nitinol and Intracranial-Aneurysm

The aim of this systematic review and meta-analysis was to synthesize the latest evidence on the efficacy and safety of Neuroform Atlas-assisted coiling of intracranial aneurysms.. We performed a comprehensive search for articles that assessed the efficacy and safety of Neuroform Atlas-assisted coiling of intracranial aneurysms. The outcome measurement was adequate occlusion, defined as Raymond-Roy Class I (RR1) + Raymond-Roy Class II (RR2) by previous studies.. Neuroform Atlas-assisted coiling is associated with an initial adequate occlusion rate of 88% and a periprocedural complication rate of 6%. The rate of initial adequate occlusion was 85% in unruptured aneurysms and 86% in wide-necked aneurysms.. Level 2, Systematic review of non-randomized and single-arm studies.

Topics: Adult; Aged; Alloys; Embolization, Therapeutic; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Retrospective Studies; Stents; Treatment Outcome

OBJECT WEB is an innovative intrasaccular treatment for intracranial aneurysms. Preliminary series have shown good safety and efficacy. The WEB Clinical Assessment of Intrasaccular Aneurysm Therapy (WEBCAST) trial is a prospective European trial evaluating the safety and efficacy of WEB in wide-neck bifurcation aneurysms. METHODS Patients with wide-neck bifurcation aneurysms for which WEB treatment was indicated were included in this multicentergood clinical practices study. Clinical data including adverse events and clinical status at 1 and 6 months were collected and independently analyzed by a medical monitor. Six-month follow-up digital subtraction angiography was also performed and independently analyzed by a core laboratory. Success was defined at 6 months as complete occlusion or stable neck remnant, no worsening in angiographic appearance from postprocedure, and no retreatment performed or planned. RESULTS Ten European neurointerventional centers enrolled 51 patients with 51 aneurysms. Treatment with WEB was achieved in 48 of 51 aneurysms (94.1%). Adjunctive implants (coils/stents) were used in 4 of 48 aneurysms (8.3%). Thromboembolic events were observed in 9 of 51 patients (17.6%), resulting in a permanent deficit (modified Rankin Scale [mRS] Score 1) in 1 patient (2.0%). Intraoperative rupture was not observed. Morbidity (mRS score > 2) and mortality were 2.0% (1 of 51 patients, related to rupture status on entry to study) and 0.0% at 1 month, respectively. Success was achieved at 6 months in 85.4% of patients treated with WEB: 23 of 41 patients (56.1%) had complete occlusion, 12 of 41 (29.3%) had a neck remnant, and 6 of 41 (14.6%) had an aneurysm remnant. CONCLUSIONS The WEBCAST study showed good procedural and short-term safety of aneurysm treatment with WEB and good 6-month anatomical results.

Topics: Adult; Aged; Alloys; Angiography, Digital Subtraction; Cause of Death; Combined Modality Therapy; Diffusion Chambers, Culture; Embolization, Therapeutic; Endovascular Procedures; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Outcome and Process Assessment, Health Care; Patient Safety; Platelet Aggregation Inhibitors; Postoperative Complications; Prospective Studies; Prostheses and Implants; Stents; Thromboembolism; Treatment Outcome

We report the results of a prospective clinical study using a new self-expanding nitinol stent (Enterprise) designed for the treatment of wide-necked intracranial aneurysms.. We treated 31 saccular, wide-necked intracranial aneurysms in 30 patients. Ten aneurysms had recanalized after prior endovascular treatment without a stent, and 21 aneurysms had not been treated before.. Stent deployment was successful in all procedures. Additional coil embolization was performed in all aneurysms. Initial complete angiographic occlusion was achieved in 6 aneurysms, a neck remnant was left in 18 aneurysms and there were 7 residual aneurysms. Angiographic follow-up examinations of 30 lesions after 6 months demonstrated 15 complete occlusions, 8 neck remnants and 7 residual aneurysms. One patient refused the 6-month angiographic follow-up. Spontaneous occlusion of the aneurysm had occurred in 14 patients, and 6 aneurysms showed recanalization. Four of these residual aneurysms were retreated. At the 6-month follow-up, 29 parent arteries were unaffected, whereas two parent vessels demonstrated minor asymptomatic narrowing at the stent site. Two patients experienced one or more possible or probable device-related serious adverse events during the 6-month follow-up period. There was no procedural morbidity or mortality at 6 months after the procedure.. The reported results demonstrated the safety and feasibility of the Cordis Neurovascular Enterprise stent in the treatment of wide-necked intracranial aneurysms. Initial clinical and angiographic results are favorable.

Topics: Adult; Aged; Alloys; Blood Vessel Prosthesis Implantation; Cerebral Angiography; Embolization, Therapeutic; Equipment Design; Feasibility Studies; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Prospective Studies; Stents; Treatment Outcome

Accero is an innovative, fully visible, self-expanding braided stent with platinum-nitinol composite wire technology, produced by Acandis.. To assess the technical success and safety of this new stent by evaluating the intraprocedural behavior and complication rate, and the short-term follow-up results.. Forty-one consecutive patients suitable for stent-assisted coiling were selected for the use of Accero in an 11-month period. Clinical, procedural, and angiographic data, as well as 30-day morbidity, were recorded. The angiographic results, clinical follow-up at 30 days, and early imaging follow-up at 3 or 6 months were analyzed, when available.. Forty-one aneurysms were treated with stent-assisted coiling. All cases were elective, of which 19 were previously untreated aneurysms and 22 were recurrent aneurysms. Aneurysm location was anterior communicating artery complex (16), basilar (12 cases), middle cerebral artery bifurcation (9 cases), and internal cerebral artery (4 cases). The stent was successfully deployed and aneurysm occlusion with coils achieved in 100% of our patients. One case of on table in-stent thrombosis occurred, which resolved after administration of glycoprotein IIB/IIIA inhibitor, with no clinical consequence, and one case of postoperative hematoma at the arteriotomy site, which was managed conservatively. On early follow-up, available for 37 patients, the complete occlusion rate was 76%, with only two recurrences needing further treatment. Satisfactory aneurysm occlusion was therefore achieved in 95% of cases.. Stent-assisted coiling with the Accero braided stent proved safe and effective.

Topics: Adult; Aged; Alloys; Biomedical Technology; Endovascular Procedures; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Platinum; Prospective Studies; Retrospective Studies; Self Expandable Metallic Stents; Treatment Outcome

Conventional coiling is standard for treatment of ruptured intracranial aneurysms. We compared clinical and angiographic outcomes between intrasaccular flow disruption with the Woven EndoBridge (WEB) and conventional coiling in patients with aneurysmal subarachnoid hemorrhage (aSAH) using a propensity score-matched analysis.. This is a retrospective study of consecutive patients with aSAH treated with the WEB or conventional coiling between 2010 and 2019. Baseline characteristics, procedural complications, angiographic results, and functional outcome were compared between both groups.. Fifty-two patients treated with the WEB and 236 patients treated by coiling were included. The WEB group was characterized by a higher patient age (P = 0.024), a wider aneurysm neck (P < 0.001), and more frequent location at the posterior circulation (P = 0.004). Procedural complications were comparable between WEB (19.2%) and coiling (22.7%, P = 0.447). In-hospital mortality rates were higher in the coiling group (WEB: 5.8%, coiling: 17.8%; P = 0.0034). Favorable outcome (modified Rankin scale ≤2) was obtained in 51.3% after WEB embolization and in 55.0% after coiling (P = 0.653). Retreatment was performed in 26.4% of patients after WEB and in 25.8% after coiling (P = 0.935). Propensity score analysis confirmed these results and revealed higher adequate occlusion rates at midterm follow-up for WEB-treated aneurysms (WEB: 93.9%, coiling: 76.2%, P = 0.058).. Compared with conventional coiling, aSAH patients treated with the WEB have a similar clinical and potentially improved angiographic outcome at midterm follow-up. The WEB might be considered as an alternative to conventional coiling for the treatment of RIAs, in particular for those with wide-necked and thus challenging anatomy.

