Biomechanics and hemodynamics of stent-retrievers.
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ABSTRACT:
SUBMITTER: Kuhn AL
PROVIDER: S-EPMC7820689 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe 'first pass effect' (FPE), which was originally described with stent retrievers, designates a (near-)complete revascularization obtained after a single device pass with no rescue therapy, and is associated with improved clinical outcome and decreased mortality.ObjectiveWe report the rate and benefits of FPE in the Aspiration versus Stent Retriever (ASTER) trial.Materials and methodsASTER is a randomized trial comparing angiographic revascularization with the stent retriever (SR) and contact aspiration (CA) thrombectomy techniques, assessed by an external core laboratory using the modified Thrombolysis in Cerebral Infarction (mTICI) scale. Rates of FPE (defined by mTICI 2c/3 after a single pass with no rescue therapy) were compared between patients treated with SR and CA techniques. Outcomes were compared between FPE-SR and FPE-CA patients, and between FPE and non-FPE patients.ResultsFPE was achieved in 97/336 patients (28.9%), with no significant difference between SR and CA (respectively 53/169 patients (31.3%) vs 44/167 patients (26.3%), adjusted RR for CA versus SR 0.84, 95% CI 0.54 to 1.31; p=0.44). After prespecified adjustment for allocated arm and randomization stratification factors, FPE in patients was associated with a significantly improved clinical outcome and a decreased mortality, and a significantly lower rate of hemorrhagic transformation and procedural complications than in non-FPE patients.ConclusionIn the ASTER trial, similar rates of FPE were achieved with SR and CA, and FPE was associated with a significantly improved outcome. New techniques and devices to improve the rate of FPE are warranted.Trial registration numberUnique identifier: NCT02523261.
| S-EPMC7146919 | biostudies-literature
Project description:Successful recanalization after endovascular stroke therapy (EVT) did not translate into a good clinical outcome in randomized trials. The goal of the study was to identify the predictors of a good outcome after mechanical thrombectomy with stent retrievers.A retrospective analysis of a prospectively collected database included consecutive patients treated with stent retrievers. We evaluated the influence of risk factors for stroke, baseline NIHSS score, Alberta Stroke Program Early CT (ASPECT) score, recanalization rate, onset-to-recanalization and onset-to-groin puncture time, and glucose levels at admission on good outcomes. The number of stent passes during procedure and symptomatic hemorrhage rate were also recorded. A modified Rankin Scale (mRS) score of 0-2 at 90 days was considered as a good outcome.From January 2011 to 2014, 70 consecutive patients with an acute ischemic stroke underwent EVT with stent retrievers. The absence of a medical history of diabetes was associated with good outcomes. Apart from diabetes, the baseline demographic and clinical characteristics of patients were similar between subjects with poor outcome versus those with good outcomes. Median time from onset to recanalization was significantly shorter in patients with good outcomes 245 (IQR: 216-313 min) compared with poor outcome patients (315 (IQR: 240-360 min); P = 0.023). Symptomatic intracranial hemorrhage was observed in eight (21.6%) of 37 patients with poor outcomes and no symptomatic hemorrhage was seen in patients with good outcomes (P = 0.006). In multivariate stepwise logistic regression analysis, a favorable ASPECT score (ASPECT > 7) and successful recanalization after EVT were predictors of good outcomes. Every 10-year increase was associated with a 3.60-fold decrease in the probability of a good outcome at 3 months. The probability of a good outcome decreases by 1.43-fold for each 20 mg/dL increase in the blood glucose at admission.To achieve a good outcome after EVT with stent retrievers, quick and complete recanalization and better strategies for patient selection are warranted. We need randomized trials to identify the significance of tight blood glucose control in clinical outcome during or after EVT.
