Interlocking detachable coil occlusion in the endovascular treatment of intracranial aneurysms: preliminary results.

PURPOSETo present our preliminary experience with the recently developed interlocking detachable coils in the treatment of intracranial aneurysms.METHODSTwo aneurysms of the basilar tip, two of the internal carotid artery, and one of the posterior inferior cerebellar artery were treated by an endovascular technique using interlocking detachable coils. Three of the patients had undergone unsuccessful surgical clipping. Three-month and 1-year control angiograms were obtained.RESULTSIn all patients but one, who had an aneurysm of the internal carotid artery, the aneurysmal sac was occluded with preservation of the parent artery and did not show recanalization on the follow-up control angiograms. In the other patient who had a wide-necked aneurysm of the internal carotid artery, the sac could not be totally obliterated and showed contrast filling in the neck remnant at 3-month angiography. None of the patients experienced neurologic deficit after treatment.CONCLUSIONBecause they are soft and retrievable, interlocking detachable coils, with their immediate coil release design, may provide an alternative to surgery in the future treatment of endovascular aneurysms.     

Combined use of stents and coils to treat experimental wide-necked carotid aneurysms: preliminary results.

PURPOSETo develop a new technique to treat wide-necked side-wall aneurysms, combining the implantation of intraarterial stents with the endosaccular placement of coils.METHODSBilateral side-wall aneurysms were surgically created on the carotid arteries of four dogs. In each animal, Guglielmi detachable coils were introduced into one of the aneurysms after implantation of a balloon-expandable Strecker stent within the parent artery, adjacent to the aneurysm orifice. The contralateral aneurysms were treated with coils alone.RESULTSIn two dogs, one of the stented and both nonstented aneurysms remained partially open for 4 weeks after subtotal packing with coils. In another two dogs, tight aneurysm packing with coils resulted in complete occlusion of all four aneurysms. Bulging of the coil mass resulted in 30% to 75% narrowing of the nonstented parent arteries. At 4 and 5 weeks, significant stenosis resulting from reactive hyperplasia was observed in all stented carotid arteries.CONCLUSIONBased on these preliminary results, we conclude that Guglielmi detachable coils can be introduced into an aneurysm cavity through Strecker stents. The stents allow tighter packing of wide-necked aneurysms by preventing coils from migrating or bulging into the parent arteries.     

Interlocking detachable platinum coils,a controlled embolization device: Early clinical experience

Purpose: To present the early clinical experience of a new mechanically controlled-release embolization device<+>—<+>the interlocking detachable coil (IDC)—in complex embolization outside the head. Methods: IDCs were used only when conventional embolization techniques were considered too risky or unsafe. The coils consist of unfibered coiled platinum (0.012 inch), mechanically connected to a pusher wire and deployed through a Tracker 18 catheter. IDCs come in a range of diameters (2<+>–<+>8 mm) and lengths (1<+>–<+>30 cm). Results: A total of 87 IDCs were used for 27 procedures in 25 patients (mean 14.5 years) to occlude 31 arteries or vascular lesions. Control of the coil and its release were satisfactory and all coils were fully retrievable up to the point of deployment. Two IDC coils embolized inadvertently but were retrieved; there were no other complications. The IDC coils could not be satisfactorily placed in one high-flow arteriovenous (AV) fistula, and in another case there was a small residual fistula. Occlusion was produced in 29 of 31 lesions. Ancillary techniques were needed in 5 patients: temporary balloon occlusion in 2 and 0.038-inch coils in 3. Conclusion: The IDC coil is an effective device that allows controlled embolization to be performed, especially in aneurysms and in high-flow AV fistulas in children.     

In Vitro Observation of Air Bubbles during Delivery of Various Detachable Aneurysm Embolization Coils

Objective

Device- or technique-related air embolism is a drawback of various neuro-endovascular procedures. Detachable aneurysm embolization coils can be sources of such air bubbles. We therefore assessed the formation of air bubbles during in vitro delivery of various detachable coils.