Topics: Adult; Aged; Alloys; Aneurysm, Ruptured; Cerebral Angiography; Endovascular Procedures; Female; Hospital Mortality; Humans; Intracranial Aneurysm; Male; Middle Aged; Postoperative Complications; Propensity Score; Retrospective Studies; Subarachnoid Hemorrhage; Surgical Mesh; Treatment Outcome

Beyond aneurysmal occlusion, metallic flow diverters (FDs) can induce an adverse endovascular reaction due to the foreignness of metal devices, hampering FD endothelialization across the aneurysm neck, and arterial healing of intracranial aneurysms. Here, we evaluated the potential benefits of an FD coating mimicking CD31, a coreceptor critically involved in endothelial function and endovascular homeostasis, on the endothelialization of FDs implanted in vivo.. Nitinol FD (Silk Vista Baby) and flat disks were dip-coated with a CD31-mimetic peptide via an intermediate layer of polydopamine. Disks were used to assess the reaction of endothelial cells and blood elements in vitro. An aneurysm rabbit model was used to compare in vivo effects on the arterial wall of CD31-mimetic-coated (CD31-mimetic, n=6), polydopamine-coated (polydopamine, n=6), and uncoated FDs (bare, n=5) at 4 weeks post-FD implantation. In addition, long-term safety was assessed at 12 weeks.. In vitro, CD31-mimetic coated disks displayed reduced adhesion of blood elements while favoring endothelial cell attachment and confluence, compared to bare and polydopamine disks. Strikingly, in vivo, the neoarterial wall formed over the CD31-mimetic-FD struts at the aneurysm neck was characteristic of an arterial tunica media, with continuous differentiated endothelium covering a significantly thicker layer of collagen and smooth muscle cells as compared to the controls. The rates of angiographic complete occlusion and covered branch arterial patency were similar in all 3 groups.. CD31-mimetic coating favors the colonization of metallic endovascular devices with endothelial cells displaying a physiological phenotype while preventing the adhesion of platelets and leukocytes. These biological properties lead to a rapid and improved endothelialization of the neoarterial wall at the aneurysm neck. CD31-mimetic coating could therefore represent a valuable strategy for FD biocompatibility improvement and aneurysm healing.

Topics: Alloys; Angiography; Animals; Biocompatible Materials; Blood Vessel Prosthesis; Cerebral Arteries; Drug-Eluting Stents; Endothelial Cells; Indoles; Intracranial Aneurysm; Male; Platelet Endothelial Cell Adhesion Molecule-1; Polymers; Rabbits; Tunica Intima

Background Flow diverter (FD) malapposition is associated with stroke-related complications. We document the use of self-expanding nitinol stents to remove/reduce the ledge of a FD deployed for aneurysm treatment. Methods We identified five patients who were treated with the Pipeline embolization device (PED) in conjunction with a Neuroform EZ stent for inadequate wall apposition of the ends of the FD at our institution between May 2014 and July 2015. Among other parameters, angiographic results, cone-beam computed tomography assessment of wall apposition and patient clinical outcome were evaluated. Results Incomplete device end apposition was seen in three cases, and precarious positioning of the distal end of the PED over the aneurysm neck was seen in two cases. In all five cases, successful treatment with good wall apposition and proper pinning of the PED distal edge was achieved using an additional Neuroform EZ stent. Appropriate aneurysm neck coverage and flow stagnation was seen in all cases. The combination of high radial outward force and open-cell design permits the Neuroform EZ stent to jail the malappositioned edges of the FD while maintaining good vessel-wall apposition itself and prevent migration of the PED. Short-term follow-up angiography showed device patency and complete aneurysm obliteration in all cases. Conclusions Preliminary results of this small case series suggest that the Neuroform EZ stent allows for effective treatment of FD malapposition in selected patients amenable for this endovascular approach. Long-term and larger cohort studies are needed to validate these results.

Topics: Adult; Aged; Alloys; Angiography, Digital Subtraction; Blood Vessel Prosthesis; Cerebral Angiography; Cone-Beam Computed Tomography; Embolization, Therapeutic; Female; Humans; Imaging, Three-Dimensional; Intracranial Aneurysm; Male; Middle Aged; Prosthesis Design; Retrospective Studies; Stents; Tomography, X-Ray Computed; Treatment Outcome

Metal-induced encephalopathy after stent-assisted coil embolization is extremely rare. The present report describes two patients who presented with symptomatic intracranial parenchymal edematous lesions after stent-assisted coil embolization. A 64-year-old woman underwent stent-assisted coil embolization for a left internal carotid artery aneurysm; 21 days after the procedure she presented with right hand weakness and MRI revealed multifocal white matter lesions. Another woman aged 52 years underwent stent-assisted coil embolization for right vertebral artery aneurysm; 18 days after the procedure she presented with left-sided sensory disturbance and MRI demonstrated multiple white matter lesions. Treatment in both cases resulted in improvement of these lesions after steroid pulse therapy, and the patients had no associated morbidity 4 months after the procedures. Clinicians should monitor for neurologic symptoms and postoperative delayed radiologic parenchymal edematous changes associated with the metal allergic reaction after nitinol stent-assisted coil embolization.

Topics: Alloys; Brain Diseases; Embolization, Therapeutic; Female; Humans; Hypersensitivity, Delayed; Intracranial Aneurysm; Magnetic Resonance Imaging; Middle Aged; Nickel; Stents; White Matter

The PulseRider is a novel endovascular device specifically designed to treat bifurcation intracranial aneurysms with wide necks. In an international series, we report the results of PulseRider stent-assisted coiling of 15 patients (9 women and 6 men; mean age, 62.6 years) with 15 unruptured wide-neck (median dome size, 8 mm; median neck size, 5 mm) bifurcation aneurysms. Failure of PulseRider treatment occurred in 1 case, and 1 intraprocedural thromboembolic complication was observed. There was no mortality or neurologic permanent morbidity at discharge and at 1 month. Immediate angiographic outcome showed 12 complete occlusions and 2 neck remnants. Follow-up at 6 months was available for 3 aneurysms and demonstrated 2 complete aneurysm occlusions and 1 growing neck remnant. In this small series of selected patients, PulseRider stent-assisted coiling of wide-neck bifurcation aneurysms was feasible with low procedural complication rates. Angiographic follow-up will be required to evaluate the efficacy of the PulseRider device.

