Abstract
During endovascular coiling, unexpected procedure-related complications such as coil misplacement have been reported, and these complications may induce emboli or thrombotic vessel occlusion. A malpositioned detached coil contained and immobilized within an intracranial aneurysm is difficult to remove using current methods. We report an effective retrieval technique for detached coils. The ‘thread and catch technique’ can be used when the malpositioned detached coil is immobilized within the aneurysm.
Keywords: Thread and catch technique, coil retrieval method, malpositioned detached coil
Introduction
Endovascular coiling, a procedure used for the treatment of cerebral aneurysms, has been used more frequently in the past few years. 1 However, in some cases, unexpected procedure-related complications such as coil malposition have been reported. These can occur at the time of coil introduction or after detachment has occurred. 2 A complete coil or coil loops within the lumen of the parent artery or the vasculature distal to the aneurysm may induce emboli or thrombotic vessel occlusion. Despite continual technological improvements in materials and techniques, the risk of coil malposition, even in the hands of experienced and skilled operators, remains. 3 Coil malposition due to coil stretching and premature detachment can be resolved using a retrieval method such as the simple snare technique, direct aspiration, or the use of a retrievable stent device or other new retrieval devices as in previous reports. 1 , 2 However, although the detached coil is completely inserted into the sac to form a mass, there may be cases in which the coil does not protrude to the outside of the neck or there are no remaining loops or coil ends. In this case, the coil becomes difficult to remove with previously used methods. Therefore, we have devised a method to remove already detached coils and report the ‘thread and catch technique’.
Case illustration
A middle-aged woman was referred for endovascular treatment of an incidental, unruptured, distal internal carotid artery aneurysm measuring 3.2 mm × 2.9 mm in size with a 2.7 mm neck associated with the origin of the anterior choroidal artery. Although the aneurysm was relatively small, the patient was anxious about aneurysm and wanted active treatment. Therefore, we decided to perform endovascular treatment with coiling.
Technique
In the case of a small aneurysm with a critical branching vessel incorporated into its sac, previous studies have reported the usefulness of the ‘two-coil technique’ and so we decided to try the ‘two-coil technique’. 4 Initial aneurysm selection was performed with a first steam-shaped microcatheter (Headway 17, MicroVention, Inc., Tustin, CA, USA); a frame was made with the first coil (Galaxy Complex Xtrasoft, 2.5 mm × 3.5 cm, Codman & Shurtleff, Inc., Raynham, MA, USA). When the first frame coil was inserted, an angiogram was performed before coil detachment and the anterior choroidal artery was well visualized. A second coil insertion was attempted by inserting another microcatheter (Headway 17, MicroVention). Due to the placement of the first microcatheter, the second microcatheter could not be positioned properly. Accordingly, the first frame coil (Galaxy) was detached, and another coil (HyperSoft 3D, 1.5 mm × 2.0 cm, MicroVention) was inserted into the first microcatheter. When a control angiogram was performed, the anterior choroidal artery origin was compromised, and delayed partial visualization of the branch vessel was confirmed. When the second microcatheter was removed and a control angiogram was performed, the same pattern was observed again. We tried to reposition the loop on the neck of the frame using the microcatheter and coil, but this was not effective. Therefore, we removed the HyperSoft coil and passed another coil with thread-like movements (Axium Helix, 2.5 mm × 4.0 cm, Medtronic, Inc., Minneapolis, MN, USA) into the loop to remove the first frame coil (Figure 1). Attempts were made to capture the tip of the thread-like coil (Axium) passing through the first detached coil using a gooseneck snare (Amplatz GooseNeck®, SK200, eV3 Endovascular, Inc., Plymouth, MN, USA). To easily pass the thread-like coil, we intentionally passed one of two frame coil loops packed near the aneurysmal neck using a helical coil with a slightly larger loop diameter. Specifically, we first passed a thread-like coil (Axium) through the initial malpositioned detached coil. This thread-like coil was curled at the distal side of the aneurysm as we advanced the microcatheter and unrolled the tangled thread-like coil. Next, the expanded thread-like coil tip was captured using the snare. A control angiogram confirmed that not only was the aneurysm patent, but the branching vessel and parent artery were patent as well (Figure 2).
Figure 1.
Schematic representation of the process of retrieving a detached coil. (a) The detached coil fixed in the aneurysmal sac compromises the branching artery without remaining loops or coil ends. (b) In order to thread the malpositioned detached coil with another thread-like coil, the thread-like coil was passed into the loop of the malpositioned detached coil. (c) Using the microcatheter, the tangled thread-like coil was spread out. (d) The expanded coil tip was captured with a gooseneck microsnare. (e) The thread-like coil was completely fixed with the snare. (f) The two microcatheters were removed simultaneously.
Figure 2.
The process of retrieving the detached coil. (a) After the first frame coil was detached, the anterior choroidal artery was compromised. (b) Another thread-like coil was passed into the loop of the first frame coil (i.e. the malpositioned detached coil) and the frame coil was strung onto another thread-like coil. (c) Using the microcatheter, the tangled thread-like coil was unrolled. (d) The expanded coil tip was captured with a gooseneck snare. (e) The thread-like coil was completely captured with the snare, and the two microcatheters were removed simultaneously. (f) A control angiogram showed a patent branching vessel and parent artery.
Discussion
The malpositioning of detached coils which compromises the branching vessel and parent artery is a well-known complication associated with endovascular coiling. 3 Although this risk is relatively low, coil misplacement can result in significant thromboembolic complications, including brain ischemia. 5 To address this potential complication, numerous techniques and various strategies to remove misplaced coils have been reported, but none are easy and reliable. 6 Until now, snares have been the most commonly used devices in these cases. Catching a coil with a microsnare is possible in the majority of cases involving blood vessels with diameters ≥3 mm, and is significantly easier if the coil is open. 7 This applies to most cases in which there is accidental coil migration during aneurysmal coiling. However, if the malpositioned detached coil is immobilized within the aneurysm, retrieval with a stent retriever becomes very difficult. 8 If the opening loop of the detached coil cannot be found, it cannot be removed with the existing snare alone. Under these circumstances, persistent use of a microsnare and stent retriever carries a higher risk of vessel injury. Therefore, we designed a method to capture the detached coil using a microsnare by inserting a thread on an initially malpositioned detached coil, using another coil that behaved like a thread. Once the coil passed through the existing malpositioned detached coil, it was not difficult to capture the coil with the microsnare, and there was little injury or stress on the vessel.
Our study had some limitations. First, in small arteries, the vessel lumen diameter was frequently insufficient to allow the necessary opening of the microsnare loop. Second, we would expect potential difficulty if there are more than two detached coils packed densely in the aneurysm and requiring removal.
In conclusion, our experience in this case may suggest additional options for the retrieval of a malpositioned detached coil. The ‘thread and catch technique’ can be used when the malpositioned detached coil is immobilized within the aneurysm.
Acknowledgement
SHL contributed to the study conception and design, acquisition of clinical and imaging data, manuscript drafting and revision. DCS contributed to the study conception and design, manuscript drafting and revision. JCP contributed to the acquisition of clinical and imaging data. DHL contributed to the study conception and design, interpretation of the imaging and clinical data, manuscript drafting and revision, and study supervision.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
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