Mean Blood Flow Velocity Research Articles

Effect of acupuncture combined with repetitive transcranial magnetic stimulation on motor function and cerebral hemodynamics in children with spastic cerebral palsy with spleen-kidney deficiency

To investigate the clinical effect of acupuncture combined with repetitive transcranial magnetic stimulation in the treatment of children with spastic cerebral palsy with spleen-kidney deficiency, as well as its effect in improving cerebral hemodynamics. A total of 220 children with spastic cerebral palsy were divided into observation group and control group using a random number table, with 110 children in each group. The children in the control group were given rehabilitation training and repetitive transcranial magnetic stimulation, and those in the observation group were given acupuncture in addition to the treatment in the control group. Acupuncture was performed at Zusanli (ST36), Xuanzhong (GB39), Sanyinjiao (SP6), Pishu (BL20), Shenshu (BL23), Qihai (CV6), Quchi (LI11), Neiguan (PC6), Hegu (LI4) and Tianshu (ST25) once every other day, three times a week for 3 consecutive months. The two groups were compared in terms of Gross Motor Function Measure (GMFM), Fine Motor Function Measure (FMFM), comprehensive function score for children with cerebral palsy, clinical outcome, and related cerebral hemodynamic parameters (mean blood flow velocity [Vm], systolic peak velocity [Vs], and resistance index [RI] of the cerebral artery). After treatment, both groups had significant increases in the scores of GMFM, FMFM and comprehensive function (cognitive function, speech function, motor ability, self-care, and social adaptability,P<0.01), and the observation group had significantly better improvements in the scores of GMFM (domains A, B and C), FMFM (domains B, C, D and E), and comprehensive function than those of the control group (P<0.01). The therapeutic effect of the observation group (93/110, 84.55%)was superior to that of the control group (80/110, 72.73%, P<0.05). The observation group had significantly higher Vs and Vm and a significantly lower RI than the control group (P<0.01). In the treatment of children with spasmodic cerebral palsy with spleen-kidney deficiency, acupuncture combined with repeated transcranial magnetic stimulation can significantly improve their motor function, comprehensive function, and clinical outcome, which may be associated with the regulation of cerebral hemodynamics.

Preoperative transcranial Doppler and cerebral oximetry as predictors of delirium following valvular heart surgery: a case-control study.

Delirium is a frequent and serious complication after cardiac surgery with cerebral hypoperfusion as one from the key pathophysiological mechanisms. Middle cerebral artery (MCA) mean blood flow velocity (MFV) measured by transcranial Doppler has been used as a marker of cerebral perfusion, and cerebral oximetry (rSO2) value as a marker of its adequacy. This prospective observational trial examined the predictive value of MCA MFV and rSO2, measured immediately before induction of anesthesia, for delirium after valvular heart surgery in elderly patients. In 113 patients, delirium was evaluated for 7days postoperatively, using the confusion assessment method for the intensive care unit. The primary endpoint was the occurrence of postoperative delirium. Overall, 16 patients (14%) exhibited delirium. MCA MVF values could not predict the development of delirium. Preoperative statin use, geriatric depression scale score, and low preoperative rSO2 (< 60%) showed association with delirium occurrence in univariable analysis. After multivariable analysis, only the low preoperative rSO2 (< 60%) (OR 6.748, 95% CI 1.647-27.652, P = 0.008) remained as an independent predictor of delirium. Preoperative MCA MFV was not significantly associated with delirium after valvular heart surgery in elderly patients, while a low baseline rSO2 value was associated with a sevenfold increased risk of delirium.

Effects of Resistance Exercise and Nutritional Supplementation on Dynamic Cerebral Autoregulation in Head-Down Bed Rest.

Head-down bed rest (HDBR) is commonly considered as ground-based analog to spaceflight and simulates the headward fluid shift and cardiovascular deconditioning associated with spaceflight. We investigated in healthy volunteers whether HDBR, with or without countermeasures, affect cerebral autoregulation (CA). Twelve men (at selection: 34 ± 7 years; 176 ± 7 cm; 70 ± 7 kg) underwent three interventions of a 21-day HDBR: a control condition without countermeasure (CON), a condition with resistance vibration exercise (RVE) comprising of squats, single leg heel, and bilateral heel raises and a condition using also RVE associated with nutritional supplementation (NeX). Cerebral blood flow velocity was assessed using transcranial Doppler ultrasonography. CA was evaluated by transfer function analysis and by the autoregulatory index (Mxa) in order to determine the relationship between mean cerebral blood flow velocity and mean arterial blood pressure. In RVE condition, coherence was increased after HDBR. In CON condition, Mxa index was significantly reduced after HDBR. In contrast, in RVE and NeX conditions, Mxa were increased after HBDR. Our results indicate that HDBR without countermeasures may improve dynamic CA, but this adaptation may be dampened with RVE. Furthermore, nutritional supplementation did not enhance or worsen the negative effects of RVE. These findings should be carefully considered and could not be applied in spaceflight. Indeed, the subjects spent their time in supine position during bed rest, unlike the astronauts who perform normal daily activities.