Topics: Adult; Aged; Alloys; Cerebral Angiography; Embolization, Therapeutic; Equipment Design; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Retrospective Studies; Stents; Treatment Failure; Treatment Outcome

Thin film nitinol can be processed to produce a thin microporous sheet with a low percentage of metal coverage (<20%) and high pore attenuation (∼70 pores/mm(2)) for flow diversion. We present in vivo results from the treatment of experimental rabbit aneurysms by using a thin film nitinol-based flow-diversion device.. Nineteen aneurysms in the rabbit elastase aneurysm model were treated with a single thin film nitinol flow diverter. Devices were also placed over 17 lumbar arteries to model perianeurysmal branch arteries of the intracranial circulation. Angiography was performed at 2 weeks (n = 7), 1 month (n = 8), and 3 months (n = 4) immediately before sacrifice. Aneurysm occlusion was graded on a 3-point scale (grade I, complete occlusion; grade II, near-complete occlusion; grade III, incomplete occlusion). Toluidine blue staining was used for histologic evaluation. En face CD31 immunofluorescent staining was performed to quantify neck endothelialization.. Markedly reduced intra-aneurysmal flow was observed on angiography immediately after device placement in all aneurysms. Grade I or II occlusion was noted in 4 (57%) aneurysms at 2-week, in 6 (75%) aneurysms at 4-week, and in 3 (75%) aneurysms at 12-week follow-up. All 17 lumbar arteries were patent. CD31 staining showed that 75% ± 16% of the aneurysm neck region was endothelialized. Histopathology demonstrated incorporation of the thin film nitinol flow diverter into the vessel wall and no evidence of excessive neointimal hyperplasia.. In this rabbit model, the thin film nitinol flow diverter achieved high rates of aneurysm occlusion and promoted tissue in-growth and aneurysm neck healing, even early after implantation.

Topics: Alloys; Animals; Cerebral Angiography; Disease Models, Animal; Embolization, Therapeutic; Intracranial Aneurysm; Pancreatic Elastase; Rabbits; Stents

A cerebral aneurysm occurs as a result of a weakened blood vessel, which allows blood to flow into a sac or a ballooned section. Recent advancement shows that a new device, 'flow-diverter', can divert blood flow away from the aneurysm sac. People found that a flow-diverter based on thin film nitinol (TFN), works very effectively, however there are no studies proving the mechanical safety in irregular, curved blood vessels. Here, we study the mechanical behaviors and structural safety of a novel microstructured TFN membrane through the computational and experimental studies, which establish the fundamental aspects of stretching and bending mechanics of the structure. The result shows a hyper-elastic behavior of the TFN with a negligible strain change up to 180° in bending and over 500% in radial stretching, which is ideal in the use in neurovascular curved arteries. The simulation determines the optimal joint locations between the TFN and stent frame. In vitro experimental test qualitatively demonstrates the mechanical flexibility of the flow-diverter with multi-modal bending. In vivo micro X-ray and histopathology study demonstrate that the TFN can be conformally deployed in the curved blood vessel of a swine model without any significant complications or abnormalities.

Topics: Alloys; Animals; Disease Models, Animal; Endovascular Procedures; Intracranial Aneurysm; Materials Testing; Stents; Swine

Flow-diverter stents are emerging for the endovascular treatment of difficult-to-treat or otherwise untreatable cerebral aneurysms (wide-neck, fusiform, dissecting, blisterlike, or giant). We assessed the clinical safety and efficacy of the Flow-Redirection Endoluminal Device.. This was an institutional review board-approved single-center observational clinical study in 29 patients with 34 aneurysms elected to be treated by endovascular intervention. After providing informed consent, patients were included according to the following criteria: aneurysm fundus-to-neck ratio <2 or neck diameter >4 mm, fusiform, dissecting, or giant aneurysms. The primary end point for clinical safety was the absence of death, absence of major or minor stroke, and absence of transient ischemic attack. The primary end point for treatment efficacy was complete angiographic occlusion according to the O'Kelly Marotta grading scale immediately after the procedure and at follow-up after 3 and 6 months (O'Kelly Marotta D: complete occlusion).. The Flow-Redirection Intraluminal Device deployment was technically successful in all cases. In 26/29 (89%) of patients, the primary end point of safety was reached; in the 3 remaining patients, 1 disabling ischemic stroke and 2 minor strokes with complete recovery at follow-up were observed. Angiographic (DSA and MRA) and clinical follow-up were available after 3 months in 29/29 (100%) and after 6 months in 25/29 (86%) patients (after 6 months, only MRA follow-up was performed according to our study protocol and institutional standard). At 3-month follow-up, complete occlusion was reached in 19/34 aneurysms (O'Kelly Marotta D: 19/34; 56%). At 6-month follow-up, aneurysm occlusion was complete in 22/30 aneurysms (O'Kelly Marotta D: 22/30; 73%).. Deployment of the Flow-Redirection Intraluminal Device flow-diverter stent is safe and effective in the treatment of difficult-to-treat or otherwise untreatable intracranial aneurysms.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Cerebral Angiography; Endotamponade; Equipment Design; Equipment Safety; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Magnetic Resonance Angiography; Male; Middle Aged; Stents; Treatment Outcome

Endovascular treatment of wide-neck anterior communicating artery aneurysms can often be challenging. The Woven EndoBridge (WEB) device is a recently developed intrasaccular flow disrupter dedicated to endovascular treatment of intracranial aneurysms. The aim of this study was to investigate the feasibility, safety, and efficacy of the WEB Dual-Layer and WEB Single-Layer devices for the treatment of wide-neck anterior communicating artery aneurysms.. Patients with anterior communicating artery aneurysms treated with the WEB device between June 2013 and March 2014 in 5 French centers were analyzed. Procedural success, technical complications, clinical outcome at 1 month, and immediate and 3- to 6-month angiographic follow-up results were analyzed.. Ten patients with unruptured anterior communicating artery aneurysms with a mean neck diameter of 5.4 mm were treated with the WEB. Treatment failed in 3 of the 10 aneurysms without further clinical complications. One patient developed a procedural thromboembolic event, and the other 6 had normal neurologic examination findings at 1-month follow-up. Immediate anatomic outcome evaluation showed adequate occlusion (total occlusion or neck remnant) in 6 of 7 patients. Angiographic control was obtained in all patients, including 6 adequate aneurysm occlusions (3 complete occlusions and 3 neck remnants) at short-term follow-up.. In our small series, treatment of wide-neck anterior communicating artery aneurysms with the WEB device was feasible and safe. However, patient selection based on the aneurysm and initial angiographic findings in the parent artery is important due to the limitations of the WEB device navigation.

Topics: Aged; Alloys; Cerebral Angiography; Embolization, Therapeutic; Equipment Design; Equipment Safety; Feasibility Studies; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Treatment Outcome

Stent-assisted embolization (SAE) has broadened the scope of endovascular cerebral aneurysm treatment. The risks associated with stent selection and configuration are poorly defined. In this study, the authors aimed to characterize the risk factors that contribute to complications in SAE of intracranial aneurysms.. Over a 10-year period, a single surgeon treated 486 aneurysms with SAE in which open-cell Neuroform or closed-cell Enterprise stents were used. Single stents were used in 386 cases, overlapping stents were deployed in 80 cases, and Y-configuration stents were used in the remaining 20 cases. All neurological complications, which included transient deficits, were analyzed; disabling strokes and death were considered major complications. The chi-square test and multivariate logistic regression were used to evaluate the influence of aneurysm size and morphology, aneurysm location, stent selection, and stent configuration on complication rates.. There were 7 deaths (1.4%), 9 major strokes (1.9%), and 18 minor neurological complications (3.7%). For all complications, multivariate analysis revealed that large aneurysm size (10-25 mm; p = 0.01), giant aneurysm size (> 25 mm; p = 0.04), fusiform aneurysm morphology (p = 0.03), and using a Y-configuration stent (p = 0.048) were independent risk factors. For the major complications, independent risk factors included an aneurysm in the posterior circulation (p = 0.02), using an overlapping stent configuration (p = 0.03), and using a Y-configuration stent (p < 0.01).. In this series, SAE for cerebral aneurysm treatment carried an acceptable complication rate. With continued innovations in techniques and devices and with increased experience, the complication rates associated with SAE may be even lower in the future.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Blood Vessel Prosthesis; Embolization, Therapeutic; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Risk Factors; Stents; Stroke; Treatment Outcome; Young Adult

