(Radiology. 2000;217:904-906.)
© RSNA, 2000
Neurovascular Embolization: In Vitro Evaluation of a Mechanical Detachable Platinum Coil System1
Kieran J. Murphy, MB, FRCPC,
Shinya Mandai, MD,,
Philippe Gailloud, MD,
Henrik Clint, B Eng,
Kazimierz Szopinski, MD, PhD,
Helen Quie, BSc,
Jean-Baptiste Martin, MD and
Daniel A. Rüfenacht, MD
1 From the Department of Radiology, Hospital Cantonal De Geneve, University of Geneva, Switzerland (K.J.M., S.M., P.G., J.B.M., D.A.R.); the Department of Radiology, B-100, Johns Hopkins Medical Institution, 600 N Wolfe St, Baltimore, MD 21287 (K.J.M.); the Department of Neurosurgery, Kagawa Central Perfectua Hospital, Kagawa, Japan (S.M., K.S.); and Cook Europe (Bjaerverskov, Denmark) (H.C., H.Q.). Received May 3, 1999; revision requested June 17; revision received February 9, 2000; accepted February 22. Supported in part by Cook Europe (Bjaerverskov, Denmark). Address correspondence to K.J.M.
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ABSTRACT
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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.
Index terms: Aneurysm, therapy, 172.757 • Aneurysm, vein of Galen, 1765.73 • Arteries, therapeutic embolization, 17.757 • Arteriovenous malformations, 172.75 • Fistula, arteriovenous, 172.75 • Fistula, carotid-cavernous, 172.75 • Fistula, therapeutic embolization, 172.757 • Phantoms
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INTRODUCTION
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The use of coils in interventional neuroradiology has developed rapidly over the past 10 years and is now an accepted treatment alternative for many pathologic conditions (1–7). Endovascular techniques have become the treatment of choice for some intracranial vascular disease, such as basilar tip aneurysms. Several detachable coil systems are currently available to treat vascular disease, but only the Guglielmi detachable coil system (Target Therapeutics, Freemont, Calif) can be deployed and retrieved reliably. This system uses electrolysis to separate a coil from the guide wire. Since its introduction, the Guglielmi system has been widely used not only for occlusion of cerebral aneurysms but also for packing of the venous sinuses. Results with the Guglielmi system are encouraging, but it is expensive and, as more coils are placed, the time for electrolytic detachment becomes progressively prolonged.
Other currently available detachable coil systems are mechanical and less reliable. They detach as soon as the junction (the detachment zone) between the coil and the guide wire protrudes beyond the microcatheter tip. This makes premature detachment a major risk, and coil repositioning can be problematic. Vessel trauma can result as the hard guide wire protrudes into the vascular lumen during and after detachment.
We created 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 detachment time that is fast, reliable, and predictable; and (c) does not require that the guide wire protrude beyond the microcatheter tip during detachment. The purpose of this study was to evaluate results with the platinum coil detachment system and to determine the safety and reliablility of coil detachment when used as a vascular occlusive device for neuroradiologic applications. We tested the coils with in vitro silicone models.
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Materials and Methods
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In this study, we evaluated two types of platinum coils (Detach-18; Cook Europe, Bjaerverskov, Denmark): a 0.015-inch-diameter "regular" coil and a 0.014-inch-diameter "soft" coil. These coils are both available in preshaped diameters and lengths. The coils were mounted on a 0.014-inch-diameter Teflon-coated stainless steel guide wire by means of a microthread that screwed clockwise into the hollow base of the platinum coil (Fig 1). The coils were mounted and ready for introduction (Figs 2, 3). The guide wire was not reused.
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Figure 1. Magnified image of the detachment area shows the threaded end of the guide wire (closed arrow) and the hollow end of the platinum coil (open arrow). (Original magnification, x25.)
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Figure 2. The coil is prepackaged in a plastic holder (white arrow) and is loaded into the microcatheter by passing the pusher wire through the locking device in the valve of the Y adapter. The black arrow indicates the direction to move the pusher wire to advance the coil.
