Successful Retrieval of Migrated Coil Tangle in Femoral Artery Following Aneurysm Embolization: A Case Report

Introduction

Stretching of embolization coils is a rare known complication during or after an endovascular procedure [1]. In these cases, many different strategies can be adopted, depending on the site of coil placement and further possible complications such as thrombosis, embolism, or vascular occlusion [2]. Coil stretching is not predictable, and is rarely recognized. Dislocation of parts of the coil to other parts of the body depends on variable conditions such as blood flow direction and the nature of the vessels involved (veins and arteries) [3]. When retrieval of the stretched coil is indicated, there are many choices for endovascular approaches. The best choice will depend on the location of the dislocation and the risk of damaging the vessel’s intimal layer.

Endovascular management of coil migration lacks standardization, with treatment options including anticoagulation, antiplatelet therapy, and mechanical retrieval using snares, stent retrievers, or intracranial stents, depending on the clinical scenario and operator preference [4,5].

While stent retrievers are not specifically approved for this use, their off-label application has been shown to be both safe and effective, as evidenced by a series of cases demonstrating their practicality and success in retrieving displaced coils [6]. We report a case of complete endovascular management, consisting of mitigation of coil migration following an intracranial aneurysm embolization procedure.

Case Report

A 63-year-old female smoker, with a history of chronic hypertension, presented with acute headaches without neurological deficits (Glasgow Coma Scale score of 15). Brain computed tomography (CT) and CT angiography scans revealed a Hunt and Hess grade 2 subarachnoid hemorrhage with 6 cerebral aneurysms.

On day 1 of hospitalization, cerebral arteriography was urgently performed, via the right common femoral artery. This confirmed 6 intracranial aneurysms located at the basilar apex (7 mm); the azygos anterior cerebral artery (A2–A3 segment, 4 mm); the right middle cerebral artery bifurcation (6 mm); the right middle cerebral artery (M1 segment, 3 mm); the left middle cerebral artery (M1 segment, 2 mm); and the left internal carotid artery (C7 segment, 3 mm). Based on the subarachnoid hemorrhage distribution, the basilar apex aneurysm and the azygos anterior cerebral artery aneurysm were prioritized for treatment. The embolization procedure was performed with simple coiling, through a co-axial system with an 8-French long sheath, a 6-French intermediate catheter, and a microcatheter. The procedure was uneventful, with no angiographic or neurological complications.

One of the remaining untreated brain aneurysms, the right sylvian bifurcation aneurysm, was favorable to coiling with a “remodeling technique” for its configuration, and endovascular therapy was indicated and performed the next day (day 2). For this second procedure, a left femoral access was chosen, using a co-axial system with a long sheath and a 6-French intermediate catheter in the right internal carotid artery, using a “remodeling technique”. The aneurysm was coiled with 3 bare coils, but during placement of the fourth coil, the microcatheter was displaced into the parent vessel, resulting in coil unraveling and a loop herniating into the petrous segment of the right internal carotid artery. Thrombotic phenomena in the superior branch of the right sylvian artery were promptly treated with intravenous aspirin (500 mg) and tirofiban (bolus of 33 ml and continuous infusion). This medical approach was used to disaggregate the blood that was already aggregating on the coil and to reduce the risk of further aggregation on the stretched coil, which is a foreign body and promotes the risk of blood aggregation.

To secure the unraveled coil and complete the embolization, a “Y-stenting” technique in the right sylvian bifurcation was employed using 2 stents [7]. After releasing the stents, the embolization of the aneurysmal sac was completed with 3 additional bare coils. Angiographic control showed successful repositioning of the coil loop against the arterial wall and occlusion of the aneurysm. Left femoral access was sealed using a vascular closure device. After the procedure, double antiplatelet therapy with aspirin, 100 mg/day, and clopidogrel, 75 mg/day, was started.