Neurovascular coupling and cerebral autoregulation in atrial fibrillation

The risk of cognitive decline and stroke is increased by atrial fibrillation (AF). We sought to determine whether neurovascular coupling and cerebral autoregulation are blunted in people with AF in comparison with age-matched, patients with hypertension and healthy controls. Neurovascular coupling was assessed using five cycles of visual stimulation for 30 s followed by 30 s with both eyes-closed. Cerebral autoregulation was examined using a sit–stand test, and a repeated squat-to-stand (0.1 Hz) manoeuvre with transfer function analysis of mean arterial pressure (MAP; input) and middle cerebral artery mean blood flow velocity (MCA Vm; output) relationships at 0.1 Hz. Visual stimulation increased posterior cerebral artery conductance, but the magnitude of the response was blunted in patients with AF (18 [8] %; mean [SD]) and hypertension (17 [8] %), in comparison with healthy controls (26 [9] %) (P < 0.05). In contrast, transmission of MAP to MCA Vm was greater in AF patients compared to hypertension and healthy controls, indicating diminished cerebral autoregulation. We have shown for the first time that AF patients have impaired neurovascular coupling responses to visual stimulation and diminished cerebral autoregulation. Such deficits in cerebrovascular regulation may contribute to the increased risk of cerebral dysfunction in people with AF.

Blade needle treatment improves cervicogenic dizziness by increasing blood flow of vertebral basilar artery

To investigate the therapeutic effect of blade needle therapy for cervicogenic dizziness (CD) and changes of blood flow of vertebral artery in patients with CD. A total of 60 patients with CD were equally randomized into medication (16 women and 14 men, 38.9±10.9 years in age) group and blade needle group (17 women and 13 men, 40.1±12.4 years in age). Patients of the blade needle group were treated by performing blade needle stimulation (longitudinal cutting along the musculoaponeurotic layer) to the tender points (attachment points) of the bilateral superior and inferior oblique muscles of the head, major and minor posterior cephalic rectus, about 2/3 of suboccipital nuchal line, and near the cervical processes of C1-C2 segments. The treatment was conducted once every 3 days for 15 days. Patients of the medication group were ordered to take Flunarizine Hydrochloride capsules (10 mg) once every night for 15 days. Transcranial Doppler was used to measure changes of mean blood flow velocities of the left vertebral artery (LVA), right vertebral artery (RVA), and basilar artery (BA) before and after the treatment. The therapeutic effect was assessed according to the Criteria for Diagnosis and Therapeutic Effect Evaluation of Syndromes or Illnesses of Traditional Chinese Medicine (1994) and the Assessment Scale for Symptoms and Function of Cervicogenic Dizziness (2017). Following the treatment, of the two 30 cases in the medication and blade needle groups, 5 (16.7%) and 7 (23.3%) were cured, 16 (53.3%) and 20 (66.7%) were improved in their symptoms, 9 (30.0%) and 3 (10.0%) failed, with the effective rate being 70.0% and 90.0%, respectively. The effective rate of the blade needle was significantly superior to that of the medication (P<0.05). The scores of vertigo, neck-should pain, daily living and work, psychology, social adaptation, and total score of the assessment scale, as well as the average blood flow velocities of LVA, RVA and BA were considerably increased in both groups in comparison with their own pre-treatment (P<0.05), and obviously higher in the blade needle group than in the medication group (P<0.05). Blade needle treatment has a good clinical effect in the treatment of CD patients, which is probably associated with its function in increasing blood perfusion of the brain tissue, and thus being worthy of clinical application.

Effect of "Tongdu Tiaoshen" needling combined with swallowing training on dysphagia, cerebral blood flow and serum BDNF and NGF levels in ischemic stroke patients

