Cerebral Artery Blood Flow Research Articles

Value of cerebral hypoxic-ischemic injury markers in the early diagnosis of sepsis associated encephalopathy in burn patients with sepsis

Value of cerebral hypoxic-ischemic injury markers in the early diagnosis of sepsis associated encephalopathy in burn patients with sepsis

Middle Cerebral Artery Pulsatility Index Correlates with Prognosis and Diastolic Dysfunctions in Acute Ischemic Stroke

ObjectiveTo determine transcranial Doppler ultrasonography (TCD) parameters related to unfavorable outcomes, and to clarify the correlations between those parameters and heart functions in acute ischemic stroke without major vessel stenoses and occlusions. Materials and methodsPatients were selected from a comprehensive stroke center between October 2012 and June 2019. Inclusion criteria were: 1) acute ischemic stroke without major vessel stenoses and occlusions; and 2) ability to measure blood flow in the middle cerebral artery by TCD. Unfavorable outcomes were defined as a modified Rankin Scale score of 2–6 at 3 months after onset. First, we investigated TCD parameters related to unfavorable outcomes. Second, correlations between those parameters and heart functions as assessed by transthoracic echocardiography were evaluated. ResultsWe screened 1,527 consecutive ischemic stroke patients, including 130 patients (109 [83%] male; median age, 60 years). Middle cerebral artery pulsatility index (M1 PI) (Odds ratio (OR) 0.057, 95%confidence interval (CI) 0.007–0.494, p = 0.009) was independently associated with unfavorable outcomes. Concerning the relation between M1 PI and heart functions, peak early filling velocity/velocity of mitral annulus early diastolic motion (E/e') (OR 1.195, 95%CI 1.011–1.413, p = 0.037) was a factor independently associated with high M1 PI. ConclusionsHigh M1 PI predicts unfavorable outcome regardless of ischemic stroke subtype without major vessel stenoses and occlusions. High M1 PI correlates with high E/e', suggesting diastolic dysfunction.

Прогнозирование перинатального исхода при преэклампсии на основании доплерометрических показателей

Objective of the Review: To present current literature data on the prediction of perinatal outcomes in pregnant women with preeclampsia and on potential strategies for improving the prediction of outcomes of pregnancy complicated by preeclampsia based on Doppler parameters. Key points. The results of studies devoted to the choice of the most optimal Doppler indicators that can be used to predict perinatal outcome are presented. This review presents an analysis of the accuracy of Doppler parameters (pulsation index in the middle cerebral and umbilical arteries, resistance index, cerebroplacental ratio) in predicting adverse perinatal outcomes in pregnancy complicated by preeclampsia. A review of the current literature on the prediction of perinatal outcomes and management of pregnant women with preeclampsia and potential strategies improving the prediction of outcomes of pregnancy complicated by preeclampsia. Conclusion. Currently, dopplerometry in obstetric practice is a highly accurate prognostic method for determining the perinatal outcome in complicated pregnancy. This method allows to predict the actual risk to the fetus, monitor and evaluate its degree along with other methods of antenatal care, and also allows you to choose the time and method of delivery if the risk of intrauterine death of the fetus is high. Keywords: parameters of fetal cerebral hemodynamics, velocity and pulsation of blood flow in the middle cerebral artery, cerebroplacental ratio, gestational period, Doppler parameters, preeclampsia.

Acupuncture Effects on Cerebral Blood Flow during Normoxia and Normobaric Hypoxia: Results from a Prospective Crossover Pilot Study

Cerebral blood flow (CBF) is significantly influenced by exposure to hypoxia, both hypobaric and normobaric. Alterations in cerebral blood flow can play a crucial role in the pathogenesis of acute mountain sickness (AMS) and its symptoms, especially headache, dizziness, and nausea. Acupuncture has been proven to be effective in treating some cerebrovascular disorders and PC6 Nei Guan stimulation seems to enhance cerebral blood flow. Therefore, we have hypothesized that PC6 Nei Guan stimulation could affect CBF in acute hypoxia and could be used to contrast AMS symptoms. We evaluated blood flow in the middle cerebral artery (MCA) in normoxia, after 15 min in normobaric hypoxia (fraction of inspired oxygen (FiO2) 14%, corresponding to 3600 m a.s.l.) in basal conditions, and after PC6 Nei Guan stimulation, both by needle and by pressure. No comparisons with other acupuncture points and sham acupuncture were done. PC6 stimulation seemed to counteract the effects of acute normobaric hypoxia on end-diastolic velocity (EDV) in MCA, especially after acupuncture, and significantly reduced systolic and diastolic blood pressure. A rebalance of CBF could control some AMS symptoms, but further studies are necessary.