Materials and Methods

A closed circuit simulating a typical endovascular coiling procedure was primed with saline solution degassed by a sonification device. Thirty commercially available detachable coils (7 Axium, 4 GDCs, 5 MicroPlex, 7 Target, and 7 Trufill coils) were tested by using the standard coil flushing and delivery techniques suggested by each manufacturer. The emergence of any air bubbles was monitored with a digital microscope and the images were captured to measure total volumes of air bubbles during coil insertion and detachment and after coil pusher removal.

Results

Air bubbles were seen during insertion or removal of 23 of 30 coils (76.7%), with volumes ranging from 0 to 23.42 mm³ (median: 0.16 mm³). Air bubbles were observed most frequently after removal of the coil pusher. Significantly larger amounts of air bubbles were observed in Target coils.

Conclusion

Variable volumes of air bubbles are observed while delivering detachable embolization coils, particularly after removal of the coil pusher and especially with Target coils.     

Structural limitations of currently available microcatheters and coils for endovascular coiling of very small aneurysms

Introduction Coil embolization for very small aneurysms (<3 mm in maximum diameter) has been considered a technically challenging method due to increased risk of potential aneurysm perforation during the procedure. We present our observations about the structural limitations of eight types of microcatheters and three types of detachable coils, and technical pitfalls in the coiling of very small aneurysms. Methods The structures of each type of microcatheter and coil were carefully evaluated under a stereoscopic microscope. The evaluation the microcatheters was focused on the distance between the distal end of the distal marker and the tip of microcatheter. The evaluation of the coils was focused on the length of the detachment zone. Results With markers of the coil delivery systems and microcatheters aligned under fluoroscopic visualization according to the manufacturers’ recommendations, the stiff detachment zones protruded approximately 0.2–1 mm from the microcatheter tip. The lengths of the detachment zone, which is known to be a stiff segment, of the currently available coils were approximately 0.5–0.8 mm. The distance between the distal end of the distal markers of the microcatheters and the detachment zone of the coil ranged from approximately 1.2 to 2.8 mm. Conclusion To prevent rupture of very small aneurysms during coiling, the distal marker of the selected microcatheter should be carefully located near the aneurysm neck, considering all the structural characteristic of the currently available coils and microcatheters. Refinement of currently available devices may be essential to achieve safer coiling of very small aneurysms.     

The nature of thrombosis induced by platinum and tungsten coils in saccular aneurysms.

PURPOSETo compare the efficacy and biocompatability of electrolytic and mechanically detachable embolization coils of two metal types.METHODSExperimental saccular aneurysms in pigs were used to assess embolization induced by platinum or tungsten coils. Longitudinal angiographic and histologic studies were performed on treated and untreated (control) aneurysms to compare thrombosis and cellular responses after embolization with electrolytically detachable platinum coils and with mechanically detached tungsten coils.RESULTSFewer tungsten than platinum coils were needed to induce thrombosis. The inflammatory response within the aneurysmal lumen was more florid in embolized aneurysms than in control aneurysms. No difference was found in the timing or extent of accumulation of eosinophils, lymphocytes, or polymorphs between the two coils used. Giant cell responses were more marked in treated aneurysms; tungsten coils more than platinum coils. The amount of collagen and fibrosis present increased over the study period and was similar in treated and control aneurysms.CONCLUSIONThe coil type influenced the initial cellular response but had little effect on the rate or degree to which blood clot within the aneurysm was replaced by fibrous tissue.     