To observe the efficacy of Tongdu Tiaoshen (dredging Governor Vessel and regulating mind) needling combined with swallowing training in the treatment of ischemic stroke (IS) with dysphagia, and to investigate its effect on cerebral blood flow and serum levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). A total of 100 IS inpatients with dysphagia were enrolled in the present study, and randomly and equally divided into control group and treatment group by using a random number table. The patients of the control group received routine swallowing training including tongue extending and retracting, cheek-muscle training, breathing exercise, and laryngopharyngeal exercise, beginning from the 2nd day after hospitalization. The patients of the treatment group received manual acupuncture stimulation of Dazhui (GV14), Fengfu (GV16), Shenting (GV24), Shendao (GV11), Baihui (GV20), Shuigou (GV26), etc., on the basic treatment as those mentioned in the control group. The treatment was conducted once daily, 5 times per week and for 4 successive weeks. The swallowing ability was tested by using video fluoroscopic swallowing study (VFSS), Kubota water swallowing test, and the standard swallowing function assessment (SSA) scale, separately, and patients' daily life quality was assessed by using swallowing related quality of life questionnaire (SWAL-QOL). The cerebral hemodynamics including mean blood flow velocity (Vm), maximum peak flow speed (Vs), and vascular resistance index (RI) of the bilateral cerebral arteries was detected by transcranial color Doppler ultrasound tests, and serum BDNF and NGF contents were assayed by enzyme linked immunosorbent assay. The therapeutic effect of swallowing ability was evaluated after the treatment. After 4 weeks' treatment, the scores of Kubata water swallowing test, SSA, and SWAL-QOL and RI were considerably decreased (P<0.01), and the VFSS scores, Vs and Vm levels as well as serum BDNF and NGF contents were significantly increased (P<0.01) in both groups compared with their own pre-treatment. Of the 48 and 49 cases in the control and treatment groups, 4 (8.33%) and 8(16.33%) were cured, 26 (54.17%) and 33 (67.35%) effective, 18 (37.50%) and 8 (16.33%) failed, with the effective rate being 62.50% and 83.67%, respectively. The therapeutic effect of the treatment group was significantly superior to that of the control group in the effective rate (P<0.05), and in lowering the scores of Kubota water swallowing test, SWAL-QOL, SSA, RI, and in up-regulating the scores of VFSS, Vs and Vm, and serum BDNF and NGF levels (P<0.01). Tongdu Tiaoshen needling combined with swallowing training is effective in improving swallowing ability, promoting cerebral blood flow and in up-regulating serum neurotrophic factor levels in patients with dysphagia after ischemic stroke.

Transcranial Doppler 24 Hours after Carotid Endarterectomy Accurately Identifies Patients Not at Risk of Cerebral Hyperperfusion Syndrome

Intra-operative transcranial Doppler (TCD) is the gold standard for prediction of cerebral hyperperfusion syndrome (CHS) in patients after carotid endarterectomy (CEA) under general anaesthesia. However, post-operative cerebral perfusion patterns may result in a shift in risk assessment for CHS. This is a study of the predictive value of additional post-operative TCD measurements for prediction of CHS after CEA. This was a retrospective analysis of prospectively collected data in patients undergoing CEA with available intra- and post-operative TCD measurements between 2011 and 2016. The mean blood flow velocity in the middle cerebral artery (MCAVmean) was measured pre-operatively, intra-operatively, and post-operatively at two and 24h. Intra-operative MCAVmean increase was compared with MCAVmean increase two and 24h post-operatively in relation to CHS. Cerebral hyperperfusion (CH) was defined as MCAVmean increase≥100%, and CHS as CH with the presence of headache or neurological symptoms. Positive (PPV) and negative predictive values (NPV) of TCD measurements were calculated to predict CHS. Of 257 CEA patients, 25 (9.7%) had CH intra-operatively, 45 (17.5%) 2h post-operatively, and 34 (13.2%) 24h post-operatively. Of nine patients (3.5%) who developed CHS, intra-operative CH was diagnosed in two and post-operative CH in eight (after 2h [n=5] or after 24h [n=6]). This resulted in a PPV of 8%, 11%, and 18%, and a NPV of 97%, 98%, and 99% for intra-operative, 2h and 24h post-operative TCD, respectively. TCD measurement of the MCAVmean 24h after CEA under general anaesthesia is most accurate to identify patients who are not at risk of CHS.

High-intensity interval training combined with resistance training improved apnea-hypopnea index but did not modify oxygen desaturation index and oxygen saturation nadir in obese children with obstructive sleep apnea.

To investigate the effect of high-intensity interval training (HIIT) combined with resistance training (RT) on sleep indices and vascular functions in obese children with obstructive sleep apnea (OSA). A quasi-experimental study. Forty-four obese children with OSA were allocated into either an exercise intervention (n = 22) or a usual care control group (n = 22). The exercise group received 24min of HIIT (> 60% heart rate reserved) and 20min of RT (50-80% one-repetition maximum), three times per week for 8weeks. Primary outcomes included the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and oxygen saturation (SaO2) nadir. Secondary outcomes included the Sleep-Related Breathing Disorder-Pediatric Sleep Questionnaire (SRBD-PSQ) scores, vascular functions (flow-mediated dilation and mean blood flow velocity), and anthropometric variables. Outcomes were measured at baseline, at week 8, and at week 16. No baseline differences were observed between groups. The compliance rate of exercise training was 99.47%. The AHI significantly decreased in the exercise group compared with the control group at week 16 (median AHI 1.30 to 0.60 and 1.00 to 1.60 episode/h, p = 0.01), but not at week 8. There were no differences between the groups in regard to the ODI and SaO2 nadir and any secondary outcomes at weeks 8 and 16 (all p > 0.05). The eight-week HIIT combined with RT decreased AHI in obese children with OSA at week 16 follow-up. No changes in the ODI, SaO2 nadir, SRBD-PSQ, vascular function, and anthropometric outcomes were revealed at any time point. Further research is warranted.

