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Abstract
Background The difficulties in obtaining complete and stable endovascular occlusion are most evident for ruptured aneurysms exhibiting a wide neck and unfavorable geometric features. The aim of our study was to present our experience with the Comaneci temporary bridging device in ruptured wide neck aneurysms.
Methods From May to July 2017, 29 ruptured aneurysms underwent endovascular embolization with the Comaneci device. Angiographic and clinical results were retrospectively analyzed.
Results 29 ruptured intracranial aneurysms from different locations were included. Successful embolization was achieved in all lesions; complete post-procedure occlusion was seen in 25 (86%) cases. Insufficient embolization or neck remnant was observed in four cases (13.7%). Complications probably related, directly related, or indirectly related to the device occurred in 3.44% of patients (1/29 patients). At least one angiographic follow-up was performed in each of the 29 cases. The 12 month follow-up examination has yet to be done.
Conclusion The Comaneci device offers a new promising and reliable technique that can safely support aneurysm coiling occlusion even in a rupture environment. However, long term monitoring of patients treated by this device is mandatory.
- aneurysm
- device
- hemorrhage
- subarachnoid
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Introduction
The endovascular treatment of wide neck, ruptured, and unruptured intracranial aneurysms continues to evolve with the advent of new techniques and medical devices. For some of these lesions, the use of the standard endovascular approach is insufficient.1–3
New technical improvements, such as three-dimensional coils, balloon assisted remodeling, polymer embolization, stents, and flow diversion devices have allowed endovascular surgeons to treat previously prohibitive lesions.4
The temporary bridging device—the Comaneci—represents a new treatment paradigm for intracranial aneurysms with unfavorable anatomical features. The device itself is a temporary stent which covers the aneurysmal neck in order to prevent protrusion of coils into the parent vessel during embolization of the aneurysm.
In this case series, we report our initial experience using the Comaneci device for the endovascular treatment of 29 ruptured wide neck intracranial aneurysms.
Material and methods
The Comaneci device is a compliant radiopaque mesh composed of 12 nitinol wires mounted on a 182 cm core wire figure 1. The device is CE marked, approved in Canada, and under the approval process by the US Food and Drug Administration. The distal end of the device consists of a 7 mm flexible tip, allowing for gentle and safe navigation. The device is released via a 0.021 inch microcatheter. The cell size of the device measures 1.33 mm2 at the nominal diameter of 3.0 mm.
A Comaneci device deployed in a glass model aneurysm.
Three versions of the device are available. The standard version has a length of 32 mm, which shortens to 12 mm when deployed in a vessel of 4.0 mm in diameter. The shorter version (Comaneci Petit) measures 24 mm before deployment and contracts to 21 mm when fully deployed in a vessel of 3.0 mm in diameter. A third version is also available—the Comaneci 17 is delivered via a 0.017 inch microcatheter. It measures 22 mm before deployment and contracts to 16 mm when fully opened in a vessel of 3.0 mm in diameter.5 The extent of expansion can be adjusted by the operator via a slider at the handle.
Patient population and lesion characteristics
The present study is a retrospective case series of patients with ruptured aneurysms and subarachnoid hemorrhage treated at our institution between May 2017 and July 2017. To date, published case series have reported on the use of the Comaneci device in unruptured aneurysms in the anterior circulation.6 There is one published case report in ruptured aneurysms treated with the assistance of the Comaneci device.5
All of the 29 treated lesions were de novo ruptured aneurysms (table 1). The indications for treatment with the Comaneci device were categorized as ruptured saccular aneurysm with a dome/neck ratio of <2 or wide neck intracranial aneurysms. All patients were informed about the procedure according to the local institutional policy. Written informed consent was obtained from every patient.
Aneurysmal characteristics—baseline anatomy, complications, follow-up, immediate occlusion rate, device model used, and time of inflation
Endovascular procedure
All procedures were performed under general anesthesia and via transfemoral arterial access in a dedicated biplane neuroangiography suite. The diagnostic catheter was exchanged over an exchange length wire for a 6 F Chaperon guiding catheter (Microvention). A distal access catheter, Navien, was used in six cases for additional distal support (0.058 mm or 0.072 mm; Medtronic). Next, roadmap angiography was performed, and an Echelon microcatheter (Medtronic) was advanced over a microwire inside the aneurysmal sac. A few loops of the first coil were made to anchor the microcatheter inside the sac. A 0.021 inch microcatheter was navigated into the parent artery and placed distally to the aneurysmal sac.
Selection of which Comaneci model to use (Comaneci, Comaneci 17, or Comaneci Petit) was based on pretreatment measurements of the target artery and the geometry of the aneurysm itself.
