Full Intrasaccular: Understanding the Basics

This session provides a highly practical perspective on intrasaccular flow disruption, moving beyond device deployment toward the more important questions of case selection, anatomical suitability, sizing, learning curve, and integration with other endovascular techniques. A particularly valuable aspect of the discussion is the distinction between what can technically be treated with an intrasaccular device and what represents an appropriate case, especially early in the learning curve.

One of the strongest messages is that initial cases should be selected for procedural simplicity rather than anatomical complexity. Wide-neck bifurcation aneurysms with relatively straight access, favorable neck visualization, and good alignment between the parent vessel and aneurysm axis appear particularly suitable for gaining familiarity with the technique. The basilar tip is highlighted as a potentially favorable starting anatomy because access may be relatively direct and the aneurysm–parent vessel relationship clearly appreciated, whereas ACom aneurysms may require more demanding catheter shaping and navigation. Nevertheless, location alone should not determine suitability: individual aneurysm geometry, access route, neck configuration, branch incorporation, and anticipated device orientation are more informative than the anatomical label itself. Operators should therefore progress from geometrically forgiving cases toward increasingly complex anatomies as experience develops.

The discussion also emphasizes the importance of the axis of approach. Intrasaccular devices are mechanically different from coils, and their deployment depends on controlled microcatheter positioning and predictable opening of the implant within the sac. Microcatheter shaping may therefore need to be more deliberate than during conventional coiling, particularly when the aneurysm is eccentric to the parent-vessel axis. An unfavorable approach angle can make otherwise acceptable anatomy considerably more challenging. Successful treatment is thus not simply a question of whether a device fits the aneurysm dimensions, but also how it will enter, expand, orient, and interact with the neck and adjacent branches.

Similarly, sizing should not be based exclusively on aneurysm dimensions. The available space at the neck and within the parent vessel must also be considered, particularly when intentional or potential device protrusion is anticipated. Excessive protrusion may compromise an adjacent branch or the parent vessel, whereas carefully controlled neck coverage may, in selected anatomies, improve isolation of the aneurysm or an unfavorable bleb. This becomes especially relevant in bifurcation aneurysms, where millimeters can determine whether the construct remains anatomically acceptable, illustrating the transition from simple dimensional sizing toward three-dimensional procedural planning.

The cases involving blebs are particularly instructive. A bleb at or near the neck can complicate both coiling and intrasaccular treatment: catheter or coil interaction with a fragile irregular component may be undesirable, while complete coverage with an intrasaccular implant may require some degree of device protrusion. Controlled “bulging” across the neck can sometimes be used strategically to isolate such anatomy, but should be regarded as an advanced rather than routine technique. Its feasibility depends on parent-vessel space, branch anatomy, device characteristics, and operator experience. Importantly, a case that can be successfully treated by an experienced operator is not necessarily an appropriate introductory case.

Another strength of the session is its rejection of an overly device-centric approach. Complex examples demonstrate combinations of intrasaccular treatment, coiling, and flow diversion, with each component addressing a different anatomical or haemodynamic problem. Rather than competing with coils or flow diverters, intrasaccular devices may be complementary in selected aneurysms: they can provide neck-level flow disruption or support coil retention, while flow diversion can modify inflow and reconstruct the parent vessel. These cases support a broader philosophy of anatomy-driven multimodality treatment rather than forcing every aneurysm into a single-device strategy.

The discussion of follow-up imaging is equally relevant. After flow-modifying treatment, angiographic success should not necessarily be judged according to the same expectations as immediate mechanical packing with coils. Progressive thrombosis, reduced aneurysmal filling, remodeling of the neck, and reconstruction of the parent vessel may occur over time. A small, stable residual filling pattern therefore does not automatically carry the same meaning as a recurrent or enlarging coil-treated aneurysm. However, the panel’s reassuring observations regarding stable remnants and absence of rebleeding should be regarded as expert clinical experience rather than universal evidence. Residual filling still requires longitudinal assessment, taking into account stability, morphology, aneurysm type, and clinical context.

In ruptured aneurysms, a major attraction of intrasaccular flow disruption is the potential to avoid or reduce permanent parent-vessel stenting and intensive antiplatelet therapy, while procedural efficiency may offer an additional advantage in the acute setting. This must be balanced against thromboembolic complications, and antiplatelet requirements cannot be reduced to a universal rule; they depend on the device, degree of protrusion, parent-vessel interaction, adjunctive implants, and procedural findings. Claims that intrasaccular treatment is categorically safer than coiling, or that antiplatelet therapy is unnecessary, should therefore be interpreted cautiously and within the individual anatomical and clinical context.

Perhaps the most important lesson is that mastery of intrasaccular treatment is less about learning how to deploy a device than about learning how to select the right anatomy for it. Straightforward access, favorable axial alignment, predictable neck coverage, and limited branch conflict are desirable early in the learning curve, while increasing experience allows extension toward more complex anatomies through sophisticated sizing, controlled protrusion, and combination strategies.

The session also reinforces an important principle of contemporary aneurysm treatment: technical success should not be defined solely by immediate angiographic disappearance of the aneurysm. The objective is durable exclusion of the pathological component while preserving physiological arterial anatomy and allowing favorable vascular remodeling. Ultimately, intrasaccular flow disruption is best understood not as a replacement for coiling, stent-assisted techniques, or flow diversion, but as an additional—and increasingly versatile—component of the neurointerventional toolbox.