Willis covered stent in the treatment of a recurrent blood blister-like aneurysm after pipeline implementation: A case report

Abstract

Blood blister-like aneurysms (BBAs) are fragile and difficult to treat. However, the optimal treatment has yet to be determined. Pipeline embolization devices and Willis covered stent implementation are still controversial strategies for treating BBA. Herein, we report a case of recurrent BBA successfully treated with a Willis covered stent. A long-term follow-up angiography after the procedure indicated complete occlusion of the aneurysm. This case demonstrates the safety and efficacy of applying the Wills cover stent in the treatment of recurrent BBA after Pipeline implantation.

Blood blister-like aneurysms (BBAs) are relatively rare owing to their morphology. They mostly originate from the anterior wall of the upper clinoid process of the internal carotid artery (ICA), accounting for 0.3–1% of all intracranial aneurysms, 0.9–6.5% of ICA aneurysms, and 1.0% of ruptured aneurysms.¹ BBAs are small sized, have unclear necks, and fragile walls composed of adventitia, fibrous tissue, and thin thrombus.² Although they resemble saccular aneurysms, the high risks of rupture and recurrence are challenging. Various treatment options have been attempted, but the optimal strategy remains controversial.³ Recently, there has been growing interest in using the Pipeline embolization device (PED; Medtronic Neurovascular, Irvine, CA, USA) for treating BBA. Unfortunately, patients still have a risk of recurrence.⁴ Herein, we report a case of short-term recurrence of BBA treated with PED combined with coil embolization and successfully retreated with a Willis covered stent (WCS, MicroPort, Shanghai, China) in the second stage. To the best of our knowledge, this is the first report on the use of WCS in the treatment of recurrent BBA after PED implantation.

1. Case report

1.1. Brief history

A 56-year-old male presented with a headache for 2 days and transient loss of consciousness for 1 day. Computed tomography (CT) revealed subarachnoid hemorrhage (SAH). The patient had a history of hypertension with poor control for 16 years, and the highest blood pressure recorded was more than 150/110 ​mmHg. In addition, the patient had no remarkable medical history and did not smoke or drink. After admission, the patient was treated with oxygen inhalation, blood pressure control, dehydration to reduce intracranial pressure, and maintenance of water-electrolyte balance. Digital subtraction angiography (DSA) revealed a small aneurysm in the supraclinoidal segment of the left ICA. Considering the blood blister-like morphology, we could not rule out BBA. Emerging PED-assisted coil embolization was performed. After the operation, the patient was treated with dual antiplatelet therapy (DAPT; aspirin 100 mg/day and Clopidogrel 75 mg/day). Postoperative sedation and analgesia were continued, and blood pressure was strictly controlled at approximately 110/70 ​mmHg. A cerebrospinal fluid replacement was performed to remove the hemorrhage. There was no aggravation of the clinical signs or symptoms. Seven days after the operation, DSA revealed that the aneurysm had recurred, and the sac had become larger. WCS implantation was planned for further treatment.

1.2. Operation process

Under general anesthesia and heparinization, an 8F guiding catheter (Envoy, Codman Neurovascular, USA) was placed in the left carotid artery segment, and a 5F intermediate catheter (Navien, Covidien, Medtronic, USA) was placed in the left M1 segment through the PED. Then, under the guidance of a microwire, a 3.5 ∗ 13 mm WCS was delivered to the lesion site, and the 5F intermediate catheter was withdrawn to the proximal end of the PED. Multiple control angiograms were obtained during the procedure to confirm the positioning of the stent and avoid covering any important branches. The stent was then deployed by balloon inflation at 6 atm. DSA showed that the aneurysm was immediately occluded, and the parent artery was patent. After the procedure, XperCT showed no fresh intracranial hemorrhage, and intra-arterial rotational angiography (Vaso CT, Philips Healthcare, Best, the Netherlands) showed good adherence. No new neurological deficits were observed after recovery from anesthesia. Computed tomography angiography (CTA) showed no recurrence before discharge.

After 4 months, DSA showed that the aneurysm was completely occluded, and that the patency of the arteries was satisfactory. In addition, the patient had satisfactory clinical outcomes (modified Rankin scale score, 0). After 21 months, CTA revealed no recurrence or stent stenosis. DAPT was continued for 4 months postoperatively. Continued use of aspirin throughout life was recommended (see Fig. 1).

Fig. 1.

The case of a recurrent BBA treated with Willis covered stent after Pipeline implementation.

A: DSA identified an aneurysm along the dorsum of the left ICA. B: The aneurysm is embolized using PED-assisted coiling during the first operation. C: Recurrence is found on the 7-day DSA follow-up examination after the first surgery. D: Complete occlusion of the BBA is demonstrated on immediate postoperative angiography using the Willis covered stent. E: Complete occlusion of the BBA is observed at the 4-month DSA follow-up. F: The aneurysm is completely occluded, and the patency of the arteries is satisfactory on the 21-month CTA follow-up examination.

BBA, blood blister-like aneurysms; DSA, digital subtraction angiography; ICA, internal carotid artery; PED, Pipeline embolization device; CTA, computed tomography angiography.

2. Discussion

BBAs are relatively rare but challenging in the clinic. Their small size and saccular-like morphology make them easily misdiagnosed. In addition, fragile walls pose a high risk of rupture and rapid expansion within a short period. While the development of angiography has helped discover small aneurysms, it is still inconclusive. Therefore, the definitive diagnosis is reserved only for histopathology.² However, it is impossible to identify the tissue for all aneurysms.⁵ Any ruptured aneurysms of the supraclinoidal segment should be considered as BBA until proven otherwise.⁶ In this case, the ruptured aneurysm was characterized by a blood blister-like shape and located at the anterior wall of the supraclinoidal ICA. In addition, it enlarged in a short period after surgery. Therefore, we considered it a classical BBA.

