We aimed to investigate the role of pretreatment collateral status in predicting the efficacy and safety of endovascular treatment (EVT) in acute ischaemic stroke due to cervical and/or cerebral ...arterial occlusions.
Relevant full-text articles published since 1 January 2000, investigating correlations between collateral status and any efficacy or safety outcome in patients undergoing EVT in cohort or case-control studies, or randomised clinical trials, were retrieved by PubMed and manual search. Two authors extracted data from eligible studies and assessed study quality. Risk ratios (RR) were pooled for good versus poor collaterals for outcomes based on a random-effects model. Sensitivity and subgroup analyses were conducted.
In total, 35 (3542 participants) and 23 (2652 participants) studies were included in qualitative review and quantitative meta-analysis, respectively. Overall, good pretreatment collaterals increased the rate of favourable functional outcome at 3 months (RR=1.98, 95% CI 1.64 to 2.38; p<0.001), and reduced the risks of periprocedural symptomatic intracranial haemorrhage (RR=0.59, 95% CI 0.43 to 0.81; p=0.001) and 3-month mortality (RR=0.49, 95% CI 0.38 to 0.63; p<0.001), as compared with poor collaterals, in patients with acute ischaemic stroke under EVT. No individual study could alter the estimate of overall effect of collateral status, but there were moderate to significant heterogeneities between subgroups of studies with different modes of EVT, different arterial occlusions and different collateral grading methods.
Good pretreatment collateral status is associated with higher rates of favourable functional outcome, and lower rates of symptomatic intracranial haemorrhage and mortality, in patients with acute ischaemic stroke receiving endovascular therapies.
Newtonian fluid model has been commonly applied in simulating cerebral blood flow in intracranial atherosclerotic stenosis (ICAS) cases using computational fluid dynamics (CFD) modeling, while blood ...is a shear-thinning non-Newtonian fluid. We aimed to investigate the differences of cerebral hemodynamic metrics quantified in CFD models built with Newtonian and non-Newtonian fluid assumptions, in patients with ICAS.
We built a virtual artery model with an eccentric 75% stenosis and performed static CFD simulation. We also constructed CFD models in three patients with ICAS of different severities in the luminal stenosis. We performed static simulations on these models with Newtonian and two non-Newtonian (Casson and Carreau-Yasuda) fluid models. We also performed transient simulations on another patient-specific model. We measured translesional pressure ratio (PR) and wall shear stress (WSS) values in all CFD models, to reflect the changes in pressure and WSS across a stenotic lesion. In all the simulations, we compared the PR and WSS values in CFD models derived with Newtonian, Casson, and Carreau-Yasuda fluid assumptions.
In all the static and transient simulations, the Newtonian/non-Newtonian difference on PR value was negligible. As to WSS, in static models (virtual and patient-specific), the rheological difference was not obvious in areas with high WSS, but observable in low WSS areas. In the transient model, the rheological difference of WSS areas with low WSS was enhanced, especially during diastolic period.
Newtonian fluid model could be applicable for PR calculation, but caution needs to be taken when using the Newtonian assumption in simulating WSS especially in severe ICAS cases.
