Additional Coil Research Articles

The Society for Gastrointestinal Intervention. Are We, as an Organization of Disparate Disciplines, Cooperative or Competitive?

The Society for Gastrointestinal Intervention. Are We, as an Organization of Disparate Disciplines, Cooperative or Competitive?

Potential advantages and limitations of the Leo stent in endovascular treatment of complex cerebral aneurysms

Objective The Leo self-expandable stent is a new retractable stent that is delivered via a conventional catheter. The aim of this study was to evaluate the use of this stent for endovascular treatment of complex aneurysms. Methods Twenty-eight complex cerebral aneurysms (27 saccular and 1 fusiform) in 28 patients were treated electively. They were located at the internal carotid artery (17), basilar trunk (3), anterior cerebral artery (1), anterior communicating artery (3), vertebral artery (2) and middle cerebral artery (2). One aneurysm exhibited recanalization after primary endovascular treatment without stent. Clinical outcome was assessed with the modified Glasgow Outcome Scale. Results Deployment of Leo stent was successful in 26 lesions, and difficulties in stent positioning due to tortuous cerebral circulation in 2 cases, which were treated with Neuroform stent. Additional coil embolization was performed in 26 lesions. No permanent neurological deficits were encountered consequent to endovascular procedure. Complete or partial occlusion immediately after stent deployment was achieved in all aneurysms. There was no immediate coil embolization was chosen in 3 cases because of subsequent reduced filling of the aneurysms with contrast agent on angiograms. There were 3 asymptomatic parent artery occlusion related to the deployment of the Leo stent, one stent migration. Follow-up revealed patent stents in the remaining cases. No angiographic recurrences arose. Conclusion The Leo stent is very useful for endovascular treatment of complex cerebral aneurysms because it is easy to navigate and place precisely. A drawback is that in-stent thrombosis caused by stent placement and stiffer delivery catheters to place larger stents.

E-023 Progressive occlusion in aneurysms treated with stent assisted coiling: flow diversion?

BackgroundTreatment of intracranial aneurysms using stent assisted coiling (SAC) has broadened the range of endovascular therapies for these aneurysms.ObjectiveOur goal was to assess the long term durability of SAC with...

Efficient generation of a magnetic field‐free line

Signal encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the region of interest. One way to increase the sensitivity of the method is to scan the region of interest with a field-free line (FFL) instead of the FFP. Recently, the first feasible FFL coil setup was introduced. The purpose of this article is to improve the efficiency of the FFL coil geometry even further. In order to reduce the electrical power loss of the setup, an additional Maxwell coil pair is introduced that is tailored to generate the static part of the FFL field. Using the proposed coil assembly, the electrical power loss for the generation of a rotating FFL is considerably reduced compared to previously known coil setups. Furthermore, the quality of the generated FFL is significantly increased. The proposed coil assembly is almost as efficient as an equivalent FFP scanner. Furthermore, the assembly cannot only be used for FFL imaging but for FFP imaging as well. Hence, the findings of this article denote an important step toward the first practical implementation of the FFL coil geometry.

Asymmetrical giant magnetoimpedance in exchange-biased NiFe

Linear asymmetrical magnetoimpedance (MI) has been obtained in thin multilayer strips of exchange-coupled FeNi(5 nm)/IrMn(15 nm)/FeNi(40 nm)/Cu(100 nm)/FeNi(40 nm)/IrMn(15 nm)/FeNi(5 nm), in which the MI response is enhanced by including a Cu layer between the two 40 nm NiFe layers. The antiferromagnetic layer creates an exchange bias that shifts both the hysteresis loop and the MI response. The asymmetrical MI peak positions are shifted to higher magnetic field as the probe frequency increases. Linear MI behavior can be tuned around zero external field without the need for external biasing fields or additional coils, by changing the frequency. The impedance of a planar magnetic conductor was modeled based on a modified Stoner–Wohlfarth energy density.