Treatment of carotid artery aneurysms with platinum coils: an experimental study in dogs

The objectives of this study were to investigate the consistency, patency, and natural history of a vein graft canine aneurysm model and to determine the effectiveness of various coil designs on inducing aneurysm thrombosis. Twenty-one sacculuslike aneurysms were created in mongrel dogs by anastomosing a vein pouch to the common carotid artery. The model produced wide-neck aneurysms with 100% patency. The canine vein graft aneurysm provided an excellent model for the evaluation of endovascular devices. Three types of specially designed platinum coils were placed in the aneurysms: those with simple curves, those with complex curves, and those with flower petal curves and silk fibers. These coils were placed by the endovascular route by means of microcatheters. Flower petal coils with silk fibers were effective in producing thrombosis of the aneurysms, suggesting that coils of the appropriate design may be useful in the endovascular treatment of aneurysms. The other coil designs evaluated, those with simple and complex curves without silk fibers, demonstrated insufficient thrombogenicity and spatial stability.     

Neurovascular embolization: in vitro evaluation of a mechanical detachable platinum coil system

The authors evaluated a mechanically detachable platinum coil system intended for neurovascular use. The introduction characteristics, ease of delivery, ease of retrieval, and detachability were studied with fluoroscopic guidance with in vitro silicone models. All the coils passed easily through the microcatheter. The detachment maneuver occurred within 20 seconds with 20 or fewer rotations of the pusher wire. One of 229 coils detached prematurely but only after deliberate and extreme manipulation. The detachment system is safe, reliable, and consistent and will be useful for interventional neuroradiologists.     

Embolization of dural arteriovenous fistulas with interlocking detachable coils.

Our clinical experience with interlocking detachable coils for the embolization of high-flow dural arteriovenous fistulas is reported. Interlocking detachable coils are useful for transarterial and transvenous embolizations of dural arteriovenous fistulas because (a) immediate coil detachment is possible, (b) the coils can be replaced easily, (c) detached coils rarely migrate, and (d) fewer interlocking detachable coils than conventional fiber coils are required for successful embolization.     

Cerebral aneurysm perforations complicating therapy with Guglielmi detachable coils: a meta-analysis

BACKGROUND AND PURPOSE: The risk of intraprocedural aneurysm perforation in patients with previously ruptured aneurysms tends to be higher than that of patients with previously unruptured aneurysms, but a statistically significant difference has not been shown. Our purpose was to define the rates of occurrence and of morbidity and mortality associated with aneurysmal perforation associated with coil embolization. METHODS: A meta-analysis of the results from 17 published retrospective reports of aneurysm perforations complicating therapy with Guglielmi detachable coils (GDCs) was performed. Rates of perforation and associated morbidity and mortality in previously ruptured and unruptured aneurysms were calculated. The mechanism of perforation was noted. RESULTS: The risk of intraprocedural perforation was significantly higher in patients with ruptured aneurysms compared with patients with unruptured aneurysms (4.1% vs 0.5%; P <.001). The combined risk of permanent neurologic disability and death associated with intraprocedural aneurysm perforation was 38% for ruptured aneurysms and 29% for unruptured aneurysms. The morbidity and mortality rates with perforations caused by coils (39%) and microcatheters (33%) were similar. The morbidity and mortality rate for microguidewire perforations was considerably lower (0%, n = 4) than the rates for coils and microcatheters, but number of cases was too low to indicate statistical significance. CONCLUSION: The risk of aneurysm perforation during GDC therapy is much higher in patients with previously ruptured aneurysms than in those with unruptured aneurysms. The morbidity and mortality rates are substantial for perforations caused by coils and microcatheters, whereas they seem to be much lower for perforations caused by microguidewires.     