Abstract 11243: Novel Peptide for Cardiopulmonary Resuscitation

Introduction: While effective for out-of-hospital cardiac arrest, therapeutic hypothermia can be difficult to timely implement clinically. No drugs exist for improving neurologically intact survival. We have developed a novel peptide (TAT-PHLPP) that inhibits PH domain and Leucine rich repeat Protein Phosphatases (PHLPP), leading to Akt activation and mimicking of the protective effects of therapeutic hypothermia without the need of physical cooling. Hypothesis: We hypothesize that when administered intravenously during CPR, TAT-PHLPP improves neurologically intact survival. Methods: We conducted parallel studies in mouse and swine models. In C57BL6 mice (n = 72), we induced a 8 or 12-min asystolic cardiac arrest with KCl, followed by initiation of CPR and blinded randomized administration of TAT-PHLPP (7.5 mg/kg) or saline placebo. The primary outcomes were 4-h and 5-day survival, mean arterial blood pressure (MAP) and cerebral blood flow (CBF). We assessed PHLPP-NHERF1 binding and glucose utilization (via pyruvate dehydrogenase (PDH) phosphorylation and ATP generation). In 16 swine, we induced 5 min of VF followed by ACLS with vest CPR and administered two doses of TAT-PHLPP or saline. Survival (24 h) and neurological function were assessed. Plasma biomarkers taurine and glutamate levels in mice were measured and validated in CA patients (n=68) with a shockable rhythm at the time of hospital arrival, 6, 24, 48, and 72 h post-hospital arrival. Results: In mice, compared to saline, TAT-PHLPP significantly improved 4-h and 5-day survival, increased post-ROSC MAP and CBF, inhibited PHLPP-NHERF1 binding, increased p-Akt, decreased p-PDH (increased activity) at 15 min post-ROSC, enhanced ATP generation in both heart and brain, and reduced plasma taurine and glutamate levels. In swine, TAT-PHLPP improved 24 h neurologically intact survival (1/9 in control vs. 6/7 with peptide, p < 0.01). In patients, taurine levels were higher in non-survivors (n=44) than survivors (n=24) at 6 h of post-hospital arrival (65.9 ± 34.8 vs. 45.6 ±23.7, p< 0.001). Conclusions: TAT-PHLPP has high translational potential as a first-of-class biologic treatment to reproduce critical outcomes of therapeutic hypothermia and improve cardiac arrest survival.

Green Tea Extract Concurrent with an Oral Nutritional Supplement Acutely Enhances Muscle Microvascular Blood Flow without Altering Leg Glucose Uptake in Healthy Older Adults.

Postprandial macro- and microvascular blood flow and metabolic dysfunction manifest with advancing age, so vascular transmuting interventions are desirable. In this randomised, single-blind, placebo-controlled, crossover trial, we investigated the impact of the acute administration of green tea extract (GTE; containing ~500 mg epigallocatechin-3-gallate) versus placebo (CON), alongside an oral nutritional supplement (ONS), on muscle macro- and microvascular, cerebral macrovascular (via ultrasound) and leg glucose/insulin metabolic responses (via arterialised/venous blood samples) in twelve healthy older adults (42% male, 74 ± 1 y). GTE increased m. vastus lateralis microvascular blood volume (MBV) at 180 and 240 min after ONS (baseline: 1.0 vs. 180 min: 1.11 ± 0.02 vs. 240 min: 1.08 ± 0.04, both p < 0.005), with MBV significantly higher than CON at 180 min (p < 0.05). Neither the ONS nor the GTE impacted m. tibialis anterior perfusion (p > 0.05). Leg blood flow and vascular conductance increased, and vascular resistance decreased similarly in both conditions (p < 0.05). Small non-significant increases in brachial artery flow-mediated dilation were observed in the GTE only and middle cerebral artery blood flow did not change in response to GTE or CON (p > 0.05). Glucose uptake increased with the GTE only (0 min: 0.03 ± 0.01 vs. 35 min: 0.11 ± 0.02 mmol/min/leg, p = 0.007); however, glucose area under the curve and insulin kinetics were similar between conditions (p > 0.05). Acute GTE supplementation enhances MBV beyond the effects of an oral mixed meal, but this improved perfusion does not translate to increased leg muscle glucose uptake in healthy older adults.