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In vitro tests were performed with use of silicone models of a dural arteriovenous fistula of the transverse sinus, a carotid-cavernous fistula, and an aneurysm of a vein of Galen. These models exhibited test conditions that we believe are comparable to in vivo conditions, although the in vitro analysis of the coils was limited by the lack of blood elements. The models were created from arterial corrosion casts obtained from two nonfixed human specimens with a technique that has been previously described (8–12). The technique allowed us to create a range of fistulae that mimicked disease with different degrees of severity, as well as venous stenoses or occlusion. The models were then connected to a systolic-diastolic pump (Drapier, Collin, France), which delivered pulsatile flow in a continuous system to simulate venous blood flow. A circulating fluid (one-third glycerine and two-thirds water) was chosen that simulated the viscosity of human blood. The use of in vitro aneurysm and arteriovenous fistula models allowed creation of a controlled environment with reproducible parameters such as volume, coil placement, and flow dynamics.
With fluoroscopic guidance, a microcatheter (Microferret; Cook Europe) was passed into the venous sinus, and the coils were introduced with road map guidance. To check the safety of the system, the detachment zone of each coil was passed beyond the catheter tip before detachment and then retrieved into the microcatheter. Digital subtraction angiography was performed after each coil was introduced. All fluoroscopic studies were recorded on videotape.
The microcatheter had a 2.4-F distal lumen and two distal markers 3 cm apart. When a 1-cm-long marker on the guide wire was positioned just proximal to the proximal marker on the microcatheter, the coil was correctly positioned for detachment (Fig 4). When the coil was placed in the desired position, the guide wire was locked in place at the valve of the Y adapter by using the locking device (essentially a modified torque device). This prevented unwanted motion of the coil and guide wire that could potentially cause a vascular perforation during the rotations of the detachment process. The coil was deployed by means of counterclockwise rotation of the guide wire by using the locking device. After the final counterclockwise rotation, the coil was released from the microcatheter tip, and the base was automatically oriented into the center of the coil pack (Fig 5).
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Figure 4. Digital subtraction angiogram depicts the in vitro model of a vein of a Galen aneurysm and was acquired with road map guidance before coil detachment. The proximal marker on the pusher wire (arrowhead) is clearly seen in correct alignment with the marker for the proximal tip (white arrow) of the microcatheter. The marker for the distal tip of the microcatheter (black arrow) is in the aneurysm.
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Figure 5. Digital subtraction angiogram depicts the in vitro model of a vein of Galen aneurysm and was acquired with road map guidance after several coil detachments. The inward orientation of the detached coil (open arrow) and the threaded tip of the guide wire (closed arrow) are depicted.
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A total of 229 coils as long as 70 cm were detached. The first 55 coils were designed to require eight counterclockwise turns of the guide wire to achieve detachment. One of the 55 coils, which was 70 cm long, detached prematurely after we had deliberately pulled it in and out of the coil pack multiple times to induce premature detachment. Thereafter, the length of the detachment zone was increased, and 20 rotations were required to achieve detachment. No further detachments occurred despite aggressive manipulation. One hundred seventy-four coils were detached after 20 rotations.
We recorded the operator’s subjective experience and sensations down the guide wire during coil delivery, detachment, and retrieval, as well as any fluoroscopic evidence of catheter-coil binding or catheter motion.
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Results
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During the delivery process, friction between the coils and the catheter was minimal, and retrieval was easy. The 229 coils were deployed without difficulty. Coil delivery was smoother with the 0.014-inch soft coil than with the 0.015-inch regular coil. Detachment was reliable, consistent, and reproducible. With eight rotations, all 55 coils detached within 5 seconds; with 20 rotations, all 174 coils detached within 10–15 seconds. Rotation of the guide wire did not cause rotation of either the coil being deployed or the coil pack.
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Discussion
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These in vitro tests demonstrate that the platinum coil system evaluated in this study is fast, robust, and reliable, and detachment time did not increase with progressive coil deployment as occurs with the currently available electrolytic systems. This system gives the neuroradiologist the ability to control the coil position and is a major advantage over the other mechanical systems currently available. Because the coils are mounted and the guide wire is not reused, the system obviates the laborious and often difficult coil-loading procedure used with other mechanical coil systems.