Distal-tip shape-consistency testing of steam-shaped microcatheters suitable for cerebral aneurysm coil placement

BACKGROUND AND PURPOSE: Although the selection of microcatheter for endovascular aneurysmal treatment is one important factor in patient outcome, the use of steam shaping for achieving safe entry and stability during coil placement has not, to our knowledge, been systematically evaluated. The goal of this study was to compare the durability of distal microcatheter steam shaping in five different catheters with typical intraprocedural stresses that are similar to those encountered during aneurysm coil placement. METHODS: Distal tips of microcatheters were shaped into a 90 degrees turn with distal straight-segment lengths of 3, 5, or 7 mm by using steam, performed according to the instructions for use included with each catheter. In a water bath kept at body temperature, the changes in catheter tip angle were recorded and measured following microcatheter insertion into a guiding catheter, microguidewire insertion through the microcatheter, and Guglielmi detachable coil (GDC) placement through the microcatheter. RESULTS: The degree of distal microcatheter straightening with typical intraprocedural manipulations was more pronounced on braided microcatheters and on microcatheters with 3- or 5-mm distal-shaped segments. The degree of spontaneous recovery of the initially steamed shape was more pronounced with nonbraided catheters. The most significant single variable contributing to straightening of a steam-shaped catheter tip was the effect of microguidewire insertion. The catheter-tip straightening effect encountered with inserting GDCs was less than that encountered with microguidewire insertion. We demonstrated that the decreased catheter-tip angle encountered with a large-magnitude straightening stress spontaneously recovered once the stress was removed or when it was reduced to a smaller magnitude stress. CONCLUSION: Our study shows that, although braided microcatheters are suitable for maintaining durable configurations when long distal-tip lengths are permissible, nonbraided microcatheters demonstrate the most durable distal-tip configurations when short distal-tip lengths are called for. This may be one of significant factors in catheter choice for endovascular treatment of aneurysm.     

Combined stent implantation and endosaccular coil placement for treatment of experimental wide-necked aneurysms: a feasibility study in swine.

PURPOSETo assess the feasibility of combining stent implantation in the parent artery with endosaccular coil placement for the treatment of experimentally created wide-necked aneurysms.METHODSWide-necked aneurysms were surgically created on the common carotid artery in 12 swine. A metal stent was endovascularly implanted across each aneurysm neck and its effect documented anigiographically. If the aneurysm remained patent, a microcatheter was introduced into the aneurysm through the stent mesh. Electrically detachable coils were delivered into the aneurysm sac to produce thrombosis.RESULTSAfter stent implantation, one carotid artery thrombosed and two aneurysms spontaneously occluded. In the other 9 cases, coils were deposited through the stent to occlude the aneurysm. Complete aneurysm packing was possible in all 9 cases. The presence of the stent allowed placement of small coils near the aneurysm neck, thus contributing to the safe occlusion of small remnants in the final stages of aneurysm packing.CONCLUSIONThe combination of stent implantation and coil placement is feasible in the treatment of experimental wide-necked saccular aneurysms. The stent maintains patency of the parent artery while allowing aneurysm occlusion by endosaccular coil placement through the stent''s mesh. Occlusion of small aneurysm remnants is possible with no fear of coil hernation or migration into the parent artery. Long-term studies will be necessary before application to treatment of selected intracranial aneurysms.     

Magnetic Catheter Manipulation in the Interventional MR Imaging Environment

PurposeTo evaluate deflection capability of a prototype endovascular catheter, which is remotely magnetically steerable, for use in the interventional magnetic resonance (MR) imaging environment.Materials and MethodsCopper coils were mounted on the tips of commercially available 2.3–3.0-F microcatheters. The coils were fabricated in a novel manner by plasma vapor deposition of a copper layer followed by laser lithography of the layer into coils. Orthogonal helical (ie, solenoid) and saddle-shaped (ie, Helmholtz) coils were mounted on a single catheter tip. Microcatheters were tested in water bath phantoms in a 1.5-T clinical MR scanner, with variable simultaneous currents applied to the coils. Catheter tip deflection was imaged in the axial plane by using a “real-time” steady-state free precession MR imaging sequence. Degree of deflection and catheter tip orientation were measured for each current application.ResultsThe catheter tip was clearly visible in the longitudinal and axial planes. Magnetic field artifacts were visible when the orthogonal coils at the catheter tip were energized. Variable amounts of current applied to a single coil demonstrated consistent catheter deflection in all water bath experiments. Changing current polarity reversed the observed direction of deflection, whereas current applied to two different coils resulted in deflection represented by the composite vector of individual coil activations. Microcatheter navigation through the vascular phantom was successful through control of applied current to one or more coils.ConclusionsControlled catheter deflection is possible with laser lithographed multiaxis coil-tipped catheters in the MR imaging environment.     

