Quantifying expert resistance perception from vessel wall deformation in intracranial catheter navigation

Intracranial catheter navigation relies on haptic cues interpreted as resistance. However, resistance perception is subjective, limiting standardized training. Prior studies measured forces at the proximal device end, but vessel-wall deformation during catheter advancement has not been synchronized with expert resistance judgment. In this feasibility study, outer-wall strain was used as a relative index of wall deformation in a tortuous vascular phantom.

Six board-certified neurointerventionalists, each performing one navigation trial, advanced a 0.021 inch microcatheter over a 0.014 inch microguidewire through a tortuous vascular phantom with nine sequential bends, eight instrumented with outer-wall strain gauges. Operators reported mild resistance and unacceptable resistance, defined as resistance beyond which advancement was judged unsafe in this phantom. Vessel strain was recorded continuously without real-time feedback.

In this phantom, when mild resistance was first reported, maximum strain among instrumented gauges reached 410.8±102.9 µε, localized approximately two bends proximal to the catheter tip, on average. At unacceptable resistance, maximum strain increased to 850.3±219.8 µε at the most proximal gauge. Peak strain location shifted proximally as perceived resistance escalated, and further distal tip advancement ceased. Strain at unacceptable resistance consistently exceeded that at mild resistance.

In this phantom, expert resistance perception was associated with reproducible vessel-wall strain patterns. Because microstrain values are model-specific, they should be viewed as relative deformation indices, not patient-applicable thresholds or measures of in vivo wall stress. Linking subjective resistance to quantifiable wall deformation may support objective assessment of resistance perception and proficiency-based simulation training, pending validation.