Cavitation-vibration coupling mechanism in ultrasonic guidewire vascular ablation.

Effective treatment of diverse vascular occlusions requires precise energy delivery and tissue-specific ablation strategies. This study systematically investigates the coupled mechanical vibration and cavitation mechanisms of a novel flexible ultrasonic guidewire during ablation of calcified, lipid-rich, and thrombotic occlusion mimics. Integrating numerical simulations and experimental validation, this work elucidates the dynamic interplay between ultrasonic parameters and tissue-specific ablation outcomes. For calcified mimics, mechanical vibrational impact is the dominant ablation mechanism, achieving substantial material removal primarily through fracture. Lipid-rich tissue ablation is driven by emulsification via cavitation microjets and acoustic streaming, generating microparticles with sizes of 10-250 μm, controllable by ultrasonic power. Thrombus ablation involves initial penetration followed by erythrocyte lysis, primarily mediated by transient cavitation. Crucially, guidewire bending significantly attenuates tip vibration amplitude, resulting in a reduction of 14.3-30.9 %, with titanium alloy exhibiting superior energy transmission stability under curvature compared to nickel-titanium. These findings highlight distinct, tissue-dependent ablation paradigms: mechanical fragmentation for hard tissues compared to cavitation and streaming induced emulsification or lysis for soft tissues. This mechanistic understanding is foundational for designing adaptive ultrasonic guidewires capable of adjusting energy delivery modes based on real time feedback of tissue characteristics, thereby enhancing the precision and efficacy of endovascular interventions.