Abstract TP112: Mechanism of Recurrent Stroke in Patients with Atherosclerotic Vertebrobasilar Disease in Relation to Hemodynamics

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Joanna D Schaafsma ◽  
Frank L Silver ◽  
Scott E Kasner ◽  
Louis R Caplan ◽  
Linda Rose-Finnell ◽  
...  
Keyword(s):  
Recurrent Stroke ◽  
Posterior Circulation ◽  
Low Flow ◽  
Flow Measurements ◽  
Quantitative Mr ◽  
Perforating Artery ◽  
Recurrent Strokes ◽  
Stroke Mechanism ◽  
Prospective Longitudinal ◽  
Distal Flow

Objectives: Patients with symptomatic atherosclerotic vertebrobasilar disease are at high risk for recurrent stroke and we have demonstrated that distal flow status is independently associated with this risk. Our aim was to assess the mechanism of recurrent strokes in these patients related to their distal flow status. Methods: Patients with symptomatic atherosclerotic vertebrobasilar disease were enrolled in a prospective longitudinal cohort study (VERiTAS) with a median follow-up of 23 months. Large-vessel flow in the posterior circulation distal to the stenosis and/or occlusion was measured on quantitative MR angiography and dichotomized into normal or low flow. Three observers, who were blinded to the distal flow status, independently reviewed the imaging done at the time of the recurrent stroke to classify the most likely stroke mechanism. Results: Ten out of 72 enrolled patients had a recurrent stroke in the posterior circulation. Four patients were determined to have embolic infarcts, four patients had infarcts caused by plaques that occluded a branch or perforating artery (junctional plaques), and two patients had imaging that suggested hemodynamic infarction. Five of the ten patients with recurrent strokes had low distal flow. Of these, two patients had hemodynamic infarcts, one patient had an embolic infarct, and two patients had a junctional plaque. None of the five patients with normal flow had hemodynamic infarcts, three patients had embolic infarcts, and two patients had a junctional plaque. Conclusion: Despite the small numbers, there seems to be a higher risk of hemodynamic infarction in patients with low flow distal to symptomatic vertebrobasilar disease than in the presence of normal distal flow. This would confirm the hypothesis that in addition to embolic strokes and those related to junctional plaque, patients with low distal flow are at risk for hemodynamic infarction. Further studies are required to determine whether flow measurements could be used to select patients who may benefit from endovascular treatment of atherosclerotic vertebrobasilar disease.

Abstract 14021: Angiographic and Hemodynamic Features of Symptomatic Vertebrobasilar Disease: Baseline Data from the VERiTAS Study

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sepideh Amin-Hanjani ◽  
Xinjian Du ◽  
Linda Rose-Finnell ◽  
Dilip Pandey ◽  
DeJuran Richardson ◽  
...  
Keyword(s):  
Basilar Artery ◽  
Stroke Risk ◽  
Posterior Circulation ◽  
Study Cohort ◽  
Collateral Flow ◽  
Flow Measurements ◽  
Hemodynamic Assessment ◽  
Basilar Arteries ◽  
Vessel Flow ◽  
Distal Flow

Introduction: Atherosclerotic vertebrobasilar disease (VBD) is a significant etiology of posterior circulation stroke. In addition to thromboembolism, regional hypoperfusion is considered an important potential contributor to stroke risk. To examine the role of hemodynamic compromise in VBD, a prospective observational multi-center study, Vertebrobasilar Flow Evaluation and Risk of Transient Ischemic Attack and Stroke (VERiTAS), has recently been conducted. Here we report baseline features and vessel flow measurements from the study cohort. Methods: Baseline demographic and clinical data was collected in patients with recent vertebrobasilar TIA or stroke and ≥50% atherosclerotic stenosis or occlusion in vertebral and/or basilar arteries. Large vessel flow in the vertebrobasilar territory was assessed using quantitative MRA (QMRA). Results: The cohort (n=75, 56% male) had a mean age of 65.5 (range 40 to 90) years; two thirds presented with ischemic stroke. Hypertension (93%) and hyperlipidemia (79%) were the most prevalent vascular risk factors. Vertebral and basilar artery flows correlated negatively with degree of stenosis in the affected vessel, and positively to the minimal diameter at the site of stenosis (p<0.01). A threshold effect was evident, with affected vessel flows dropping significantly in patients with ≥70% stenosis or occlusion (p<0.05). Tandem disease involving the basilar and either or both the vertebrals had the greatest impact on immediate downstream flow in the basilar artery (38 ml/min vs. 74 ml/min, p<0.01). Assessment of distal flow status, incorporating collateral flow, however correlated neither with multifocality of disease nor severity of the maximal stenosis. Conclusions: Flow in stenotic posterior circulation vessels correlate with residual diameter and stenosis and drop significantly in the setting of tandem disease. However, distal flow status, incorporating collateral capacity, is not well predicted by the severity or location of the disease. Final clinical outcome results from the ongoing VERiTAS study will further clarify the relevance of anatomic stenosis and hemodynamic assessment to predicting stroke risk in patients with vertebrobasilar disease.

