Carotid Artery Blood Flow Velocity Research Articles

Transcranial Doppler in Childhood Moyamoya: An Underutilized Tool?

BackgroundChildren with moyamoya are at high risk for incident and recurrent stroke. Transcranial Doppler (TCD) ultrasound is an attractive option to screen high-risk populations for moyamoya and to provide stroke risk stratification information due to its safety and cost-effectiveness. We used TCD to evaluate cerebral blood flow velocities in children with presurgical moyamoya and to determine if velocities differ between children with stable and unstable disease. MethodsFourteen participants aged ≤21 years with a radiographic diagnosis of moyamoya or moyamoya-like arteriopathy underwent a research TCD at a median age of 7.2 years. TCDs were performed outside of the setting of acute stroke and before surgical revascularization. Arteriopathy was classified as unstable if the participant had a stroke or transient ischemic attack within three months preceding the TCD. ResultsMiddle cerebral artery and internal carotid artery (ICA) blood flow velocities were elevated. The median M1 velocity was 138 cm/s (interquartile range [IQR] 106 to 168). Individual M1 flow velocities were a median of 5.0 S.D.s above age-based normative values. The median distal ICA velocity was 146 cm/s (IQR 124 to 163). Individual ICA flow velocities were a median of 5.9 S.D.s above normative values. Participants with unstable arteriopathy had higher M1 velocities compared with those with stable arteriopathy (170 vs 119 cm/s, P = 0.0003). We did not identify velocity differences based on comorbid conditions or age. ConclusionsThese preliminary data suggest that TCD is a promising tool for screening for cerebral arteriopathies in high-risk pediatric populations and assessment for unstable disease.

Estimation of Mouse Carotid Arterial Wall Shear Stress Using High-Frequency Ultrasound Imaging.

Wall shear stress (WSS) is a crucial hemodynamic factor that promotes atherosclerosis (plaque) development in arteries; although the relationship between WSS and arterial atherosclerosis has been explored in many animal studies, it is not fully understood. No suitable tool, however, exists for rapidly estimating dynamic WSS in small-animal studies. This study proposes a 40-MHz high-frequency ultrasound (HFUS) imaging system for dynamic WSS estimation based on mouse carotid artery blood flow velocity gradient measurements by vector Doppler imaging (VDI). Aliasing reduces the accuracy of Doppler measurements, which can be prevented by increasing the imaging frame rate. Conventionally, imaging is performed at two tilted angles by alternating between the angles; in the proposed method, the frame rate was doubled by imaging at each tilted angle sequentially and by then temporally aligning the sequences based on pulsatile flow characteristics. Velocity estimation using this method had low errors for both a steady-flow straight-tube and pulsatile flow 60%-stenosis phantom. The method was tested for wild-type (WT) C57BL/6 mice at 16 weeks old and apolipoprotein E knockout (ApoE KO) mice at 16 and 24 weeks old; differences in time-averaged and oscillatory WSS were observed, and histology confirmed that the 24-week ApoE KO mice with the highest oscillatory WSS had the greatest plaque formation. The proposed HFUS WSS imaging method can predict the location and extent of plaque development; thus, this method is useful for small-animal studies investigating the WSS effect on atherosclerotic plaque development.

Associations between Aortic Stiffness, Cerebral Artery Resistance and White Matter Integrity in Women with a History of Preeclampsia

Purpose: Preeclampsia is a pregnancy complication characterized by new-onset hypertension and systemic organ dysfunction. Women with a history of preeclampsia (hxPE) have a greater cerebral white matter ischemic damage burden and a three-fold elevated risk of vascular dementia later in life compared with healthy pregnancy independent of traditional cardiovascular risk factors. Aortic stiffness promotes the transmission of deleterious pulsatile pressure to the distal cerebral circulation, resulting in increased cerebrovascular resistance (CVR) that contributes to compromised brain blood flow and structure. We hypothesized that young women with hxPE would have greater aortic stiffness and CVR compared to healthy pregnancy, and CVR would be related to lower cerebral white matter microstructural integrity (WMI). Methods: Women with hxPE (N=10) were matched with healthy pregnancy controls (N=11) by age (28-42 years), educational attainment, body mass index, and postpartum duration (1-5 years). Aortic stiffness was quantified as carotid-femoral pulse wave velocity (CFPWV). 4D flow and diffusion tensor magnetic resonance images were acquired to evaluate internal carotid and middle cerebral artery (MCA) blood flow velocity and WMI (fractional anisotropy), respectively (3T MRI, GE). CVR index was calculated as the ratio of central mean arterial pressure to regional flow velocity. Results: Women with hxPE tended to exhibit higher CFPWV compared with controls (6.3±0.8 vs 5.6±0.7 m/s, P=0.09 adjusted for mean arterial pressure). CVR did not differ at the internal carotid artery (2.2±0.4 vs 2.0±0.3 mmHg s cm -1 , P=0.30) but was higher at the MCA among women with hxPE (2.4±0.3 vs 2.1±0.4 mmHg s cm -1 , P=0.08). In the entire group, CFPWV was associated with greater CVR at the internal carotid (r=0.41, P=0.07) and MCA (r=0.48, P=0.03). Although WMI did not differ between groups, greater MCA CVR was related to lower WMI overall (r=-0.45, P=0.049) and in select white matter tracts (corpus callosum genu, r=-0.53, P=0.02; cingulum hippocampus, r=-0.43, P=0.06; superior frontooccipital fasciculus, r=-0.46, P=0.04). Conclusions: Women with hxPE had elevated aortic stiffness that was associated with greater CVR. Greater CVR was related to lower WMI in subcortical watershed regions susceptible to reduced perfusion. These findings indicate that aortic stiffness may contribute to early declines in WMI via CVR in women with hxPE. Supported by AHA Transformational Project Award (969732) to GLP and NIH grant 1S10OD025025-01 to VM This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Disability in multiple sclerosis is associated with vascular factors: An ultrasound study

