The C-FLOW study: catheter-induced changes in flow dynamics in thromboaspiration.

BACKGROUND: Super large-bore 0.088" aspiration catheters (SLAC) are increasingly used for endovascular stroke treatment. Prior in-vitro studies suggest that maximizing the catheter-to-vessel ratio improves distal flow control and may reduce distal embolization. However, the hemodynamic consequences of catheter insertion - particularly changes in local flow velocity - are unknown. We evaluated the relationship between catheter size, volumetric flow, and tip velocity using controlled bench-top models. METHODS: Two flow systems were built: Setup #1 with a single-path taper and Setup #2 with a proximal bypass simulating collaterals. Four catheters (Zoom 88, Sofia 88, HiPoint 88, RED 72) were tested. Flow was recorded under open and catheter-in-place conditions. Volumetric flow was measured downstream across five runs per configuration, and catheter tip velocity was calculated from flow and effective annular area. RESULTS: In Setup #1, SLAC produced modest reductions in volumetric flow (-4.5% to -6.1%), while RED 72 reduced flow by -3.2%. Despite these limited flow changes, calculated tip velocities increased markedly with the larger catheters: HiPoint 88 + 573%, Zoom 88 + 488%, Sofia 88 + 434%, compared with +102% for RED 72. In Setup #2 SLAC caused substantial reductions in volumetric flow (-55.2% to -58.6%), whereas RED 72 reduced flow by -18.5%. Velocity amplification remained disproportionate: HiPoint 88 + 197%, Zoom 88 + 159%, Sofia 88 + 151%, versus +70% for RED 72. CONCLUSION: In an experimental model, SLAC produce modest reductions in bulk flow but generate marked increases in the local estimated mean annular velocity at the catheter tip. Future translational and clinical studies should confirm and investigate potential implications of these findings.