Abstract
BACKGROUND
Optimal treatment options for ruptured blood blister–like aneurysms (BBAs) and dissecting aneurysms (DAs) have not yet been established. Endovascular treatment may achieve vessel reconstruction with the preservation of antegrade blood flow; however, securing curative hemostasis at the fragile rupture point remains a major concern.
OBSERVATIONS
Two ruptured BBAs and two ruptured DAs treated by stent-assisted coiling with the semijailing technique in the last 2 years are described herein. The devices used were braided stents and i-ED coils, which are new low-memory shape and extremely soft coils. Neither rebleeding nor ischemic complications were observed. All patients had a favorable outcome and showed no recurrence after treatment.
LESSONS
All aneurysms were treated without ischemic complications or rebleeding. The good compatibility of braided stents and the new concept coils in stent-assisted coiling by the semijailing technique provides insight into these intractable hemorrhagic vascular pathologies.
KEYWORDS: blood blister–like aneurysm, dissecting aneurysm, ruptured, endovascular treatment
ABBREVIATIONS: 3D = three-dimensional, BA = basilar artery, BBA = blood blister–like aneurysm, DA = dissecting aneurysm, DSA = digital subtraction angiography, LVIS = Low-Profile Visualized Intraluminal Support
Unlike traditional saccular aneurysms with a defined aneurysm neck, ruptured blood blister–like aneurysms (BBAs) and intracranial dissecting aneurysms (DAs) have a broad-based shallow neck and, thus, are more challenging to treat.1 BBAs and DAs are both treated using endovascular techniques, including coiling, stent-assisted coiling, and flow-diverting stenting, or microsurgery, such as clipping or trapping with or without bypass surgery. The optimal treatment approach depends on the size and location of the aneurysm, as well as the vessels involved or the patient’s condition. Although reconstructive treatments using an endovascular approach may be ideal, securing definitive hemostasis for the vascular pathologies of subarachnoid hemorrhage remains a major issue. Although coils underlying the rupture point may promote hemostasis and enhance endothelialization,2 their insertion into such a confined space with an extremely thin and fragile vessel wall is very challenging. To date, the majority of coils used in aneurysm embolization have been three-dimensional (3D) shaped bare platinum or coated coils. We herein present our patient series of ruptured BBAs and DAs, which were treated by stent-assisted coiling with i-ED coils (Kaneka), which are low-memory shape and extremely soft coils.
Study Description
Between 2021 and 2023, four ruptured intracranial aneurysms (2 BBAs and 2 DAs) were treated by an endovascular approach. Patient demographics and aneurysm morphologies are shown in Table 1. Under general anesthesia, all patients underwent stent-assisted coiling with dual antiplatelet therapy (aspirin 200 mg and clopidogrel 300 mg) just before endovascular treatment. Heparin was administered to keep the activated clotting time around 250 seconds. We used a large-bore guiding catheter with a lumen of over 0.093 inch. Two 3.4-French catheters, the TACTICS (Technocrat Corporation) were used as distal access catheters to stabilize each microcatheter for a stent and for coils.
TABLE 1.
Patient series of ruptured BBAs and DAs
| Case No. | Age, yrs | Sex | Diagnosis | Initial H&H Grade | Time to NET (days) | FU Duration, mos | mRS Score |
|---|---|---|---|---|---|---|---|
| 1 |
38 |
M |
BBA |
3 |
0 |
16 |
0 |
| 2 |
79 |
F |
BA-DA |
1 |
11 |
26 |
3 |
| 3 |
75 |
M |
ICA-DA |
1 |
15 |
13 |
0 |
| 4 | 66 | F | BBA | 2 | 16 | 12 | 0 |
FU = follow-up; H&H = Hunt and Hess; ICA = internal carotid artery; mRS = modified Rankin Scale; NET = neuroendovascular treatment; VA = vertebral artery.
