In vitro experiments of vessel wall apposition between the Enterprise and Enterprise 2 stents for treatment of cerebral aneurysms

Effects of Enterprise 2 stent-assisted coil embolization for wide-necked intracranial aneurysms

BACKGROUND

This study analyzed the safety and efficacy of Enterprise 2 stent-assisted coil embolization for wide-necked intracranial aneurysms by examining stent-vessel apposition, operative complications, embolization outcomes, and clinical outcomes.

METHODS

We retrospectively reviewed the medical records of patients with wide-necked intracranial aneurysms who underwent Enterprise 2 stent-assisted coiling in our hospital from November 2018 to October 2019. Intraoperative VasoCT was performed immediately after stent release in a continuous cohort of patients to observe stent-vessel apposition. Patient demographic, clinical, and imaging data were recorded and analyzed.

RESULTS

A total of 106 wide-necked aneurysms in 106 patients were treated. Stent release was successful in all patients. Twenty-one patients were enrolled consecutively for VasoCT scanning, and incomplete stent apposition was observed in 5 (23.8%). Perioperative complications occurred in 10 patients (9.4%): cerebral infarction in 6, intraoperative coil prolapse in 1, puncture site pseudoaneurysm in 1, deep vein thrombosis at multiple sites in 1, and transient brainstem mass effect in 1. Among the 95 aneurysms with angiographic follow-up, embolization was satisfactory (Raymond-Roy classifications I and II) in 89 (93.7%). Hyperlipidemia was an independent risk factor for incomplete aneurysm occlusion. At the last clinical follow-up, seven patients had a poor clinical outcome (modified Rankin Scale score ≥ 3). Independent risk factors for poor outcomes were preoperative subarachnoid hemorrhage at presentation and cerebral infarction.

CONCLUSION

Enterprise 2 stent-assisted coiling for treatment of wide-necked intracranial aneurysms showed good safety and efficacy; however, incomplete stent apposition can still occur in vessels with a large curvature. Preoperative subarachnoid hemorrhage at presentation and cerebral infarction are the main reasons for poor clinical outcomes after stent-assisted coil embolization.

Comparison of Enterprise stent 2 with 1 in assisting coiling of ruptured aneurysms: a real-world study

Aim: To investigate the effectiveness and safety of the Enterprise 2 (E2) stent versus the Enterprise 1 (E1) stent in treating ruptured intracranial aneurysms (RIAs) in China. Materials & methods: The authors conducted an electronic medical record analysis for patients with RIAs who underwent E1/E2 deployment. The main outcomes were immediate complete occlusion (ICO), patient functional outcomes, complications and aneurysm recurrence. Results: Stent deployment was successful in all patients (E2: 90; E1: 270). ICO and patients with good functional outcomes at discharge were similar between E2 and E1 (80.0% vs 75.1% and 78.7% vs 81.1%, respectively). The E2 group had a significantly lower complication rate compared with the E1 group (7.8% vs 16.4%; odds ratio: 0.36; 95% CI: 0.15-0.91; p = 0.031). By 6 months post-discharge, the two groups had comparable patient functional outcomes and aneurysm recurrence (E2 vs E1: 80.2% vs 81.9% and 13.3% vs 14.9%). Conclusion: Compared with the E1 stent, the E2 stent had similar effectiveness but a lower complication risk in treating RIAs.

Endovascular treatment with the Enterprise stent versus the Neuroform or Low-Profile Visualized Intraluminal Support stent for unruptured aneurysms

Aim: To compare outcomes among patients undergoing endovascular treatment for unruptured intracranial aneurysm (UIA) with the Enterprise stent versus the Neuroform or Low-Profile Visualized Intraluminal Support (LVIS) stent. Patients & methods: Patients undergoing endovascular procedure for UIA were classified into Enterprise stent and Neuroform or LVIS stent group. Groups were propensity-score matched and generalized estimating equations were used for outcomes assessment. Results: There were no significant between-group differences in length of stay or mortality. The Enterprise group had significantly lower odds of UIA-related inpatient readmissions versus the Neuroform/LVIS group (odds ratio: 0.62; 95% CI: 0.42-0.91). Conclusion: Enterprise stent use was associated with significantly lower readmissions versus competitor stent, with no difference in other study outcomes.

The Enterprise2 Stent for Endovascular Treatment of Intracranial Aneurysms: Short-Term Results From a Single Center Experience

Background: Self-expanding devices, such as the Enterprise VRD (EP-VRD) have widely used for stent-assisted coiling treatment in wided-necked aneuryms while some thromboembolic complications were reported due to its incomplete stent apposition (ISA). We report our experiences on the novel Enterprise2 (EP-VRD2) stent in vivo in the treatment of intracranial and cranial cervical junction aneurysms.

Methods: Twenty-five consecutive patients with intracranial or cranial cervical junction aneurysms were treated with EP-VRD2 stents retrospectively collected in our institution. We use the ‘jailing' technique in all cases and deployed the stent by using pushing over the outer curve technique. The 3- or 6-monthS follow-up was done regularly by DSA.

Results: Twenty-five EP-VRD2 stents were implanted to treat 21 aneurysms at the siphon segment of internal carotid artery (ICA), one at the petrous segment, two at the cervical segment, one at the verteral artery with five accompanied with stenosis. Two patients had kinking during the procedure and were solved by microwire or microcatheter massaging. Four patients with a larger arc angle and a smaller radius of the parent vessel was detected ISA. No patient underwent the ischemic event after the operation. Twenty-three of 25 patients were evaluated after 3- or 6-months by DSA, 22 showed complete occlusion (RROC1), one slight re-stenosis in the follow-up within those five patients with stenosis. A length of 23 mm seemed associated with ISA (p < 0.01).