These coils are intended for use as vascular occlusion devices in the arterial and venous systems. Possible clinical uses include the treatment of dural arteriovenous fistulas and any vascular occlusion, including intracranial aneurysms, in which conventional coil embolization is indicated. Use for peripheral vascular indications—such as splenic, hepatic, or renal artery aneurysms—is also feasible. We have now treated 70 patients with nonaneurysmal indications for neurointervention in a multicenter European trial of the coil at eight European university investigational centers. A trial for the treatment of aneurysms is ongoing.
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ACKNOWLEDGMENTS
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We thank Jean H. Fasel, MD, Kenji Sugiu, MD, and Michel Muster, RT, for their assistance in this project.
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FOOTNOTES
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Author contributions: Guarantors of integrity of entire study, K.J.M., D.A.R.; study concepts, K.J.M., S.M.; study design, H.C., S.M., K.J.M.; definition of intellectual content, K.J.M.; literature research, J.B.M., K.J.M.; experimental studies, P.G., S.M., K.J.M.; data acquisition, S.M.; data analysis, S.M., K.J.M.; manuscript preparation, K.S., K.J.M.; manuscript editing, K.J.M.; manuscript review, H.Q., K.J.M.
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REFERENCES
|
|---|
-
Vinuela F, Duckwiler G, Mawad M. Guglielmi detachable coil embolization of acute intracranial aneurysms: perioperative anatomical and clinical outcome in 403 patients. J Neurosurg 1997; 86:475-482.[Medline]
-
Guglielmi G, Vinuela F, Duckwiler G, et al. Electrothrombosis of saccular aeurysms via endovascular approach. I. Electrochemical basis technique, and experimental results. J Neurosurg 1991; 75:1-7.[Medline]
-
Guglielmi G, Vinuela F, Duckwiler G, et al. Electrothrombosis of saccular aneurysms via endovascular approac. II. Preliminary clinical results. J Neurosurg 1991; 75:8-14.[Medline]
-
Guglielmi G, Vinuela F, Duckwiler G, et al. Cavernous carotid fistula caused by a ruptured intracavernous aneurysm: endovascular treatment by electrothrombosis with detachable coils. Neurosurgery 1992; 31:591-592.[Medline]
-
Guglielmi G, Vinuela F, Duckwiler G, et al. Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils. J Neurosurg 1992; 77:515-524.[Medline]
-
Guglielmi G, Vinuela F. Intracranial aneurysms: Guglielmi electrothrombotic coils. Neurosurg Clin N Am 1994; 5:427-435.[Medline]
-
Mawad ME, Mawad JK. Long term histopathologic changes in canine aneurysms embolized with Guglielmi detachable coils. AJNR Am J Neuroradiol 1995; 16:7-13.[Abstract]
-
Raymond J, Roy D, Bojanowski M, Moumdjian R, L’Esperance L. Endovascular treatment of acutely ruptured and unruptured aneurysms of the basilar bifurcation. J Neurosurg 1997; 86:211-219.[Medline]
-
Pierot L, Boulin A, Castings L, et al. Selective occlusion of basilar artery aneurysms using controlled detachable coils: report of 35 cases. Neurosurgery 1996; 38:948-954.[Medline]
-
McDougall CG, Halbach VV, Dowd CF, et al. Endovascular treatment of basilar tip aneurysms using electrolytically detachable coils. J. Neurosurg 1996; 84:393-399.[Medline]
-
Mandai S, Kinugasa K, Ohmoto T. Direct thrombosis of aneurysms with cellulose acetate. I. Results of thrombosis in experimental animals. J Neurosurg 1992; 77:497-500.[Medline]
-
Gailloud P, Pray JR, Muster M, Piotin M, Fasel J, Rufenacht DA. An in vitro anatomic model of human cerebral arteries with saccular arterial aneurysms. Surg Radiol Anat 1997; 19:119-121.[Medline]
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ABSTRACT
INTRODUCTION