| S-EPMC4475551 | biostudies-other
Project description:Endovascular treatment with stent retriever thrombectomy is a major advancement in the standard of care in acute ischemic stroke (AIS). The modalities through which thrombi embed along stent retriever following mechanical thrombectomy (MTB) have not yet been elucidated. Using scanning electron microscopy (SEM), we analyzed the appearance of thrombi retrieved by MTB from AIS patients, when embedded into the stent retriever. We observed that the organization and structural compactness vary for compositionally different thrombi. The modalities of attachment onto the stent vary according to thrombus composition and organization.
| S-EPMC9110407 | biostudies-literature
Project description:Introduction: Aging has many effects on the cardiovascular system, including changes in structure (aortic composition, and thus stiffening) and function (increased proximal blood pressure, and thus cardiac afterload). Mouse models are often used to gain insight into vascular aging and mechanisms of disease as they allow invasive assessments that are impractical in humans. Translation of results from murine models to humans can be limited, however, due to species-specific anatomical, biomechanical, and hemodynamic differences. In this study, we built fluid-solid-interaction (FSI) models of the aorta, informed by biomechanical and imaging data, to compare wall mechanics and hemodynamics in humans and mice at two equivalent ages: young and older adults. Methods: For the humans, 3-D computational models were created using wall property data from the literature as well as patient-specific magnetic resonance imaging (MRI) and non-invasive hemodynamic data; for the mice, comparable models were created using population-based properties and hemodynamics as well as subject-specific anatomies. Global aortic hemodynamics and wall stiffness were compared between humans and mice across age groups. Results: For young adult subjects, we found differences between species in pulse pressure amplification, compliance and resistance distribution, and aortic stiffness gradient. We also found differences in response to aging between species. Generally, the human spatial gradients of stiffness and pulse pressure across the aorta diminished with age, while they increased for the mice. Conclusion: These results highlight key differences in vascular aging between human and mice, and it is important to acknowledge these when using mouse models for cardiovascular research.
| S-EPMC8573132 | biostudies-literature
Project description:PurposeThis study aimed to investigate the cost-effectiveness of stent retriever (SR) versus best medical management (BMM) in patients with basilar artery occlusion (BAO) in China.MethodsWe used a two-step approach to compare the cost-effectiveness of SR plus BMM with that of BMM alone over 20 years. A decision tree was initially constructed for the first 3 months, followed by a Markov model for the subsequent period. Collected data on clinical aspects were extracted from the BAOCHE investigation, while costs-related information was sourced from previously published research. The key metric for evaluating the primary outcome was the incremental cost-effectiveness ratio (ICER), achieved $/QALY. The threshold for identifying SR as highly cost-effective was set at an ICER below $12,551/QALY, SR was deemed cost-effective if the ICER ranged from $12,551 to $37,654 per QALY. Uncertainty was addressed using scenario, one-way sensitivity, and probabilistic sensitivity analyses (PSA).FindingsFor Chinese patients with BAO, the 20-year cost per patient was $8678 with BMM alone and $21,988 for SR plus BMM. Effectiveness was 1.45 QALY for BMM alone, and 2.77 QALY for SR plus BMM. The ICER of SR + BMM versus BMM alone was $10,050 per QALY. The scenario and one-way sensitivity analyses revealed that in certain situations the ICER could exceed $12,551 per QALY, but remain below $37,654 per QALY. Results from the PSA suggested that SR was likely to be cost-effective for Chinese patients with BAO, with a probability exceeding 98% when considering a willingness-to-pay (WTP) threshold of $12,551 per QALY.ImplicationsOur study indicates that SR is an intervention option that is highly likely to be cost-effective for Chinese patients with BAO, with a probability of over 98% under the current WTP threshold of $12,551 per QALY.
