Acandis (Germany)

Due to their effect on aneurysm hemodynamics, flow diverters (FD) have become a routine endovascular therapy for intracranial aneurysms. Since over- and undersizing affect the device’s hemodynamic abilities, selecting the correct device diameter and accurately simulating FD placement can improve patient-specific outcomes. The purpose of this study was to validate the accuracy of virtual flow diverter deployments in the novel Derivo® 2 device. We retrospectively analyzed blood flows in ten FD placements for which 3D DSA datasets were available pre- and post-intervention. All patients were treated with a second-generation FD Derivo® 2 (Acandis GmbH, Pforzheim, Germany) and post-interventional datasets were compared to virtual FD deployment at the implanted position for implanted stent length, stent diameters, and curvature analysis using ANKYRAS (Galgo Medical, Barcelona, Spain). Image-based blood flow simulations of pre- and post-interventional configurations were conducted. The mean length of implanted FD was 32.61 (±11.18 mm). Overall, ANKYRAS prediction was good with an average deviation of 8.4% (±5.8%) with a mean absolute difference in stent length of 3.13 mm. There was a difference of 0.24 mm in stent diameter amplitude toward ANKYRAS simulation. In vessels exhibiting a high degree of curvature, however, relevant differences between simulated and real-patient data were observed. The intrasaccular blood flow activity represented by the wall shear stress was qualitatively reduced in all cases. Inflow velocity decreased and the pulsatility over the cardiac cycle was weakened. Virtual stenting is an accurate tool for FD positioning, which may help facilitate flow FDs’ individualization and assess their hemodynamic impact. Challenges posed by complex vessel anatomy and high curvatures must be addressed.

Abstract A study was undertaken to analyze the biochemical basis of resistance in bhendi accessions as influenced by inorganic nutrients against Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae). Two bhendi accessions namely, Salem Local and Arka Anamika were used for this study. Mean nymphal population was minimum in K alone treated plants followed by NPK applied plants of both the accessions. Nymphal populations were higher in Arka Anamika when compared to Salem Local in both preliminary and confirmatory field screenings. Among the biochemical factors, the total phenol concentration was maximum in leaves of Salem Local treated with Potassium. The reducing and non-reducing sugar concentrations were maximum in leaves of Arka Anamika irrespective of the treatments. Total sugars concentration was found to be minimum in Salem Local irrespective of the treatments. Regarding nitrogen content, leaves of Salem Local accession had minimum quantity, irrespective of all the treatments. Phosphorus and potassium content were comparatively higher in the leaves of Salem Local than in Arka Anamika.

Selective therapeutic hypothermia (TH) showed promising preclinical results as a neuroprotective strategy in acute ischemic stroke. We aimed to assess safety and feasibility of an intracarotid cooling catheter conceived for fast and selective brain cooling during endovascular thrombectomy in an ovine stroke model. Transient middle cerebral artery occlusion (MCAO, 3 h) was performed in 20 sheep. In the hypothermia group (n = 10), selective TH was initiated 20 minutes before recanalization, and was maintained for another 3 h. In the normothermia control group (n = 10), a standard 8 French catheter was used instead. Primary endpoints were intranasal cooling performance (feasibility) plus vessel patency assessed by digital subtraction angiography and carotid artery wall integrity (histopathology, both safety). Secondary endpoints were neurological outcome and infarct volumes. Computed tomography perfusion demonstrated MCA territory hypoperfusion during MCAO in both groups. Intranasal temperature decreased by 1.1 °C/3.1 °C after 10/60 minutes in the TH group and 0.3 °C/0.4 °C in the normothermia group (p < 0.001). Carotid artery and branching vessel patency as well as carotid wall integrity was indifferent between groups. Infarct volumes (p = 0.74) and neurological outcome (p = 0.82) were similar in both groups. Selective TH was feasible and safe. However, a larger number of subjects might be required to demonstrate efficacy.

It has been hypothesized that microstents which are used to prevent coil protrusion in the treatment of cerebral aneurysms may have flow diverting and therefore occlusive effects. In a rabbit elastase aneurysm model, we investigated the aneurysm occlusion rate and vessel reaction of a braided Accero stent prototype with porosity in the lower range of other available (non-flow-diverter) microstents. Ten aneurysms were induced the right subclavian artery in New Zealand white rabbits and treated with the Accero stent prototype. In each subject, a second stent was implanted in the abdominal aorta to cover the origins of branch arteries. Angiographic follow-up and explantation of the devices and aneurysms for histological analysis were performed after 3months (n = 5) and 6months (n = 5). Grades I (< 50%) and II (> 50%) occlusion rates were observed in 9 (90%) and 1 (10%) of ten aneurysms treated with the stent device. The mean reduction in contrast filling at 6months was 42.1% (p = .02). Neointima thickness was significantly higher in the subclavian artery than in the abdominal aorta after 3 (p = .03), whereas not after 6months (p = .1). No cases of inadequate wall apposition, branch artery occlusion or stent thrombosis were observed. The present study showed flow remodelling properties of the device prototype with progredient aneurysm occlusion. A larger in vivo study with induced aneurysm should be done to confirm these results.

Particle image velocimetry (PIV) is a commonly used method for in vitro investigation of fluid dynamics in biomedical devices, such as flow diverters for intracranial aneurysm treatment. Since it is limited to transparent blood substituting fluids like water-glycerol mixture, the influence of coagulation and platelet aggregation is neglected. We aimed at the development and the application of a modified platelet rich plasma as a new PIV fluid with blood-like rheological and coagulation properties. In standardized intracranial aneurysm silicone models, the effect of this new PIV plasma on the fluid dynamics before and after flow diverter implantation was evaluated and compared with water-glycerol measurements. The flow diverting effect was strongly dependent on the used fluid, with considerably lower velocities achieved using PIV plasma, despite the same starting viscosity of both fluids. Moreover, triggering coagulation of PIV plasma allowed for intra-aneurysmal clot formation. We presented the first in vitro PIV investigation using a non-Newtonian, clottable PIV plasma, demonstrating a mismatch to a standard PIV fluid and allowing for thrombus formation.

Flow diverters are widely extended in clinical practice for intracraneal aneurysms treatment. They are formed by a dense mesh of braided wires that partially occludes the aneurysm neck and restores the blood flow into the parent vessel. The occlusion degree is highly dependant on the distribution of the wires under the aneurysm, which is affected by the vessel geometry. Nowadays, there are no clinical indicators of the covering ratio once the flow diverter is deployed. We propose a novel method for the simulation of the flow diverter local porosity before its deployment into the parent vessel. We validate the method on curved silicon models, obtaining a correlation of 0.9 between the simulated values and the measured porosity on the deployed flow diverter.

Abstract New implants for vascular therapy like flow diverters are made of tiny braided wires. The radio opacity of these wires is poor, which makes assessment of implant expansion and exact positioning difficult. Additional markers only allow the estimation of the current device position, but they also induce artefacts that impair the assessment during the intervention and in follow-up examination. A new strategy to increase implant visibility is the braiding of composite wires with a radiopaque core along the whole implant. This paper shows some useful combinations of these new wires on a phantom study with five vascular implants.