBJECTIVES: The current study aimed to identify risk factors on admission for the development of central fever in patients with SAH...
August 23, 2016: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/27550986/post-exercise-syncope-wingate-syncope-test-and-visual-cognitive-function
#19
Dylan C Sieck, Matthew R Ely, Steven A Romero, Meredith J Luttrell, Pedro M Abdala, John R Halliwill
Adequate cerebral perfusion is necessary to maintain consciousness in upright humans. Following maximal anaerobic exercise, cerebral perfusion can become compromised and result in syncope. It is unknown whether post-exercise reductions in cerebral perfusion can lead to visual-cognitive deficits prior to the onset of syncope, which would be of concern for emergency workers and warfighters, where critical decision making and intense physical activity are combined. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood velocity, induced by maximal anaerobic exercise and head-up tilt, result in visual-cognitive deficits prior to the onset of syncope...
August 2016: Physiological Reports
https://www.readbyqxmd.com/read/27544864/two-stage-cerebral-hemodynamic-changes-in-staged-carotid-angioplasty-and-stenting
#20
Fei Wu, Lei Huang, Gang Lu, Liang Ge, Xiaolong Zhang, Wenjie Cao, Qiang Dong
BACKGROUND/OBJECTIVE: We sought to assess the different patterns of cerebral hemodynamic changes in staged carotid angioplasty and stenting (CAS). METHODS: We prospectively recruited a cohort of patients with regular angioplasty or staged angioplasty from October 2013 to August 2015. The hemodynamic changes, including peak systolic, end-diastolic, and mean flow velocities in the ipsilateral middle cerebral artery (MCA) and the contralateral anterior cerebral artery (ACA), were recorded by transcranial Doppler ultrasound...
August 17, 2016: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
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