Abstract TMP37: Prevalence of Carotid Webs in Cryptogenic Stroke

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Joel Nunez ◽  
Payam Sajedi ◽  
Oluwatosin Thompson ◽  
Prashant Raghavan ◽  
Steven Kittner ◽  
...  
Keyword(s):  
Recurrent Stroke ◽  
Cryptogenic Stroke ◽  
Young Patients ◽  
Posterior Wall ◽  
Filling Defect ◽  
Recurrent Strokes ◽  
Carotid Bulb ◽  
Stroke Mechanism ◽  
Atherosclerotic Risk Factors ◽  
Stroke In Young

Introduction: Carotid Webs (also termed “atypical FMD”) are characterized by a focal, intraluminal filling defect along the posterior wall of the carotid bulb. They have been reported in association with recurrent stroke in young patients without atherosclerotic risk factors and may represent an unrecognized and potentially treatable cause of stroke. Stroke mechanism appears to be related to sluggish blood flow and thrombi formation. The purpose of our study was to determine the prevalence of carotid webs in patients with cryptogenic stroke after standard complete stroke evaluation. Methods: Retrospective analysis of all patients under age 55 presenting with ischemic strokes 9/2009- 8/2015. CTA has been found to be reliable in detecting webs, so was chosen as the modality for interpretation. 119 cryptogenic stroke patients were identified; 41 of these had CTA. De-identified CTAs were evaluated on TerraRecon by two experienced, board certified, fellowship trained neuroradiologists, with disagreement adjudicated by a third neuroradiologist. Readers were blinded to age, gender, and laterality of stroke. Results: Carotid webs were identified in 7 (17%) cases. Presenting stroke was on the same side as the carotid web in all cases. One case had superimposed thrombus, zero had atherosclerosis, and zero had classic features of fibromuscular dysplasia. One patient had recurrent strokes in the territory. Mean age of patients with carotid web was 38.3 years (range 30-41) with 6 (86%) women and 1 (14%) male. Five patients (71%) were African American. Discussion: Carotid webs were identified in a significant portion of strokes previously diagnosed as cryptogenic. More research is needed to determine the natural history and optimal treatment of patients with carotid webs and more detailed carotid evaluation to identify webs should be considered as part of the stroke evaluation.

Fetal renal artery blood flow – Normal ranges

Ultrasound ◽  
2021 ◽  
pp. 1742271X2110224
Author(s):  
Sonja Brennan ◽  
David Watson ◽  
Michal Schneider ◽  
Donna Rudd ◽  
Yogavijayan Kandasamy
Keyword(s):  
Blood Flow ◽  
Renal Artery ◽  
Interobserver Reliability ◽  
Intraclass Correlation ◽  
Renal Arteries ◽  
Artery Blood Flow ◽  
Flow Measurements ◽  
Prospective Longitudinal Study ◽  
Normal Ranges ◽  
Prospective Longitudinal

Introduction The study objectives were to develop standard charts for fetal renal artery blood flow to define normal ranges and to assess the reliability of the measurements. Methods This prospective, longitudinal study reviewed 72 low-risk singleton pregnancies who had serial ultrasound examinations. Pulse wave Doppler was used to obtain the resistivity and pulsatility indices of the fetal renal arteries. Standard charts of the fetal renal arteries were created using mixed effects modelling and the intra- and interobserver reliability for the renal blood flow measurements was analysed. Results Standard charts of the normal ranges of the renal artery resistive index (RI) and pulsatility index (PI) of the fetal renal arteries were created. The 3rd, 5th, 10th, 50th, 90th, 95th and 97th centiles were calculated. The intraclass correlation coefficient was acceptable for intraobserver reliability (RI = 0.66, PI = 0.88) and poor for interobserver reliability (RI = 0.11, PI = −0.56). Conclusions These novel charts demonstrate the change of the fetal renal artery blood flow during pregnancy. These may be used in clinical practice to detect variations from these normal ranges and be useful in future studies of kidney function projection.

