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Vascular and Interventional Radiology |
1 From the Div of Diagnostic and Interventional Radiology, Geneva Univ Hospital, Switzerland (K.J.M., D.A.R.); Dept of Radiology, Johns Hopkins School of Medicine, B-100, 600 N Wolfe St, Baltimore, MD 21287 (K.J.M., K.T.S.); Dept of Neuroradiology and Therapeutic Angiography, Hôpital Lariboisière, Paris, France (E.H.); Dept of Neuroradiology and Vascular Radiology, Hôpital d’Adultes de la Timone, Marseilles, France (O.L.); Dept of Diagnostic and Therapeutic Neuroangiography, Hospital General de Cataluña, Barcelona, Spain (L.G.); Dept of Radiology and Neuroradiology, Alfried-Krupp-Krankenhaus, Essen, Germany (D.K.); Dept of Neuroradiology, Bayerische Julius-Maximilians Universität, Würzburg, Germany (L.S.); and Dept of Radiology, Ålborg Sygehus Syd, Denmark (N.J.B.). From the 1999 RSNA scientific assembly. Received Mar 24, 2000; revision requested May 25; revision received Aug 23; accepted Sep 11. Address correspondence to K.J.M. (e-mail: kmurphy@jhmi.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Sixty patients (21 men, 39 women; age range, 26–75 years; mean age, 56.2 years) were treated in seven centers. Ease of introduction of the coil to the microcatheter, effect of coil passage on the microcatheter shape and stability during its delivery, retrievability of the coil before and after the transition zone passed beyond the microcatheter, detachment of the coil, and effect of coil rotation on the microcatheter stability were evaluated. The detachment system itself was evaluated for premature detachment, failure of the coil to detach, detachment time, number of turns, visibility of radiopaque markers, number of coils deployed per patient, and percentage of vessel occlusion obtained. A 0.015-inch-diameter regular coil and a 0.014-inch-diameter soft coil were used.
RESULTS: A total of 1,061 coils were used; 1,009 were detached. The number of coils deployed ranged from four to 104 (mean, 17 coils). The coils passed easily through the microcatheter. The detachment maneuver occurred within 5–25 seconds, with five to 60 turns of the introducing wire. One premature coil detachment occurred without clinical sequela; 100% occlusion of the vessel lumen was achieved in 53 patients; 80%–90%, in four; and 70%–80%, in two. There were no device-related complications.
CONCLUSION: The detachment system was safe and reliable. This is a useful system for coil embolization in neurovascular diseases.
Index terms: Aneurysm, intracranial, 17.73 • Cerebral blood vessels, therapeutic embolization, 17.1264 • Fistula, arteriovenous, 17.75 • Interventional procedures, technology, 17.1264
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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However, when a large number of coils are deployed, the time of coil detachment becomes prolonged, and this can be a major limitation in complicated procedures. The alternative detachable coil systems currently available are mechanical and are usually based on clamped ball, looped ribbon, or interlocked cylinder designs (15,16). These detach as soon as the junction or detachment zone between the coil and the pusher wire protrudes beyond the microcatheter tip (15–20). This makes premature detachment a considerable risk, and coil repositioning can cause problems. Coil detachment can even occur within the microcatheter in tortuous vessels. Because the current coil mechanisms require that the detachment zone protrude beyond the microcatheter tip, the hard pusher wire protrudes into the vascular lumen during and after detachment, and this can result in vessel trauma.
In collaboration with William Cook Europe (Bjæverskov, Denmark), we developed a mechanically detachable platinum coil called the Detach-18 system. Our aim was to create a microcatheter-based retrievable platinum coil detachment system that (a) does not detach when the detachment zone passes out of the microcatheter; (b) has a fast, reliable, and predictable detachment time; and (c) does not require the pusher wire to protrude beyond the microcatheter tip during detachment.
The purpose of this study was to determine the safety and reliability of this detachment system when used as a vascular occlusive device for neuroradiologic applications.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Exclusion criteria were participation in other clinical trials that might interfere with this trial, any history of mental illness or psychiatric complaint, presence of acute life-threatening illness other than the neurologic disease to be treated with the detachable platinum coil, presence of sepsis in a hemodynamically unstable condition, or intubation because of complications other than the neurologic disease to be treated with the detachable platinum coil. Patients in whom coils were used to treat saccular aneurysms on the cerebral arteries were excluded from the study.
Two types of coils, a 0.015-inch-diameter regular coil and a 0.014-inch-diameter soft coil with various size configurations (spiral, J, tornado, straight), were used in the study. These are available in preshaped diameters and lengths. They are mounted on a Teflon-coated stainless steel pusher wire by means of a microthread that screws clockwise into the hollow base of the platinum coil. The pusher wire is 0.015 inch in diameter for the regular coils and 0.014 inch in diameter for the soft coils. (The Detach-11 system [William Cook Europe], not used in this study, is mounted on a 0.009-inch-diameter pusher wire.)