BackgroundAlthough multiple sclerosis (MS) is an immune-related disorder, pharmaceutical interventions targeting the immune system do not stop or reverse disability progression; the major challenge for this condition. Studies show that disability progression in MS is associated with vascular comorbidity and brain volume loss, indicating that a multi-targeted approach is required to prevent debilitation. The aim of the present study was to examine the associations between vascular ultrasound, disability, biochemistry and lifestyle data in people with MS (pwMS). MethodsExtracranial vascular ultrasound was performed on 51 pwMS and 25 age-matched controls. Sonographic interrogation determined carotid intima-media thickness (cIMT) and abnormal blood flow patterns. Disability was assessed using the Expanded Disability Status Scale (EDSS). Biochemical and lifestyle data were obtained for all participants. ResultsThe EDSS had a highly significant positive association with the cIMT of the right (r = 0.63; p = 0.001) and left (r = 0.49; p = 0.001) common carotid arteries and negative associations with the peak systolic blood flow velocity of the right vertebral artery (r = -0.42; p = 0.01) as well as end-diastolic velocity of the left internal carotid artery (r = -0.47; p = 0.01). These associations were significantly influenced by biochemical and lifestyle factors. Both cIMT and age showed significant associations with the EDSS. When cIMT was adjusted for age in a regression analysis, the association between the EDSS and the cIMT remained significant (p < 0.01), while the age association was reduced to being significant only at 10% (p = 0.06). There was no association between the use of MS medication and the EDSS (p = 0.56). ConclusionPwMS who had increased cIMT, a surrogate marker for atherosclerosis, and reduced carotid artery blood flow velocities were at risk for greater disability over and above the effect of aging. These findings provide important information for disease management and disability prevention in pwMS. Modification of diet and lifestyle may promote the unhindered flow of essential nutritional factors into the brain in pwMS.

Differences In Blood-flow Patterns Of The Carotid Artery Between Two Exercise Modalities At Three Intensities

Endothelial shear stress (ESS), frictional force produced by red blood cells on endothelial cells, helps to maintain endothelial homeostasis, and help to determine blood flow patterns. Purpose: This study seeks to determine exercise-induced blood flow patterns in the carotid artery during different exercise modalities (back squat and treadmill running) at 3 different intensities. Methods: Fourteen participants (7 males and 7 females) participated in a repeated measures study design. Three sessions were performed to obtain baseline measurements, 1-repetition maximum back squat test (1RM Squat), and treadmill maximum oxygen uptake test (VO2max). Two more sessions, for squat and treadmill, were randomized within a week after the baseline measurements. Squat intensities selected: low = 45% 1RM, moderate = 65% 1RM, and high = 85% 1RM. Running intensities were selected using blood lactate levels: low = 0-2 mmol/L, moderate = 2-4 mmol/L, and high >4.0 mmol/L from the VO2max test. Blood flow patterns of the carotid artery (diameter and blood flow velocity) and presence of turbulence determined by calculation of Reynolds number (Re), were obtained using ultrasound imaging and Doppler. Data analysis used a 2-way repeated-measures ANOVA, with Holm-Bonferroni post-hoc analysis to determine pairwise differences between modalities and intensity. Statistical significance was set at α = 0.05. Results: There were main effects and interaction between intensity and exercise modalities (p < 0.05) for ESS. Pairwise comparisons showed difference in moderate (p < 0.05) and high (p < 0.05) intensity in both modalities (Figure 1A) compared to low intensity. Similarly, there was a main effect of exercise intensity (p < 0.05) for Re. Pairwise comparisons indicate significant difference (p < 0.05) in high intensity in both modalities (Figure 1B) compared to low intensity. Conclusion: Results indicated turbulent blood flow patterns across all intensities and modalities; however, high intensity treadmill yields greater turbulent blood flow. Furthermore, ESS increases linearly as intensity increases, with greater magnitude in moderate and high intensity treadmill. Clinicians should be aware of differences in carotid artery hemodynamics at different exercise intensities and modes to prescribe better exercise interventions.