A Low-Profile Visualized Intraluminal Support (LVIS) device (Microvention, Terumo) was used as a neck-bridging stent and was deployed by the semijailing technique. The i-ED coils were inserted into and around the rupture point during and after stent deployment. Neither rebleeding nor ischemic complications were observed. The outcomes of the four patients were favorable, with a modified Rankin Scale score of 0 in three patients and 3 in one patient.
Illustrative Cases
Case 1
A 37-year-old male patient developed subarachnoid hemorrhage due to ruptured BBA in the left internal carotid artery detected by digital subtraction angiography (DSA) (Fig. 1A) and 3D-DSA (Fig. 1B arrow). Stent-assisted coil embolization was performed on the day of the onset of subarachnoid hemorrhage. Anterior choroidal artery branching distal from the aneurysm dilation was noted. An LVIS stent was placed with three i-ED coils measuring 2 mm × 4 cm, 2 mm × 3 cm, and 1 mm × 3 cm (Fig. 1C and D). Technical recommendations for the semijailing technique and the distribution of i-ED coils are shown in Video 1. Angiography (Fig. 1E) and cone-beam computed tomography (CT; Fig. 1F) performed after the procedure showed a stent with packed coils underlying the obliterated aneurysm and the preservation of the anterior choroidal artery. Follow-up imaging performed 6 months after treatment showed no recurrence.
VIDEO 1. Clip showing the procedures of Case 1 performed, including stent deployment and coil embolization, at 4× speed. With the microcatheter guided distal to the aneurysm, the LVIS stent was half-deployed. The microcatheter position and coil distribution were adjusted to preserve the anterior choroidal artery. The stent is fully deployed and a total of three coils were placed in the jail cavity. Click here to view.
FIG. 1.
Case 1. A ruptured BBA in the left carotid artery on DSA (A) and 3D-DSA (arrow) (B). DSA after full deployment of the LVIS stent and coil embolization (C and D) shows the widespread distribution of coils along the injured vessel wall, including the aneurysm (arrow). DSA (E) and cone-beam CT (F) after treatment shows the obliterated aneurysm and the preservation of the anterior choroidal artery.
Case 2
A 79-year-old female patient developed subarachnoid hemorrhage due to ruptured DA in the basilar artery (BA) detected by DSA (Fig. 2A arrow). Contrast-enhanced vessel wall imaging showed chronological changes in aneurysm wall enhancement in the BA (Fig. 2B arrow), suggesting the culprit aneurysm. High-resolution cone-beam CT revealed an intimal flap and pseudoaneurysm dilation, which led to the final diagnosis of ruptured DA (Fig. 2C). Stent-assisted coil embolization was performed 11 days after subarachnoid hemorrhage. To preserve antegrade flow and perforating arteries, an LVIS stent was placed with three i-ED coils measuring 2 mm × 3 cm, 1.5 mm × 2 cm, and 1 mm × 2 cm (Fig. 2D). Technical recommendations for the semijailing technique and the distribution of i-ED coils are shown in Video 2. Angiography (Fig. 2E) and cone-beam CT (Fig. 2F) performed after the procedure showed a stent with packed coils underlying the obliterated aneurysm and the preservation of the BA.
VIDEO 2. Clip showing the procedures of Case 2 performed, including stent deployment and coil embolization, at 4× speed. The LVIS stent was half deployed to cover the neck of the dissecting aneurysm in the BA. The i-ED coils expanded softly and broadly in the dilated space. Final angiography showed preservation of the BA and complete obliteration of the aneurysm. Click here to view.
FIG. 2.
Case 2. Initial DSA shows an irregularly shaped BA, indicating dissection, and an aneurysm is observed (arrow) (A). Vessel wall imaging shows aneurysm wall enhancement in the BA, and morphological changes at the dissection site over time (B) (arrow 1: the day of onset, arrow 2: day 4, arrow 3: day 10). High-resolution cone-beam CT shows an intimal flap (arrow) and pseudoaneurysmal dilatation (arrowhead), which led to the final diagnosis of a ruptured dissecting aneurysm (C). DSA after full deployment of the LVIS stent and coil embolization shows the distribution of the coils into the aneurysm and pseudo-lumen (arrow) (D). DSA shows complete obliteration (arrow) and preservation of the BA (E). Cone-beam CT shows stent deployment and coil positions (F, arrow).