Currently, the treatment methods include surgery and endovascular therapy. Various surgical techniques have been attempted, including clipping, trapping, wrapping, and suture rapiers. However, uncontrollable intraoperative hemorrhage, vascular wall laceration, and postoperative stenosis or occlusion of the parent artery remain challenging.⁷ With advances in techniques, endovascular therapy seems to provide comparable outcomes with surgery.⁸ However, the risks of hemorrhage or ischemic complications and recurrence make it controversial.⁹ Considering the fragile walls, rapid configurational changes, and growth in a short period, coil embolization is difficult and faces the challenge of a high rate of recurrence. Therefore, stent-assisted coil embolization (SAC) is considered a better strategy.¹⁰ Zhu D indicated that braided stents have higher metal coverage and are more suitable for coiling around the neck of aneurysms than laser-engraving stents.¹¹ However, the vasospasm caused by SAH affects the choice of stent size, which may lead to poor apposition and a high risk of recurrence.

Flow diverters (FDs) represent a paradigm shift in endovascular treatments.¹² The metal mesh can prevent blood from entering the aneurysm, reduce the flow velocity, increase the likelihood of flow stagnation, and promote fast thrombosis.13, 14, 15 New intima gradually forms over the mesh surface, and aneurysm occlusion is eventually achieved.^10,16 Recently, there have been an increasing number of reports on the treatment of ruptured aneurysms using FD. Lin N indicated that the coil is indispensable when FD is used in the acute stage for ruptured aneurysms.¹⁷ The purpose is to accelerate thrombi formation and promote rapid healing of aneurysms. Lee J performed a meta-analysis of BBAs and indicated that FD was more effective in radiographic outcomes, but had similar clinical outcomes in comparison with SAC.¹⁸ While Lin N investigated the outcomes of 104 intracranial aneurysms and found that FD combined with coil embolization can provide a higher occlusion rate, and lower recurrence rate and perioperative bleeding risk.¹⁹ Cohen JE also indicated that FD could robustly decrease the risk of bleeding.²⁰ PED combined with coil embolization is used as treatment for the first time in this case.

Unfortunately, the patient still had short-term recurrence, 7 days after the operation. Although the treatment of FD is characterized by delayed healing, aneurysm enlargement may indicate an unstable state. Therefore, salvage was necessary during the second stage. Moreover, microcatheter cannot pass through the deployed PED and coil embolization is impossible; optional strategy overlapped with a stent within the PED. Fang Y pointed out that overlapping stents can provide a higher occlusion rate, lower recurrence rate, and lower risk of perioperative bleeding in BBA.²¹ However, it is clear that overlapping another stent cannot achieve immediate occlusion of an aneurysm. Under strict DAPT, recurrence and rupture are still possible.²² On the other hand, Zhu D performed a meta-analysis and pointed out that the strategy of multiple FDs was not better than a single FD.²³ Thus, we attempted another strategy.

WCS is a novel device specifically designed for intracranial vessels, which can isolate the aneurysm from circulation and achieve instant occlusion of the aneurysm.²⁴ The safety and efficacy of complex aneurysms have been primarily demonstrated. Fang C retrospectively reviewed 13 patients with BBAs and indicated that WCS implantation is safe and feasible.²⁵ Liu L also concluded that WCS was a promising strategy for BBAs.²⁶ However, the incidence of endoleak and the existence of branches limit its application.27, 28, 29 This was also one of the reasons why we primarily chose PED. Considering that spasm of the parent artery increased the incidence of endoleak, WCS was not the preferred choice. Chang H summarized the application of WCS and double-stent-assisted coils in the treatment of BBAs and concluded that they were both safe and efficient. However, WCS provided a higher rate of immediate occlusion.³⁰ Meanwhile, Qi Y retrospectively reviewed five patients and pointed out that WCS implantation in patients with BBA who have recurrence after stent-assisted coil embolization may be a safe and feasible strategy.³¹ The case suggests that WCS is effective and safe in the treatment of BBA, consistent with the previous reports. In this case, vasospasm was relieved, and the aneurysmal sac, neck, and branches were fully displayed after one-stage PED implantation. The deployed PED can also be used as a conduit to facilitate the passage and implantation of the WCS. Additionally, the changed geometry of the parent artery and hemodynamic alterations can reduce the incidence of endoleaks. As a result, WCS can easily avoid branch vessels from just covering the neck of the aneurysm. During operation, the WCS was successfully delivered to the position and deployed. DAPT was continued for 4 months postoperatively; aspirin use continued throughout life. Postoperative follow-up revealed no recurrence or related complications.

This is the first case of recurrent BBA treated with WCS in a patient using PED. This report aimed to encourage interventional physicians to attempt this strategy to further verify its safety and efficacy.

Ethical approval

The study was approved by the ethics committee of the First Affiliated Hospital of Zhengzhou University. All clinical practices and observations were conducted in accordance with the Declaration of Helsinki.

Patient consent

Written informed consent was obtained from the patient for publication of the case report and any accompanying images.

Author contributions

Yu Fu: Writing - original draft, Feng Fan: Writing - review & editing, Jing Li: Investigation, Sheng Guan: Writing - review & editing.

Declaration of competing interest

Sheng Guan is an editorial board member for Journal of Interventional Medicine and was not involved in the editorial review or the decision to publish this article. All authors declare that there are no competing interests.