HydroSoft™ and HydroFrame®: Hydrogel-Coated Coils for Enhanced Packing Density in Aneurysm Embolization
By Modern Medical Solutions Editorial Team
HydroSoft™ and HydroFrame® from MicroVention Terumo are hydrogel-coated platinum coils that swell 2–4× their initial volume in blood, increasing volumetric packing density and reducing aneurysm recanalization compared to bare-platinum coils, with the HELPS randomised trial demonstrating improved 12-month occlusion outcomes.
The Hydrogel Volume-Expansion Mechanism
HydroSoft™ and HydroFrame® coils are built on a platinum wire substrate, identical in dimensional and flexibility characteristics to standard bare-platinum coils during delivery. The defining feature is a biocompatible hydrogel polymer layer covalently bonded to the outer surface of each coil. Upon contact with blood inside the aneurysm sac, the hydrogel absorbs water and swells to 2–4 times its initial volume over approximately 5–10 minutes, increasing the effective volume of each deployed coil and filling the spaces between adjacent coil loops.
This volume expansion mechanism directly addresses the primary cause of long-term aneurysm recanalization after bare-platinum coiling: compaction of the coil mass over time that creates residual neck or sac void space allowing blood flow re-entry. By expanding after deployment, HydroSoft and HydroFrame fill the residual void before blood can enter it, maintaining a higher packing density across the long-term post-procedure course.
HydroFrame® vs. HydroSoft™: Roles in the Coiling Protocol
HydroFrame is the framing coil variant: placed first into the aneurysm to establish the primary basket scaffold. HydroFrame’s hydrogel expansion after framing tightens the basket against the aneurysm wall and creates a denser initial grid, consolidating the frame before filling. HydroFrame is available in 10 (0.010 in wire) and 18 (0.018 in wire) versions for small-vessel and standard applications respectively.
HydroSoft is the finishing coil variant: placed after framing to fill the residual void within the established basket. HydroSoft 3D provides a complex three-dimensional shape for conforming to irregularly shaped residual spaces, while HydroSoft Helical provides a simple helix geometry for more uniform void spaces. Both HydroSoft variants use a lower-modulus formulation than HydroFrame, allowing them to pack into tight remaining spaces without displacing previously placed coils.
Catalog Reference
HydroFrame 10: 100405HFRM-V (4 mm × 5 cm) through 101036HFRM-V (10 mm × 36 cm). HydroFrame 18: 180619HFRM-V (6 mm × 19 cm) through 182048HFRM-V (20 mm × 48 cm). HydroSoft 3D: 100102HFRM-V (1 mm × 2 cm) through 100620H2HS-V (6 mm × 20 cm). HydroSoft Helical: same diameter and length range as HydroSoft 3D. All variants delivered via Headway 17 microcatheter.
The swelling kinetics are consistent across all HydroSoft and HydroFrame variants: swelling begins within 2 minutes of blood contact and reaches approximately 90% of final volume within 10 minutes. Post-deployment angiography should be performed after allowing full swelling time — typically 10 minutes after the final coil is placed — to accurately assess occlusion grade.
Clinical Evidence: HELPS Trial and Registry Data
The HELPS (Hydrogel Endovascular Aneurysm Treatment) randomised controlled trial compared hydrogel coils (HydroCoil, the predecessor to the current HydroSoft/HydroFrame generation) to bare-platinum coils in 500 patients. At 12 months, the hydrogel arm demonstrated significantly improved angiographic occlusion (Raymond–Roy class I or II) compared to bare platinum, with no increase in procedural complication rates. Retreatment rates were also significantly lower in the hydrogel arm.
Registry data from high-volume centres using the current HydroSoft and HydroFrame generation confirm durable occlusion rates consistent with the HELPS trial findings. Hydrogel coils are particularly effective in aneurysms with wide necks, large dome volumes, and previous incomplete coiling where recanalization has already occurred — precisely the cases where bare-platinum packing density is hardest to achieve and maintain.
Ordering Through Modern Medical Solutions
Modern Medical Solutions is the authorised MicroVention Terumo distributor for Tajikistan and Afghanistan. HydroSoft and HydroFrame are available across the full catalog range for neurointerventional programmes in Tajikistan and Afghanistan.
Contact Modern Medical Solutions to discuss HydroSoft and HydroFrame alongside Cosmos bare-platinum coils as a complete MicroVention Terumo aneurysm coiling portfolio, including guidance on hybrid coiling protocol design for your patient population.