High-Field Magnetic Resonance Imaging of the Pelvis

Today, magnetic resonance imaging (MRI) is a standard imaging modality for various pathologic disorders in the human pelvis. It has given proof of its usefulness in the diagnosis of several benign and malignant disorders, and it is routinely used for the local staging of different tumors even when confined to specific parts of a pelvic organ. Signal-to-noise ratio and motion artifacts of the examined organ and adjacent bowel structures are major factors for image quality. Setting at 3 T with surface coils avoids technical limitations and discomfort of additional endovaginal or endorectal coils. Definition of high field seems fuzzy because of the availability of MRI machines with 3, 7 T, or higher; therefore, the general aspects of MRI of pelvic structures with emphasis on uterus, ovary, and prostate gland and attention to promising newer techniques such as 3 T, dynamic contrast imaging, and diffusion-weighted imaging are reviewed in this article.

Delayed Cranial Nerve Palsy After Coiling of Carotid Cavernous Sinus Aneurysms

Detachable endovascular coils have become a common treatment strategy for carotid cavernous sinus aneurysms (CCAs), but previously unrecognized postprocedure complications may emerge as longer follow-up data are accumulated. In this report, the authors document the first known cases of delayed cranial neuropathy following CCA coiling in 3 patients, all of whom present at least a year postprocedure without aneurysm regrowth. The potential mechanisms underlying this syndrome are discussed as well as their implications on the selection and optimal endovascular management of CCA patients. Three previously healthy females aged 50, 60, and 62 underwent CCA coiling at our institution and subsequently developed ipsilateral cranial nerve palsies at 56, 28, and 14 months, respectively, post-procedure. At presentation, all 3 patients had a new, recurrent area of flow in their CCA without changes in aneurysm size. One patient declined further treatment. In the other 2 patients, a stent was placed across the aneurysm neck, and one patient underwent additional coiling. Unfortunately, all 3 patients remained symptomatic at their latest follow-up. Because of the intimate anatomic environment of the cavernous sinus, neural elements within it may be particularly susceptible to persistent mass or dynamic effects exacerbated by remnant or recurrent flow across the neck of a coiled aneurysm. These 3 cases prompted the authors to advocate for more aggressive efforts to achieve and maintain CCA occlusion. Furthermore, when such efforts are unsuccessful, consideration of traditional carotid occlusion strategies with or without bypass is warranted.

The effects of downstream magnetic field on current-free double layers and beam formation in the Njord helicon plasma device

The Njord device was constructed with the aim of investigating instabilities and turbulence in plasmas with flows and beams, which are common also in space plasmas. Njord is an inductively coupled helicon plasma device with 13.56 MHz RF power inserted into the working gas by means of a saddle antenna through a 13.8 cm inner diameter Pyrex tube. The source plasma expands through a 7 cm long and 20 cm wide port into a 0.6 m diameter and 1.2 m long chamber. Two magnetic field coils around the source and one additional downstream coil produce a magnetic field of about 25 mT at maximum.We have characterized current-free double layers in argon plasmas, and we find that they are generated at the position where the plasma expands into the main chamber. Further, the effect of shaping the magnetic field from an expanding one to a mirror shaped field by means of the downstream coil has been investigated. The downstream density and the plasma potential increase significantly when all the magnetic field lines in the source are passing also through the port–dome intersection without intersecting the port walls. The ion beam disappears when the plasma potential increases up to a potential similar to that in the source.

Embolization of the Gastroduodenal Artery Before Selective Internal Radiotherapy: A Prospectively Randomized Trial Comparing Standard Pushable Coils with Fibered Interlock Detachable Coils