In vitro evaluation of coils for endovascular therapy.

PURPOSETo evaluate the physical characteristics and behavior of coils for endovascular therapy.METHODSMechanically 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.RESULTSThe 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.CONCLUSIONStiffer 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.     

Long-term angiographic and histopathologic findings in experimental aneurysms of the carotid bifurcation embolized with platinum and tungsten coils.

PURPOSETo evaluate the long-term outcome of endovascular occlusion of arterial aneurysms effected with metal coils.METHODSMicrosurgical methods were used to produce carotid bifurcation aneurysms in 20 rabbits and the radiologic and histologic changes were examined. Eight of these aneurysms were occluded with electrically detachable platinum coils (Guglielmi detachable coils [GDCs] and nine were treated with mechanically detachable tungsten coils (mechanical detachable system [MDS]). Three aneurysms remained untreated and served as controls. One animal died of embolic complications 12 hours after endovascular treatment. After observation periods of 3 to 6 months, the remaining animals were examined by intraarterial digital subtraction angiography and subsequent fixation and light and electron microscopy.RESULTSLarge open spaces without signs of thrombosis were found between the loops of the coil baskets in 12 aneurysms (six treated with GDCs and six treated with MDS) regardless of the observation period. In very densely packed aneurysms (four cases with complete occlusion as determined by angiographic criteria), the coil surfaces were for the most part covered by thin cell layers; however, complete endothelialization was never seen. In aneurysms with an initial partial occlusion of 70% to 90%, coil compaction and/or recanalization was a consistent finding. A comparison of the radiologic findings with the histologic aspect revealed that the degree of occlusion was often overrated on the radiographs (in eight of 17 cases). In general, the fibrous tissue reaction appeared to be slightly more pronounced in aneurysms occluded with tungsten coils.CONCLUSIONSPlatinum and tungsten coils were not always effective in causing endoluminal thrombosis leading to long-term occlusion by organized thrombus.     

Coil treatment of a fusiform upper basilar trunk aneurysm with a combination of “kissing” neuroform stents,TriSpan-, 3D- and fibered coils,and permanent implantation of the microguidewires

Endovascular coil occlusion of fusiform intracranial aneurysms without sacrifice of the parent artery can be technically challenging. Bridging of wide aneurysm necks with stents is common practice for side-wall aneurysms but is less frequently used for bifurcation aneurysms. We describe the technical aspects of the successful coil occlusion of a fusiform aneurysm of the upper basilar trunk, with preservation of the parent vessel. The procedure comprised the following steps: (a) stenting of the left V1- and proximal V2 segments; (b) simultaneous deployment of two Neuroform stents from both P1 segments down to the basilar artery (kissing stents) (c) using a TriSpan device to hold (d) three-dimensional electrolytically detachable coils in place and (e) filling the aneurysmal lumen mainly with fibered electrolytically detachable coils; and finally (f) cutting the extracorporeal part of both microguidewires below the skin level in both groins, leaving the microguidewires as they were used for the deployment of the stents in place, thus reaching from both P2 segments down to the basilar artery and further proximally.     

