RESUMEN
INTRODUCTION: Modern coil-adjunctive intracranial stent designs have increased metal surface coverage to construct putative 'flow diverter lights.' This is rooted in the assumption that flow diversion is linearly correlated with metal surface coverage rather than being a threshold to be reached by device porosity and design. OBJECTIVE: To evaluate this assumption, by performing computational flow analysis on three aneurysm models treated with low metal surface coverage stents (ATLAS and Enterprise), a Pipeline flow diverter, and the LVIS Blue stent. METHODS: Computational flow analysis was performed on virtual deployment models entailing deployment of an ATLAS, Enterprise, LVIS Blue, or Pipeline. The impact of device deployment on velocity vectors at the neck, maximum wall shear stress, inflow rate into the aneurysm, and turnover time was determined. RESULTS: Velocity vector plots demonstrated low magnitude, localized inflow jets for Pipeline only; asymmetric, selectively high inflow jets were seen for LVIS Blue, and broader velocity vector clusters were seen for Atlas and Enterprise. Reduction in wall shear stress as compared with baseline was significant for all devices and greatest for the Pipeline. Mean peak wall shear stress was significantly lower for LVIS Blue in comparison with ATLAS or Enterprise but significantly lower for Pipeline than for LVIS Blue. Reduction of inflow rate into the aneurysm was significant for LVIS Blue and Pipeline but significantly lower for Pipeline than for LVIS Blue. Turnover time was statistically similar for ATLAS, Enterprise, and LVIS Blue, but significantly increased for Pipeline. CONCLUSION: Considerable differences in peak wall shear stress, inflow rates, and turnover time between flow diverters, moderate- and low-porosity stents reinforce the assumption that effective flow diversion represents a threshold in device design, encompassing metal surface coverage only in part.
Asunto(s)
Simulación por Computador , Diseño de Equipo , Hemodinámica/fisiología , Stents Metálicos Autoexpandibles , Velocidad del Flujo Sanguíneo/fisiología , Simulación por Computador/normas , Diseño de Equipo/métodos , Humanos , Aneurisma Intracraneal/fisiopatología , Aneurisma Intracraneal/cirugía , Stents Metálicos Autoexpandibles/normas , Estrés MecánicoRESUMEN
OBJECTIVE: To evaluate the rate of neointimal development and thrombus formation of surface-modified flow diverters in single antiplatelet therapy (SAPT) using optical coherence tomography (OCT) in a porcine model. METHODS: We divided 10 experimental pigs into two groups. One group (n=6) received dual antiplatelet therapy (DAPT) and the other group (n=4) received SAPT. Four stents (two per carotid artery) were implanted in both groups. The stents used were the Pipeline Flex embolization device (PED Flex), Pipeline Flex with Shield technology (PED Shield), and the Solitaire AB stent. All animals underwent weekly angiography and OCT. The OCT data were analyzed using the following measurements: neointimal ratio ((stent - lumen area)/stent area), stent-coverage ratio (number of stent struts covered by neointima/total stent struts), and the presence or absence of thrombus formation per 1 mm cross-section. RESULTS: PED Flex and Shield in the SAPT group had higher neointimal ratios than in the DAPT group (P<0.001, respectively). In the DAPT group, the speed of endothelial growth on day 7 in the PED Shield group was higher than that in the PED Flex group (P<0.001). In the SAPT group, PED Flex demonstrated significantly more thrombus formation on day 7 than PED Shield (P<0.001). CONCLUSIONS: The PED Shield stent showed faster endothelial growth than the other devices and comparable neointimal volume. There was significantly less thrombus formation on PED Shield than PED Flex when using SAPT in a porcine model.