The purpose of this article is to report on the long-term success rates of Silk flow-diverter (FD) treatment in a multicenter prospective study for the treatment of complex aneurysms.. Between May 2008 and January 2011, all consecutive patients featuring complex intracranial aneurysms eligible for FD treatment with the Silk in three neurovascular centers were included. Clinical and imaging data were assessed during hospitalization and follow-up.. Five patients were initially asymptomatic, 20 patients showed various neurological symptoms. Twenty-eight FDs were implanted in 25 patients treating 28 aneurysms. The immediate procedure-related morbidity was 8% (two of 25), mortality 0%. One procedure-related death was observed during follow-up (in-stent thrombosis). Compared to the immediate result nearly two of three aneurysms improved during follow-up; all angiographically confirmed inflow changes took place within six months after treatment. Final anatomic outcome in 24 aneurysms of 22 patients comprised 14 (59%) with complete occlusion, seven (29%) with a neck remnant, two (8%) with residual filling <50%, none with residual filling >50% and one (4%) unchanged in comparison to its pretreatment status. Postinterventional recanalizations were seen in three of 13 (23%) aneurysms treated with FD alone; none were observed in 15 aneurysms treated with adjunctive coiling.. Anatomic presentation and location are key for successful FD treatment. The rate of successful occlusion increases during follow-up. Postinterventional monitoring for at least six months is paramount, as anatomic outcome is not reliably predictable and recanalizations may occur in initially completely occluded aneurysms.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angiography, Digital Subtraction; Cerebral Angiography; Embolization, Therapeutic; Endovascular Procedures; Female; Humans; Intracranial Aneurysm; Magnetic Resonance Angiography; Male; Middle Aged; Prospective Studies; Prosthesis Design; Radiography, Interventional; Retrospective Studies; Stents; Tomography, X-Ray Computed; Treatment Outcome

Stents are promising medical devices widely used in the prevention of cerebral aneurysm rupture. As the performance of stents depends on their mechanical properties and cell configuration, the aim of this study was to optimize the stent design and test the hemodynamic properties by using computational solid mechanics and computational fluid dynamics. In order to test their performance, computer-based cerebral aneurysm models that mimic the conditions present after implantation into the human brain were tested. The strut configuration selected was the closed-cell type, and nitinol was chosen as the material for stent manufacture because the innate characteristics of this material increase stent flexibility. Three ideal sample stent types with different cell configurations were manufactured. Computational solid mechanics analysis of the sample stents showed over 30% difference in flexibility between stents. Furthermore, using a cerebral aneurysm model simulation, we found that the stents eased the hemodynamic factors of the cerebral aneurysm and lessened the flow velocity influx into the sac. A decrease in flow velocity led to a 50-60% reduction in wall shear stress, which is expected to prevent aneurysm rupture under clinical conditions. Stent design optimization was carried out by simulation and electropolishing. Corrosion resistance and surface roughness were evaluated after electropolishing performed under variable conditions, but 40 V and 10 s were the most optimal.

Topics: Alloys; Blood Flow Velocity; Cerebrovascular Circulation; Computer Simulation; Computer-Aided Design; Elasticity; Endovascular Procedures; Hemodynamics; Humans; Intracranial Aneurysm; Materials Testing; Models, Cardiovascular; Prosthesis Design; Prosthesis Failure; Stents; Stress, Mechanical; Surface Properties

The use of a stand-alone flow diverter (FD) stent has demonstrated itself as an efficacious endovascular approach to intracranial aneurysm treatment. FD stents that are currently available adopt an interwoven braided design. The relatively low radial stiffness intrinsic to this design could cause difficulty in deployment and poor stent-wall apposition, leading to high complication rates. A new FD stent is proposed to overcome the problems of the interwoven FD stents. The new device is manufactured from a Nitinol tube through a laser-cutting technique, and its unique structure allows for both low porosity and high packaging efficiency. Computational simulation using Abaqus has been conducted to investigate the radial stiffness and longitudinal flexibility of the new device. The new device exhibits high radial stiffness when compared to interwoven FD stents and superior longitudinal flexibility. Results from on-going in-vivo experiments and CFD simulations have also demonstrated the efficacy of the new device as a FD stent.

Topics: Alloys; Animals; Computer Simulation; Finite Element Analysis; Hemodynamics; Humans; Intracranial Aneurysm; Materials Testing; Porosity; Rabbits; Stents; Stress, Mechanical

Brain arterial aneurysms are localised dilatation in the wall of cerebral arteries that are common among adult population and associated with high incidence of morbidity and mortality. Using flow diverter stent alone to treat cerebral aneurysm is recognized as a safe and effective method. However, flow diverter stents currently available have limitations due to their braided structures. In this paper a novel flow diverter stent is proposed. It is made out of nitinol tubes that provide adequate radial stiffness and tailored surface coverage to overcome problems of currently available braided stents while retaining low porosity and excellent longitudinal flexibility. Finite element analysis using Abaqus has been conducted to investigate radial stiffness, longitudinal flexibility, and maximum strain during packaging of a series of novel stent designs with varied geometric parameters. Results show that porosity below 70% can be achieved and provides radial stiffness and longitudinal flexibility comparable to those of the Neuroform stent that is commonly used for stent assisted coiling. The novel flow diverter has showed great potential for direct treatment of cerebral aneurysms.

Topics: Alloys; Animals; Cerebrovascular Circulation; Equipment Design; Finite Element Analysis; Intracranial Aneurysm; Stents; Swine

The intracranial nitinol stent named the Enterprise Vascular Reconstruction Device has poor radiographic visibility. The characteristics of closed-cell intracranial stents were investigated and the efficacy of intraoperative stent visualization examined with the 80 kV high-resolution XperCT protocol, which is a flat detector C-arm volume acquisition functionality system integrated with the angiography equipment. We treated 39 aneurysms with stent-assisted coil embolization. The aneurysms were located on the internal carotid artery in 24 cases, the anterior communicating artery (AcomA) in three, the basilar artery (BA) in 10, and the vertebral artery in two. Intraoperative 80 kV XperCT was performed in all cases after deposition of the stent. We evaluated the coverage of the aneurysm neck, incomplete stent apposition (ISA), and shift of vessels. Accurate stent visualization was achieved in 29 of the 39 cases without coil and delivery wire artifact. Coverage of the aneurysm neck succeeded in 28 cases; there was one case of BA top Y-configuration stenting in which the stent was dislocated into the aneurysm. ISA was detected in nine cases, including seven kinks and one flattening in the carotid siphon and one kink in the BA top. We detected linearization of vessels due to stent deployment in three AcomA cases and three BA top cases. We conclude that intraoperative 80 kV XperCT is an efficient modality for the evaluation of ISA. Stent kinking in the carotid siphon and linearization in distal vessels can be detected with this protocol.