| S-EPMC10688905 | biostudies-literature
Project description:ImportanceStent retriever-based thrombectomy is highly beneficial in large vessel occlusion (LVO) strokes. Many stent retriever designs are currently available, but comparison of these technologies in well-conducted studies is lacking.ObjectiveTo determine whether thrombectomy for LVO stroke with the pRESET stent retriever is noninferior to treatment with the Solitaire stent retriever.Design, setting, and participantsThis study was a multicenter, prospective, randomized, controlled, open-label, adaptive, noninferiority trial with blinded primary end point evaluation. Between October 2019 and February 2022, multicenter participation occurred across 19 research hospitals and/or universities in the US and 5 in Germany. Patients with LVO stroke were enrolled and included up to 8 hours after symptom onset.InterventionsPatients underwent 1:1 randomization to thrombectomy with the pRESET or Solitaire stent retriever.Main outcomes and measuresThe primary outcome was the difference in the rate of 90-day functional independence across the 2 devices, using a -12.5% noninferiority margin for the lower bound of the 1-sided 95% CI of the difference between pRESET and Solitaire retrievers.ResultsOf 340 randomized patients, 170 (50.0%) were female, and the median (IQR) age was 73.0 (64.0-82.0) years. The study procedure was completed in 322 of the 340 randomized patients. The primary end point of 90-day functional independence was achieved by 95 patients (54.9%; 95% CI, 48.7-61.1) in the pRESET group and in 96 (57.5%; 95% CI, 51.2-63.8) in the Solitaire group (absolute difference, -2.57%; 95% CI, -11.42 to 6.28). As the lower bound of the 95% CI was greater than -12.5%, the pRESET retriever was deemed noninferior to the Solitaire retriever. The noninferiority of pRESET over Solitaire was also observed in the secondary clinical end point (90-day shift in modified Rankin Scale score) and in both angiographic end points (Expanded Treatment in Cerebral Infarction [eTICI] score of 2b50 or greater within 3 passes: 146 of 173 [84.4%] vs 149 of 167 [89.2%]; absolute difference, -4.83%; 95% CI, -10.84 to 1.19; eTICI of 2c or greater following the first pass: 76 of 173 [43.7%] vs 74 of 167 [44.3%]; absolute difference, -0.63%; 95% CI, -9.48 to 8.21). Symptomatic intracranial hemorrhage occurred in 0 patients in the pRESET group and 2 (1.2%) in the Solitaire group. Mortality occurred in 25 (14.5%) in the pRESET group and in 24 (14.4%) in the Solitaire group at 90 days. Findings of the per-protocol and as-treated analyses were in concordance with findings of the intention-to-treat analysis.Conclusions and relevanceIn this study, among patients with LVO stroke, thrombectomy with the pRESET stent retriever was noninferior to thrombectomy with the Solitaire stent retriever. Findings suggest that pRESET offers a safe and effective option for flow restoration and disability reduction in patients with LVO stroke.
| S-EPMC10762632 | biostudies-literature
Project description:Endovascular treatment of paraclinoid aneurysms is preferred in clinical practice. Flow alterations caused by stents and coils may affect treatment outcome.To assess hemodynamic changes following stent-assisted coil embolization (SACE) in subtotally embolized paraclinoid aneurysms with residual necks that were predisposed to recanalization.We studied 27 paraclinoid aneurysms (seven recanalized and 20 stable) treated with coils and Enterprise stents. Computational fluid dynamic simulations were performed on patient-specific aneurysm geometries using virtual stenting and porous media technology.After stent placement in 27 cases, aneurysm flow velocity decreased significantly, the reduction gradually increasing from the neck plane (11.9%), to the residual neck (12.3%), to the aneurysm dome (16.3%). Subsequent coil embolization was performed after stent placement and the hemodynamic factors decreased further and significantly at all aneurysm regions except the neck plane. In a comparison of recanalized and stable cases, univariate analysis showed no significant differences in any parameter before treatment. After stent-assisted coiling, only the reduction in area-averaged velocity at the neck plane differed significantly between recanalized (8.1%) and stable cases (20.5%) (p=0.016).Aneurysm flow velocity can be significantly decreased by stent placement and coil embolization. However, hemodynamics at the aneurysm neck plane is less sensitive to coils. Significant reduction in flow velocity at the neck plane may be an important factor in preventing recanalization of paraclinoid aneurysms after subtotal SACE.