Patient Informed Consent
The necessary patient informed consent was obtained in this study.
Discussion
Observations
An optimal treatment strategy for ruptured BBAs and DAs has not yet been established. An endovascular approach for these intractable pathologies may be ideal for preserving antegrade flow and the involved vessels.3 However, in contrast to microsurgical trapping or endovascular parental artery occlusion with or without bypass surgery, securing definitive hemostasis at the rupture point by other endovascular options represents a major concern. Rebleeding during or after endovascular treatment is detrimental, particularly under antiplatelet therapy for conventional neck-bridging or flow-diverting stents.4 The case series presented herein suggests a treatment option for these intractable and challenging vascular pathologies using an endovascular approach with modern coil technologies.
The mechanism underlying vascular wall repair through thrombus formation involves platelet aggregation, which forms the core of the thrombus, and coagulation with the generation of fibrin and fibrous proteins.2 This cascade promotes the healing of injured vessel walls and is necessary for the initiation of hemostasis and repair of the vessel wall. Therefore, stents and a sufficient number of coils underlying the injured vessel wall may strengthen thrombus formation and secure hemostasis.
The packing of coils in the fragile vessel walls of ruptured BBAs and DAs is very challenging. The procedure described herein is characterized by the insertion of as many i-ED coils as possible, which have a low-memory shape and are extremely soft, in stent-assisted coiling by the semijailing technique. This technique would be beneficial since it allows the microcatheter to move flexibly and to insert coils with minimal stress along the wall of BBAs and DAs. As shown in Videos 1 and 2, i-ED coils expanded softly and broadly in the dilated space and were distributed in a different direction by rewinding them. If the conventional jailing technique were used, on the contrary, it would be technically tricky to seat a microcatheter at the optimal position and insert enough coils into the cramped dissecting space. The i-ED coils have also been used for saccular intracranial aneurysms.5 This specific movement may be explained by the low k-factor of i-ED coils, which represents the stiffness of coils. The k-factor is calculated using the following formula: (coil strand diameter4 × rigidity ratio)/8 × (primary diameter of coils3 × coil pitch). The k-factor of i-ED coils is 2.2 × 10−6. The k-factor of other currently available coils has not been reported. In comparison with previous data based on the simplified method to calculate relative softness of coils with the formula (coil strand diameter × rigidity ratio)/(primary diameter of coils × coil pitch),6 the value of i-ED coils is 0.12. We propose the use of such low-memory and soft coils when stent-assisted coiling is the treatment of choice for ruptured BBAs and DAs.
LVIS stents may promote hemostasis and facilitate the successful healing of injured aneurysm walls. High metal coverage (23%) and a small cell structure (0.9 mm) provide better protection across an injured aneurysm wall and exert the flow diversion effect.7,8 LVIS stents may be used safely and effectively even immediately after rupture.9–12 Although flow-diverting stents for BBAs or ruptured DAs represent a treatment option, they require some time for endothelialization. The use of a braided stent and low-memory shape coils may achieve immediate hemostasis without increasing bleeding during the procedure.
Lessons
Stent-assisted coil embolization with i-ED coils using a braided stent has potential as a treatment option for ruptured BBAs and DAs to achieve immediate hemostasis and preserve parental antegrade flow.
Author Contributions
Conception and design: Matsushige, Takahashi. Acquisition of data: Takahashi, Hashimoto, Hara, Hosogai, Kobayashi. Analysis and interpretation of data: Matsushige, Takahashi. Drafting the article: Matsushige. Critically revising the article: Takahashi. Reviewed submitted version of manuscript: Matsushige, Takahashi, Hara, Hosogai, Kobayashi. Approved the final version of the manuscript on behalf of all authors: Matsushige. Administrative/technical/material support: Takahashi. Study supervision: Horie.
Supplemental Information
Videos
Video 1. https://vimeo.com/908270189.
Video 2. https://vimeo.com/908271988.
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