On day 3, the patient reported severe left thigh pain, initially suspected to be a hematoma from the femoral access. Ultrasound showed a hyperechoic floating body within the femoral artery (Figure 1) and turbulent flow at Color-Doppler evaluation. Unenhanced CT confirmed partial coil migration. The stretched coil extended from the right middle cerebral artery through the thoracoabdominal aorta to the left common femoral artery, where a tangled loop floated in the vessel lumen (Figure 2).

Given the risk of femoral artery occlusion, intervention to remove the coil was performed [2].

Ascending ultrasound-guided access on the left superficial femoral artery was carried out and angiography was performed through a 5-French vascular introducer placed on a guide wire with the distal end just distal to the tangle (Figure 3).

A snare-type retrieval system was used to successfully capture and remove the coil via a vascular sheath (Figure 4). The unraveled portion was cut and implanted into subcutaneous tissue outside the vessel. A manual hemostasis procedure was performed and post-procedural CT control confirmed resolution of the coil loop (Figure 5). Six months later, follow-up MRI demonstrated complete aneurysm occlusion with no neurological deficits, and no further coil migration was observed.

Discussion

Despite significant progress in endovascular techniques for intracranial aneurysms, coiling and balloon-assisted coiling remain the primary and standard first-line therapeutic options [8].

Complications from endovascular treatment of intracranial arteries are generally associated with access site issues and systemic adverse effects from diagnostic neuro-endovascular angiography and therapy. These complications are typically categorized as thromboembolic or hemorrhagic, with the former as the most frequent (4.7–12.5%) [4,8].

The incidence of endovascular coil migration can be considered both an intraprocedural and delayed complication. It has been widely described in the literature and migration rates variably range from 0.5–6% in the literature, and are associated with mispositioning, partial coil stretching, partial prolapse, and displacement of coils from the aneurysmal sac [9,10]. The main complications for stretched migrated coils are thrombosis, occlusion of proximal large-caliber arteries, or emboligenous triggering, which may occlude distal vessels [10]. The event can be asymptomatic or can become clinically evident when migration is complicated by thrombosis [3,7,8].

Technical advances in interventional radiology have been accompanied by the creation of dedicated tools used for the retrieval of endovascular bodies [11]. A strict description of coil migration is crucial to identify the right treatment, as the therapeutic approach should be performed in relation to the particular type of coil migration and in consideration of the patient’s risk of complications.

Intraprocedural immediate retrieval of an unraveled coil can be performed by pulling back the delivery wire or microcatheter, or by using a snare wire or other devices such as stent retriever systems [12,13]. However, in some cases, complete retrieval of the coil is impossible due to the risk of distal dislocation and possible reperfusion of the aneurysmal sac. In addition, a forced recapture can cause intimal artery lesions or rupture of the aneurysmal sac with devastating consequences in the case of cerebral aneurysms.

Sometimes the only option for the operator is to secure the coil to the vessel wall, to prevent further migration and aid in the process of inclusion of the stretched coil inside the intimal wall [14]. Another treatment possibility is to stretch the unraveled coil as much as possible in the large-caliber artery, and bury it into the vessel wall after fixing it in subcutaneous tissue.

In our case, we successfully removed the tangle residue coil placed in the left common femoral artery, stretching the unraveled coil to prevent loop development, and buried it in subcutaneous tissue, next to the site of endovascular puncture. The peculiarity of the presented case is represented by the management of the complication through an endovascular approach, rather than a more invasive surgical intervention with the related risks and more prolonged recovery time.

Conclusions

This case highlights the challenges and complexities of managing embolization coil migration, a rare but significant complication. Prompt detection and intervention were essential to prevent further complications, such as vascular occlusion and thrombosis. Using an innovative snare retrieval technique, the stretched coil was successfully removed and secured, minimizing patient risk. This case underscores the importance of tailored treatment strategies based on coil location and patient-specific risks, avoiding more invasive approaches such as surgical intervention. Continuous advancements in interventional radiology will likely improve management options for such complications in the future.