Abstract P606: Hemodynamic Predictors of Multiple Recurrent Strokes in the Patients With Prior Lacunar Stroke

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Adam H de Havenon ◽  
Alexandra Kvernland ◽  
Alen Delic ◽  
Ka-ho Wong ◽  
Nazanin Sheibani ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Logistic Regression ◽  
Failure Time ◽  
Recurrent Stroke ◽  
Cox Proportional Hazards Model ◽  
Lacunar Stroke ◽  
Blood Pressures ◽  
Recurrent Strokes ◽  
The Mean

Background: Recurrent stroke has higher morbidity and mortality than incident stroke. We evaluated hemodynamic risk factors for multiple recurrent strokes. Methods: We included patients in the SPS3 trial. The primary predictor was the top tertile, compared to the bottom tertile, of the mean systolic blood pressure (mSBP) and blood pressure variability represented as standard deviation (sdSBP) using blood pressures from day 30 of the trial to the end of follow-up. We excluded blood pressures from the first 30 days to reduce confounding from the trial’s intervention. We fit a logistic regression model to ≥2 recurrent strokes from day 30 to the end of follow-up and, to accurately analyze the multiple failure-time data, we ordered the multiple failure events to the Prentice, Williams and Peterson extension of the Cox proportional-hazards model. Results: We included 2,882 patients, of which 223 had a recurrent stroke and 41/223 had ≥2 recurrent strokes for a total of 272 strokes. The mean (SD) number of blood pressure readings was 78.0 (37.4). The etiology of the 272 strokes was 161 (59.2%) lacunar, 22 (8.1%) intracranial atherosclerosis, 10 (3.7%) extracranial atherosclerosis, 24 (8.8%) cardioembolic, and 55 (20.2%) cryptogenic or other. In both unadjusted and adjusted logistic regression models and PWP Cox models, the top tertile of sdSBP was consistently predictive of multiple recurrent strokes, while mSBP was not (Tables 1/2). Conclusions: We found that in patients with an index lacunar stroke, higher SBP variability, but not mean SBP, was predictive of multiple recurrent strokes of varying mechanisms.

Abstract 2668: Lacunar Strokes In Patients With Symptomatic Intracranial Stenosis

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Amir Khan ◽  
Scott E Kasner ◽  
Michael J Lynn ◽  
Marc I Chimowitz ◽  
Keyword(s):  
Recurrent Stroke ◽  
Microvascular Disease ◽  
Intracranial Stenosis ◽  
Stroke Recurrence ◽  
Lacunar Stroke ◽  
Cox Proportional Hazard ◽  
Significant Difference ◽  
Index Stroke ◽  
Cox Proportional Hazard Models ◽  
Recurrent Strokes

Background and Purpose: Lacunar strokes are conventionally attributed to a distinct microvascular pathophysiology, but the “lacunar hypothesis” has been challenged since some small deep infarcts are identified in patients with sources of cardioembolism or large vessel atherosclerotic disease. We hypothesized that patients with intracranial stenosis with a lacunar stroke presentation would have a lower risk of recurrent stroke than those with an index non-lacunar stroke, and that their recurrent strokes would predominantly be lacunar. Methods: We analyzed subjects enrolled with an index stroke into the Warfarin Aspirin Symptomatic Intracranial Disease (WASID) trial. The index and endpoint strokes were classified as lacunar or non-lacunar by central adjudication. The primary endpoint was recurrent ischemic stroke. Cox proportional hazard models were generated with stratification for severity of stenosis. Results: 347 subjects were enrolled after an index stroke, 38 were lacunar and 309 were non-lacunar. Over a mean follow-up of 1.8 years there was no significant difference in stroke recurrence between patients whose index stroke was lacunar (7/38; 18%) vs. non-lacunar (69/309; 22%) (HR 0.79, 95%CI: 0.36-1.71). Further, no significant differences were found when groups were stratified by 50-69% stenosis (HR 0.50, 95%CI:0.12-2.1) and ≥70% stenosis (HR 0.87, 95%CI: 0.34-2.2) but power was limited. Of the 7 recurrent strokes in patients whose index stroke was lacunar, all 7 were non-lacunar and 3 were in the territory of the stenotic artery. Of the 69 recurrent strokes in patients whose index stroke was non-lacunar, 6 (9%) were lacunar of which 4 were in the territory of the stenotic artery. Conclusions: The risk of recurrent stroke due to intracranial stenosis was similar in patients who presented with lacunar vs. non-lacunar strokes, and all recurrent strokes in patients presenting with lacunar stroke were non-lacunar. These findings suggest that the pathophysiology of index and recurrent strokes in patients presenting with a lacunar stroke and intracranial stenosis is related to the stenosis and not microvascular disease. Therefore, patients with intracranial stenosis who present with lacunar strokes should be included in future trials investigating secondary stroke prevention for symptomatic intracranial stenosis.