Does respiratory drive modify the cerebral vascular response to changes in end-tidal carbon dioxide?

What is the central question of this study? There is an interaction between the regulatory systems of respiration and cerebral blood flow, because the mediator (CO2 ) is the same for both physiological systems. We examined whether the traditional method for determining cerebrovascular reactivity to CO2 is modified by changes in respiration. What is the main finding and its importance? Cerebrovascular reactivity was modified by voluntary changes in respiration during hypercapnia. This finding suggests that an alteration in the respiratory system may result in under- or overestimation of cerebrovascular reactivity determined by traditional methods in healthy adults. The cerebral vasculature is sensitive to changes in the arterial partial pressure of CO2 . This physiological mechanism has been well established as a cerebrovascular reactivity to CO2 (CVR). However, arterial CO2 may not be an independent variable in the traditional method for assessment of CVR, because the cerebral blood flow response is also affected by the activation of respiratory drive or higher centres in the brain. We hypothesized that CVR is modified by changes in respiration. To test our hypothesis, in the present study, 10 young, healthy subjects performed hyper- or hypoventilation to change end-tidal CO2 ( ) with different concentrations of CO2 in the inhaled gas (0, 2.0 and 3.5%). We measured middle cerebral artery mean blood flow velocity by transcranial Doppler ultrasonography to identify the cerebral blood flow response to change in during each set of conditions. In each set of conditions, was significantly altered by changes in ventilation, and middle cerebral artery mean blood flow velocity changed accordingly. However, the relationship between changes in middle cerebral artery mean blood flow velocity and as a response curve of CVR was reset upwards and downwards by hypo- and hyperventilation, respectively, compared with CVR during normal ventilation. The findings of the present study suggest the possibility that an alteration in respiration might lead to under- or overestimation of CVR determined by the traditional methods.

The association between NIRS and Doppler ultrasonography in preterm infants with patent ductus arteriosus

Objective: To determine if near-infrared spectroscopy (NIRS), which is easier to obtain than Doppler ultrasonography (USG), may be used in accordance with Doppler USG to provide additional data for assessment of organ blood flow velocities in preterm infants with hemodynamically significant PDA.Study design: Thirty-one infants who were treated with ibuprofen for closure of PDA were monitored continuously with NIRS. Cerebral, mesenteric, and renal arterial blood flow velocities were measured with Doppler USG before and after the treatment.Results: While cerebral, mesenteric, and renal fractional oxygen extraction (FTOE) measurements decreased significantly (p = .042, p < .001, p < .001, respectively), NIRS measurements (p = .016, p < .001, p < .001, respectively) and mean blood flow velocities (p = .003, p = .011, p = .002, respectively) increased significantly after the treatment. There was a significant correlation between pretreatment cerebral and mesenteric FTOE and resistive index (RI) values (r = 0.45, p = .01, and r = 0.46, p = .01, respectively). However, no correlation was observed between renal FTOE values and renal RI (r = 0.33, p = .06). Posttreatment cerebral, renal, and mesenteric FTOE values correlated positively with corresponding RI (r = 0.41, p = .02; r = 0.39, p = .02; r = 0.65, p < 01; respectively). Pretreatment and posttreatment cerebral, mesenteric, and renal FTOE values and arterial mean velocities were inversely correlated (pretreatment: r = 0.69, p < .01; r = 0.72, p < .01; r = 0.77, p < .01; posttreatment: r = 0.54, p = .01; r = 0.69, p < .01; r = 0.38, p = .01; respectively).Conclusion: As Doppler and NIRS measurements correlated significantly, we concluded that NIRS might be used in monitoring organ blood flow in preterm infants with PDA, which may provide additional data for management of this condition.

Measuring Cerebral Carbon Dioxide Reactivity With Transcranial Doppler and Near-Infrared Spectroscopy in Children With Ventricular Septal Defect