Sleep deprivation impairs cognitive performance, alters task-associated cerebral blood flow and decreases cortical neurovascular coupling-related hemodynamic responses

Sleep deprivation (SD) is a common condition and an important health concern. In addition to metabolic and cardiovascular risks, SD associates with decreases in cognitive performance. Neurovascular coupling (NVC, "functional hyperemia") is a critical homeostatic mechanism, which maintains adequate blood supply to the brain during periods of intensive neuronal activity. To determine whether SD alters NVC responses and cognitive performance, cognitive and hemodynamic NVC assessments were conducted prior to and 24 h post-SD in healthy young male individuals (n = 10, 27 ± 3 years old). Cognition was evaluated with a battery of tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Hemodynamic components of NVC were measured by transcranial Doppler sonography (TCD) during cognitive stimulation, dynamic retinal vessel analysis (DVA) during flicker light stimulation, and functional near infrared spectroscopy (fNIRS) during finger tapping motor task. Cognitive assessments revealed impairments in reaction time and sustained attention after 24 h of SD. Functional NIRS analysis revealed that SD significantly altered hemodynamic responses in the prefrontal cortex and somatosensory cortex during a motor task. NVC-related vascular responses measured by DVA and TCD did not change significantly. Interestingly, TCD detected decreased task-associated cerebral blood flow (CBF) in the right middle cerebral artery in sleep deprived participants. Our results demonstrate that 24 h of SD lead to impairments in cognitive performance together with altered CBF and hemodynamic components of cortical NVC responses.

Association of Hemodynamic and Cerebrovascular Responses to Exercise With Symptom Severity in Adolescents and Young Adults With Concussion.

Aerobic exercise has become a useful method to assist with postconcussion management. Exercise can exacerbate concussion symptoms even when symptoms are not apparent at rest. Few studies have examined the reasons for symptom exacerbation during exercise following a concussion. We had 2 primary objectives: (1) to delineate cardiopulmonary and cerebrovascular responses to exercise in adolescents and young adults with a concussion and healthy controls and (2) to determine the association between cerebrovascular responses and symptom burden. We recruited participants with a recent concussion from a sport concussion clinic between September 1, 2018, and February 22, 2020. They were included if their concussion occurred <3 weeks before initial testing and if they were symptomatic at rest. Participants were excluded if they sustained a concussion in the past year (excluding index injury), reported history of neurologic disorders, or were using medications/devices that may alter neurologic function. Participants completed a progressive, symptom-limited, submaximal exercise protocol on a stationary bicycle. We assessed heart rate, blood pressure, fraction of end tidal CO2 (FETCO2), and middle cerebral artery blood flow velocity (CBF) and cerebrovascular function (vasoactivity and autoregulation) at seated rest and during exercise. We conducted 107 exercise tests (40 concussed, 37 healthy participants initially; 30 concussed at follow-up). Concussed participants were tested initially (mean 17.6 ± 2.2 [SD] years of age; 55% female; mean 12.5 ± 4.7 days postconcussion) and again 8 weeks later (mean 73.3 ± 9.5 days postconcussion). Control participants (mean 18.3 ± 2.4 years; 62% female) were tested once. FETCO2 increased throughout the exercise protocol as heart rate increased, reached a plateau, and declined at higher exercise intensities. CO2 explained >25% of the variation in resting CBF (R 2 > 0.25; p < 0.01) in most (73% individuals). Within the concussion group, resting symptom severity and the heart rate at which FETCO2 reached a plateau explained ∼2/3s of variation in exercise-induced symptom exacerbation (R 2 = 0.65; FETCO2 β = -1.210 ± 0.517 [SE], p < 0.05). There was a moderate, statistically significant relationship between cerebrovascular responses to CO2 at rest (cerebral vasoactivity) and cerebrovascular responses to exercise-induced changes in FETCO2 (R 2 = 0.13, p = 0.01). The arterial CO2 response and symptom exacerbation relationship during postconcussion aerobic exercise may be mediated by increased sensitivity of cerebral vasculature to exercise-related increase in CO2.