Endovascular treatment of cerebral aneurysms: An in vitro study with detachable platinum coils and tricellulose acetate polymer

OBJECTIVE. The purpose of our experimental study was to determine the effectiveness of filling the cavity of in vitro aneurysms with detachable platinum coils and the combination of detachable platinum coils and liquid embolic agent. MATERIALS AND METHODS. Silicone aneurysm models were connected to a circulatory system to simulate arterial flow. A microcatheter was used to introduce detachable coils into the aneurysm cavities. First, platinum coils were introduced until the point of minimal dense packing, indicated by aneurysmal circulatory exclusion. Packing was continued up to maximal dense packing, indicated by protrusion of the coil into the parent artery. Volumetric ratios (coil volume-aneurysm volume) were calculated for minimal and maximal dense packing. Then, after purposeful undercoiling of aneurysm models, a micropump system was used to fill the aneurysm by stepwise injection of tricellulose acetate polymer through the coil mesh until angiographic aneurysm exclusion was completed. The volumetric ratios of maximal packing with coils and tricellulose acetate polymer in relation to the aneurysm volume were calculated. RESULTS. Maximal dense packing ratios with coils (mean, 32.5%; standard deviation [SD], 3%) were slightly higher than those with the minimal dense packing (mean, 28. 2%; SD, 3%) but were always less than 37%. The ratios of packing with the combined use of coils and tricellulose acetate polymer were greater than 100% (mean, 124.4%; SD, 15%). CONCLUSION. Knowledge of the volumetric ratio of maximal dense packing was useful for effective filling with coils and tricellulose acetate polymer. The combined use of coils and liquid polymer appeared more effective than the use of coils alone for the complete occlusion of the aneurysm lumen.     

Usefulness of the Guglielmi detachable coil for embolization of a systemic venous collateral after Fontan operation: A case report

Embolization of collateral veins is often treated with rigid coils(Gianturco and interlocking detachable coils type).However,when dealing with tortuous and dilated collateral veins,there is a high risk for technical failure and coil migration due to inflexibility of the coils.To safely and successfully solve this problem,Guglielmi detachable coils(GDC) can be used for embolization.Their flexibility allows for easy navigation in tortuous veins,low risk of unintended coil release or coil migration,and safe deployment.A 12-year-old girl with a single ventricle had severe cyanosis and a low exercise tolerance 5 years after Fontan procedure.The symp-toms were caused by a tortuous and dilated collateral from the left phrenic vein into the left pulmonary vein,forming a right-to-left shunt.The collateral,which had a large diameter and high flow,and therefore a high risk of coil migration,was successfully embolized with 8 GDC.There were no complications such as coil migration or cerebral infarction.Transcatheter embolization increased her systemic oxygen saturation from 81%-84% to 94%-95%,and increased her ability to exercise.The embolization procedure using flexible GDC was low risk compared with other rigid coil embolization techniques when performing embolization of tortuous and dilated collateral veins.     

Endovascular treatment of a wide-neck renal artery bifurcation aneurysm

Wide-neck renal artery aneurysms are difficult or impossible to treat endovascularly with Guglielmi detachable coils. The authors report a case of embolization of a wide-neck aneurysm of the right renal artery bifurcation with the combination of a TrisPan coil (neck-bridge device developed by Boston Scientific Target) and Guglielmi detachable coils. Complete occlusion of the aneurysm with preservation of the renal artery and its branches was shown with angiography performed after the procedure.     

Emergent management of ruptured pericallosal-callosomarginal artery aneurysm using stent-assisted coil embolization

We present a case of a ruptured bilobed pericallosal aneurysm successfully treated with coil embolization through a Neuroform stent. A 48-year-old male presented with subarachnoid hemorrhage (SAH) following rupture of a previously clipped aneurysm at the bifurcation of the pericallosal and callosomarginal arteries, primarily along the pericallosal artery, Hunt and Hess grade 5. After an initial unsuccessful attempt to embolize the wide-neck aneurysm with a detachable coil, a 4×15 Neuroform stent was uneventfully deployed across the aneurysm neck followed by successful coil embolization using detachable coils. We believe this case describes the first successful use of the Neuroform stent to assist in coiling of a wide-neck pericallosal-callosomarginal aneurysm. This case highlights the expanding role of emergency endovascular therapies to manage severe SAH.