Conclusion: The EP-VRD2 performed well in our small patient series; however, ISA could still occur with a sharp angle of the parent vessel.

Recent advances in stent-assisted coiling of cerebral aneurysms

INTRODUCTION

Stent-assisted coiling (SAC) of intracranial aneurysms paved the way for endovascular coiling of wide-neck and bifurcation aneurysms, improving rates of aneurysm obliteration and recurrence. In this review, we provide a comprehensive review of the most recent advances related to stent-assisted coiling of intracranial aneurysm.

AREAS COVERED

The authors have made an attempt to cover the inception, applications, and limitations of SAC of intracranial aneurysms. Special focus is given to 1) the current and recently introduced SAC techniques, 2) most recent advances in device technology, and 3) outcome data for the discussed techniques and devices. The authors also discuss the potential future direction of SAC.

EXPERT OPINION

technical refinements in the field of SAC should continue to focus on device development and addressing the limitations of SAC, namely aneurysm recurrence and need of antiplatelet agents. Although the recurrence rate of SAC has not been shown to be inferior to flow diverters, the use of intrasaccular and intravascular flow diverters are likely to expand in the future at the expense of SAC.

Analysis of the Anatomical Factors Affecting Ability to Navigate Penumbra Catheter through Internal Carotid Siphon

Objective

The efficacy and safety of aspiration thrombectomy using Penumbra catheter with acute large vessel occlusion in the anterior circulation have been reported in previous studies. In some cases, the carotid siphon (CS) is elongated, and with this anatomy, especially where there is bifurcation of the ophthalmic artery (OA), navigation of Penumbra catheters into distal internal carotid artery (ICA) is interrupted, which is known as the 'ledge effect'. We investigate the anatomical characteristics of CS that cause interruption of navigation of the Penumbra catheter.

Methods

Between January 2015 and March 2018, mechanical thrombectomy using Penumbra 60 was performed on 51 patients with middle cerebral artery (MCA) or intracranial ICA occlusion. Patients were divided into two groups: The 'ledge-effect' group those in whom the Penumbra catheter was unable to be navigated into the distal ICA through the CS, and 'no ledge-effect' group those in whom this was possible. The anatomical characteristics of CS, the diameter of ICA, diameter of OA, OA/ICA ratio and radius of the CS were evaluated using angiographical imaging.

Results

The 'ledge-effect' group numbered eight cases (17%). Only the value of the CS radius was significantly smaller in the ledge-effect group (p = 0.0019), other parameters were not significantly different between the groups. The cutoff radius value was 3.62 mm.

Conclusion

The most notable anatomical factor affecting possibility of navigation of the Penumbra catheter through the CS was the CS radius. This could be useful information when devices used in mechanical thrombectomy are selected.

Three-Dimensional Strain Measurements of a Tubular Elastic Model Using Tomographic Particle Image Velocimetry

The evaluation of strain induced in a blood vessel owing to contact with a medical device is of significance to examine the causes leading to vascular injury and rupture. The development of a method to assess strain in largely deformed elastic materials is expected. This study's scope was to measure strain in deformed tubular elastic mock vessels using tomographic particle image velocimetry (tomo-PIV), and to show the applicability of this measurement method by comparing the results with data derived from a finite element analysis (FEA). Strain distribution was calculated from the displacement distribution, which in turn was measured by tracking fluorescent 13 μm particles in a transparent tubular elastic model using tomo-PIV. The von Mises strain distribution was calculated for a model whose inner diameter was subjected to a pressure load, because of which it expanded from 25 to 27.5 mm, adjusting to the diameter change of a human aorta during heartbeat. An FEA simulating the experiment was also conducted. Three-dimensional strain was successfully measured by using the tomo-PIV method. The radial strain distribution in the model linearly decreased outward (from the its inner to its outer side), and the result was consistent with the data obtained from the FEA. The mean von Mises strain measured using tomo-PIV was comparable with that obtained from the FEA (tomo-PIV: 0.155, FEA: 0.156). This study demonstrates the feasibility of utilizing tomo-PIV to quantitatively assess the three-dimensional strain induced in largely deformed elastic models.

Deployment technique that takes advantage of the characteristics of Enterprise VRD2: an in vitro study

Background

Enterprise VRD, a stent frequently used to assist coil embolization of cerebral aneurysms, has been upgraded to reduce the risk of incomplete stent apposition (ISA), a known risk factor for thromboembolic complications.

Objective

To compare the performances of Enterprise VRD and Enterprise VRD2 in curved vessels, and to investigate a deployment method that takes advantage of the features of Enterprise VRD2 to achieve better vessel wall apposition.

Materials and methods

A silicone vascular model connected to a temperature-adjustable perfusion circuit was used. First, Enterprise VRD and Enterprise VRD2 were deployed under fluoroscopy and then ISA was evaluated as the stent cross-sectional area ratio at the curved segment of the vessel. For the measurements, each stent was deployed in vessels with different angles of curvature. Second, the incidence of ISA after insertion of Enterprise VRD2 by the ‘pushing over outer curve technique’, in which stents are deployed along the outer curve of vessels with continuous wire advancement, was compared with ‘Heller's push and pull technique’.

Results

For all stents, the cross-sectional area ratio decreased with acute curvature of the vessel. Comparisons of the two stents showed that Enterprise VRD2 was better than Enterprise VRD in maintaining a greater cross-sectional area ratio in curved vessels. In addition, kinking with an acute curvature was also minimized with Enterprise VRD2. Furthermore, ISA was reduced using our technique with Enterprise VRD2.

Conclusions

Enterprise VRD2 is superior to Enterprise VRD in reducing ISA in curved vessels and can alter ISA according to the deployment technique used.