Topics: Alloys; Cerebral Angiography; Cone-Beam Computed Tomography; Contrast Media; Embolization, Therapeutic; Equipment Design; Equipment Failure; Female; Follow-Up Studies; Humans; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Intracranial Aneurysm; Intraoperative Complications; Iopamidol; Japan; Male; Sensitivity and Specificity; Stents

To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out.. Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations. We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom.. We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.1 lp/mm allows struts to be visualized. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. Measured absorbed doses are shown to be lower than 50 mGy Computed Tomography Dose Index (CTDI).. By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values. Experimental results compare well with imaging simulations.

Topics: Alloys; Humans; Imaging, Three-Dimensional; Intracranial Aneurysm; Phantoms, Imaging; Radiation Dosage; Radiographic Image Interpretation, Computer-Assisted; Stents; Tomography, X-Ray Computed; X-Rays

A flexible, low profile, flow diversion stent could replace endovascular coiling for the treatment of intracranial aneurysms. Micropatterned-thin film nitinol (TFN) is a novel biomaterial with high potential for use in next-generation endovascular devices. Recent advancements in micropatterning have allowed for fabrication of a hyperelastic thin film nitinol (HE-TFN). In this study, the authors describe in vitro and in vivo testing of novel HE-TFN based flow diverting stents. Two types of HE-TFN with expanded pores having long axes of 300 and 500 μm were used to fabricate devices. In vitro examination of the early thrombotic response in whole blood showed a possible mechanism for the device's function, whereby HE-TFN serves as a scaffold for blood product deposition. In vivo testing in swine demonstrated rapid occlusion of model wide-neck aneurysms. Average time to occlusion for the 300-μm device was 10.4 ± 5.5 min. (N = 5) and 68 ± 30 min for the 500-μm device (N = 5). All aneurysms treated with bare metal control stents remained patent after 240 min (N = 3). SEM of acutely harvested devices supported in vitro results, demonstrating that HE-TFN serves as a scaffold for blood product deposition, potentially enhancing its flow-diverting effect. Histopathology of devices after 42 days in vivo demonstrated a healthy neointima and endothelialization of the aneurysm neck region. HE-TFN flow-diverting stents warrant further investigation as a novel treatment for intracranial aneurysms.

Topics: Alloys; Animals; Disease Models, Animal; Female; Humans; Intracranial Aneurysm; Materials Testing; Porosity; Stents; Swine

Thin film nitinol produced by sputter deposition was used in the design of microstents intended to treat small vessel aneurysms. Thin film microstents were fabricated by "hot-target" dc sputter deposition. Both stress-strain curves and differential scanning calorimetry curves were generated for the film used to fabricate stents. The films used for stents had an A(f) temperature of approximately 36 degrees C allowing for body activated response from a microcatheter. The 10 microm film was only slightly radio-opaque; thus, a Td marker was attached to the stents to guide fluoroscopic delivery. Thin film microstents were tested in a flow loop with and without nitinol support skeletons to give additional radial support. Stents could be compressed into and easily delivered with <3 Fr catheters. Theoretical frictional and wall drag forces on a thin film nitinol small vessel vascular stent were calculated, and the radial force exerted by thin film stents was evaluated theoretically and experimentally. In vivo studies in swine confirmed that thin film nitinol microstents could be deployed accurately and consistently in the swine cranial vasculature.

Topics: Alloys; Aneurysm; Animals; Blood Vessel Prosthesis Implantation; Intracranial Aneurysm; Stents; Swine

Stent-assisted coiling is an accepted endovascular treatment (EVT) for wide-necked intracranial aneurysms. The Neuroform stent (Target Therapeutics, Fremont, Calif) is a flexible nitinol self-expandable stent that was designed to potentially overcome the limitations of balloon expandable coronary stents in the intracranial circulation. The aim of this study was to reenforce the use of this stent for EVT of wide-necked cerebral aneurysms.. Between March 2005 and March 2008, 24 patients harboring wide-necked cerebral aneurysms were treated with stent reconstruction of the aneurysm neck. Inclusion criteria restricted the group to adult patients with wide-necked intracranial aneurysms (ruptured and unruptured lesions). Immediate postprocedure angiography studies were performed to determine successful coil occlusion of the aneurysm as well as patency of the parent vessel. We assessed the clinical history, aneurysm dimensions, and technical detail of the procedures, including any difficulties with stent placement and deployment, degree of aneurysm occlusion, and complications. Clinical outcome was assessed with the Glasgow Outcome Scale (GOS).. The stent was easily navigated and precisely positioned in 24 of 26 cases. However, technical difficulties occurred in 9 patients, including difficulties in crossing the stents interstice in 6 cases, inadvertent stent delivery (n = 1), and incapacity of stent delivery (n = 1) and incapacity of crossing the neck (n = 1). These latter 2 cases were classified as failures of the stent-assisted technique. A single procedural complication occurred, involving transient nonocclusive intrastent thrombus formation, which was treated uneventfully with abciximab. Seventeen patients experienced excellent clinical outcomes (GOS 5), with good outcomes (GOS 4) in 5 patients and a poor outcome (GOS 3) in 2 patients. There were no treatment-related deaths or neurologic complications (mean clinical follow-up, 12 months). Angiographic results consisted of 17 complete occlusions, 4 neck remnants, and 3 incomplete occlusions.. The Neuroform stent is very useful for EVT of wide-necked intracranial aneurysms because it is easy to navigate and to deploy accurately. In most cases, the stent can be deployed precisely, even in very tortuous carotid siphons. Although in some cases delivery and deployment was challenging, clinically significant complications were not observed.

Topics: Adult; Aged; Alloys; Aneurysm, Ruptured; Carotid Artery Diseases; Cerebral Angiography; Embolization, Therapeutic; Equipment Design; Female; Glasgow Outcome Scale; Humans; Intracranial Aneurysm; Male; Middle Aged; Stents; Tomography, X-Ray Computed; Treatment Outcome

The authors demonstrate the feasibility of a new procedure to create intracranial interrupted microvascular anastomosis. Self-closing nitinol surgical clips were used for a pericallosal artery-pericallosal artery side-to-side bypass in a 52-year-old man harboring an unruptured large aneurysm located on the right A2 segment. The outflow artery was found to arise from the dome of the aneurysm, which was considered unsuitable for stand-alone clip ligation or coil occlusion. After bypass patency was intraoperatively confirmed using near-infrared indocyanine green videoangiography, the aneurysm and feeding artery were embolized with coils and safely occluded. Both postoperative courses were uneventful. The patient was discharged neurologically intact on the 5th postembolization day. Postprocedure angiography demonstrated no ipsilateral aneurysm filling and excellent bilateral distal outflow from the left anterior cerebral artery.

Topics: Alloys; Anastomosis, Surgical; Cerebral Angiography; Corpus Callosum; Embolization, Therapeutic; Humans; Intracranial Aneurysm; Male; Middle Aged; Neurosurgical Procedures; Surgical Instruments; Vascular Surgical Procedures

We report a case of a 70-year-old man harboring a wide-necked thrombosed giant aneurysm of the left middle cerebral artery (MCA) on the M1 segment. The patient presented with generalized tonic-clonic seizures. A computerized tomography scan showed a calcified aneurysmal wall with perianeurysmal swelling. The aneurysm was successfully embolized using closed-cell nitinol stent-assisted coiling (Leo, BALT Co., Montmorency, France).

