Technical problems associated with new designs of Guglielmi detachable coils

Abstract

Background and purpose: Recently, we experienced several technical problems that were directly related to new designs of Guglielmi detachable coils (GDCs). We herein present cases involving those problems and propose probable causes.

Methods: We reviewed the clinical and angiographic data of 269 consecutive patients with intracranial aneurysms who had been treated with GDCs between May 1996 and October 2001. We focused on newly encountered technical problems: spontaneous premature coil detachment, backward slipping of the coil into the microcatheter lumen after detachment, and undesirable detachment of the coils at the parent artery. The occurrence and clinical consequences of the problems were investigated before and after the introduction of a new GDC (SynerG) design. Additionally, to confirm the potential causal relationship, in vitro observations and simulation tests were performed.

Results: Of the 269 patients, 69 underwent embolization between March and October of 2001. Among those, we encountered technical problems in 10 (14.5%) cases. The overall number of events was 12, including spontaneous detachment (n = 5), backward slipping of the coil into the microcatheter lumen after detachment (n = 4), and undesirable coil detachment with a segment of the coil remaining at the parent artery (n = 3). No similar problems occurred among the 200 patients treated during the period between May 1996 and February 2001, when the new design coil had not yet been introduced. In vitro observations suggested that the long and stiff segment of the SynerG coil, especially the SR type, was a highly probable cause of these technical problems.

Conclusion: Our clinical experience showed a high incidence of technical problems, and in vitro observations suggested that the new GDC designs could be responsible for them. For safe aneurysm treatment, details of embolization techniques should be modified.

Fig 1.

Backward slipping of proximal segments of the coils after detachment. A, Case 1: 54-year-old woman with basilar artery aneurysm. During coil insertion, a coil (GDC-10, Soft, SR, SynerG, 2 mm × 6 cm) was slightly withdrawn to modify its placement. However, significant resistance was felt after several millimeters had been retrieved. The coil could not be withdrawn or advanced any further. When the catheter with the coil was retrieved, the previously delivered coil (2 mm × 4 cm GDC-10) was also moved. We found that the two coils were firmly interlocked with each other. Image shows that catheter is removed with the two coils by simply pulling. B, Fluoroscopic image from case 1 shows the two coils to be tightly jammed into the microcatheter lumen. C, Magnified photographic image from case 1 shows the two coils to be tightly jammed into the microcatheter lumen. D, Case 2: 53-year-old woman with ruptured basilar bifurcation aneurysm. After the second coil (GDC-10, 2-diameter, Soft, SR, SynerG, 4 mm × 8 cm) had been placed and detached uneventfully, the delivery wire was slowly retrieved approximately 10 cm under direct visualization by using fluoroscopy. After that, it was somewhat rapidly and completely withdrawn from the microcatheter. Fluoroscopic image obtained immediately after the withdrawal shows that several centimeters of the coil was pulled back through the microcatheter.

Fig 2.

Undesirable detachment with proximal segment of the coil remained at the parent artery. A, Case 9: 66-year-old woman with ruptured posterior inferior cerebellar artery aneurysm. It was impossible to insert the last 2 mm of the second coil (GDC-10, Soft, SR, SynerG, 2 mm × 2 cm) into the aneurysm because of excessive resistance. Image shows that microcatheter is pushed out by counterforce. We could not avoid detaching the coil while leaving the proximal 2 mm in the parent artery. B, Final angiogram from case 9 shows proximal part of the coil within the parent artery.

Fig 3.

Spontaneous premature detachment of coils. A, Case 5: 42-year-old man with ruptured anterior communicating artery aneurysm. Significant resistance was felt while inserting the last several millimeters of the last coil (GDC-10, Soft, SR, SynerG, 2 mm × 1 cm). Because of the resistance, the coil bent at the coil detachment zone, just beyond the catheter tip. The coil was spontaneously detached. B, Magnified image from case 5 shows distal end of the delivery wire of this case (left) and a normally (electrically) detached coil (right). C and D, Case 6: 46-year-old man with ruptured anterior communicating artery aneurysm. Two coils (GDC-10, Ultrasoft, SR, SynerG, 2 mm × 2 cm and 2 mm × 1 cm) were migrated into distal A2 during the procedure. They were removed with a snare (Goose-Neck Snare; Microvena, White Bear Lake, MN). Fluoroscopic images show that one of the coils is entrapped by the snare loop. The long and straight proximal segment of the coil is paradoxically helpful for capturing and holding with the snare loop.

Fig 4.

Photographs and fluoroscopic image show the proximal segment of SynerG GDC. One division of the ruler in photographs = 1 mm. A, Photograph shows the proximal segments of non-SynerG (left) and SynerG-SR (right) GDC. B, Photograph shows the long and straight proximal segment of the SynerG-SR GDC (GDC-10, Ultrasoft, SR, SynerG, 2 mm × 1 cm). C, Photograph shows the long and straight proximal segment of the SynerG-SR GDC (GDC-10, Soft, SR, SynerG, 2 mm × 1 cm). D, Photograph shows the long platinum wire loop to hold a 9-0 polypropylene thread loop. Note the length of the wire loop. E, Fluoroscopic image shows 2 mm × 8 cm SynerG-SR (left) and the same sized non-SynerG (right) GDC. Note the different proximal parts of the coils. The diameter of the black circle is 10 mm.

Fig 5.

Photographs of in vitro observation for spontaneous coil detachment (simulation study). A, SynerG-SR GDC is easily bent at the detachment zone. B, SynerG-SR GDC is easily fractured with repeated bending. C, Non-SR SynerG GDC is also easily bent at the detachment zone. On the other hand, it is very difficult to bend the detachment zone of non-SynerG GDC. D, When strong and persistent force is applied, non-SynerG GDC is also bent, but it does not occur at detachment zone.