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: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: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: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
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:Non-invasive, repeated interrogation of the same wound is necessary to understand the tissue repair continuum. In this work, we sought to test the significance of non-invasive high-frequency high-resolution ultrasound technology for such interrogation. High-frequency high-resolution ultrasound imaging was employed to investigate wound healing under fetal and adult conditions. Quantitative tissue cellularity and elastic strain was obtained for visualization of unresolved inflammation using Vevo strain software. Hemodynamic properties of the blood flow in the artery supplying the wound-site were studied using color Doppler flow imaging. Non-invasive monitoring of fetal and adult wound healing provided unprecedented biomechanical and functional insight. Fetal wounds showed highly accelerated closure with transient perturbation of wound tissue cellularity. Fetal hemodynamics was unique in that sharp fall in arterial pulse pressure (APP) which was rapidly restored within 48h post-wounding. In adults, APP transiently increased post-wounding before returning to the pre-wounding levels by d10 post-wounding. The pattern of change in the elasticity of wound-edge tissue of diabetics was strikingly different. Severe strain acquired during the early inflammatory phase persisted with a slower recovery of elasticity compared to that of the non-diabetic group. Wound bed of adult diabetic mice (db/db) showed persistent hypercellularity compared to littermate controls (db/+) indicative of prolonged inflammation. Normal skin strain of db/+ and db/db were asynchronous. In db/db, severe strain acquired during the early inflammatory phase persisted with a slower recovery of elasticity compared to that of non-diabetics. This study showcases a versatile clinically relevant imaging platform suitable for real-time analyses of functional wound healing.
| S-EPMC7682876 | biostudies-literature
Project description:In-stent restenosis (ISR) represents a major drawback of stented superficial femoral arteries (SFAs). Motivated by the high incidence and limited knowledge of ISR onset and development in human SFAs, this study aims to (i) analyze the lumen remodeling trajectory over 1-year follow-up period in human stented SFAs and (ii) investigate the impact of altered hemodynamics on ISR initiation and progression. Ten SFA lesions were reconstructed at four follow-ups from computed tomography to quantify the lumen area change occurring within 1-year post-intervention. Patient-specific computational fluid dynamics simulations were performed at each follow-up to relate wall shear stress (WSS) based descriptors with lumen remodeling. The largest lumen remodeling was found in the first post-operative month, with slight regional-specific differences (larger inward remodeling in the fringe segments, p < 0.05). Focal re-narrowing frequently occurred after 6 months. Slight differences in the lumen area change emerged between long and short stents, and between segments upstream and downstream from stent overlapping portions, at specific time intervals. Abnormal patterns of multidirectional WSS were associated with lumen remodeling within 1-year post-intervention. This longitudinal study gave important insights into the dynamics of ISR and the impact of hemodynamics on ISR progression in human SFAs.
| S-EPMC8455500 | biostudies-literature
Project description:Our recent study on the effects of neutering (including spaying) in Golden Retrievers in markedly increasing the incidence of two joint disorders and three cancers prompted this study and a comparison of Golden and Labrador Retrievers. Veterinary hospital records were examined over a 13-year period for the effects of neutering during specified age ranges: before 6 mo., and during 6-11 mo., year 1 or years 2 through 8. The joint disorders examined were hip dysplasia, cranial cruciate ligament tear and elbow dysplasia. The cancers examined were lymphosarcoma, hemangiosarcoma, mast cell tumor, and mammary cancer. The results for the Golden Retriever were similar to the previous study, but there were notable differences between breeds. In Labrador Retrievers, where about 5 percent of gonadally intact males and females had one or more joint disorders, neutering at <6 mo. doubled the incidence of one or more joint disorders in both sexes. In male and female Golden Retrievers, with the same 5 percent rate of joint disorders in intact dogs, neutering at <6 mo. increased the incidence of a joint disorder to 4-5 times that of intact dogs. The incidence of one or more cancers in female Labrador Retrievers increased slightly above the 3 percent level of intact females with neutering. In contrast, in female Golden Retrievers, with the same 3 percent rate of one or more cancers in intact females, neutering at all periods through 8 years of age increased the rate of at least one of the cancers by 3-4 times. In male Golden and Labrador Retrievers neutering had relatively minor effects in increasing the occurrence of cancers. Comparisons of cancers in the two breeds suggest that the occurrence of cancers in female Golden Retrievers is a reflection of particular vulnerability to gonadal hormone removal.
| S-EPMC4096726 | biostudies-literature