The purpose of this study was compare embolization of the gastroduodenal artery (GDA) using standard pushable coils with the Interlock detachable coil (IDC), a novel fibered mechanically detachable long microcoil, in patients scheduled for selective internal radiotherapy (SIRT). Fifty patients (31 male and 19 female; median age 66.6 ± 8.1 years) were prospectively randomized for embolization using either standard coils or IDCs. Procedure time, radiation dose, number of embolization devices, complications, and durability of vessel occlusion at follow-up angiography were recorded. The procedures differed significantly in time (14:32 ± 5:56 min for standard coils vs. 2:13 ± 1:04 min for IDCs; p < 0.001); radiation dose for coil deployment (2479 ± 1237 cGycm² for standard coils vs. 275 ± 268 cGycm² for IDCs; p < 0.001); and vessel occlusion (17:18 ± 6:39 min for standard coils vs. 11:19 ± 7:54 min for IDCs; p = 0.002). A mean of 6.2 ± 1.8 coils (n = 27) were used in the standard coil group, and 1.3 ± 0.9 coils (p < 0.0001) were used in the IDC group (n = 23) because additional pushable coils were required to achieve GDA occlusion in 4 patients. In 2 patients, the IDC could not be deployed through a Soft-VU catheter. One standard coil dislodged in the hepatic artery and was retrieved. Vessel reperfusion was noted in only 1 patient in the standard coil group. Controlled embolization of the GDA with fibered IDCs was achieved more rapidly than with pushable coils. However, vessel occlusion may not be obtained using a single device only, and the use of sharply angled guiding catheters hampered coil pushability.

Trapping ultracold atoms in a time-averaged adiabatic potential

We report an experimental realization of ultracold atoms confined in a time-averaged, adiabatic potential (TAAP). This trapping technique involves using a slowly oscillating ($~$kHz) bias field to time-average the instantaneous potential given by dressing a bare magnetic potential with a high-frequency ($~$MHz) magnetic field. The resultant potentials provide a convenient route to a variety of trapping geometries with tunable parameters. We demonstrate the TAAP trap in a standard time-averaged orbiting potential trap with additional Helmholtz coils for the introduction of the radio frequency dressing field. We have evaporatively cooled $5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms of $^{87}\mathrm{Rb}$ to quantum degeneracy and observed condensate lifetimes of longer than $3$ s.

破裂脳動脈瘤の治療 破裂脳動脈瘤塞栓術―１０年間の治療成績―

Although endovascular coil embolizations have increased in number, open surgery is still predominant for the treatment of ruptured cerebral aneurysms in Japan, partly because there are not enough follow-up results of endovascular coil embolization to discuss long-term outcomes of the procedure. We retrospectively analyzed radiological and clinical results in patients with ruptured cerebral aneurysms treated with coil embolization. From 1997 to 2006, 100 patients with ruptured intracranial aneurysms were treated with endovascular coil embolization. Clinical records and radiological findings of all these patients were retrospectively checked till the end of 2007. Thirty-one patients were 70 years or over in age, and 39 patients were in WFNS grade IV or V on admission. Although this cohort was older and higher in WFNS grade than in other reports, initial and follow-up results were the same. Mean follow-up periods were 42.1 months. Fifteen patients died during follow-up, and 76 patients showed complete obliterations of the aneurysm by the initial procedure. We experienced 10 major recurrences that needed retreatment, and 1 patient suffered from rebleeding while a retreatment was scheduled. Seven recurrent aneurysms were 10 mm or more in diameter at the initial treatment. The second treatment was successfully performed in 5 patients without complications or recurrences during 38 months of mean follow-up after the second procedure. One patient with a large basilar tip aneurysm suffered from a late regrowth of the aneurysm at 2.5 years after an initial tight packing, for which 4 additional treatments were performed. Endovascular treatment of ruptured cerebral aneurysms with coils seems to have good clinical and radiological results. However, the risk of regrowth, which results in bleeding, may continue until late follow-up periods, particularly in aneurysms more than 10 mm. Retreatment should be considered as soon as possible when major recurrence, which permits additional coils, occurs.