...a combination of elevated hsCRP and presence of multiple acute infarctions was associated with a highest risk of ischaemic stroke (16.7%) and a composite of cardiovascular events and vascular ...death (19.0%) within 1 year, in patient groups with different hsCRP levels and numbers of acute infarction(s).9 The risk of major bleeding within 5 years after a minor stroke or TIA was 1.5%, including a 1.1% risk of ICH, among 3847 patients in the TIAregistry.org project.7 Severe cerebral SVD significantly increases the risk of developing ICH. Enlarged perivascular space, another sign of SVD, is also related to ICH.11 In the CHANCE trial, any bleeding was increased in patients with severe SVD treated with either single or dual antiplatelet therapy.5 Furthermore, anticoagulation in patients with signs of microbleeds or severe white matter hyperintensities on MRI, also signs of SVD, may predispose such patients to ICH by 3–6 folds.12 The incidence of postevent dementia at 1 year after minor stroke and TIA were respectively 8.2% (95% CI 6.2% to 10.2%) and 5.2% (95% CI 3.4% to 7.0%), in the population-based Oxford Vascular Study.13 Compared with the general population in the UK, the prevalence of dementia in 1-year survivors after minor stroke/TIA was brought forward by approximately 4 years in those who had a minor stroke, and 2 years in those who had a TIA.13 SVD is a well-established risk factor for developing cognitive dysfunction. ...targeting the low-density lipoprotein cholesterol (LDL-C) level to be <1.8 mmol/L (70 mg/dL) is recommended to reduce the risk of major cardiovascular events for all ischaemic stroke and TIA of atherosclerotic origin, in the 2021 secondary stroke prevention guideline from American Heart Association/American Stroke Association.16 Particularly in non-cardioembolic minor stroke and TIA patients, the higher risk of ischaemic stroke in those with higher baseline LDL-C level could be neutralised by lipid-lowering treatment. In the CHANCE trial, baseline LDL-C≥ 2.6 mmol/L was associated with an increased risk of ischaemic stroke in patients without lipid-lowering treatment (adjusted HR 1.35; p<0.001), but not in those with lipid-lowering treatment (adjusted HR 0.99; p=0.91; p for interaction=0.007).17 For secondary prevention in minor stroke and TIA patients, aspirin plus clopidogrel for those with high-risk TIA or minor stroke for 21–90 days have been proven effective in two pivotal clinical trials.18 19 The nation-wide Clinical Research Collaboration for Stroke-Korea registry found aspirin plus clopidogrel effective in lowering the 90-day stroke risk, compared with aspirin or other dual antiplatelet therapies (mostly aspirin plus cilostazol), in over 10 000 minor stroke patients.20 Among Chinese minor stroke and TIA patients with CYP2C19 loss-of-function alleles (expected to have a diminished response to clopidogrel) in the CHANCE-2 trial, ticagrelor plus aspirin was more effective in reducing 90-day stroke risks than clopidogrel plus aspirin (6.0% vs 7.6%; HR 0.77; 95% CI 0.64 to 0.94; p=0.008), with similar risks of moderate or severe bleeding (0.3% in both treatment arms) but a higher risk of any bleeding (5.3% vs 2.5%).21 For those with a TIA or minor stroke with an NIHSS score ≤5 in the Acute Stroke or Transient Ischaemic Attack Treated with Ticagrelor and Aspirin for Prevention of Stroke and Death trial, ticagrelor plus aspirin significantly reduced 30-day risk of stroke or death compared with aspirin alone (5.5% vs 6.6%; HR 0.83; 95% CI 0.71 to 0.96; p=0.02), but with a significantly higher risk of severe bleeding (0.5% vs 0.1%; p=0.001).22 In summary, minor strokes are not minor.
The methodologies of computational fluid dynamics (CFD) and response surface method (RSM) were integrated to uncover the optimal correlational framework for intricate hydraulic geometric parameters ...of guide vane centrifugal pumps. Parameters such as blade number, blade wrap angle, blade outlet angle, and relative axial distance between the guide vane and impeller, as well as radial distance, are embraced as optimization design variables. Meanwhile, pump head and efficiency were chosen as responsive variables. An analysis of 46 sets of hydraulic performance data was carried out by using the Box–Behnken experimental design method. Subsequently, response surface approximation models were established between hydraulic parameters and the efficiency, as well as the head. The optimal design point was predicted and a simulation of the hydraulic characteristics for the optimal scheme was conducted; the errors were 0.846% for head and 0.256% for efficiency between the simulation results with predicted results from RSM. The optimized model demonstrates noteworthy enhancements in hydraulic performance in comparison to the original model. By analyzing the internal flow of the optimized model under transient conditions, it was found that, as the internal flow of the flow passage components is relatively disordered at small flow rates, the amplitude of pressure pulsation is affected a lot. At other flow rates, the inside pressure pulsation waveform exhibits pronounced periodicity, and the primary causes of pressure pulsation in various flow components are not the same. Wall dissipation and turbulent dissipation emerge as significant contributors to the entropy generation in this centrifugal pump. The magnitude of entropy generation is correlated with the flow rate and the structural configuration of the pump’s components. High-entropy regions concentrate around the leading and trailing edges of the blades.