Topics: Aged; Alloys; Embolization, Therapeutic; Humans; Intracranial Aneurysm; Male; Middle Cerebral Artery; Prosthesis Design; Stents

Stent systems for intracranial use are continuously improved. We report our initial experience using a new self-expanding easy-to-place nitinol stent (Enterprise) in the treatment of wide-neck intracranial aneurysms.. Between January and October 2007, 16 aneurysms in 15 patients were treated with stent assistance. Aneurysm size was a mean of 13.2 mm (median, 12 mm; range, 7-30 mm). Eight aneurysms had reopened after prior coiling, and 8 aneurysms were primarily treated, 1 after acute subarachnoid hemorrhage. Response to antiplatelet premedication was tested with a P2Y12 assay before stent placement. On a 3D angiographic workstation, stent placement was simulated to assess vessel caliber and appropriate stent length.. In all aneurysms, the stent could be placed at the exact location as predicted from the computer simulation. Stent placement proved to be technically easy without the need for recapture in all patients. Although placement of the microcatheter through the stent struts and subsequent coil placement was challenging in some patients, coiling after stent placement resulted in complete or near-complete occlusion in all aneurysms. There were no technical or clinical complications. At 6 months, angiographic follow-up in 14 aneurysms revealed 4 aneurysms recanalized to 80% occlusion, 3 of which were additionally coiled.. In this small series, delivery and deployment of the Enterprise stent was technically easy. There were no technical or clinical complications. The device was valuable in the treatment of wide-neck aneurysms. The need for antiplatelet medication in patients treated with this and other stents remains a significant disadvantage.

Topics: Adult; Aged; Alloys; Aneurysm, Ruptured; Aspirin; Cerebral Angiography; Clopidogrel; Combined Modality Therapy; Computer Simulation; Embolization, Therapeutic; Equipment Design; Female; Follow-Up Studies; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Intracranial Aneurysm; Male; Middle Aged; Platelet Aggregation Inhibitors; Premedication; Retreatment; Stents; Subarachnoid Hemorrhage; Ticlopidine

The use of vascular plug devices for the occlusion of high-flow lesions is a relatively new and successful procedure in peripheral and cardiopulmonary interventions. We report on the use and efficiency of the Amplatzer vascular plug in a small clinical series and discuss its potential for occlusion of large vessels and high-flow lesions in neurointerventions.. Between 2005 and 2007 four patients (mean age 38.5 years, range 16-62 years) were treated with the device, in three patients to achieve parent artery occlusion of the internal carotid artery, in one patient to occlude a high-flow arteriovenous fistula of the neck. The application, time to occlusion, and angiographic and clinical results and the follow-up were evaluated.. Navigation, positioning and detachment of the device were satisfactory in all cases. No flow-related migration of the plug was seen. The cessation of flow was delayed by a mean of 10.5 min after deployment of the first device. In the procedures involving vessel sacrifice, two devices had to be deployed to achieve total occlusion. No patient experienced new neurological deficits; the 3-month follow-up revealed stable results.. The Amplatzer vascular plug can be adapted for the treatment of high-flow lesions and parent artery occlusions in the head and neck. In this small series the use of the devices was uncomplicated and safe. The rigid and large delivery device and the delayed cessation of flow currently limit the device's use in neurointerventions.

Topics: Adolescent; Alloys; Aneurysm, False; Balloon Occlusion; Carotid-Cavernous Sinus Fistula; Embolization, Therapeutic; Equipment Design; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Radiography

The Guglielmi Detachable Coil introduced by the Boston Scientific Corporation has been widely used for endovascular coiling of aneurysm. Recently, Sapphire platinum detachable coils (eV3, Irvine, CA) have been introduced for aneurysm coiling. Herein, we report our clinical experience with the Sapphire coil to evaluate the incidence of coil related complications and the rate of aneurysm occlusion.. Consecutive patients who underwent embolization with Sapphire detachable coils were prospectively enrolled from January 2004 to September 2004 and the data were retrospectively analyzed. Patient demographics, including age, gender, presenting symptoms, Hunt and Hess grade, Fisher grade and locations of the vascular anomalies were collected. Additionally, complications associated with the coils and rates of aneurysm occlusion were observed and the data compiled.. 29 patients underwent Sapphire coil embolization for intracranial aneurysms. Mean age was 50 +/- 18 (mean +/- SD) years with 81% being females. Aneurysm neck reconstruction was required in 7 cases, 6 with Neuroform stent (5 unruptured aneurysms) and 1 with balloon assistance (ruptured aneurysm). In 7 cases, Sapphire coils were used along with other coils. There were no events of thromboembolism or ruptures of aneurysms during coil embolization. However, multi-diameter coils demonstrated stretching in 4 stent-assisted cases without any adverse consequences. Complete occlusion of the aneurysm was achieved in 79.31% of the patients, neck remnant in 6.89, and partial coiling was achieved in 13.79%.. The Sapphire coil could safely be used in the treatment of both ruptured and unruptured aneurysms. However, multi-diameter non-stretch resistant coils may be associated with coil stretching when used in conjunction with a stent. Further study is still required for definitive results.

Topics: Adult; Aged; Alloys; Aneurysm, Ruptured; Cerebral Angiography; Databases, Factual; Embolization, Therapeutic; Female; Humans; Intracranial Aneurysm; Iridium; Male; Middle Aged; Platinum; Retrospective Studies

Endovascular coil embolization of saccular intracranial aneurysms is safe and effective, but long-term results are dissatisfying. Reconstructive treatments using stents improve occlusion rate and protect parent vessels. We present data on our experience with a new self-expanding stent manufactured with braided nitinol wires.. Twenty-five saccular, complex, and broad-necked intracranial aneurysms in 21 patients were treated electively. They were located at the internal carotid artery (10), basilar trunk (5), cavernous carotid artery (4), basilar tip (2), anterior cerebral artery (2), anterior communicating artery (1), and middle cerebral artery (1). Eleven aneurysms exhibited recanalization after primary endovascular treatment without stent.. Stent deployment was successful in 24 lesions, and additional coil embolization was performed in 23. No permanent neurological deficits were encountered consequent to endovascular procedure. Complete or partial occlusion immediately after stent deployment was achieved in 19 aneurysms, whereas no immediate coil embolization was chosen in 6 cases. There were two thromboembolic events related to the deployment of the Leo stent, one failure of stent deployment, difficulties in stent positioning in three cases, and one asymptomatic parent artery occlusion after 7 months. Follow-up (available in 18 patients and 21 aneurysms and obtained at 3-12 mo; average, 5 mo) revealed patent stents in the remaining cases. Angiographic recurrences arose in three lesions, which were retreated without complications.. Primary and recurrence treatment of saccular and broad-necked intracranial aneurysms using the Leo stent is feasible and effective. No permanent neurological deficits were associated with stent placement. Short-term follow-up identified intact parent arteries and stable occlusion rates in the majority of cases.

Topics: Adult; Aged; Alloys; Elective Surgical Procedures; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Radiography; Stents

One of the feared complications during detachable coil embolization of cerebral aneurysms is herniation of a coil loop into the parent artery. Although coil protrusion of one or two loops into the parent vessel may not cause adverse events and in some instances can be ignored, the authors believe that coil retrieval is indicated if a free end is seen pulsating along the blood flow stream to prevent migration of the entire coil mass. In one patient, a microballoon was inflated across the neck of the aneurysm during retrieval of a herniated coil to prevent further coil herniation from the aneurysm sac. We present two cases in which prolapsed coils were successfully retrieved either using a microsnare and balloon combination or a microsnare alone. This report focuses on the efficacy of the Amplatz microsnare for such retrievals and the circumstances in which a herniated coil needs to be retrieved. We report two cases in which embolization coils partially migrated into the parent artery during endovascular treatment of cerebral aneurysm and were retrieved using the Amplatz Nitinol microsnare.