Experiência clínica com a utilização de plugs vasculares Amplatzer®

INTRODUÇÃO: Os plugs vasculares Amplatzer® I e II (PVAs I e II) são dispositivos de nitinol autoexpansíveis e de baixo perfil desenvolvidos para oclusão de estruturas vasculares. Relatamos nossa experiência com esses dispositivos em dois centros brasileiros de referência. MÉTODOS: Estudo retrospectivo dos pacientes que se submeteram a procedimentos de oclusão de estruturas vasculares diversas com PVAs desde 2005. Foram utilizadas próteses 30% a 50% maiores que o vaso-alvo, implantadas sob anestesia geral por via venosa femoral e jugular interna ou arterial femoral e braquial por cateteres terapêuticos ou bainhas longas 5 F a 8 F. RESULTADOS: Foram identificados 14 pacientes (50% do sexo masculino) com mediana de idade de 5 anos (11 meses a 70 anos) e mediana de peso de 15 kg (8 kg a 67 kg). Foram utilizados 17 plugs vasculares, sendo 2 PVAs II e 15 PVAs I, com diâmetros de 4 mm a 16 mm. Em 3 pacientes existiam dois vasos para oclusão, sendo utilizados 2 PVAs em vasos diferentes. Em 3 pacientes com fístulas coronárias houve oclusão completa dos vasos após 24 horas. Em 2 pacientes com anastomose de Blalock-Taussig houve oclusão completa da anastomose, em um deles com auxílio de molas adicionais. Em 3 pacientes com fístulas venovenosas no pós-operatório de Glenn ou Fontan houve oclusão completa dos vasos e melhora da saturação, em um deles com auxílio de molas adicionais. Outro caso de fístula venovenosa apresentava fluxo residual discreto no laboratório, com oclusão na monitorização ecocardiográfica em 24 horas. Em 2 pacientes com fístula arteriovenosa pulmonar foram utilizados, além dos PVAs, outras próteses Amplatzer e molas de Gianturco, permanecendo mínimo fluxo residual em ambos os casos. Em 2 pacientes com colaterais sistêmicopulmonares no pós-operatório de atresia pulmonar com comunicação interventricular, houve oclusão completa com auxílio de molas, sendo um imediato e outro em 24 horas. Em um paciente com síndrome da cimitarra a colateral sistêmica foi ocluída totalmente. Não houve episódios de embolização ou mortalidade. CONCLUSÕES: Os PVAs mostraram-se adequados e versáteis para oclusão de diferentes estruturas vasculares, com facilidade de implante e bons índices de oclusão. Em alguns casos, houve necessidade de uso de outros dispositivos. Nesses casos, os PVAs funcionam bem para ancorar os dispositivos adicionais.

Coil embolization of patent ductus arteriosus via the carotid artery in seven dogs

This study was designed to evaluate the feasibility and limitations of transcatheter embolization coil occlusion of patent ductus arteriosus in dogs using a carotid artery approach. Seven dogs examined at the University of California, Davis Veterinary Medical Teaching Hospital in 2002–2003 for evaluation of heart disease had congenital patent ductus arteriosus diagnosed by characteristic physical, electrocardiographic, radiographic, and anatomic and Doppler echocardiographic findings. Dogs were anesthetized for transesophageal echocardiography and transcatheter coil embolization of the ductus via the right external carotid artery. Coil embolization was achieved in all seven cases, using one to four detachable embolization coils. There were no major complications. Minor complications occurred in two dogs (additional coils placed using a femoral arterial approach and coil embolization of a left femoral artery branch). One dog was examined only 24 h post-operatively and had no murmur and trivial residual ductal flow by Doppler echocardiography. The other 6 dogs were clinically healthy when examined up to three years post-intervention. One dog had a very soft continuous murmur and mild residual ductal flow; the other five had no audible continuous murmur, with only one dog having trivial residual ductal flow identified by Doppler echocardiography. Although technically challenging, coil embolization via the carotid artery is a viable alternative approach for transcatheter closure of patent ductus arteriosus in some dogs.

Neuroapplication of Amplatzer Vascular Plug for Therapeutic Sacrifice of Major Craniocerebral Arteries: An Initial Clinical Experience

Clinical use of the Amplatzer vascular plug in the cardiopulmonary and peripheral vasculatures has been described extensively in the literature. We present our initial experience in adapting this device for therapeutic sacrifice of major craniocerebral arteries. Between July 2007 and November 2008, 8 patients (mean age 59.1 years; range 18 to 82 years) underwent therapeutic occlusion of major craniocerebral arteries using the device, for direct caroticocavernous fistula (1 patient), symptomatic unruptured giant cavernous internal carotid aneurysms (2 patients), and preoperative embolisation before surgical resections of skull base tumours that had encroached upon the internal carotid or vertebral artery (5 patients). The plugs were used alone or in conjunction with detachable platinum coils. The applications of the device, as well as the angiographic and clinical results of the procedures were evaluated. Applications of the plugs were straightforward and successful in all cases, with hermetic occlusions of all target arteries. When used without additional coils, several plugs were deployed in tandem to achieve complete occlusion of the artery. No migration of the device was seen. No patient developed untoward neurological deficits following the procedures, and the 3- and/or 6-month follow-up showed stable results. The Amplatzer vascular plug could be a valuable addition to the neurointerventional armamentarium, particularly in therapeutic occlusion of major craniocerebral arteries. Rigidity of the delivery system limits its current use to vessels below the skull base. The potential risk of distal thromboembolism also requires further evaluation.