Effect of breath-hold on the responses of arterial blood pressure and cerebral blood velocity to isometric exercise.

The present study examined the effect of breath-hold without a Valsalva maneuver during isometric exercise on arterial blood pressure (ABP) and cerebral blood flow (CBF). Twenty healthy adults (15 men and five women) randomly performed only breath-hold without a Valsalva maneuver (BH), and an isometric handgrip exercise for 30s at 40% of individual maximal voluntary contraction with continuous breathing (IHG) and with breath-hold without the Valsalva maneuver (IHG-BH). Mean ABP (MAP) and blood velocity in the middle (MCA Vmean) and posterior cerebral arteries (PCA Vmean) were continuously measured throughout each protocol. MAP was elevated during the IHG-BH compared with IHG (P < 0.001) and BH (P = 0.001). Similarly, both MCA Vmean and PCA Vmean were higher during IHG-BH compared with IHG and BH (all P < 0.001). Moreover, the relative change in MAP from the baseline was correlated with that in both cerebral blood velocities during the BH (MCA Vmean: r = 0.739, P < 0.001 and PCA Vmean: r = 0.570, P = 0.009) and IHG-BH (MCA Vmean: r = 0.755, P < 0.001 and PCA Vmean: r = 0.617, P = 0.003) condition, but not the IHG condition (P = 0.154 and P = 0.306). These results indicate that during isometric exercise, a breath-hold enhances an exercise-induced increase in MAP and, consequently, MCA Vmean and PCA Vmean.

To Study Acute Changes in Brain Oxygenation on MRI in Healthcare Workers Using N95 Mask and PPE Kits for Six Hours a Day.

Background Due to long working hours wearing an N95 mask and PPE kit during the COVID-19 pandemic, the healthcare workers (HCWs) complained of headaches, confusion, and exhaustion. This study was therefore performed to study the changes in brain oxygenation. Aim To compare brain oxygenation in health care workers wearing an N95 mask with a PPE kit versus a three-ply mask during an intensive care setting for 6 hours. Materials and Methods Thirty clinicians and 30 paramedical staff participated in the study. The control (three-ply mask) and subject (N95 mask with PPE) groups included 15 clinicians and 15 paramedical staff. A comparative analysis of brain oxygenation using a 3T magnetic resonance imaging (MRI) machine was performed in these two groups at the beginning and the end of their work shift. Results The mean age of the individuals in the control and subject groups was 30.8 and 30.13 years, respectively. The median value of brain oxygenation in the control and subject groups in the pre-shift was between 33 and 31 and post-shift was 30 and 24. The drop in brain oxygenation in subjects was more than the controls ( p = 0.004) in the post-shift assessments. The cerebral blood flow (CBF) in the bilateral middle cerebral artery (MCA) using arterial spin labeling (ASL) showed a rise in CBF in both groups post-shift as compared with the pre-shift values. The median values of the right and left MCA in the control and subject groups pre-shift were 82.75/83.45 and 89.75/106.65. The post-shift median values of both MCAs of the control and subject groups were 115.65/115.55 and 109.60/119.49. Conclusion MRI-BOLD imaging revealed a significant drop in brain oxygenation in the subject group as compared with the control group. Multiphasic-ASL showed a compensatory rise in CBF in both groups.

Impaired dynamic cerebral autoregulation in young adults with mild depression.