A comparative analysis of sonographic carotid artery Doppler indices in type 2 diabetics and non-diabetics

Background and Aim: Diabetes mellitus type 2 is a chronic metabolic disorder of global concern with signs of hyperglycemia due to insulin resistance, relative lack of insulin, or both. Stroke is a possible complication of this metabolic disorder as a result of advanced carotid artery atherosclerosis, which diabetic patients develop with attendant carotid blood flow changes. The present study evaluated sonographic carotid artery blood flow velocities in individuals with type 2 diabetics and compared with values in normoglycemic controls. Materials and Methods: This was a prospective case–control study, in which we evaluated carotid Doppler indices in 125 consenting confirmed type 2 diabetics (cases) and 125 age- and gender-matched normoglycemic healthy controls for a period of 6 months (October 2019 to March 2020). The diabetics (cases) were recruited using systematic sampling method and the controls via convenience sampling. Demographic data and anthropometric measurements as well as ultrasound findings were entered into a Microsoft Office Excel Database and analyzed using International Business Machines (IBM) Statistical Package for Social Sciences (SPSS) Version 21. Tables, scatter-plot graphs, and bar charts were used in showing and evaluating the findings. Pearson’s correlation coefficient was used to assess correlation between two continuous variables. Results: The mean age of type 2 diabetics was 67.06±9.8 years, whereas that of the non-diabetics was 66.98±10.7. Females were in majority in both groups (64 in diabetics and 70 in non-diabetics). There were 61 males in the diabetics and 55 males in the non-diabetics. The mean carotid blood flow velocities in the diabetics and non-diabetics were, respectively, as follows: common carotid artery (CCA) end-diastolic velocity (EDV) 21.03±2.3 and 25.22±2.5, CCA peak systolic velocity (PSV) 81.70±4.1 and 83.60±3.6, internal carotid artery (ICA) EDV 17.99±5.6 and 21.57±2.0, ICA PSV 69.30±5.1 and 73.87±2.1, and ICA/CCA PSV ratio 0.83±01 and 0.91±0.1. Conclusion: Type 2 diabetics had significantly lower carotid blood flow velocities than non-diabetics. This suggests that proper management and compliance with care may reduce the development of features of atherosclerosis in type 2 diabetics.

Respiratory Variations in Peak Peripheral Artery Velocities and Waveforms for Rapid Assessment of Fluid Responsiveness in Traumatic Shock Patients.

BackgroundThis study aimed to assess the correlation between the variability of the end-inspiratory and end-expiratory blood flow waveform and fluid responsiveness (FR) in traumatic shock patients who underwent mechanical ventilation by evaluating peripheral arterial blood flow parameters.Material/MethodsA cohort of 60 patients with traumatic shock requiring mechanical ventilation-controlled breathing received ultrasound examinations to assess the velocity of carotid artery (CA), femoral artery (FA) and brachial artery (BA). A rehydration test was performed in which of 250 mL of 0.9% saline was administered within 30 min between the first and second measurement of cardiac output by echocardiography. Then, all patients were divided into 2 groups, a responsive group (FR+) and a non-responsive group (FR−). The velocity of end-inspiratory and end-expiratory peripheral arterial blood flow of all patients was ultrasonically measured, and the variability were measured between end-inspiratory and end-expiratory.ResultsThe changes in the end-inspiratory and end-expiratory carotid artery blood flow velocity waveforms of the FR+ groups were significantly different from those of the FR− group (P<0.001). A statistically significant difference in ΔVmax (CA), ΔVmax (BA), and ΔVmax (FA) between these 2 groups was found (all P<0.001). The ROC curve showed that ΔVmax (CA) and ΔVmax (BA) were more sensitive values to predict FR compared to ΔVmax (FA). The sensitivity of ΔVmax (CA), ΔVmax (FA), and ΔVmax (BA) was 70.0%, 86.7%, and 93.3%, respectively.ConclusionsThe study showed that periodic velocity waveform changes in the end-inspiratory and end-expiratory peripheral arterial blood flow can be used for quick assessment of fluid responsiveness.