Objective
To investigate whether hemodynamic features of symptomatic intracranial atherosclerotic stenosis (sICAS) might correlate with the risk of stroke relapse, using a computational fluid ...dynamics (CFD) model.
Methods
In a cohort study, we recruited patients with acute ischemic stroke attributed to 50 to 99% ICAS confirmed by computed tomographic angiography (CTA). With CTA‐based CFD models, translesional pressure ratio (PR = pressurepoststenotic/pressureprestenotic) and translesional wall shear stress ratio (WSSR = WSSstenotic − throat/WSSprestenotic) were obtained in each sICAS lesion. Translesional PR ≤ median was defined as low PR and WSSR ≥4th quartile as high WSSR. All patients received standard medical treatment. The primary outcome was recurrent ischemic stroke in the same territory (SIT) within 1 year.
Results
Overall, 245 patients (median age = 61 years, 63.7% males) were analyzed. Median translesional PR was 0.94 (interquartile range IQR = 0.87–0.97); median translesional WSSR was 13.3 (IQR = 7.0–26.7). SIT occurred in 20 (8.2%) patients, mostly with multiple infarcts in the border zone and/or cortical regions. In multivariate Cox regression, low PR (adjusted hazard ratio HR = 3.16, p = 0.026) and high WSSR (adjusted HR = 3.05, p = 0.014) were independently associated with SIT. Patients with both low PR and high WSSR had significantly higher risk of SIT than those with normal PR and WSSR (risk = 17.5% vs 3.0%, adjusted HR = 7.52, p = 0.004).
Interpretation
This work represents a step forward in utilizing computational flow simulation techniques in studying intracranial atherosclerotic disease. It reveals a hemodynamic pattern of sICAS that is more prone to stroke relapse, and supports hypoperfusion and artery‐to‐artery embolism as common mechanisms of ischemic stroke in such patients. Ann Neurol 2019;85:752–764
BACKGROUND—Emerging studies suggest that early administration of dual antiplatelet therapy may be better than monotherapy for prevention of early recurrent stroke and cardiovascular outcomes in acute ...ischemic stroke and transient ischemic attack (TIA). We performed a meta-analysis of randomized, controlled trials evaluating dual versus mono antiplatelet therapy for acute noncardioembolic ischemic stroke or TIA.
METHODS AND RESULTS—We assessed randomized, controlled trials investigating dual versus mono antiplatelet therapy published up to November 2012 and the CHANCE trial (Clopidogrel in High-risk patients with Acute Non-disabling Cerebrovascular Events), for efficacy and safety outcomes in adult patients with acute noncardioembolic ischemic stroke or TIA with treatment initiated within 3 days of ictus. In total, 14 studies of 9012 patients were included in the systematic review and meta-analysis. Dual antiplatelet therapy significantly reduced risk of stroke recurrence (risk ratio, 0.69; 95% confidence interval, 0.60–0.80; P<0.001) and the composite outcome of stroke, TIA, acute coronary syndrome, and all death (risk ratio, 0.71; 95% confidence interval, 0.63–0.81; P<0.001) when compared with monotherapy, and nonsignificantly increased risk of major bleeding (risk ratio, 1.35; 95% confidence interval, 0.70–2.59, P=0.37). Analyses restricted to the CHANCE Trial or the 7 double-blind randomized, controlled trials showed similar results.
CONCLUSIONS—For patients with acute noncardioembolic ischemic stroke or TIA, dual therapy was more effective than monotherapy in reducing risks of early recurrent stroke. The results of the CHANCE study are consistent with previous studies done in other parts of the world.