The incidence of depression is increasing, especially in the young adult population. Impaired cognitive function is one of the characteristics of depression, which may be related to impaired cerebral autoregulation (CA). We investigated the characteristics of CA in young adults with mild depression, as well as its validity for identifying patients with depression. Patients (aged 18-35years) with Hamilton Depression Rating Scale (HAMD) scores ranging from 8 to 17 and a first episode of mild depression were enrolled in this study. Healthy volunteers were recruited as controls. Noninvasive continuous arterial blood pressure and bilateral middle cerebral artery blood flow velocity were simultaneously recorded from each subject. Transfer function analysis was applied to derive phase difference, gain, coherence and rate of recovery for the assessment of CA. Forty-three patients and 43 healthy controls were enrolled. Phase difference values were significantly compromised in young adults with mild depression and were negatively correlated with HAMD scores. Rate of recovery values estimated from depressed patients was significantly lower. The validity in identifying patients with depression was favorable for the phase difference. The cutoff phase difference value was 29.66. Our findings suggest that dynamic CA was impaired in young patients with mild depression and negatively correlated with HAMD scores. CA represented by phase difference can be used as an objective auxiliary examination of depression, and has clinical diagnostic value for the early identification of patients with depression.

Outcomes in 1-year Cohort After Transcarotid Artery Revascularization in the ROADSTER2 Trial

Transcarotid artery revascularization (TCAR) is a novel and attractive alternative to carotid endarterectomy (CEA) or transfemoral carotid artery stenting for interventional treatment of carotid artery stenosis in high-risk patients. In a direct carotid approach, TCAR uses temporary reversal of cerebral arterial blood flow to offer neuroprotection from emboli during stent placement. At present, the optimal surgical management for high-risk patients is unknown. We aimed to evaluate the 1-year safety and efficacy of TCAR in a prospective clinical trial.

Concussion history in rugby union players is associated with depressed cerebrovascular reactivity and cognition.

Recurrent contact and concussion in rugby union remains a significant public health concern given the potential increased risk of neurodegeneration in later life. This study determined to what extent prior-recurrent contact impacts molecular-hemodynamic biomarkers underpinning cognition in current professional rugby union players with a history of concussion. Measurements were performed in 20 professional rugby union players with an average of 16 (interquartile range [IQR] 13-19) years playing history reporting 3 (IQR 1-4) concussions. They were compared to 17 sex-age-physical activity-and education-matched non-contact controls with no prior history of self-reported concussion. Venous blood was assayed directly for the ascorbate free radical (A•- electron paramagnetic resonance spectroscopy) nitric oxide metabolites (NO reductive ozone-based chemiluminescence) and select biomarkers of neurovascular unit integrity (NVU chemiluminescence/ELISA). Middle cerebral artery blood flow velocity (MCAv doppler ultrasound) was employed to determine basal perfusion and cerebrovascular reactivity (CVR) to hyper/hypocapnia ( ). Cognition was assessed by neuropsychometric testing. Elevated systemic oxidative-nitrosative stress was confirmed in the players through increased A•- (p<0.001) and suppression of NO bioavailability (p<0.001). This was accompanied by a lower CVR range ( ; p=0.045) elevation in neurofilament light-chain (p=0.010) and frontotemporal impairments in immediate-memory (p=0.001) delayed-recall (p=0.048) and fine-motor coordination (p<0.001). Accelerated cognitive decline subsequent to prior-recurrent contact and concussion history is associated with a free radical-mediated suppression of CVR and neuronal injury providing important mechanistic insight that may help better inform clinical management.

Abstract MP15: Arterial Hypertension And Cognitive Disorders: Cerebral Vascular Reserve

The study of functional and restructuring disorders of large and small cerebral vessels that are a target for arterial hypertension (AH) is important for the prognosis of cognitive disorders (CD). The relationship between cerebral vascular reserve and CD in 378 outpatients with controlled AH stage II and low SCORE risk of CVD examined. The median age – 57,3±8,91 years. The average duration of AH was 11,5±6,2 years. SCORE risk of CVD &lt;5 %. All AH patients were examined according to the international recommendations and cognitive functioning was assessed by MoCA scale, blood flow in the middle cerebral artery was investigated by transcranial Doppler (TCD) on the HDI 7, Philips, USA with functional respiratory hypo- and hypercapnic ventilation tests.The integrative index of vasomotor reactivity (IVMR) was calculated for cerebral vascular reserve identification: IVMR=[(V apnea -V hyper )/V 0 ]•100%, V apnea - the average maximum velocity of blood flow after 20s of apnea (cm/s), V hyper - the average maximum velocity of blood flow after 20s of hyperventilation (cm/s), V 0 - the average maximum velocity at rest (cm/s). Non-dementia cognitive disorders were found in 125 (33 %) - 24,32±0,11 points on MOCA scale. The significant decrease in the IVMR was found according to the results of the TCD examination of cerebralvascular reserve testing in patients with AH and CD (44.0±1.2, p&lt;0,001), which indicates the close relationship between the value of IVMR and CD even in patients with controlled AH (rs = +0.54; p&lt;0.001). It is necessary to clarify the cerebral vascular reserve and the vasomotor reactivity index even when controlling AH due to the high risk of the development and progression of cognitive disorders, which worsen the prognosis of cardiovascular events and quality of life.