The device was loaded into the microcatheter and navigated to a position providing optimal coverage of the aneurysm neck. The device was unsheathed by withdrawal of the microcatheter to achieve complete neck coverage of the aneurysm. This was followed by cautious expansion of the device using the control handle. The correct expansion of the device, with proper adaptation to the circumference of the parent artery, was documented and facilitated by fluoroscopy at various angles. Once the proper position of the device was confirmed, complete coil occlusion of the aneurysm was achieved. Any coil loops that could eventually interact with the bridging mesh of the device were repositioned to avoid any complications. Finally, the Comaneci device was manually ‘deflated’ before detachment of the last coil, to confirm the stable position of the coil structure inside the sac. This was followed by recapture of the device into the microcatheter and safe withdrawal from the parent artery.
Antiplatelet and anticoagulation regimen
No dual antiplatelet medication was assigned to any of the treated patients. Acetylsalicylic acid was administrated to one patient for 2 weeks, in anticipation of any possible thromboembolic complications due to protrusion of coils into the parent artery. Intravenous heparin was administered during all procedures to maintain an activated clotting time of 250–300 s. Heparinization was not reversed at the conclusion of the procedures.
Follow-up schedule
At the conclusion of the treatment, 25 of the aneurysms showed complete angiographic occlusion on the immediate post-procedure angiogram. Follow-up examinations were assigned on the third and 12th months after the intervention. The angiographic results from the third month examination were classified into three grades: complete occlusion, neck remnant, and incomplete occlusion.
Results
Twenty-nine patients (13 women and 16 men, mean age 54.5 years) with 29 intracranial aneurysms were considered for treatment with the Comaneci device in our initial usage of this new technique: nine aneurysms of the anterior communicating artery, one aneurysm of the anterior cerebral artery, seven aneurysms of the middle cerebral artery, six side wall aneurysms of the internal carotid artery, and six aneurysms of the basilar artery (two of which were basilar tip).
None of the treated patients had previous endovascular treatment. The decision to perform endovascular treatment was considered by a multidisciplinary team of neuroradiologists and neurosurgeons.
The mean fundus diameter of all lesions included in the series was 5.38 (range 2.7–11.0 mm), with a mean neck size of 4.28 mm (range 1.9–7.4 mm). At the time of treatment, 20 patients (68.9%) had a modified Rankin Scale (mRS) score of 0, five patients (17.24%) had a score of 1, and four patients had a score of 2. Patients with an mRS score of 2 were presented with CT evidence of subarachnoid hemorrhage—Fisher II, III, or IV grade. Among the 29 aneurysms treated with the Comaneci device, complete occlusion on the post-embolization angiography was observed in 25 (86%) cases, compared with 4 (13.7%) cases with a neck remnant. By the time the patients were discharged from the hospital, there were no changes in their mRS score.
The third month angiographic follow-up was performed in all cases. Twenty-eight showed complete aneurysmal occlusion, and one had neck remnant. The 12 month follow-up angiography has yet to be done in all patients. Aneurysmal rebleeding was not observed as a complication in this case series.
Technical results
A stable position, with proper expansion of the device and coverage of the aneurysmal neck, as well as trouble free insertion and withdrawal, was observed in 28 cases. In one case, due to a severe vasospasm, the device was not fully opened but provided enough coverage of the neck to provide protection of the parent artery.
Complications
One complication which might have been device related occurred in patient No 7, who presented with Fisher III grade subarachnoid hemorrhage and a ruptured left supracerebrallar artery aneurysm. While withdrawing the device into the microcatheter, there were some noticeable changes in the coil structure inside the aneurysmal. No pathological findings were observed on the post-procedural angiogram. The patient developed cerebellar ataxia 24 hours after the procedure. Analysis of this case lead to the conclusion that a stable basket of coils was not achieved, and that this led to coil protrusion, compromising the origin of the left superior cerebellar artery (SCA) (figure 2).
Aneurysm on the left superior cerebellar artery, treated with coils and supported by a Comaneci device. At the end of the procedure, there was good flow in the left superior cerebellar artery.
The clinical symptoms of cerebellar ataxia in patient No 7 resolved in 1 week and the patient was discharged from the hospital without any neurological deficit.
In the same case a severe vasospasm of the parent artery (right posterior cerebral artery) near the distal tip of the device after expansion was observed. This may be related to a possible over expanding of mesh of the device in an effort to achieve better aneurysmal neck coverage and to protect the origin of the left SCA. On the first follow-up angiogram, 3 months later, no recanalization of the aneurysmal sac was observed but the angiogram revealed left SCA occlusion figure 3. According to our experience, the left SCA occlusion might have been related to possible coil protrusion in front of the vessel origin. Moreover, disturbance of the normal intraluminal blood flow could have been a result of the vasospasm from the present subarachnoid hemorrhage observed on the patient’s admission to hospital.
Aneurysm on the left superior cerebellar artery, bridging aneurysmal neck with the Comaneci device, and spasm at the distal end of the device (arrow). On the 3 month follow-up angiogram, there was no filling of the left superior cerebellar artery.
In the remaining 28 patients, no ischemic or hemorrhagic complications were reported. In our opinion, there were no complications related to the Comaneci device.