Neurologic impairment is frequently observed in children with congenital heart disease. Impairment in cerebrovascular carbon dioxide reactivity (CO2R) is related with poor neurologic outcomes. The present study examined CO2R measured with transcranial Doppler (TCD) and near-infrared spectroscopy (NIRS) in children with ventricular septal defect undergoing cardiac surgery. Prospective, paired controlled study. Operating room of a tertiary care center. Twenty children with ventricular septal defect and younger than 1 year were enrolled, and 17 children were studied (age: 6.0 ± 2.0 mo, weight 5.9 ± 1.0 kg). After induction of anesthesia and tracheal intubation, the lungs were ventilated and mechanical ventilation was initiated. Partial pressure of end-tidal carbon dioxide (PETCO2) was adjusted at 4 different levels (30, 35, 40, and 45 mmHg). Paired measurements of middle cerebral artery mean blood flow velocity (VMCA) by TCD and tissue oxygen index (TOI) by NIRS were recorded at each level of PETCO2. CO2R was calculated as the percentage change of VMCA and TOI per mmHg change in PETCO2. Systemic hemodynamic parameters were recorded. As PETCO2 rose from 30 to 45 mmHg, VMCA and TOI increased linearly (p < 0.001 for both), and CO2R-TCD and CO2R-NIRS were calculated to be 2.8% ± 0.9%/mmHg and 1.2% ± 0.3 %/mmHg, respectively. CO2R-NIRS was significantly lower compared with CO2R-TCD (p < 0.001). Significant correlations were found between VMCA and TOI (r = 0.487; p < 0.001) and between ΔVMCA and ΔTOI (r = 0.693; p < 0.001), but not between CO2R-TCD and CO2R-NIRS (r = 0.18; p = 0.24). With the increase of PETCO2, cardiac index, systemic vascular resistance index, and mean arterial pressure remained constant (p > 0.05 for all) and the heart rate decreased significantly (p = 0.018). During anesthesia, CO2R remains preserved in children with a ventricular septal defect. Even though there is lack of correlation between CO2R-TCD and CO2R-NIRS, changes in TOI and VMCA were correlated as the PETCO2 changed. NIRS may be used as a surrogate to investigate CO2R when the ultrasound window is poor.

Clinical Usefulness of Transcranial Doppler as a Screening Tool for Early Cerebral Hypoxic Episodes in Patients with Moderate and Severe Traumatic Brain Injury.

Brain tissue oxygenation (PbtO2) in traumatic brain injury (TBI) is known to be dependent on cerebral blood flow (CBF) which remains difficult to assess during the very early phase of TBI management. This study evaluates if blood flow velocity measurement with 2D color-coded transcranial Doppler (TCD) can predict cerebral hypoxic episodes in moderate-to-severe TBI measured with a PbtO2 probe. This is a prospective observational study of serial TCD measurements to assess blood flow velocity and its association with PbtO2. Measurements were done bilaterally on the middle cerebral artery (MCA) early after the insertion of PbtO2 monitoring, daily for 5days and during dynamic challenge tests. Physiological parameters affecting PbtO2 and Doppler velocities were collected simultaneously (PaO2, PaCO2, hemoglobin [Hb] level, intracranial pressure, and cerebral perfusion pressure [CPP]). We enrolled 17 consecutive patients with a total of 85 TCD studies. Using 2D color-coded TCD, signal acquisition was successful in 96% of the cases. Twenty-nine (34%) TCD measures were performed during an episode of cerebral hypoxia (PbtO2 ≤ 20mmHg). For early episodes of cerebral hypoxia (occurring ≤ 24h from trauma), all Vmean < 40cm/s were associated with an ipsilateral PbtO2 ≤ 20mmHg (positive predictive value 100%). However,when considering all readings over the course of the study, however, we found no correlation between PbtO2 and MCA's mean blood flow velocity (Vmean). Vmean is also positively correlated with PaCO2, whereas PbtO2 is also correlated with PaO2, CPP, and Hb level. Early TCD measurements compatible with low CBF (mean velocity < 40cm/s) detect brain tissue hypoxia early after TBI (≤ 24h) and could potentially be used as a screening tool before invasive monitoring insertion to help minimize time-sensitive secondary injury. Various factors influence the relationship between Vmean and PbtO2, affecting interpretation of their interaction after 24h.

The Relationship Between Left Ventricular Systolic Function And Cerebral Blood Flow

PURPOSE: The positive relationship between cardiac output and cerebral blood flow (CBF) has been indicated in healthy individuals and patinets with cardiovascular diseases. Previous studies reported that the reduced cardiac output was related with a low brain volume and an increased risk for Alzheimer’s disease. Also, compromised left ventricular (LV) diastolic function was reported to be associated with a cerebral white matter lesions. Therefore, cardiac function may play an important role for the maintenance of CBF. However, the relationship between LV systolic function and CBF is still unclear. The purpose of this study was to test our hypothesis that the LV systolic function would be associated with CBF. METHODS: Sixty-three outpatients who presented to our hospital due to transient loss of consciousness were enrolled (59 ± 22 years old, rang 17 to 93 years old, 31 females). LV function was assessed by stroke volume (SV), LV ejection fraction (LVEF) and mass (LVmass) by echocardiography, and preejection period (PEP), ejection time (ET) and ET/PEP by phonocardiogram. ET was corrected by heart rate (ETc). On the other hand, CBF was estimated from systolic, diastolic and mean blood flow velocity in middle cerebral artery (MCA), measured by transcranaial Doppler ultrasound. The multiple linear regression analysis was performed using MCA blood flow velocities (MCAv) as independent variables, and age, sex and each LV funtion as dependent variables. RESULTS: SV, LVEF, LVmass and PEP were not correlated with MCAv. In contrast, ETc was significantly correlated with both systolic (β = 0.32, P = 0.01) and mean (β = 0.25, P = 0.02) MCAv. ET/PEP was significantly correlated with systolic MCAv (β = 0.22, P = 0.04) only. CONCLUSIONS: These results indicated that LV systolic function evaluated by phonocardiogram may play more siginifcant role for regulating CBF as compared with that by echocardiography such as LVEF.