Ten days of high dietary sodium does not impair cerebral blood flow regulation in healthy adults.

High dietary sodium impairs cerebral blood flow regulation in rodents and is associated with increased stroke risk in humans. However, the effects of multiple days of high dietary sodium on cerebral blood flow regulation in humans is unknown. Therefore, the purpose of this study was to determine whether ten days of high dietary sodium impairs cerebral blood flow regulation. Ten participants (3F/7M; age: 30±10years; blood pressure (BP): 113±8/62±9mmHg) participated in this randomized, cross-over design study. Participants were placed on 10-day diets that included either low- (1000mg/d), medium- (2300mg/d) or high- (7000mg/d) sodium separated by ≥four weeks. Urinary sodium excretion, beat-to-beat BP (finger photoplethysmography), middle cerebral artery velocity (transcranial Doppler), and end-tidal carbon dioxide (capnography) was measured. Dynamic cerebral autoregulation during a ten-minute baseline was calculated and cerebrovascular reactivity assessed by determining the percent change in middle cerebral artery blood flow velocity to hypercapnia (8% CO2, 21% oxygen, balance nitrogen) and hypocapnia (via mild hyperventilation). Urinary sodium excretion increased in a stepwise manner (ANOVA P=0.001) from the low, to medium, to high condition. There were no differences in dynamic cerebral autoregulation between conditions. While there was a trend for a difference during cerebrovascular reactivity to hypercapnia (ANOVA P=0.06), this trend was abolished when calculating cerebrovascular conductance (ANOVA: P=0.28). There were no differences in cerebrovascular reactivity (ANOVA P=0.57) or conductance (ANOVA: P=0.73) during hypocapnia. These data suggest that ten days of a high sodium diet does not impair cerebral blood flow regulation in healthy adults.

Dynamic cerebral autoregulation during early orthostatic exercise in patients with severe traumatic brain injury: Further exploratory analyses from a randomized clinical feasibility trial

In patients with severe traumatic brain injury, there is limited evidence of the clinical effect of early orthostatic exercise, although such exercise may strengthen systemic or cerebral hemodynamic responses to head-up tilt, thereby minimizing orthostatic intolerance. We measured dynamic cerebral autoregulation (dCA) and the occurrence of orthostatic intolerance after four weeks of regular orthostatic exercise by head-up tilt using a tilt table with integrated stepping using the ERIGO® tilt-table and comparing it to standard care. Thirty-four patients with severe traumatic brain injury admitted to a neurocritical care unit were included in this randomized clinical trial. Middle cerebral artery blood flow velocity (MCAv), non-invasive mean arterial pressure, heart rate and PaCO2 were recorded; dCA was measured by the non-invasive mean flow index (nMxa). Transition from the supine position to head-up tilt triggered a 10–16% decrease in MCAv and increased nMxa in both groups at all time points (P < 0.05), with no differences between groups. There was no difference in the number of episodes with orthostatic intolerance (5 vs 3; 1 vs 2; 1 vs 0) at baseline, two weeks and four weeks, respectively, and no association between changes in PaCO2-adjusted nMxa and the occurrence of orthostatic reactions (P = 0.35). Early orthostatic exercise does not affect dynamic cerebral autoregulation and does not protect against orthostatic intolerance in patients with severe traumatic brain injury. Trial registration: ClinicalTrials.gov identifier: NCT02924649. Registered on 3rd October 2016.