Topics: Adult; Aged, 80 and over; Alloys; Cerebral Angiography; Device Removal; Embolization, Therapeutic; Female; Humans; Intracranial Aneurysm

Intracranial stenting is increasingly being used to treat intracranial aneurysms and stenoses. We wanted to assess the utility of magnetic resonance angiography (MRA) in the follow-up of patients treated with various types of intracranial stents and to assess the utility of performing gadolinium-enhanced MRA. A total of 19 patients having undergone intracranial stenting for aneurysms were imaged by MRI at 1.5T. A total of 20 stents were placed in 19 patients. In addition to conventional T2- and diffusion-weighted MRI, 3D time-of-flight MRA was performed before and after contrast administration. In the case of metallic INX stents (N = 7), there was a signal drop at the level of the vessel. which did not allow to evaluating the parent vessel, whereas this was visible in Nitinol stents (N = 8). Additionally a stent with a wire had a small artifact (N = 3). Contrast administration also improved vessel lumen visualization. In the case of Nitinol stents, MRA can be used to reliably demonstrate the vessel lumen after intracranial stenting. The use of postcontrast 3D time-of-flight imaging helps improve the intraluminal definition.

Topics: Adult; Aged; Alloys; Contrast Media; Female; Humans; Image Processing, Computer-Assisted; Intracranial Aneurysm; Iopamidol; Magnetic Resonance Angiography; Male; Middle Aged; Stents; Treatment Outcome

The authors report their experience with the use of the Neuroform Microdelivery System for intravascular reconstruction. They assess the technical feasibility of the system, the efficacy of the combined application of stent and detachable coils, and the follow-up findings.. Fifty patients found to harbor a complex wide-necked intracranial aneurysm were selected for the study. Different strategies were chosen and the performance and technical success of the device were evaluated. Stent placement was recorded as optimal or suboptimal with respect to the stent position. Clinical and angiographic follow-up examinations were obtained. Forty-six patients with 48 intracranial aneurysms were treated, leading to a technical success rate of 92%. Forty-two lesions were located in the anterior circulation. In every case the dome/neck ratio was less than 2 and the mean aneurysm size in these patients was 8.8 mm. The most frequent clinical presentation was subarachnoid hemorrhage in 48% of cases. Stent placement was optimal in 81.2% of cases and suboptimal in 18.8%. In 31% of cases, the investigators encountered difficulties in placing the Neuroform stent. Clinical follow up was recorded in all patients and angiographic follow up was obtained in 63%. There were no cases of repeated hemorrhage. In a single case in which only the stent was implanted progressive thrombosis was identified during the follow-up period. The procedure-related morbidity and mortality rates were 8.6 and 2.1%, respectively.. On the basis of the results, the authors conclude that the Neuroform self-expanding stent is a flexible and useful device that can be readily and safely maneuvered through tortuous intracranial vessels, enabling the endovascular treatment of complex wide-necked aneurysms. Early in the authors' experience, stent delivery presented difficulties; however, a second generation of devices has resolved this limitation. Although the early results are promising, the long-term benefit of this technique has to be proved by angiographic and clinical follow-up examinations.

Topics: Adult; Aged; Alloys; Aneurysm, Ruptured; Angiography, Digital Subtraction; Angioplasty, Balloon; Cerebral Angiography; Combined Modality Therapy; Embolization, Therapeutic; Equipment Design; Equipment Failure; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Outcome Assessment, Health Care; Retreatment; Stents; Subarachnoid Hemorrhage; Survival Rate; Technology Assessment, Biomedical

The endovascular treatment of cerebral aneurysms with coils poses significant technical challenges, particularly with respect to wide-necked aneurysms. We present the results of our initial experiences in using a stent for endovascular treatment of aneurysms, with an emphasis on potential applications, technical aspects, and associated complications. Twenty-three wide-necked aneurysms from 22 patients were treated during the 13-month study period. Seven patients presented with subarachnoid hemorrhage. Aneurysms were located at the internal carotid artery (n=14), the vertebral artery (n=3), the basilar artery (n=5), and the middle cerebral artery (n=1). A Neuroform stent2 was used for stent-assisted procedures. Premedication with antithrombotic agents was available for unruptured cases. Postprocedural antithrombotic medication was prescribed for all patients. Nineteen aneurysms were primarily stented, followed by coil placement. For five of these aneurysms, stenting was performed subsequent to failure of an attempt to frame with an initial coil. Stenting for the remaining four aneurysms was performed as a rescue procedure to prevent the migration of previously placed coils. Complete occlusion was obtained in ten aneurysms, nearly complete occlusion (95% or more occluded) in 11 aneurysms, and partial occlusion (less than 95% occluded) in one aneurysm. In one aneurysm, we failed to navigate the microcatheter into the aneurysmal sac through the interstices of the stent. Stent thrombosis was noted during the procedure in one patient. Hemorrhagic complication on the 25th day after the procedure was noted in one patient. No procedure-related complications were observed during the procedure or during follow-up in the remaining 20 patients, including seven patients who did not receive antithrombotic agents prior to endovascular treatment owing to recent subarachnoid hemorrhage. To overcome the technical limitation in the coiling of wide-necked aneurysms, stent-assisted coil embolization may be a technically feasible and relatively safe method, even though longer periods of follow-up are required.

Topics: Adult; Aged; Alloys; Angiography, Digital Subtraction; Catheterization; Embolization, Therapeutic; Feasibility Studies; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Stents; Treatment Outcome

A new neurovascular microstent, the Cordis Enterprise stent, composed of nitinol, with a closed cell design, was specifically developed for the treatment of wide-necked intracranial cerebral aneurysms. The purpose of this study was to evaluate the safety, feasibility, and initial clinical results of using this device in patients.. In clinical evaluation, five patients ranging in age from 54 to 71 years were electively treated. The smallest aneurysm measured 3.3 x 2.9 mm, and the largest aneurysm measured 10.6 x 8.5 mm (neck and height measurements).. All five cases (100%) were technically successful without complications. In each case, the stent was accurately placed in the desired location, immediately followed by coil embolization to the desired degree of occlusion with a satisfactory result. The poststent and coil-occlusion angiogram demonstrated excellent blood flow across the stent, with satisfactory positioning of the coils within the aneurysm in all cases (100%). No patient suffered any clinical or neurologic complications, and all were discharged 1-3 days postprocedure, in stable condition with no new neurologic deficits.. In early clinical studies, the Cordis Enterprise stent performed well. The stent was able to be well visualized, deployed easily, could be repositioned if needed, and was accurately placed without technical difficulties. The closed cell design allowed all coils to be placed within the aneurysm and remain outside the flow of the parent artery. No periprocedural complications were encountered.