The coils are provided mounted and ready for introduction. The pusher wire is not reused. The coil is delivered through a microcatheter with a 2.5–1.9-F distal lumen, with two distal markers 3 cm apart. Both the Detach-18 and Detach-11 coil systems will pass through an Excel 14 microcatheter (Target Therapeutics). When a 1-cm-long marker on the pusher wire is positioned just proximal to the proximal marker on the microcatheter, the coil is correctly positioned for detachment. When the coil is placed in the desired position, the pusher wire is locked in place at the valve of the Y adapter with a locking device (essentially, a modified torque device). This prevents unwanted motion of the coil and pusher wire that could cause a vascular injury during the rotations of the detachment process. The coil is deployed by means of counterclockwise rotation of the pusher wire, by using the locking device. With the final counterclockwise rotation, the coil is released from the microcatheter tip. All of the detachment process takes place in the microcatheter.
We evaluated the ease of introduction of the coil to the microcatheter, the effect of coil passage on the microcatheter shape and stability during its delivery, the retrievability of the coil before and after the transition zone passed beyond the microcatheter, the detachment of the coil, and the effect of coil rotation on the microcatheter stability. In addition, the detachment system itself was evaluated for premature detachment, failure of the coil to detach, detachment time, the number of turns needed, visibility of radiopaque markers, the number of coils deployed per patient, and the percentage of vessel occlusion obtained. The operator completed a study evaluation form for each coil deployed for each of the items just mentioned. The study evaluation of coil delivery was completed by the primary operator at each institution, who, with the exception of three, was an author (K.J.M., E.H., O.L., L.G., D.K., L.S., N.J.B., D.A.R.). In three centers, more than one interventionalist had been trained in the use of the coil, and they, too, completed the study evaluations, but only the senior physicians were authors of this article.
Sixty patients (21 men, 39 women; age range, 26–75 years; mean age, 56.2 years) were treated in seven European academic medical centers during 18 months. Thirty-two patients were treated for the following dural arteriovenous fistulas: lateral sinus (n = 9), sigmoid sinus (n = 6), cavernous sinus (n = 4), transverse sinus (n = 3), transverse and sigmoid sinus (n = 4), carotid cavernous (n = 2), occipital sinus (n = 3), and nonspecified (n = 3). Thirty-one patients were treated with venous embolization, and one patient with carotid cavernous fistulas was treated with occlusion of the internal carotid artery. Nineteen patients were treated for intracranial aneurysms with occlusion of the internal carotid artery (n = 14), vertebral artery (n = 3), basilar artery (n = 1), or parasinus pouch (n = 1). One patient was treated for a pseudoaneurysm of the carotid artery with occlusion of the external carotid artery.
Two patients were treated for the following arteriovenous malformations: subclavian artery and neck (n = 1), with embolization, and parietal mixed pial and dural (n = 1), with occlusion of the meningeal artery. No coils other than the detachable platinum coils were used in the patients during this study.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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During the delivery process, the friction between the coils and the catheter was minimal, and retrieval was easy. Coil delivery was smoother with the soft 0.014-inch coil than with the regular 0.015-inch coil. When the detachment zone of a coil was passed beyond the catheter tip, it was still possible to retrieve the coil into the microcatheter without premature detachment. Rotation of the pusher wire during the detachment process did not cause rotation of either the coil being deployed or the coil pack. The detachment maneuver occurred within 5–25 seconds, with five to 60 counterclockwise turns of the introducing wire. The 1-cm marker on the pusher wire was clearly and easily visible in all cases, even when imaging was performed through the temporal bone (Figs 1b, 2b). There were no device-related complications.
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In one patient, immediate coil migration in the transverse sinus was observed, and in one patient, the position of the coil changed slightly (it was too large for the artery in which it was placed). In one patient, premature coil detachment was observed. In this patient, the coil had to be repositioned more than 10 times. For the final placement, the guiding catheter had to be advanced, and this may have caused kinking of the distal end of the coil, leading to congestion of the distal part of the coil in the microcatheter. The distal part of the coil was deposited in the lower sigmoid sinus, while the proximal part stayed in place in the upper sigmoid sinus. In these patients, coil migration, coil motion, or premature detachment were not considered complications because they occurred without an adverse outcome, that is, an outcome that was different from one that would otherwise have occurred for the patient. In these patients, the coil migration occurred on the venous side, and the coil was included in the overall venous sinus coil pack at the end of the procedure.