Effect of calculated plasma osmolality and atherogenic index of plasma on carotid artery blood flow velocities.

The increase in carotid artery blood flow velocity is a measure of the severity of the carotid artery stenosis caused by atherosclerosis. Carotid artery stenosis is progressive and is of great importance due to the risk of stroke it creates. As an alternative to radiological examinations in these patients, patient follow-up can be facilitated by associating novel laboratory parameters with the severity of stenosis. In this study, we aimed to investigate the effect of the calculated plasma osmolality and atherogenic index of plasma on carotid artery blood flow velocities in patients with carotid artery stenosis. A total of 161 patients diagnosed with carotid artery stenosis who admitted to our clinic between May 2018 and May 2020 were retrospectively analyzed. According to the carotid artery blood flow velocities measured with the Doppler ultrasonography, the patients were divided into two groups as "Normal flow velocity group" (n = 62) and "Increased flow velocity group" (n = 99). The calculated plasma osmolality, atherogenic index of plasma, and mean platelet volume were significantly associated with increased carotid artery blood flow velocity (p < 0.001, p < 0.001, p = 0.006; respectively). Calculated plasma osmolality and atherogenic index of plasma were identified as independent predictors of increase in carotid artery blood flow velocity (p < 0.001, p < 0.001; respectively). In the Receiver Operating Characteristic curve analysis, the plasma osmolality cut-off value, which predicts the increase in carotid artery blood flow velocity was found to be 291.45 mOsm/kg (Area Under the Curve: 0.746, p < 0.001, 65.7% sensitivity, and 67.7% specificity), and atherogenic index of plasma cut-off value was 0.20 (Area Under the Curve: 0.735, p < 0.001, 65.7% sensitivity, and 66.1% specificity). There was a significant relationship between the increase in carotid artery blood flow velocity and the increase in plasma osmolality and atherogenic index of plasma values. As a result, we can predict the increase in carotid artery blood flow velocity, that is, the increase in the severity of the carotid artery stenosis, with plasma osmolality and atherogenic index of plasma values that can be calculated simply from routine biochemical tests.

Endothelial Shear Stress In The Common Carotid Artery During Boxing Training

PURPOSE: Endothelial function is highly regulated by the interaction between blood flow and the endothelium. Endothelial shear stress (ESS) is defined as the dragging force generated by this interaction and it has been reported that low ESS affects nitric oxide bioavailability which in turn might increase blood pressure. Exercise programs are one of the best suited approaches to prevent high blood pressure, however, there are no studies describing changes on ESS in the common carotid artery during specific modalities of exercise, such as boxing training. Therefore, the purpose of this study was to quantify ESS in the common carotid artery during maximal and submaximal boxing training in normotensive and pre-hypertensive subjects. METHODS: A cohort of 5 healthy normotensive and 5 pre-hypertensive subjects matched by age, gender, height, and weight were recruited for this study. All 10 subjects performed two boxing tests. The first was a graded maximal boxing test to estimate their maximal oxygen uptake (VO₂max). The second one, performed 48 hours after the first evaluation, was a 2-workload steady-state boxing test at 60%VO2max and at 95%VO2max for 3 minutes each. A high-definition Doppler ultrasound recorded common carotid artery diameters and blood flow velocities throughout each steady-state condition. ESS was estimated using Womersley’s approximation. RESULTS: There was a significant increase in antegrade ESS with higher workloads in both groups (p < 0.05 for all). No difference were found in anterograde ESS at baseline (Normotensive: 33.9±13.9 dynes/cm2, Pre-HTA: 34.7±5.5 dynes/cm2; p = 0.936), at 60%VO₂max (Normotensive: 51.3±19.1 dynes/cm2, Pre-HTA: 49.6±7.6 dynes/cm2; p = 0.894, and at 95%VO₂max (Normotensive: 72.9±30.9 dynes/cm2 , Pre-HTA: 85.2±12.5 dynes/cm2; p = 0.560) between both groups. Meanwhile, no retrograde blood flow was present at baseline for either groups, but it was identified at 60%VO₂max (Normotensive: 8.1±0.7 dynes/cm2, Pre-HTA: 7.8±7.8 dynes/cm2; p = 0.971) and 95%VO₂max (Normotensive: 22.5±18.9 dynes/cm2 , Pre-HTA: 20.8±5.6 dynes/cm2; p = 0.891). CONCLUSIONS: ESS increases in an exercise-intensity manner during boxing training in normotensive and prehypertensive population. Boxing training might be beneficial in high blood pressure prevention due to increments on ESS.