Reader Response: Association of Ventricular Arrhythmias With Dementia: The Atherosclerosis Risk in Communities (ARIC) Study

Norby et al.1 report their interesting findings on the relationship between ventricular arrhythmias and dementia. As they note, speculative mechanisms underlying the observed relationship may include brain hypoperfusion. We previously had the opportunity to directly measure the effects of premature ventricular contractions (PVC) on intracranial hemodynamics.2 Using simultaneous transcranial Doppler ultrasound and electrocardiography, we measured middle cerebral artery blood flow velocity during PVC in comparison to blood flow velocity before and after PVC. Compared with the preceding beat, we found significant reductions in peak, mean, and diastolic velocities (30.7%, 34.2%, and 29.6%, respectively) for PVC. Compared with the following beat, we also found significant reductions in peak, mean, and diastolic velocities (37.1%, 30.3%, and 36.2%, respectively) for PVC. Moreover, using similar measurement techniques, we found substantial intracranial hemodynamic effects of atrial fibrillation, including dramatic changes before and immediately after cardioversion.3 We believe that these findings offer some mechanistic perspectives on the epidemiologic observations of the link between cardiac arrhythmias and dementia.1,4

Interrelations of Cerebral Hemodynamics with Parameters of Cardiac Function and Brain Tissue in Patients with Ischemic Stroke.

We analyzed interrelations between the cerebral blood flow, cardiac output, and condition of the brain substance in 530 patients with ischemic stroke. Dependencies between the linear blood flow velocities in all arteries supplying the brain, as well as between the total volume blood flow through the internal carotid arteries and left ventricular stroke volume were revealed. The severity of atrophy was maximum in the parietal lobes (median 1.5 (1.0; 2.0)) and minimum in the occipital lobes (median 0.5 (0; 1.0)). Temporal lobes cortical atrophy significantly correlated with changes in the limbic system and in the periventricular and deep white matter; a significant weak inverse correlation of this parameter with blood flow in the middle cerebral artery was also found. Changes in the periventricular white matter (but not in deep white matter) demonstrated a significant inverse correlation with blood flow in the middle and anterior cerebral arteries.

The Effect of K ATP Channel Blocker Glibenclamide on CGRP-Induced Headache and Hemodynamic in Healthy Volunteers.

BackgroundCalcitonin gene-related peptide (CGRP) dilates cranial arteries and triggers headache. The CGRP signaling pathway is partly dependent on activation of ATP-sensitive potassium (KATP) channels. Here, we investigated the effect of the KATP channel blocker glibenclamide on CGRP-induced headache and vascular changes in healthy volunteers.MethodsIn a randomized, double-blind, placebo-controlled, cross-over study, 20 healthy volunteers aged 18–27 years were randomly allocated to receive an intravenous infusion of 1.5 μg/min CGRP after oral pretreatment with glibenclamide (glibenclamide-CGRP day) or placebo (placebo-CGRP day). The primary endpoints were the difference in incidence of headache and the difference in area under the curve (AUC) for headache intensity scores (0–14 h) between glibenclamide and placebo. The secondary endpoints were the difference in AUC for middle cerebral artery blood flow velocity (VMCA), superficial temporal artery (STA) and radial artery (RA) diameter, facial flushing, heart rate (HR) and mean arterial blood pressure (MAP) (0–4 h) between glibenclamide and placebo.ResultsWe found no significant difference in the incidence of headache between glibenclamide-CGRP day (14/20, 70%) and placebo-CGRP day (19/20, 95%) (P = 0.06). The AUC for headache intensity, VMCA, STA, RA, facial skin blood flow, HR, and MAP did not differ between glibenclamide-CGRP day compared to placebo-CGRP day (P > 0.05).ConclusionPretreatment with a non-selective KATP channel inhibitor glibenclamide did not attenuate CGRP-induced headache and hemodynamic changes in healthy volunteers. We suggest that CGRP-induced responses could be mediated via activation of specific isoforms of sulfonylurea receptor subunits of KATP channel.

Analysis of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage with High Frequency Transcranial Duplex Ultrasound

The aim of this manuscript is to present a sonography-based method that allows in vivo imaging of blood flow in cerebral arteries in mice. We demonstrate its application to determine changes in blood flow velocities associated with vasospasm in murine models of subarachnoid hemorrhage (SAH).