Passive Control of Unstable Characteristics of a High Specific Speed Diagonal-Flow Fan by an Annular Wing

1990 ◽  
Author(s):  
Kenji Kaneko ◽  
Toshiaki Setoguchi ◽  
Masahiro Inoue
Keyword(s):  
Flow Rate ◽  
Geometrical Parameter ◽  
Energy Input ◽  
Passive Control ◽  
Internal Flow ◽  
Flow Region ◽  
Low Flow ◽  
Performance Tests ◽  
Flow Measurements ◽  
Specific Speed

A passive control of an unstable characteristics of a high specific speed diagonal-flow fan has been proposed. It is possible to eliminate the unstable characteristics of pressure-flow rate curve in a low flow region without deterioration of performance at design point. The control action is done naturally (passively) without any energy input. The inlet nozzle of an ordinary diagonal-flow fan was replaced by an annular wing with Göttingen 625 airfoil section. The mechanism of the passive control and the optimum geometrical parameter are discussed on the basis of the performance tests and internal flow measurements.

Intraoperative use of transit time flow measurement improves patency of newly created radiocephalic arteriovenous fistulas in patients requiring hemodialysis

2020 ◽  
Vol 21 (6) ◽  
pp. 990-996
Author(s):  
Anna E Cyrek ◽  
Johannes Bernheim ◽  
Benjamin Juntermanns ◽  
Peri Husen ◽  
Arkadius Pacha ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Fistula ◽  
Transit Time ◽  
Intraoperative Ultrasound ◽  
Low Flow ◽  
Flow Measurements ◽  
Technical Problems ◽  
Arteriovenous Fistulas ◽  
Time Flow ◽  
Observation Period

Background: The autologous arteriovenous fistula is the primary choice to establish hemodialysis access without high failure rates. Intraoperative ultrasound flow measurements of newly created autologous arteriovenous fistulas represent a possibility of quality control and may therefore be a tool to assess their functionality. The aim of our study was to correlate intraoperative blood flow with access patency. Methods: Between March 2012 and March 2015, intraoperative transit time flow measurements were collected on 89 patients. Measurements were performed 5–10 min after the creation of a standardized anastomosis using 3–6 mm flow probes. To examine the correlation between intraoperative blood flow and access patency, groups of patients with high (> 200 mL/min) versus low flow (< 200 mL/min) were enrolled. Patients were assessed clinically and with ultrasound every 3 months. Data were analyzed retrospectively. Results: In the current short-term follow-up, including 89 patients (age 62 ± 3 years), 61 (68.5%) of the autologous arteriovenous fistulas were currently being used in an observation period ranging from 3 months to 3 years (mean observation period 546 ± 95 days) postoperatively. The intraoperative blood flow in patients with functioning autologous arteriovenous fistula (78) was significantly higher than that of patients without functioning autologous arteriovenous fistulas (407 ± 25 vs 252 ± 42 mL/min, respectively; p < 0.005) (11). Conclusion: The intraoperative measurement of blood flow is a useful tool to predict the outcome of maturation in autologous arteriovenous fistula. With this method, technical problems can be detected and corrected intraoperatively. Routine implementation of intraoperative flow measurements has to be examined by prospective controlled trials.

scholarly journals The influence of conceptual model structure on model performance: a comparative study for 237 French catchments

2013 ◽  
Vol 17 (10) ◽  
pp. 4227-4239 ◽  
Author(s):  
W. R. van Esse ◽  
C. Perrin ◽  
M. J. Booij ◽  
D. C. M. Augustijn ◽  
F. Fenicia ◽  
...  
Keyword(s):  
Conceptual Model ◽  
Performance Metrics ◽  
Low Flow ◽  
Multiple Time ◽  
Large Set ◽  
Model Structure ◽  
Flow Measurements ◽  
Flexible Approach ◽  
Fixed Model ◽  
Model Structures