Crystal Structure of Iodotyrosine Deiodinase, a Novel Flavoprotein Responsible for Iodide Salvage in Thyroid Glands

The flavoprotein iodotyrosine deiodinase (IYD) salvages iodide from mono- and diiodotyrosine formed during the biosynthesis of the thyroid hormone thyroxine. Expression of a soluble domain of this membrane-bound enzyme provided sufficient material for crystallization and characterization by x-ray diffraction. The structures of IYD and two co-crystals containing substrates, mono- and diiodotyrosine, alternatively, were solved at resolutions of 2.0, 2.45, and 2.6 A, respectively. The structure of IYD is homologous to others in the NADH oxidase/flavin reductase superfamily, but the position of the active site lid in IYD defines a new subfamily within this group that includes BluB, an enzyme associated with vitamin B(12) biosynthesis. IYD and BluB also share key interactions involving their bound flavin mononucleotide that suggest a unique catalytic behavior within the superfamily. Substrate coordination to IYD induces formation of an additional helix and coil that act as an active site lid to shield the resulting substrate.flavin complex from solvent. This complex is stabilized by aromatic stacking and extensive hydrogen bonding between the substrate and flavin. The carbon-iodine bond of the substrate is positioned directly over the C-4a/N-5 region of the flavin to promote electron transfer. These structures now also provide a molecular basis for understanding thyroid disease based on mutations of IYD.

A Long-Term View at Clipping Versus Coiling for Ruptured Aneurysm

The results of the long-term follow-up of the ISAT patients are mostly confirmatory [1]. ISAT remains the most influential trial comparing clipping versus coiling of ruptured aneurysms. Only cases that fulfilled the condition of clinical equipoise were enrolled. In other words, only patients who were considered adequate candidates for clipping and for coiling were randomized. The initial report of the results of the study indicated that coiling was associated with a relative reduction in the risk of death and dependency at 1 year of 23.9% compared with clipping (absolute risk reduction 7.4%) [2]. During the first year after treatment, coiled patients had a slightly higher incidence of rebleeding from the treated aneurysm and required re-treatment (typically additional coiling) 6.9 times more often than clipped patients [2, 3]. However, there were concerns about the durability of coiling in patients who are often quite young at the time of their subarachnoid hemorrhage. During a mean follow-up of 9 years (range 6‐14 years), the risk of rebleeding from the treated aneurysm remained low in both groups, although it was higher in the coiling group (the difference was actually significant in the per protocol analysis, which accounted for a patient assigned to the clipping group who requested to be coiled instead and later rebled). It is possible that current risk of aneurysm rebleeding after coiling could be lower than those seen in ISAT because technological improvement now allows higher rates of complete aneurysm obliteration, but this possibility remains to be proven. There were no differences in fatal cases of rebleeding between the two groups. Clipping did not eliminate the risk of late rebleeding from the treated aneurysm. Bleeding could also occur from another previously known but untreated aneurysm or from aneurysms which formed de novo after enrollment in the trial. Table 1 shows the distribution of cases of rebleeding according to bleeding source and treatment arm.

Effective control of ion fluxes over large areas by magnetic fields: From narrow beams to highly uniform fluxes

An effective control of the ion current distribution over large-area (up to 103 cm2) substrates with the magnetic fields of a complex structure by using two additional magnetic coils installed under the substrate exposed to vacuum arc plasmas is demonstrated. When the magnetic field generated by the additional coils is aligned with the direction of the magnetic field generated by the guiding and focusing coils of the vacuum arc source, a narrow ion density distribution with the maximum current density 117 A m−2 is achieved. When one of the additional coils is set to generate the magnetic field of the opposite direction, an area almost uniform over the substrate of 103 cm2 ion current distribution with the mean value of 45 A m−2 is achieved. Our findings suggest that the system with the vacuum arc source and two additional magnetic coils can be effectively used for the effective, high throughput, and highly controllable plasma processing.