Endothelial shear stress in the common carotid artery during boxing training in prehypertension

PURPOSEEndothelial function is highly regulated by the friction between blood flow and the endothelium. Endothelial shear stress (ESS) is defined as the dragging force generated by this interaction and it has been reported that low ESS affects nitric oxide bioavailability which in turn might increase blood pressure. Exercise programs are one of the best suited approaches to treat high blood pressure, however, there are no studies describing changes on ESS in the common carotid artery during upper‐body exercise, such as boxing training. Therefore, the purpose of this study was to quantify ESS in the common carotid artery during 60% and 95% of the maximal boxing exercise capacity in normotensive and pre‐hypertensive subjects.METHODSA total of 5 healthy normotensive and 5 pre‐hypertensive subjects matched by age, gender, height, and weight were recruited for this study. All 10 subjects performed two boxing exercise tests. The first was a graded maximal boxing test to estimate their maximal oxygen uptake (VO2max). The second one, performed 48 hours after the first evaluation, was a 2‐workload steady‐state boxing test at 60%VO2max and at 95%VO2max for 3 minutes each. A high‐definition Doppler ultrasound recorded common carotid artery diameters and blood flow velocities throughout each steady‐state condition. ESS was estimated using Womersley’s approximation.RESULTSThere was a significant increase in antegrade ESS with higher workloads in both groups (p &lt; 0.05 for all). No difference were found in anterograde ESS at baseline (Normotensive: 33.9±13.9 dynes/cm2, Pre‐HTA: 34.7±5.5 dynes/cm2; p = 0.936), at 60%VO2max (Normotensive: 51.3±19.1 dynes/cm2, Pre‐HTA: 49.6±7.6 dynes/cm2; p = 0.894, and at 95%VO2max (Normotensive: 72.9±30.9 dynes/cm2, Pre‐HTA: 85.2±12.5 dynes/cm2; p = 0.560) between both groups. Meanwhile, no retrograde blood flow was present at baseline for either groups, but it was identified at 60%VO2max (Normotensive: 8.1±0.7 dynes/cm2, Pre‐HTA: 7.8±7.8 dynes/cm2; p = 0.971) and 95%VO2max (Normotensive: 22.5±18.9 dynes/cm2, Pre‐HTA: 20.8±5.6 dynes/cm2; p = 0.891).CONCLUSIONESS increases in an exercise‐intensity manner during boxing training in normotensive and prehypertensive population. Boxing training might be beneficial in high blood pressure prevention due to increments on ESS.

Carotid artery blood flow velocities during open-heart surgery and its association with delirium: A prospective, observational pilot study.

The aim of this prospective observational single-centre pilot study was to evaluate the association between alterations in carotid artery blood flow velocities during cardiac surgery and postoperative delirium.Carotid artery blood flow velocity was determined perioperatively at 5 different timepoints by duplex sonography in 36 adult cardiac surgical patients. Delirium was assessed using the Confusion Assessment Method for the ICU and the Intensive Care Delirium Screening Checklist. Additionally, blood flow velocities in the middle cerebral arteries, differences in regional cerebral tissue oxygenation and quantity and quality of microemboli were measured.Delirium was detected in 7 of 36 patients. After cardiopulmonary bypass carotid artery blood flow velocities increased by +23 cm/second (95% confidence interval (CI) 9-36 cm/second) in non-delirious patients compared to preoperative values (P = .002), but not in delirious patients (+3 cm/second [95% CI -25 to 32 cm/second], P = .5781). Middle cerebral artery blood flow velocities were higher at aortic de-cannulation in non-delirious patients (29 cm/second [inter-quartile range (IQR), 24-36 cm/second] vs 12 cm/second [IQR, 10-19 cm/second]; P = .017). Furthermore, brain tissue oxygenation was higher in non-delirious patients during surgery.Our results suggest that higher cerebral blood flow velocities after aortic de-clamping and probably also improved brain oxygenation might be beneficial to prevent postoperative delirium.

Safety and Clinical Efficacy of Yangxue Qingnao Granules in the Treatment of Chronic Cerebral Circulation Insufficiency: A Systematic Review and Meta-Analysis.