Causality analysis reveals the link between cerebrovascular control and acute kidney dysfunction after coronary artery bypass grafting

Background: Patients undergoing coronary artery bypass graft (CABG) surgery might experience postoperative complications and some of them, such as acute kidney dysfunction (AKD), are the likely consequence of hypoperfusion. We hypothesized that an impaired cerebrovascular control is a hallmark of a vascular damage that might favor AKD after CABG. Objective: Our aim is to characterize cerebrovascular control in CABG patients through the assessment of the relationship between mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) and to check whether markers describing MCBFV-MAP dynamical interactions could identify subjects at risk to develop postoperative AKD. Approach: MAP and MCBFV beat-to-beat series were extracted from invasive arterial pressure and transcranial Doppler recordings acquired simultaneously in 23 patients just before CABG after the induction of propofol general anesthesia. Subjects were divided into AKD group (n = 9, age: 68 ± 9, 8 males) and noAKD group (n = 14, age: 65 ± 8, 12 males) according to whether they developed postoperative AKD or not after CABG. We computed MAP and MCBFV time-domain and spectral markers as well as MCBFV-MAP cross-spectral indexes in very-low-frequency (VLF, 0.02–0.07 Hz), low-frequency (LF, 0.07–0.15 Hz) and high-frequency (HF, 0.15–0.30 Hz) bands. We also calculated model-based transfer entropy (TE) to quantify the degree of MCBFV dependence on MAP and vice versa. The null hypothesis of MCBFV-MAP uncoupling was tested via a surrogate approach associating MAP and MCBFV in different patients. Main results: Time, spectral and cross-spectral markers had a limited power in separating AKD from noAKD individuals. Conversely, TE from MAP to MCBFV was significantly above the level set by surrogates only in AKD groups and significantly larger than that computed in noAKD. Significance: The reduced cerebrovascular autoregulation in AKD patients suggest a vascular impairment likely making them more at risk of hypoperfusion during CABG and AKD after CABG.

Impaired dynamic cerebral autoregulation in trained breath-hold divers.

Breath-hold divers (BHD) experience repeated bouts of severe hypoxia and hypercapnia with large increases in blood pressure. However, the impact of long-term breath-hold diving on cerebrovascular control remains poorly understood. The ability of cerebral blood vessels to respond rapidly to changes in blood pressure represents the property of dynamic autoregulation. The current investigation tested the hypothesis that breath-hold diving impairs dynamic autoregulation to a transient hypotensive stimulus. Seventeen BHD (3 women, 11 ± 9 yr of diving) and 15 healthy controls (2 women) completed two or three repeated sit-to-stand trials during spontaneous breathing and poikilocapnic conditions. Heart rate (HR), finger arterial blood pressure (BP), and cerebral blood flow velocity (BFV) from the right middle cerebral artery were measured continuously with three-lead electrocardiography, finger photoplethysmography, and transcranial Doppler ultrasonography, respectively. End-tidal carbon dioxide partial pressure was measured with a gas analyzer. Offline, an index of cerebrovascular resistance (CVRi) was calculated as the quotient of mean BP and BFV. The rate of the drop in CVRi relative to the change in BP provided the rate of regulation [RoR; (∆CVRi/∆T)/∆BP]. The BHD demonstrated slower RoR than controls (P ≤ 0.001, d = 1.4). Underlying the reduced RoR in BHD was a longer time to reach nadir CVRi compared with controls (P = 0.004, d = 1.1). In concert with the longer CVRi response, the time to reach peak BFV following standing was longer in BHD than controls (P = 0.01, d = 0.9). The data suggest impaired dynamic autoregulatory mechanisms to hypotension in BHD. NEW & NOTEWORTHY Impairments in dynamic cerebral autoregulation to hypotension are associated with breath-hold diving. Although weakened autoregulation was observed acutely in this group during apneic stress, we are the first to report on chronic adaptations in cerebral autoregulation. Impaired vasomotor responses underlie the reduced rate of regulation, wherein breath-hold divers demonstrate a prolonged dilatory response to transient hypotension. The slower cerebral vasodilation produces a longer perturbation in cerebral blood flow velocity, increasing the risk of cerebral ischemia.