Three severe, one moderate, and two mild non–device-related adverse events, as well as one mild device-related adverse event, occurred. One patient died of intracranial hemorrhage after closure of a functioning vein of Labbé. This resulted in the development of acute cortical venous drainage with venous rupture, resulting in a fatal subarachnoid hemorrhage in the posterior fossa. The event was due to the positioning of the coil rather than to the detachable platinum coils themselves. One patient died of medical complications after urgent occlusion of surgical internal carotid artery trauma during pituitary trauma. One patient had hemiparesis due to a carotid dissection, caused by an arterial catheter placed for injections during transvenous embolization of a dural arteriovenous fistula. One patient who underwent internal carotid artery occlusion had a watershed infarct 2 hours after the occlusion, despite tolerance of an occlusion test and the presence of arterial collateral vessels.
One patient had transient central vestibular dysfunction on the day following the procedure. This event was considered due to embolization performed with cyanoacrylate adhesive in the same session. The symptoms were mild and resolved spontaneously. One patient had hemicerebellar syndrome due to clot formation in the superior cerebellar artery after coil embolization of a giant aneurysm of the P1 segment of the posterior cerebral artery. One patient had transient palsy of cranial nerves IX and XII after occlusion of a posterior fossa dural arteriovenous fistula, but this palsy resolved spontaneously.
The images and videotapes of all procedures in which there were complications were reviewed according to the study principles and deemed related to the therapy but not to the detachable platinum coil.
At the time of this writing, only 11 patients returned for 12-month follow-up. In all patients, there was no worsening of neurologic status, and the coil position has remained unchanged. (All patients were examined by using anteroposterior and lateral x-ray examination; five patients were also examined with angiography.)
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Prolongation of electrolytic coil detachment is a problem in most interventionalists’ experience when the GDC system is used in a large coil pack. This can result in considerable elongation of procedure time and, as a direct result, it increases stroke risk. Reduced procedure time also translates to reduced duration of anesthesia. Because the coils are supplied mounted and the pusher wire is not reused, use of the system eliminates the laborious and often difficult coil-loading procedure (which in one case required the use of a microscope [21]) encountered with other mechanical coil systems.
The system differs from that of the GDC in that during detachment, the pusher wire marker is aligned proximal to the proximal marker on the two-tip marker microcatheter, not distal to it as with the GDC. This pusher wire marker is larger (1 cm) and more radiopaque than that of the GDC (Figs 1b, 2b). The operator rotates the pusher wire torque device 20 times counterclockwise. This is more than the number of turns needed to achieve detachment. Detachment can be assumed to have occurred. Detachment can be visually identified by deflection of the coil tail into the coil pack, an action it has memory to complete, and by gently withdrawing the pusher wire to ensure that coil detachment has occurred, as we do with the GDC. The variation in time needed to achieve detachment is related to the speed of pusher wire rotation and the completeness of each rotation. Some operators did not pass the wire through 360° with each hand motion and rotated more slowly than others and, hence, took longer. The coil is manufactured of platinum and, therefore, should not be subject to the corrosion seen at long-term follow-up that was recently reported (21) to occur in tungsten coils.
The purpose of this study was to evaluate the detachment system and the device. We specifically included only patients with dural arteriovenous fistulas or those needing large-vessel occlusion. Now that we have shown the safety of this device, we conducted a study of this coil in acute and elective aneurysm embolization. Results are to be presented at European Society of Neuroradiology 2000 to show its safety in that application also. There is also a Detach-11 coil that is equivalent to the GDC 10 (Target Therapeutics) system. Piotin et al (22) recently reported findings in the in vitro evaluation of both the Detach-18 and Detach-11 coils in comparison with the GDC 18 (Target Therapeutics) and GDC 10 coils by using a silicone aneurysm model. The Detach-11 will be available in a soft variant. The choice of patients in this study represents prudent selection in the interest of staged clinical evaluation rather than any deficiency in the coil. Publication of the multicenter aneurysm clinical trials data in a peer-reviewed journal will follow.
The detachable platinum coil system has been shown in this in vivo study to be a safe, reliable, consistent neurovascular embolization device that has a fast detachment time. It may represent an important addition to the interventional radiologist’s armamentarium, making possible new, complicated endovascular procedures involving deployment of a large number of coils, as well as considerably shortening the duration of routine procedures and, therefore, procedural stroke risk.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, K.J.M., D.A.R., E.H.; study concepts, K.J.M., E.H.; study design, K.J.M.; literature research, K.J.M., K.T.S.; clinical studies, K.J.M., E.H., D.A.R., O.L., L.G., D.K., L.S., N.J.B.; data acquisition, K.J.M., E.H.; data analysis/interpretation, K.J.M., K.T.S.; statistical analysis, K.J.M., K.T.S.; manuscript preparation, K.J.M., K.T.S.; manuscript definition of intellectual content, K.J.M., K.T.S., E.H., D.A.R.; manuscript editing and revision/review, K.J.M., K.T.S., D.A.R.; manuscript final version approval, K.J.M., D.A.R.
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