To evaluate the safety and clinical efficacy of Yangxue Qingnao (YXQN) granules in the treatment of chronic cerebral circulation insufficiency (CCCI), electronic databases—PubMed, Embase, CNKI, VIP, and Wangfang—were searched for randomized controlled trials (RCTs) published up to January 2019. GRADE and RevMan 5.3.0 were used for grading and analysis, respectively. Fifteen trials involving 1211 CCCI patients were included. Subgroup analysis was performed owing to study heterogeneity. Compared to nimodipine plus routine treatment, YXQN granules plus routine treatment were more effective in increasing basilar artery (BA) blood flow velocity (mean difference (MD) = 3.34, 95% confidence interval (CI) = [2.31, 4.37], P < 0.00001), vertebral artery (VA) blood flow velocity (MD = 0.52, 95% CI = [0.27, 0.76], P < 0.0001), and internal carotid artery (ICA) blood flow velocity (MD = 7.46, 95% CI = [2.01, 12.90], P=0.007). In improving the clinical efficacy of traditional Chinese medicine (TCM) for symptoms such as headache, dizziness, and insomnia, YXQN granules plus routine treatment were shown to be superior to the following control treatments: nimodipine plus routine treatment (mean difference (M-H) = 4.21, 95% CI = [2.49, 7.12], P < 0.00001), flunarizine plus routine treatment (mean difference (M-H) = 3.92, 95% CI = [1.36, 11.29], P=0.01), troxerutin plus routine treatment (mean difference (M-H) = 4.79, 95% CI = [2.20, 10.42], P < 0.00001), and routine treatment (mean difference (M-H) = 6.13, 95% CI = [1.48, 25.34], P=0.01). Risk of bias was assessed in 15 trials. One analysis was graded using GRADE and showed poor results. Adverse events were not reported explicitly in all but one trial. Thus, this meta-analysis suggests that YXQN granules may be beneficial for patients with CCCI. However, owing to the poor quality of the clinical trials and small sample sizes, a definite conclusion on the efficacy and safety of YXQN granules cannot be drawn from existing information.

Carotid Artery Blood Flow Velocities and Cognitive Performance: Forecasting Cognitive Decline.

Carotid Artery Blood Flow Velocities and Cognitive Performance: Forecasting Cognitive Decline.

Intrauterine growth restriction results in persistent vascular mismatch in adulthood.

Intrauterine growth restriction (IUGR) increases offspring risk of chronic diseases later in life, including cardiovascular dysfunction. Our prior studies suggest biventricular cardiac dysfunction and vascular impairment in baboons who were IUGR at birth because of moderate maternal nutrient reduction. The current study reveals changes in artery sizes, distensibility, and blood flow pattern in young adult IUGR baboons, which may contribute to cardiac stress. The pattern of abnormality observed suggests that vascular redistribution seen with IUGR in fetal life may continue into adulthood. Maternal nutrient reduction induces intrauterine growth restriction (IUGR), increasing risks of chronic diseases later in life, including cardiovascular dysfunction. Using ultrasound, we determined regional blood flow, blood vessel sizes, and distensibility in IUGR baboons (8 males, 8 females, 8.8years, similar to 35 human years) and controls (12 males, 12 females, 9.5years). The measured blood vessels were larger in size in the males compared to females before but not after normalization to body surface area. Smaller IUGR normalized blood vessel sizes were observed in the femoral and external iliac arteries but not the brachial or common carotid arteries and not correlated significantly with birth weight. Mild decrease in distensibility in the IUGR group was seen in the iliac but not the carotid arteries without between-sex differences. In IUGR baboons there was increased carotid arterial blood flow velocity during late systole and diastole. Overall, our findings support the conclusion that region specific vascular and haemodynamic changes occur with IUGR, which may contribute to the occurrence of later life cardiac dysfunction. The pattern of alteration observed suggests vascular redistribution efforts in response to challenges in the perinatal period may persist into adulthood. Further studies are needed to determine the life course progression of these changes.

Decreased carotid and vertebral arterial blood-flow velocity in response to orthostatic unload in patients with severe aortic stenosis.

Responses of cerebral blood flow to the postural unloading maneuver in aortic stenosis (AS) have not been described so far. Our aim was to assess effects of orthostatic stress test on changes of carotid and vertebral artery blood flow and transaortic gradients. From consecutive 101 AS patients we selected 50 patients with severe isolated AS. Maximal and mean transaortic pressure gradients, as well as peak systolic blood-flow velocity (PSV) and end-diastolic velocity (EDV) in the common carotid artery, internal carotid artery and vertebral artery on both sides were measured by duplex ultrasound in the supine position and at 1-2 min after the assumption of the sitting position in patients with AS, and in stand-ing position in healthy controls. The orthostatic stress test induced significant decrease of carotid and vertebral arterial flow velocities in AS patients. Transaortic pressure gradients also dropped while the patients were sitting (p < 0.001). A history of syncope/presyncope was not associated with a significantly lower PSV and EDV in carotid and vertebral arteries in the upright position. In healthy controls, the velocities in carotid and vertebral arterial flow have been unchanged after maneuver reducing preload. In AS patients, decrease of carotid and vertebral arterial flow velocities and transaortic gradients in the sitting position were observed. Orthostatic test position does not ap-pear to be associated with a history of syncope/presyncope in patients with severe isolated AS, de-spite a simultaneous drop of transvalvular pressure gradient.