Topics: Aged; Alloys; Cerebral Angiography; Cerebrovascular Circulation; Embolization, Therapeutic; Equipment Design; Feasibility Studies; Female; Humans; Intracranial Aneurysm; Male; Middle Aged; Stents; Treatment Outcome

To determine the effect of Neuroform stent (Boston Scientific/Target, Fremont, CA) deployment on parent vessel lumen and detect in-stent changes in patients harboring wide-necked intracranial aneurysms treated with the stent-coil technique.. Parent vessel dimensions were quantified before and after the procedure and at intermediate follow-up examinations by use of high-resolution three-dimensional rotational angiography. By use of shaded surface segmentation of the acquired volume, measurements of the parent vessel proximal to the stent (Point A), at three points within the stented vascular segment (Points B, C, and D), and distal to the stent (Point E) at each study time were compared by use of paired t tests. Correlation between degree of in-stent stenosis and reported ischemic events was estimated by use of a linear regression model.. Stent and coil deployment had no immediate effect on parent vessel dimensions. At angiographic follow-up, there was no significant change in vessel size proximal to the stent. Within the stent and distal to it, however, there was a statistically significant 0.31- to 0.41-mm reduction in average diameter (P < 0.001, P < 0.011, P < 0.003, and P < 0.014 for Points B, C, D, and E, respectively). The highest degree of stenosis occurred at Point B, with an average decrease in cross sectional surface area of 2.4 mm (P < 0.001), corresponding to a 19% stenosis and 52% estimated increase in focal hemodynamic resistance by Poiseuille's law. No clinical correlation was noted with the degree of in-stent stenosis.. Intracranial stenting using a soft self-expanding stent without angioplasty induced a statistically, but not clinically, significant decrease in cross sectional area. Further research and longer-term follow-up are needed to elucidate the mechanism and clinical importance of this response.

Topics: Alloys; Cerebral Angiography; Cohort Studies; Constriction, Pathologic; Embolization, Therapeutic; Equipment Design; Follow-Up Studies; Humans; Imaging, Three-Dimensional; Intracranial Aneurysm; Rotation; Stents

To evaluate magnetic field interactions of commonly used biomedical implants at 3.0 Tesla.. Fourteen aneurysm clips designed for permanent placement in intracranial aneurysms, 19 coronary artery stents and 20 iliac artery stents were evaluated in an actively shielded compact 3.0 T MR system (Intera, Philips Medical Systems, Best, The Netherlands, length of magnet 1.57 m). The magnetic deflection forces (translational movement) were evaluated as follows: The implants were suspended by a fine string and placed in the magnet bore at the location of the maximum magnetic field gradient. The translational forces F (z) were calculated from the measured angle of deflection from the vertical axis. The magnetic field-induced torque (rotational forces) was evaluated as follows: Each implant was placed in the center of the magnetic bore parallel to the static magnetic field B0 (position 0 degrees ). Any possible displacement of the implant was noted on a millimeter scale and any torque qualitatively evaluated using a 5 point grading scale (0: no torque; + 4: very strong torque). The implant was turned in steps of 45 degrees, and the procedure was repeated to encompass a full 360 degrees rotation.. In 52 of the 53 devices tested, the deflection force (deflection angle: range 0-21 degrees, translational force: range 0-3.8 mN) was less than the gravitational force (i.e., the implant's weight). These devices (n = 52/53) did not show any alignment to or rotation in the magnetic field at any of the various 45 degrees -increment positions corresponding to a qualitative torque evaluation of grade 0/4. One device (n = 1/53), an iliac artery stent made of stainless steel (Zenith, Cook, Mönchengladbach, BRD), was found to have deflection forces (deflection angle 88 degrees translational force 299 mN) greatly exceeding the gravitational force as well as a pronounced torque (grade 4/4).. Out of 53 biomedical implants evaluated for magnetic field interactions at 3.0 T, one iliac artery stent made of stainless steel was found to be potentially unsafe based on ASTM criteria. MR imaging at 3.0 Tesla may be performed safely in patients with any of the other 52 different implants evaluated in this study with respect to magnetic field translational attraction and torque.

Topics: Alloys; Chi-Square Distribution; Cobalt; Coronary Vessels; Electromagnetic Fields; Humans; Iliac Artery; Intracranial Aneurysm; Magnetic Resonance Imaging; Metals; Prostheses and Implants; Rotation; Safety; Stainless Steel; Stents; Tantalum

The Neuroform stent is a self-expanding nitinol stent designed for use in wide-necked intracranial aneurysms. Heating and imaging artifacts were evaluated by using a porcine carotid artery aneurysm model in a 3T MR system. A suspended Neuroform stent was tested for deflection. No heating was measured, and no evidence of deflection of the stent was found. Imaging artifacts were minimal. MR imaging in patients with Neuroform stent-treated aneurysms is safe and feasible.

Topics: Alloys; Animals; Artifacts; Carotid Artery Diseases; Contraindications; Disease Models, Animal; Equipment Failure Analysis; Equipment Safety; Heating; Intracranial Aneurysm; Magnetic Resonance Imaging; Phantoms, Imaging; Stents; Swine

Endovascular stenting appears to be an appealing treatment modality to selected complex intracranial aneurysms. However, stents currently used for endovascular treatment are not specifically designed for the cerebrovasculature. Stent parameters, such as porosity and filament size, have to be carefully optimized for long-term successful treatment. We investigated the influence of the stent filament size on the intraaneurysmal flow dynamics in a sidewall aneurysm model in vitro. Three helical stents with 76% porosity but different filament sizes of 178, 153, and 127 microm were studied using particle image velocimetry. Twenty-four pulsatile flow conditions were investigated. The results show that stenting significantly reduces intra-aneurysmal vorticity and the mean circulation inside the aneurysm is reduced to less than 3% of its value before stenting. For constant porosity, a further reduction of the mean circulation, up to 30% can be obtained by reducing the filament diameter. For a constant Womersley number, this further reduction is accentuated with increase in the peak Reynolds number. Further reduction in the mean circulation inside the aneurysm was not achieved for the 127 microm stent. With further reduction in filament diameter, the helical stent filaments positioned against the aneurysm neck started wavering with the flow transferring added momentum into the aneurysm. For stents of smaller filament diameter, a supporting ultrastructure is required.

Topics: Alloys; Blood Flow Velocity; Cerebrovascular Circulation; Equipment Design; Hemorheology; Humans; Intracranial Aneurysm; Models, Cardiovascular; Pulsatile Flow; Sensitivity and Specificity; Stents

To evaluate the physical characteristics and behavior of coils for endovascular therapy.. Mechanically detachable coils were constructed with simple helical (4 mm X 10 cm and 8 mm X 30 cm) and pretzel shapes (4 mm X 5 cm) made from three metals using 0.003- and 0.004-in wire. Stiffness or pliability, frictional resistance, shape memory, and coil stability were evaluated in vitro.. The 0.004-in wire stock coils proved significantly stiffer when compared with the 0.003-in coils. Tungsten coils proved least pliable; platinum coils were intermediate in stiffness; and nitinol coils were softest. Frictional resistance in the catheter was greatest for stiffer coils. The 5-cm pretzel coil consistently created more frictional force than the 10- or 30-cm simple helical coils. Despite a shorter length, the 4-mm simple helical coil exerted more frictional force than the 8-mm coil. Stiffer metal coils constructed of larger-diameter wire (0.004 in) were more stable than softer coils.. Stiffer coils exert greater frictional forces within the catheter and a greater resistive force during bending but are more stable after placement. Frictional forces also depend on the complex three-dimensional shape of the coil and the diameter of the turns in that shape rather than coil length. These data suggest that a family of coils of different metals is optimal for varied intravascular needs.

Topics: Alloys; Biomechanical Phenomena; Elasticity; Embolization, Therapeutic; Equipment Design; Humans; Intracranial Aneurysm; Intracranial Arteriovenous Malformations; Materials Testing; Platinum; Tungsten