A large proportion of cases with chronic conditions including diabetes or pre-diabetes, hypertension and dyslipidemia remain undiagnosed. To include reproductive factors (RF) might be able to improve ...current screening guidelines by providing extra effectiveness. The objective is to study the relationships between RFs and chronic conditions' biomarkers. A cross-sectional study was conducted. Demographics, RFs and metabolic biomarkers were collected. The relationship of the metabolic biomarkers were shown by correlation analysis. Principal component analysis (PCA) and autoencoder were compared by cross-validation. The better one was adopted to extract a single marker, the general chronic condition (GCC), to represent the body's chronic conditions. Multivariate linear regression was performed to explore the relationship between GCC and RFs. In total, 1,656 postmenopausal females were included. A multi-layer autoencoder outperformed PCA in the dimensionality reduction performance. The extracted variable by autoencoder, GCC, was verified to be representative of three chronic conditions (AUC for patoglycemia, hypertension and dyslipidemia were 0.844, 0.824 and 0.805 respectively). Linear regression showed that earlier age at menarche (OR = 0.9976) and shorter reproductive life span (OR = 0.9895) were associated with higher GCC. Autoencoder performed well in the dimensionality reduction of clinical metabolic biomarkers. Due to high accessibility and effectiveness, RFs have potential to be included in screening tools for general chronic conditions and could enhance current screening guidelines.
Pre-treatment collateral status may be associated with the rates of successful revascularization in acute ischemic stroke patients receiving endovascular treatment (EVT). We conducted a systematic ...review and meta-analysis to synthesize relevant evidence currently available.
Relevant full-text articles published in English since January 1, 2000, reporting associations between collateral status and successful reperfusion and/or recanalization in acute ischemic stroke patients receiving EVT in cohort or case-control studies, or randomized clinical trials, were retrieved through search of PubMed. Study selection, data extraction and study quality assessment were carried out by 2 investigators. Risk ratios (RR) were pooled for good vs. poor collaterals for the outcomes of successful reperfusion and recanalization, based on random-effects models. Subgroup analyses were conducted to explore for potential factors that might interfere with the effects of pre-treatment collateral status on reperfusion by EVT.
In total, 27 studies (2,366 subjects) were included in qualitative analysis, among which 24 studies (2,239 subjects) were quantitatively analyzed. Overall, good pre-treatment collaterals significantly increased the rate of both successful reperfusion (RR 1.28, 95% CI 1.17-1.40; p < 0.001) and recanalization (RR 1.23, 95% CI 1.06-1.42; p = 0.006), as compared with poor collaterals. Subgroup analyses revealed that the effects of collateral status on successful reperfusion by EVT might be different between populations with different ethnicities.
Good pre-treatment collaterals may enhance the rates of successful reperfusion and recanalization in EVT for acute ischemic stroke. This may partly explain the favorable effects of good pre-treatment collaterals on clinical outcomes of stroke patients receiving EVT. Thus, it would be valuable to assess the collateral status prior to EVT in acute ischemic stroke. But studies are needed to further verify if the positive effects of good collaterals on revascularization by EVT are restricted to certain subgroups of patients.
The fractional pressure ratio is introduced to quantitatively assess the hemodynamic significance of severe intracranial stenosis. A computational fluid dynamics-based method is proposed to ...non-invasively compute the FPRCFD and compared against fractional pressure ratio measured by an invasive technique. Eleven patients with severe intracranial stenosis considered for endovascular intervention were recruited and an invasive procedure was performed to measure the distal and the aortic pressure (Pd and Pa). The fractional pressure ratio was calculated as
P
d
/
P
a
. The computed tomography angiography was used to reconstruct three-dimensional (3D) arteries for each patient. Cerebral hemodynamics was then computed for the arteries using a mathematical model governed by Navier–Stokes equations and with the outflow conditions imposed by a model of distal resistance and compliance. The non-invasive
P
d
-
CFD
,
P
a
-
CFD
, and FPRCFD were then obtained from the computational fluid dynamics calculation using a 16-core parallel computer. The invasive and non-invasive parameters were tested by statistical analysis. For this group of patients, the computational fluid dynamics method achieved comparable results with the invasive measurements. The fractional pressure ratio and FPRCFD are very close and highly correlated, but not linearly proportional, with the percentage of stenosis. The proposed computational fluid dynamics method can potentially be useful in assessing the functional alteration of cerebral stenosis.
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