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Neointima/diagnóstico por imagen , Neointima/tratamiento farmacológico , Inhibidores de Agregación Plaquetaria/uso terapéutico , Stents Metálicos Autoexpandibles , Trombosis/diagnóstico por imagen , Tomografía de Coherencia Óptica/métodos , Animales , Arterias Carótidas/diagnóstico por imagen , Vasos Coronarios/diagnóstico por imagen , Modelos Animales de Enfermedad , Inhibidores de Agregación Plaquetaria/farmacología , Stents Metálicos Autoexpandibles/efectos adversos , Porcinos , Trombosis/etiología , Resultado del TratamientoRESUMEN
BACKGROUND: Optical coherence tomography (OCT) is a high-resolution, intra-vascular diagnostic technique widely used for the characterization of vascular pathologies and optimization of stent implantation during percutaneous coronary intervention. OCT was used to investigate the in vivo vascular response to a new phosphorylcholine surface modified flow diverter (sPED). METHODS: In an in vivo rabbit aneurysmal model, we used two different types of flow diverters (classic Pipeline - cPED; and sPED) with or without dual antiplatelet therapy (four groups, n=10 per group). OCT cross-sectional area measurements were compared with histology in all animals. Neointimal hyperplasia (NIH) ratio was compared between OCT and histology at five different levels for each stent. The severity of NIH was also compared between the different stents, antiplatelet protocols, and vessel locations. RESULTS: OCT was used to calculate in-stent hyperplasia in 227 different locations corresponding to histology sections. OCT measurement strongly correlated with gold standard histology (r2=0.83; slope=0.988; P<0.0001). sPED had significantly less in-stent NIH than non-treated flow diverters (mean percent of lumen reduction 5.7% for sPED versus 8.9% for cPED; P<0.0001). The NIH ratio was slightly higher with dual antiplatelet therapy (DAPT) (NIH ratio=7.9% with DAPT versus 6.8% without DAPT; P<0.05). Complete and near complete occlusion rates of the aneurysms were not different with the cPED or sPED. CONCLUSION: OCT is a promising technique for immediate and long-term evaluation of flow diverter stent treatments. In an animal model, phosphorylcholine surface modified flow diverters induces less NIH after stent implant without reducing aneurysm occlusion rates.
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Aneurisma Intracraneal/cirugía , Neointima/cirugía , Fosforilcolina , Stents Metálicos Autoexpandibles , Animales , Vasos Coronarios , Procedimientos Endovasculares/instrumentación , Procedimientos Endovasculares/métodos , Hiperplasia/diagnóstico por imagen , Hiperplasia/etiología , Aneurisma Intracraneal/diagnóstico por imagen , Neointima/diagnóstico por imagen , Intervención Coronaria Percutánea/instrumentación , Intervención Coronaria Percutánea/métodos , Conejos , Distribución Aleatoria , Stents Metálicos Autoexpandibles/efectos adversos , Tomografía de Coherencia Óptica/métodosRESUMEN
BACKGROUND: Optical coherence tomography (OCT) is a high resolution intravascular imaging method that allows visualization of flow diverter struts and the vessel wall. In this study, malapposition of the flow diverter that continues into the neck of the aneurysm, named communicating malapposition (CM), was investigated as a potential factor for delayed aneurysm healing. METHODS: 40 New Zealand White rabbits underwent elastase induced aneurysm creation, and were subsequently assigned to one of four treatment groups based on flow diverter type and administration of antiplatelet therapy. All animals underwent post device deployment balloon angioplasty and subsequent OCT to assess device/vessel apposition. The incidence of CM seen on OCT was assessed with a binary scoring system: 0-CM present; 1-CM absent. At 30 days, DSA was acquired to assess aneurysm healing. Aneurysm healing on terminal DSA was measured using a previously developed 5 point scale, with a score of 3 or 4 considered a positive outcome. RESULTS: All animals were grouped into a single cohort for analysis as no difference in the rate of CM or healing was seen in the four treatment groups. Significant interaction between the absence of CM and a positive outcome was confirmed by Fisher exact test (P=0.0034). Angioplasty was shown to treat 33% of the cases of CM seen at implant, and these treated cases overwhelmingly had a positive outcome (P<0.001). CONCLUSION: The use of OCT to assess CM of flow diverters has been shown to be predictive of the 30 day healing rate of an animal model of aneurysms.
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Modelos Animales de Enfermedad , Aneurisma Intracraneal/diagnóstico por imagen , Aneurisma Intracraneal/terapia , Stents Metálicos Autoexpandibles/tendencias , Tomografía de Coherencia Óptica/métodos , Animales , Prótesis Vascular/efectos adversos , Prótesis Vascular/tendencias , Procedimientos Endovasculares/instrumentación , Procedimientos Endovasculares/métodos , Femenino , Masculino , Conejos , Stents Metálicos Autoexpandibles/efectos adversos , Factores de TiempoRESUMEN
Recent randomized clinical trials have shown the benefit of stent retrievers for endovascular intervention in patients with acute ischemic stroke. The Solitaire 2 FR 4×40 device was developed to address longer clots as well as procedural difficulties. This study was undertaken to evaluate the safety of the new device in a swine model at 0, 30, and 90â days as well as its in vitro effectiveness. There were no significant differences in the overall animal health, tissue injury, hemorrhagic or thrombogenic events related to device usage. Based on the comparison at multiple time points, the Solitaire 2 4×40 device was similar in safety and usability to the Solitaire 2 4×20 device. Due to the additional length of the device, the Solitaire 2 4×40 device may in fact provide a number of additional technical benefits in the neurothrombectomy treatment of ischemic stroke.