Abstract. Models with a fixed structure are widely used in hydrological studies and operational applications. For various reasons, these models do not always perform well. As an alternative, flexible modelling approaches allow the identification and refinement of the model structure as part of the modelling process. In this study, twelve different conceptual model structures from the SUPERFLEX framework are compared with the fixed model structure GR4H, using a large set of 237 French catchments and discharge-based performance metrics. The results show that, in general, the flexible approach performs better than the fixed approach. However, the flexible approach has a higher chance of inconsistent results when calibrated on two different periods. When analysing the subset of 116 catchments where the two approaches produce consistent performance over multiple time periods, their average performance relative to each other is almost equivalent. From the point of view of developing a well-performing fixed model structure, the findings favour models with parallel reservoirs and a power function to describe the reservoir outflow. In general, conceptual hydrological models perform better on larger and/or wetter catchments than on smaller and/or drier catchments. The model structures performed poorly when there were large climatic differences between the calibration and validation periods, in catchments with flashy flows, and in catchments with unexplained variations in low flow measurements.

scholarly journals Secondary Prevention by Structured Semi-Interactive Stroke Prevention Package in India (SPRINT INDIA) study protocol

2019 ◽  
Vol 15 (1) ◽  
pp. 109-115
Author(s):  
Mahesh Pundlik Kate ◽  
Deepti Arora ◽  
Shweta Jain Verma ◽  
PN Sylaja ◽  
Vishnu Renjith ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Coronary Artery ◽  
Secondary Prevention ◽  
Acute Stroke ◽  
Stroke Prevention ◽  
Recurrent Stroke ◽  
Standard Of Care ◽  
Clinical Trial Registry ◽  
Cardiovascular Morbidity And Mortality ◽  
Recurrent Strokes

Rationale Recurrent stroke, cardiovascular morbidity, and mortality are important causes of poor outcome in patients with index stroke. Despite the availability of best medical management recurrent stroke occur in up to 15–20% of patients with stroke in India. Education for stroke prevention could be a strategy to prevent recurrent strokes. Hypothesis We hypothesize that a structured semi-interactive stroke prevention package can reduce the risk of recurrent strokes, acute coronary artery syndrome, and death in patients with sub-acute stroke at the end of one year. Design Secondary Prevention by Structured Semi-Interactive Stroke Prevention Package in INDIA (SPRINT INDIA) is a multi-center stroke trial involving 25 centers under the Indian Stroke Clinical Trial Network. Patients with first ever sub-acute stroke within two days to three months of onset, age 18–85 years, mRS <5, showing recent stroke in imaging are included. Participants or caregivers able to read and complete tasks suggested in a stroke prevention workbook and have a cellular device for receiving short message service and watching videos. A total of 5830 stroke patients speaking 11 different languages are being randomized to intervention or control arm. Patients in the intervention arm are receiving a stroke prevention workbook, regular educational short messages, and videos. All patients in the control arm are receiving standard of care management. Summary Structured semi-interactive stroke prevention package may reduce the risk of recurrent strokes, acute coronary artery syndrome, and death in patients with sub-acute stroke. Trial registration This trial is registered with clinicaltrials.gov (NCT03228979) and CTRI (Clinical Trial Registry India; CTRI/2017/09/009600).

scholarly journals Extracellular ASC exacerbated the recurrent ischemic stroke in an NLRP3-dependent manner

2019 ◽  
Vol 40 (5) ◽  
pp. 1048-1060 ◽  
Author(s):  
Xiao-fei He ◽  
Yi-xuan Zeng ◽  
Ge Li ◽  
Yu-kun Feng ◽  
Cheng Wu ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Mouse Model ◽  
Inflammatory Responses ◽  
Recurrent Stroke ◽  
Nuclear Factor Κb ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Wild Type ◽  
Infarct Area ◽  
Recurrent Strokes

Using a photothrombotic mouse model of single stroke, we show that a single stroke onset increases the nuclear factor-κB (NF-κB), NLR family CARD domain containing protein 4 (NLRC4), and absent in melanoma 2 (AIM2) inflammasomes, as well as the mRNA levels of NLRP3. Next, using a photothrombotic mouse model of recurrent stroke, we found that recurrent strokes increased the activation of NLRP3, exacerbated the brain damage and the pro-inflammatory response in wild type (WT) mice, but not in NLRP3 knockout ( NLRP3 KO) mice. Additionally, we found that apoptosis-associated speck-like protein containing a CARD (ASC) protein level surrounding the infarct area was comparatively increased, but that ASC specks outside of microglia in both the ipsilateral and contralateral of stroke site were decreased in NLRP3 KO mice relative to wild-type (WT) controls, and the number of ASC specks surrounding the second infarct area was positively correlated to the damage scores. Mechanistically, we found that recombinant ASC (RecASC) activated NLRP3 and induced pro-inflammatory responses, exacerbating the outcome of ischemic stroke, in WT mice, but not in NLRP3 KO mice. We therefore conclude that the NLRP3 inflammasome is activated by two attacks of stroke, which act together with ASC to exacerbate recurrent strokes.

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