Clinical research of Tongqiao-Huoxue decoction for the treatment of vertebrobasilar artery insufficiency vertigo with stasis orifice type

Objective To investigate the clinical application of Tongqiao-Huoxue decoction for the treatment of vertebrobasilar artery insufficiency vertigo with stasis orifice type. Methods According to the random table method, 93 vertebrobasilar artery insufficiency vertigo patients with stasis orifice type were divided into the control group (n=46) and the treatment group (n=47). The patients in the control group were treated with fluoguizine hydrochloride, while the patients in the treatment group were treated with Tongqiao-Huoxue decoction on the basis of control group. Two groups were treated for 4 weeks. The clinical total effective rate of two groups of patients after treatment was compared. The LVA mean blood flow velocity, RVA mean blood flow velocity, BA mean blood flow velocity, total blood viscosity, plasma viscosity, erythrocyte aggregation index, fibrinogen, TC, TG, LDL-C and HDL-C were detected respectively before and after treatment. In addition, the adverse reaction incidence of two groups of patients were observed. Results The total effective rate of treatment group was 93.6% (44/47), while the total effective rate of control group was 78.3% (36/46). The difference between two groups was statistically significant (χ2=4.559, P=0.033). After treatment,the LVA mean blood flow velocity (38.34 ± 3.72 cm/s vs. 29.73 ± 3.11 cm/s, t=12.096), RVA mean blood flow velocity (41.12 ± 4.05 cm/s vs. 34.11 ± 3.86 cm/s, t=8.541),BA mean blood flow velocity (48.92 ± 5.24 cm/s vs. 40.75 ± 4.63 cm/s, t=7.962), HDL-C (2.13 ± 0.64 mmol/L vs. 1.54 ± 0.53 mmol/L, t=4.836) of treatment group were significantly higher than the control group (P<0.05), while the total blood viscosity, plasma viscosity, erythrocyteaggregation index, fibrinogen, TC, TG, LDL-C of treatment group were significantly lower than the control group (t value were 5.457, 8.875, 3.661, 6.549, 3.838, 6.369, 5.201, all Ps<0.05). No serious adverse reactions occurred during the treatment of the two groups. Conclusions The clinical curative effect of Tongqiao-Huoxue decoction for the treatment of vertebrobasilar artery insufficiency vertigo with stasis orifice type is significantly, and it can increases blood flow to the brain, improve hemorheology and lipid levels. It has the high security of the forward curative effect. Key words: Vertigo; Vertebrobasilar insufficiency; Tongqiao-Huoxue decoction; Flunarizine hydrochloride capsules; Syndrome of static blood blocking orifices

Experimental Studies for Small Diameter Grafts in an In Vivo Sheep Model-Techniques and Pitfalls.

Scientific attempts to create the "ideal" small diameter vascular graft have been compared with the "search of the holy grail." Prosthetic material as expanded polytetrafluoroethylene or Dacron shows acceptable patency rates to large caliber vessels, while small diameter (< 6 mm) prosthetic conduits present unacceptably poor patency rates. Vascular tissue engineering represents a promising option to address this problem. Thirty-two female Texel-sheep aged 6 months to 2 years underwent surgical common carotid artery (CCA) interposition using different tissue-engineered vascular substitutes. Explantation of the grafts was performed 12 (n = 12) and 36 (n = 20) weeks after surgery. Ultrasound was performed on postoperative day 1 and thereafter every 4 weeks to evaluate the graft patency. The average length of implanted substitutes was 10.3 ± 2.2 cm. Anesthesia and surgical procedure could be performed without major surgical complications in all cases.The grafts showed a systolic blood flow velocity (BFV) of 28.24 ± 13.5 cm/s, a diastolic BFV of 9.25 ± 4.53 cm/s, and a mean BFV of 17.85 ± 9.25 cm/s. Native vessels did not differ relevantly in hemodynamic measurements (systolic: 29.77 cm/s; diastolic: 7.99 cm/s ± 5.35; mean 15.87 ± 10.75). There was no incidence of neurologic complications or subsequent postoperative occlusion. Perioperative morbidity was low and implantation of conduits was generally well tolerated. This article aims to give a precise overview of in vivo experiments in sheep for the evaluation of small diameter vascular grafts performing CCA interposition, especially with regard to pitfalls and possible perioperative complications and to discuss advantages and disadvantages of this approach.

Transcranial Doppler ultrasound in vascular cognitive impairment-no dementia.

BackgroundAlthough cerebral white matter lesions (WMLs) are considered as a risk factor for vascular dementia, data on their impact on cerebral hemodynamics are scarce. We test and compare transcranial Doppler (TCD) features in WML patients with or without associated cognitive impairment.MethodsA sample of non-demented elderly patients with WMLs was consecutively recruited. Mean blood flow velocity (MBFV), pulsatility index (PI), peak systolic blood flow velocity (PSV), end-diastolic blood flow velocity (EDV), and resistivity index (RI) were recorded from the middle cerebral artery bilaterally. Global cognitive functioning, frontal lobe abilities, functional status, and WML severity were also assessed.Results161 patients satisfying the clinical criteria for vascular cognitive impairment-no dementia (VCI-ND) were age-matched with 97 presenting WMLs without any cognitive deficit. VCI-ND patients exhibited a decrease in MBFV and EDV, as well as an increase in PI, RI, and PSV. Moreover, a significant correlation between all TCD parameters and the severity of executive dysfunction was observed, whereas PI, RI, and EDV were significantly correlated with the WML load.ConclusionsVCI-ND showed a hemodynamic pattern indicative of cerebral hypoperfusion and enhanced vascular resistance. These changes may be considered as the TCD correlate of VCI-ND due to microcirculation pathology. TCD provides useful indices of the occurrence and severity of small vessel disease and executive dysfunction in elderly patients at risk of future dementia.

