Role of Microcatheter Tip Position and Microguidewire Stiffness in Safe Neuroendovascular Navigation of Distal Vessels

BACKGROUND AND PURPOSE: Advancements in neuroendovascular devices have enabled greater access to distal, tortuous vasculature. However, this expanded capability also increases the risk of serious hemorrhagic complications during device navigation. The aim of the study is to quantify how microcatheter position and microguidewire stiffness affect tip contact force at a distal middle cerebral artery segment. MATERIALS AND METHODS: A moderate tortuosity silicone model of the middle cerebral artery was used to evaluate three 0.014" Synchro SELECT microguidewires (Soft, Standard, Support) with a TrevoTrak 21 microcatheter positioned proximally in the M1 or distally in the M2 segment. Tip contact forces at the distal end of the M2 segment were recorded with a digital force gauge serving as a standardized surrogate for the distal vessel wall during motorized controlled wire advancement. From the force-distance curves, tip contact force slopes (mN/mm) and maximum tip contact forces (mN) were calculated and statistically compared across wire types and catheter positions. RESULTS: With distal microcatheter support, the average tip contact force slopes were 10.64 mN/mm (Soft), 10.85 mN/mm (Standard), and 15.28 mN/mm (Support) (p < 0.0001). With proximal support, the average slopes were significantly lower: 1.61 mN/mm (Soft), 3.15 mN/mm (Standard), and 3.87 mN/mm (Support) (p < 0.01). Distal microcatheter positioning consistently produced approximately 3 to 6-fold higher tip contact force slopes and higher maximum tip contact forces than proximal positioning. CONCLUSIONS: Microcatheter tip position and microguidewire stiffness were the primary determinants of tip contact force transmitted to distal vessel segments during neuroendovascular navigation in this model. Stiffer microguidewires exert significantly greater tip contact force, particularly when the microcatheter is positioned near the distal segment. Maintaining the microcatheter tip proximally attenuates these forces and offers a simple strategy to reduce mechanical loading of fragile distal branches during distal access procedures.