Discussion
Endovascular therapy has emerged as an accepted and, in most cases, preferred treatment for cerebral aneurysms. Difficulties in obtaining complete and stable endovascular occlusion are most evident for wide neck aneurysms and those exhibiting wide neck, unfavorable geometry features, or large or giant size.3 4 Despite the benefits of endovascular treatment of aneurysms, complete aneurysmal obliteration may not always be possible in difficult cases. Reported complications of standard coiling of wide neck aneurysms include cerebral thrombus (4.7%), bleeding (5%), and iatrogenic vasospasm (0.7%).7 Coil stretching, herniation, and even coil migration into the lumen of the parent artery increase the risk of thromboembolic complications or vessel occlusions.
Stent assisted coiling (SAC) and balloon assisted coiling (BAC) are the best established strategies for wide neck aneurysms. In an effort to better address the inherent difficulties with the endovascular treatment of wide neck aneurysms, balloon remodeling and stent assisted techniques have been developed to improve the occlusion rate during coil embolization.8 9 These have broadened the horizon of practice to allow the successful treatment of geometrically complex aneurysms. Balloon remodeling or BAC techniques involve the temporary inflation and placement of a balloon catheter across the neck of an aneurysm, allowing safe coil deployment and a stable three-dimensional coil structure to form in lesions with unfavorable neck to dome ratios. Many interventionalists prefer BAC over SAC for treatment of ruptured wide neck aneurysms, because with the balloon remodeling technique there is no need for an antiplatelet regimen.10 The Comaneci device can be used as a remodeling balloon, for temporary coverage of the aneurysm neck during coil insertion, without the drawback of blocked flow within the parent artery during expansion of the device. Once it is placed across the aneurysmal neck effectively, no further deflation or inflation of the device is required.
The main disadvantage of BAC in comparison with the Comaneci technique is the possible complete flow blockage of the parent vessel when performing deflation and inflation maneuvers. The temporary occlusion of the artery could eventually lead to thromboembolic events caused by prolonged flow arrest, endothelial damage, or vasospasm. However, in the case of an unpredictable intraprocedural aneurysmal rupture, the above mentioned limitations of the balloon technique could be in great use.11–15
Gupta et al reported an animal study that included 20 elastase induced aneurysms in which they analyzed the occurrence of endothelial11 12 injury with the Comaneci device in comparison with a compliant balloon catheter.16 The presented results show that there was no increase in endothelial injury in the Comaneci group. The aneurysmal obliteration rates in this group did not differ from those in the balloon catheter group, which demonstrated concordance between the two devices from a safety point of view.
Temporary SAC is a new alternative technique for the treatment of wide neck aneurysms. Analogous to BAC, Almekhlafi et al deployed a Solitaire stent in three cases that was completely removed at the end of the procedure. Although no complications were encountered in these three cases, a major drawback of the presented technique remains.17
Neurovascular stents were also designed to act as a scaffold to prevent intrasaccular coil protrusion into the parent artery lumen in slightly more complex and wide neck aneurysms. More recently, flow diverters have been used to treat wide based aneurysms in the anterior circulation. Flow diversion allows vessel wall reconstruction and neointimal growth across the aneurysmal neck with its exclusion of the main blood flow. Its application in ruptured aneurysms remains limited because of the need for an antiplatelet regimen and increased risk of early rebleeding18 19
Our initial experience with the Comaneci device is encouraging. Following stable positioning of the device above the neck, complete occlusion of all aneurysms was achieved. In all cases, trouble free retrieval of the device, with proper inflation and complete resheathing into the microcatheter, was performed without difficulty. The radiopacity of the mesh and the distal tip was high enough to avoid any possible interaction between the coils and the device. No parent vessel occlusions were observed.
The complication rate, possibly related, directly related, or indirectly related to the device, was 3.44% (1/29 patients). In retrospect, we also identified that the unstable coil construction and the presence of vasospasm due to subarachnoid hemorrhage may explain the above mentioned complications, and the reason on the follow-up third month angiogram that no preserved left supracerebellar artery was observed.
Lawson et al, as well as Fisher et al, 5 6 in their series of a total of 21 aneurysms treated using Comaneci device, observed two thromboembolic phenomena. However, the causes of these complications remain unclear. In addition to the studies of Lawson et al, Gupta et al, and Fisher et al, additional studies regarding safety and efficiency are needed.
Limitations of the study
The main limitations of the study are its retrospective design, the small sample size (number of patients), and the absence of a control group treated with balloon assisted and/or stent assisted techniques. In addition, any technical problems and potential complications might be related to our limited experience with the new Comaneci device.
Conclusion
Despite the limitations of our study, the results demonstrate that the Comaneci is an innovative technique for the treatment of wide neck intracranial aneurysms. However, long term follow-up in large series are needed in order to address the safety considerations and significance of this device in comparison with BAC/SAC or simple coiling outcomes.
References
Footnotes
Contributors SS and AS: conception and design of the work, data acquisition, analysis and interpretation of data for the work, and writing of the manuscript. KM, MP, and HH: critical review of the work. SS: final approval of the version to be published.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was approved by the ethics committee of UH St Ivan Rilski, Sofia.
Provenance and peer review Not commissioned; externally peer reviewed.