VFC® Volume Filling Coils: Maximising Aneurysm Packing Density in the Filling Phase

The VFC® (Volume Filling Coil) is MicroVention Terumo’s dedicated filling-phase bare-platinum coil, engineered specifically for the secondary and tertiary coiling phases after the initial framing basket has been established. Its distinguishing characteristic is a low-modulus, ultra-soft platinum wire construction that gives it a very low packing modulus — meaning the coil exerts minimal force on the aneurysm wall and on previously placed coils as it fills the remaining void space within the established basket.

The rationale for a dedicated filling coil is that the requirements for the framing phase (high radial force, shape stability, basket integrity) are fundamentally different from the requirements for the filling phase (soft conformability, low mass effect, efficient void filling). Using a single coil type for both phases involves a compromise: framing coils that are soft enough for dense final filling tend to be too floppy for stable framing, while framing coils strong enough for initial basket formation are often too stiff for optimal final filling. The VFC is optimised exclusively for the filling role.

The VFC is available in multiple diameter and length combinations covering the range of residual void volumes encountered in the filling phase of aneurysm embolization. It is delivered via Headway 17 microcatheter, consistent with the rest of the MicroVention Terumo coil portfolio. The ultra-soft platinum wire formulation provides a packing modulus lower than standard Cosmos bare-platinum filling coils, allowing denser packing in the residual spaces between framing coil loops.

VFC coils are available in complex 3D and helical shapes to match different residual void geometries. The 3D variant conforms to irregularly shaped residual spaces that a helical coil cannot fill as efficiently, while the helical variant fills more uniform cylindrical or spherical residual voids.

The VFC is used after framing is complete with Cosmos 18 or HydroFrame 18 and after any secondary framing with HydroFrame is done. The filling phase begins with the largest VFC that can be safely introduced into the remaining void space and progresses to progressively smaller coils until no further void reduction is achievable without undue resistance.

VFC is particularly effective in large aneurysms (>10 mm) where the residual void after framing is large and a dedicated soft filling coil adds meaningful packing density compared to using additional Cosmos coils for filling. In conjunction with HydroSoft for final filling, the VFC + HydroSoft combination can achieve very high packing densities in aneurysms of all sizes.

Begin filling with a VFC coil approximately 1–2 mm smaller than the mean residual void diameter. The coil should fill the space without building excessive tension against the framing basket. If moderate resistance is felt during deployment, the coil size is at the limit of the remaining space — switch to a smaller diameter for subsequent fills.

Monitor for coil herniation through the basket interstices during VFC filling. The soft VFC can potentially push through framing coil gaps under fill pressure in a loosely framed sac. If herniation occurs, stop and assess whether the framing basket requires reinforcement before proceeding with filling.

Modern Medical Solutions is the authorised MicroVention Terumo distributor for Tajikistan and Afghanistan. VFC coils are available for neurointerventional programmes in Tajikistan and Afghanistan.

Contact Modern Medical Solutions to discuss VFC as part of a complete MicroVention Terumo coiling protocol alongside Cosmos, HydroFrame, and HydroSoft coils.