Endovascular Cooling Catheter for Selective Brain Hypothermia: An Animal Feasibility Study of Cooling Performance

Therapeutic hypothermia represents a promising neuroprotective treatment in acute ischemic stroke. Selective cerebral hypothermia applied early, prior to and during endovascular mechanical recanalization therapy, may be beneficial in the critical phase of reperfusion. We aimed to assess the feasibility of a new intracarotid cooling catheter in an animal model. Nine adult sheep were included. Temperature probes were introduced into the frontal and temporal brain cortices bilaterally. The cooling catheter system was introduced into a common carotid artery. Selective blood cooling was applied for 180 minutes. Systemic and local brain temperatures were measured during cooling and rewarming. Common carotid artery diameters and flow were measured angiographically and by Doppler sonography. The common carotid artery diameter was between 6.7 and 7.3 mm. Common carotid artery blood flow velocities increased moderately during cooling and after catheter removal. Maximum cerebral cooling in the ipsilateral temporal cortex was -4.7°C (95% CI, -5.1 to -4.0°C). Ipsilateral brain temperatures dropped significantly faster and became lower compared with the contralateral cortex with maximum temperature difference of -1.3°C (95% CI, -1.5 to -1.0°C; P < .0001) and compared with systemic temperature (-1.4°C; 95% CI, -1.7 to -1.0°C; P < .0001). Sheep proved a feasible animal model for the intracarotid cooling catheter. Fast induction of selective mild hypothermia was achieved within the cooled cerebral hemisphere, with stable temperature gradients in the contralateral brain and systemic blood. Further studies are required to demonstrate any therapeutic benefit of selective cerebral cooling in a stroke model.

Carotid Arterial Hemodynamic in Ischemic Levkoaraiosis Suggests Hypoperfusion Mechanism

Background: Leukoaraiosis (ILA) is believed to be ischaemic in origin due to its similar location as that of lacunar infarctions and its association with cerebrovascular risk factors. However, its pathophysiology is not well understood. The ischaemic injuries may be a result of increased pulsatility or cerebral hypo-perfusion. We used carotid duplex ultrasound to prove that the underlying mechanism is hypo-perfusion. Methods: We compared 55 ILA patients to 44 risk factor-matched controls with normal magnetic resonance imaging (MRI) of the head. ILA diagnosis was based on MRI and was further categorised according to the Fazekas scale. We measured carotid artery blood flow velocity and diameter and calculated carotid blood flow and resistance indexes. Results: Blood flow velocities and blood flows were significantly lower in the ILA group, including diastolic, systolic and mean pressures (p ≤ 0.05). The resistance indices were higher in the ILA group, but the differences were not statistically significant. All the velocities and blood flows showed a decreasing trend with higher Fazekas score, whereas resistance indexes showed an increasing trend. Conclusions: Lower blood flow and higher resistance of carotid arteries are consistent with the hypo-perfusion theory of ILA. Carotid ultrasound could have a diagnostic and prognostic role in ILA patients.

Advice on Lifestyle Changes (Diet, Red Wine and Physical Activity) Does Not Affect Internal Carotid and Middle Cerebral Artery Blood Flow Velocity in Patients with Carotid Arteriosclerosis in a Randomized Controlled Trial

Background: A Mediterranean diet, with and without small daily amounts of red wine, and physical activity reduce the risk of cerebrovascular disease and improve cognition. An increase in cerebral blood flow may be the underlying mechanism. Under normal conditions, cerebral blood flow velocity changes in the internal carotid arteries and in large basal cerebral arteries correlate closely with cerebral blood flow changes, as the diameter of these vessels hardly changes and only the smaller vessels downstream change their diameter. Methods: A prospective randomized controlled trial was performed in 108 patients with carotid atherosclerosis (mean age 64 years, 67% men, 66% on statin therapy). Half of them were advised to follow a polyphenol-rich modified Mediterranean diet including 1-2 tomatoes, 3-5 walnuts and a bar of dark chocolate (25 g) a day and to perform moderate physical exercise for 30 min/day (lifestyle changes). Within these two groups, half of the patients were randomized either to avoid any alcohol or to drink 100 ml of red wine (women) or 200 ml of red wine (men) daily. Bilateral middle cerebral and internal carotid blood flow velocity (peak systolic, peak end-diastolic and mean) was measured at baseline and after 4 and 20 weeks using colour-coded duplex ultrasound. Insonation depth and insonation angle were used to identically place the sample volume during follow-up investigations. A general linear model with Tukey-Kramer adjustment for multiple comparisons was used to assess the primary end points. For the analysis we used the mean values of the right and left artery. Results: Neither lifestyle changes nor red wine had an effect on peak systolic, peak end-diastolic or mean cerebral blood flow velocity. Conclusions: Advice on lifestyle changes, including a modified polyphenol-rich Mediterranean diet, a glass of red wine daily and physical exercise, did not affect middle cerebral and internal carotid blood flow velocity in our patient group with carotid atherosclerosis. An increase in cerebral blood flow is thus unlikely to be the cause of the reduced risk of cerebrovascular disease and improved cognitive functioning described in the literature. One possible explanation for the fact that blood flow velocity was not affected by red wine, diet and physical activity advice is that two thirds of our patients were already on statin therapy. Statins increase cerebral blood flow and vasomotor reactivity via nitric oxide.

