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As the treatment of more complex intracranial aneurysms becomes increasingly feasible and widespread, the technical aspects of these procedures, in turn, continue to take on greater relevance. With this in mind, NeuroNews recently caught up with three experienced neurointerventionists to get their insights on optimal strategies and key considerations when utilising an innovative device pairing—the pCONUS 2 Hydrophilic Polymer Coating (HPC) neck-bridging implant and Avenir coil embolisation system (both WallabyPhenox).
Outlining the progress made between pCONUS 1 and pCONUS 2, Silvia Garbugino (Hospital Británico, Buenos Aires, Argentina)—based on her experiences with each—highlights greater conformability, petal density and overall visibility with the latest iteration, enabling improved control and device positioning while also reducing the likelihood of coils protruding into the parent artery during embolisation.
In Garbugino’s view, such “important changes” have expanded the numbers and types of aneurysms that can be treated with these devices. She also highlights the combination of pCONUS 2’s shorter shaft—resulting in a smaller amount of metal at the parent artery—alongside the HPC surface modification as a “big advantage” that allows patients to undergo aneurysm embolisation without mandatory dual antiplatelet therapy for an extended period of time.
Another notable introduction with pCONUS 2 is an update to its ‘point of articulation’, which enables lateral movement of the crown relative to the device’s shaft, thus facilitating the treatment of more complex aneurysms located in arterial bifurcations.
“Both pCONUS devices are very important in our treatment of aneurysms up to 15mm because, right now, there is no available intrasaccular device that allows for treatment of these larger aneurysm sizes,” Garbugino adds.
Recanalised aneurysms
Garbugino is also keen to emphasise the benefits she sees when operating on previously treated aneurysms that have recanalised—a phenomenon most commonly caused by coils or an intrasaccular device shifting towards the aneurysm dome over time, creating a neck remnant, or lateral compaction due to haemodynamic stress or insufficient packing density resulting in a new lobule.
“In either case,” she states, “you can retreat with pCONUS. As long as the diameter of the neck remnant is more than 3mm, you can treat those cases just as you would a new aneurysm—there is no difference. And, in cases of lateral compaction, the articulation zone and lateral movement I mentioned previously mean the smaller lobule can be treated successfully with pCONUS 2 HPC as well.”
Embellishing on this, Garbugino notes that retreatments involving lateral compaction are generally more challenging, but—provided the pCONUS 2 HPC is oversized by roughly 1mm and placed directly at the neck of the original aneurysm, without touching the dome—recanalised cases involving larger aneurysms that are not especially shallow can be resolved successfully with minimal risks by advancing the pCONUS 2 HPC “gently” and also coiling “softly”, even in the presence of previously deployed implants.
Optimal coiling and packing density
Discussing her preferred coiling practices, Garbugino starts by referring back to the design of pCONUS 2, which has six individual ‘petals’—versus the four seen with pCONUS 1—and therefore better facilitates a high degree of packing density within the aneurysm. In aneurysms larger than 6mm, she prefers to use complex, three-dimensional coils like Avenir 18 FRAME Complex that, when sized appropriately to the sac, allow her to build a “strong, stable cage” without creating risks of compaction or rupture. From there, she will pack more flexible helical coils inside that cage before filling any empty or less densely packed spaces that remain with smaller ‘finishing coils’.
In addition to advising other physicians not to be “afraid” of withdrawing their catheter and re-entering the aneurysm in order to introduce more coils, and ensure sufficient packing density has been achieved throughout the sac, Garbugino advocates fully unsheathing the pCONUS 2 HPC across the neck to enhance its stability and prevent unwanted movement. And, offering a final word of wisdom on the coiling process itself, she recommends selecting the size of the primary coils based on the distance between the pCONUS device’s crown and the aneurysm dome—as opposed to measuring from the aneurysm’s neck to its dome.
An essential message Garbugino conveys on the relevance of dense coil packing is that this will likely lead to more stable occlusion over time, particularly in larger aneurysms—a viewpoint shared by Gustavo Foa Torres and Federico Roca (both Instituto Oulton, Córdoba, Argentina).
“Based on our experience, the most important factor in obtaining durable occlusion is the complete and homogenous packing of the coils inside the sac,” Roca comments. “Of course, larger, more complex aneurysms in challenging locations mean more complex procedures, but, independent of the patient anatomy and aneurysm morphology, if you have stable positioning with pCONUS 2 HPC in the neck as well as dense coil packing, that is a strong predictor of long-term occlusion with low recanalisation rates.”
Providing anecdotal evidence of this, Roca revisits the topic of recanalised aneurysms, noting that retrospectively reviewing many of the cases they have retreated has revealed insufficient packing density as a common reason for recurrence. Roca also notes that he and his colleagues tend to be especially aggressive in seeking maximal packing density in aneurysms they feel are more likely to recanalise over time due to haemodynamic factors or other complexities stemming from their location, size, or shape.
Device sizing
Foa Torres and Roca are also aligned with Garbugino on the benefits of ‘framing’ the aneurysm walls with larger, complex coiling systems—stating that sizing of the first coil remains “critical”—before using smaller coils to concentrically fill remaining gaps. Roca notes that, over time, he and Foa Torres have learned that a more “deliberate focus” on these subsequent coils may be the true determinant of long-term durability, and prioritising dense, targeted packing at the neck is “essential” to seal the inflow zone, accelerate endothelialisation, and minimise recanalisation risk.
“Since adopting this refined concept, we have observed no recurrences and have never needed to retreat any of these patients,” Roca adds. “Regarding pCONUS, for us, the most important technical tip is to advance your microcatheter to the middle of the sac, completely open up the petals inside the sac, and then pull the microcatheter back until the petals get stuck to the neck—and you can feel that in your hands, and you can see the shape of the petals change [on imaging] when you have good apposition to the neck as well.”
Additionally, Foa Torres and Roca suggest that the pCONUS device should be oversized by 1–2mm relative to the aneurysm neck width in order to further enhance neck apposition, ensure lateral compression, and ultimately minimise dead spaces and prevent coils protruding into the parent artery.
“The pCONUS 2 HPC is very easy to recapture and reopen, and you can reposition the device and adapt it to different morphologies to achieve the right level of support,” Roca concludes. “The petals are also very soft so, in most cases, there are no perforation risks. We have treated bifurcations and sidewall aneurysms, and I think it’s a perfect device for these indications because of the improved junction between the petals and the crown with pCONUS 2. This is a great innovation.”