Transiliac ICD implantation: Defibrillation vector flexibility produces consistent success

The transiliac approach to implantable cardioverter-defibrillator (ICD) implantation is an alternative in patients for whom pectoral placements are contraindicated. The defibrillation vector is altered from the pectoral configuration because of pulse generator placement in one of the upper abdominal quadrants and separate single-coil, active-fixation defibrillation leads positioned in the high right atrium and right ventricular apex. The feasibility, safety, and complications of this approach and the results of defibrillation testing (DFT) with this configuration are described. Twenty-three patients (16 male and 7 female, mean age 65.7 +/- 13.2 years) required transiliac approach to ICD placement. The leads were inserted through the iliac vein immediately superior to the inguinal ligament. When required, a subcutaneous coil was tunneled posterior to the left ventricle from the left axilla. The right iliac vein entry was used in 17 patients, with placement of the pulse generator in the left upper quadrant in 16 patients. Atrial and ventricular lead pacing and sensing function were acceptable. Initial defibrillation success with a safety margin of 10 J was achieved in 15 patients. With the placement of an additional subcutaneous coil in the remaining 8 patients, defibrillation success with a safety margin of 10 J was increased to 19 patients, whereas defibrillation success with a safety margin of 5 J was achieved in all patients, although 1 patient required repeat testing 24 hours after implantation. There were no acute complications. Late complications occurred in 3 patients, comprised of atrial lead malfunction, device infection, and right ventricular defibrillation lead fracture. The iliac vein approach to ICD implantation is a safe and effective alternative technique. Flexibility in lead placement, defibrillation vectors, and careful DFT are required to produce a consistently effective system.

Synthesis Ti–Si–N nanocomposite coating prepared by a hybrid system of double bending filtered vacuum arc source and magnetron sputtering

In this work, various nanocomposite Ti–Si–N films have been deposited by hybrid coating system of double bending filtered vacuum arc source (DBFVAS) and magnetron sputtering techniques. Vacuum arc source has been used for the deposition of TiN and Si was incorporated by magnetron sputtering. The magnetic system of double bending filter consists of five solenoid coils and additional coil on the opposite side of vacuum chamber is supporting stabilization of the plasma flow onto substrate surface. Ti–Si–N film is deposited on the Si wafers and high speed steel (HSS) substrates with different Si content, which is controlled by magnetron current. As magnetron current increases from 0 to 1.5 A, Si content increases up to 18.2%. The deposition rate of Ti–Si–N coating layer is up to 17 nm/min. From the results Ti–Si–N coatings have been characterized as nanocomposites, consists of TiN crystallites and amorphous Si 3N 4.

Endovascular Treatment for Very Small Supraclinoid Aneurysms with Stent-Assisted Coiling. Long-Term Follow-up in Six Cases.

The endovascular treatment of very small aneurysms (lesions less than 3 mm in maximum diameter) with wide necks remains a challenge for saccular embolization. We retrospectively analyzed our data using Neuroform stent-assisted coiling for very small supraclinoid aneurysms with wide neck to evaluate the feasibility and efficacy of endovascular treatment of these lesions. We conducted a review of our experience and results of endovascular treatments in six patients with seven very small aneurysms. All aneurysms were located at the side wall of the supraclinoid segment of the ICA. They were ruptured in two patients and unruptured in four. The technique of stent-assisted coiling was used in all cases with coiling before stenting and additional coils after deployment of the stent in the same session. All patients were successfully embolized with stent-assisted coiling. The coils were introduced into the lumen for subtotal occlusion in five aneurysms and for partial occlusion in two. During one to two years follow-up angiography, all aneurysms were completely occluded and no recurrence occurred. No complications were observed. Endovascular stent-assisted coil embolization of supraclinoid very small aneurysms with wide necks is effective and feasible. Subtotal aneurysm occlusion might progress to total occlusion.