Effects of acute hypoxia on cerebrovascular responses to carbon dioxide

In normoxic conditions, a reduction in arterial carbon dioxide tension causes cerebral vasoconstriction, thereby reducing cerebral blood flow and modifying dynamic cerebral autoregulation (dCA). It is unclear to what extent these effects are altered by acute hypoxia and the associated hypoxic ventilatory response (respiratory chemoreflex). This study tested the hypothesis that acute hypoxia attenuates arterial CO2 tension-mediated regulation of cerebral blood flow to help maintain cerebral O2 homeostasis. Eight subjects performed three randomly assigned respiratory interventions following a resting baseline period, as follows: (1) normoxia (21% O2); (2) hypoxia (12% O2); and (3) hypoxia with wilful restraint of the respiratory chemoreflex. During each intervention, 0, 2.0, 3.5 or 5.0% CO2 was sequentially added (8 min stages) to inspired gas mixtures to assess changes in steady-state cerebrovascular CO2 reactivity and dCA. During normoxia, the addition of CO2 increased internal carotid artery blood flow and middle cerebral artery mean blood velocity (MCA Vmean), while reducing dCA (change in phase = -0.73 ± 0.22 rad, P = 0.005). During acute hypoxia, internal carotid artery blood flow and MCA Vmean remained unchanged, but cerebrovascular CO2 reactivity (internal carotid artery, P = 0.003; MCA Vmean, P = 0.031) and CO2-mediated effects on dCA (P = 0.008) were attenuated. The effects of hypoxia were not further altered when the respiratory chemoreflex was restrained. These findings support the hypothesis that arterial CO2 tension-mediated effects on the cerebral vasculature are reduced during acute hypoxia. These effects could limit the degree of hypocapnic vasoconstriction and may help to regulate cerebral blood flow and cerebral O2 homeostasis during acute periods of hypoxia.

Abstract 189: The Effects of Fw-ii Axial Blood Pump on Cardiogenic Shock After Acute Myocardial Infarction in a Sheep Model

Background: High-risk percutaneous coronary interventions (PCI), refractory cardiogenic shock and in-lab cardiac arrest are all associated with a high mortality rate in patients with acute myocardial infarction (AMI). The extent to which the use of FW-II axial pump can improve outcomes in cardiogenic shock is not known. Methods: In 12 adult male sheep, cardiogenic shock was induced by circumflex coronary artery ligation for 90 min, followed by 240 min of reperfusion. The animals were divided into two groups: control group had non-mechanic supportive care including dopamine, dobutamine and other drugs; FW-II axial pump group was supported with FW-II axial pump from 90 min after ischemia to 240 min after reperfusion. Hemodynamic efficacy (mean arterial pressure (MAP), cardiac index (CI), pulmonary artery pressure (PAP) and systemic vascular resistance (SVR)), left ventricular systolic / diastolic diameter, carotid artery blood flow velocity were measured at 3 specific conditions: preligation, postligation and before being euthanasiaed. Reperfusion area was detected by Evans blue, and apoptosis detection included TUNEL staining, caspase-3 activity, bax and bcl-2 relative expression in normal, borderline and infarcted myocardium. Results: Animals in control group survived for an average of 24 ± 9.6 hours, and Animals in FW-II group survived 72 hours and were euthanasiaed. Compared with control group, MAP, CI, artery diastolic velocity, and oxygen delivery index (DO2I and VO2I) were significantly higher (P &lt;0.05) in FW-II pump group; PAP and SVR was significantly lower than the control group (P &lt;0.01); Infarct ratio (percentage of the infarct area relative to the area at infarct risk) was significantly reduced in FW-II pump group with a significant difference from control group (P &lt; 0.001). Apoptotic index and bax expression of border zone myocardium were significantly lower in FW-II pump group (P&lt;0.01). However, there were no difference between control group and FW-II pump group for apoptotic index and bax expression in normal and infarcted myocardium (P &gt;0.05). Conclusion: Short-term assistance of FW-II axial pump improved the survival of cardiogenic shock by increasing systemic organ perfusion and reducing myocardial apoptosis.