Microcirculation in the conjunctiva and retina in healthy subjects

BackgroundThe aim was to determine the relationship between bulbar conjunctival microcirculation and retinal microcirculation in a healthy population.MethodA functional slit-lamp biomicroscope (FSLB) was used to measure blood flow velocity (BFV) and blood flow rate (BFR) in the conjunctiva while a retinal function imager (RFI) was used to measure macular BFV and BFR in the retina. One eye of each subject of 58 self-reported healthy subjects was imaged in the same session on the same day.ResultsThe mean BFV in the venules of the conjunctiva was 0.49 ± 0.13 mm/s, which was significantly slower than that in the retinal arterioles (3.71 ± 0.78 mm/s, P < 0.001) and retinal venules (2.98 ± 0.58 mm/s, P < 0.001). The BFR in the conjunctiva (0.09 nl/s) was also significantly lower than that in the retina (arterioles = 0.81 nl/s, venules = 0.68 nl/s, all P < 0.001). The BFVs and BFRs were not related between the conjunctiva and retina (r ranged from − 0.17 to − 0.05, all P > 0.05).ConclusionThe microcirculation in the retina appeared to be different from that in the conjunctiva.

Cardiorespiratory and Cerebrovascular Responses to Leg Cycling Exercise during Muscle Metaboreflex Activation with Blood Flow Restriction in Moderate Normobaric Hypoxia

Skeletal muscle blood flow restriction and normobaric hypoxia are strategies adopted during exercise training because the associated reductions in local or systemic oxygenation may enhance athletic performance. Both manoeuvres evoke cardiorespiratory and cerebrovascular responses but have not been studied in combination. Blood flow restriction during exercise activates metabolically sensitive group III and IV skeletal muscle afferents (i.e., muscle metaboreflex activation), while systemic hypoxia activates the peripheral chemoreflex. We sought to determine whether the cardiorespiratory and cerebrovascular response to muscle metaboreflex activation with blood flow restriction during leg cycling exercise is augmented in moderate normobaric hypoxia.Nine healthy men (age 23±2 years; mean±SE) participated in two experimental trials performed under normoxic (fraction of inspired O2 [FiO2] = 21 %) and hypoxic (FiO2 = 13.5 %; equivalent of altitude of 3500 m) conditions whilst seated in a semi‐recumbent position in an environmental chamber. Trials consisted of a resting baseline period (3 min), followed by low intensity leg cycling exercise (64±7 Watts) under free‐flow conditions (~3½ min), and then bilateral thigh cuff inflation to 100 mmHg to induce blood flow restriction and muscle metaboreflex activation (~3 ½ min). Peripheral capillary oxygen saturation (SpO2; finger pulse oximetry), mean arterial pressure (MAP; Finometer and SunTech), heart rate (HR; electrocardiogram), the partial pressure of end‐tidal carbon dioxide (PETCO2; capnography), minute ventilation (VE; pneumotachometer) and middle cerebral artery mean blood flow velocity (MCAV; transcranial Doppler) were recorded.At baseline, SpO2 was lower during hypoxia (87±1 %) than normoxia (97±1 %; P&lt;0.05), but MAP, HR, PETCO2, VE and MCAv were not different between trials (P&gt;0.05). Leg cycling under free‐flow conditions significantly increased MAP, HR, PETCO2, VE and MCAv (P&lt;0.05 vs. baseline), with no differences observed between hypoxic and normoxic trials (P&gt;0.05). MAP (Δ14±2 vs. Δ16±2 mmHg; P=0.215), HR (Δ10±2 vs. Δ8±3 b·min−1; P=0.251), PETCO2 (Δ−1.1±0.3 vs. Δ−3.4±1.8 mmHg; P=0.596), VE (Δ4±1 vs. Δ4±1 L·min−1; P=0.446) and MCAv (Δ4±2 vs. Δ4±1 cm·s−1; P=0.408) responses to blood flow restriction during leg cycling (i.e., muscle metaboreflex activation) were not different in the hypoxic and normoxic trials.These preliminary findings suggest that moderate normobaric hypoxia (FiO2 = 13.5 %) does not augment the cardiorespiratory and cerebrovascular responses to muscle metaboreflex activation with blood flow restriction during low intensity leg cycling.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.