| S-EPMC4882272 | biostudies-literature
Project description:BackgroundHemodynamic therapy with Flow-Diverters has become a fundamental option for treatment of cerebral aneurysms. A major obstacle of Flow-Diverters is the comparatively stiff microcatheter required for implantation. Consequentially, maneuverability is limited and primary catheterization of peripheral targets may be difficult or even futile in challenging vascular anatomies. To overcome this, a highly navigable microcatheter must be used to attain the desired vascular segment, followed by a hardly controllable exchange-maneuver via a long microwire, involving a high risk for wire-perforation. Our study aimed to investigate the value of low-profile stent-retrievers as a railway for introduction of the required microcatheter, which allows to maintain a stable endovascular position and reduce the risk for procedural vessel injury.Methods14cases (8females, mean-age 59y) of Flow-Diverter-Implantation requiring the use of a low-profile stent-retriever were reviewed. All cases featured a challenging vascular anatomy. After micro-catheterization of the desired segment, the stent-retriever was carefully deployed as an anchor in a secure, distal location. In all cases a pREset/LITE-stent-retriever was used for introduction of the equipment required for implantation.ResultsIn all cases the anchoring-maneuver was performed without technical complications. The stent-retrievers maintained a stable position after deployment in all situations. No potential traumatic sudden movements of the microcatheter occurred. No procedure-related perforations, dissections or vasospasms were observable during the interventions or their aftermath.ConclusionsIn our experience the stent-retriever-anchoring-maneuver represents a potentially essential and safe amendment for flow diverter treatment in technically challenging situations.
| S-EPMC7103572 | biostudies-literature
Project description:PurposePorto-systemic pressure gradient is used to prognosticate rebleeding and resolution of ascites after TIPS. This study investigates the reliability of portal pressure characteristics as quantified immediately after TIPS placement and at short-term control.Patients and methodsPortal venous pressure (PVP) and right atrial pressure (RAP) were prospectively obtained before and after TIPS as well as ≥ 48 h after TIPS procedure. Porto-systemic pressure gradients (PSG) and pressure changes were calculated. A multivariate regression analysis was performed to predict portal hemodynamics at short-term control.ResultsThe study included 124 consecutive patients. Indications for TIPS were refractory ascites, variceal bleeding or combinations of both. Pre- and post-interventional PSG yielded 16.4 ± 5.3 mmHg and 5.9 ± 2.7 mmHg, respectively. At that time, 105/124 patients (84.7%) met the target (PSG ≤ 8 mmHg). After 4 days (median), PSG was 8.5 ± 3.5 mmHg and only 66 patients (53%) met that target. In patients exceeding the target PSG at follow-up, PVP was significantly higher and RAP was lower resulting in the increased PSG. The highly variable changes of RAP were the main contributor to different pressure gradients. In the multivariate regression analysis, PVP and RAP immediately after TIPS were predictors for PSG at short-term control with moderately predictive capacity (AUC = 0.75).ConclusionBesides the reduction of portal vein pressure, the highly variable right atrial pressure was the main contributor to different pressure gradients. Thus, immediate post-TIPS measurements do not reliably predict portal hemodynamics during follow-up. These findings need to be further investigated with respect to the corresponding clinical course of the patients.
| S-EPMC8716358 | biostudies-literature
Project description:Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations. Three models were created with height to diameter ratio of 0.6, 0.7, and 0.88. The other three models were designed by altering arch height to stent diameter ratio, to be 0, 0.081, and 0.116. Particle image velocimetry experiments were conducted on each PHV to characterize velocity, vorticity, turbulent characteristics, effective orifice area, and regurgitant fraction. This study revealed that the presence of arches as well as higher stent profile reduced regurgitant flow down to 5%, while peak systole downstream velocity reduced to 58% and Reynolds Shear Stress values reduced 40%. Further, earlier reattachment of the forward flow jet was observed in PHVs with leaflet arches. These findings indicate that although both geometric factors help diminish the commissural gap during diastole, leaflet arches induce a larger jet opening, yielding to earlier flow reattachment and lower energy dissipation.
| S-EPMC5159331 | biostudies-literature