Ultrasound thrombolysis primarily relies on transient shockwaves and microjets from collapsing cavitation bubbles to mechanically disrupt thrombus structures. While demonstrating clinical potential, its efficacy remains limited by low cavitation energy transfer efficiency and unpredictable tissue damage, stemming from incomplete understanding of single bubble dynamics and the synergistic mechanisms of multi-bubble interactions.
This study introduces a hyper-viscoelastic constitutive model incorporating blood clot mechanics to analyze stress accumulation under sequential microbubble impacts. A gas-liquid-solid coupled multi-physics model quantifies bubble collapse dynamics near thrombi, integrating structural damping terms to represent energy dissipation during fluid-structure interactions. Parametric analysis reveals that jet impact intensity positively correlates with thrombus mass and ultrasound amplitude, but inversely relates to dimensionless distance, ultrasound frequency, and initial bubble radius.
The proposed rate-dependent Ogden-Prony model effectively captures thrombus behaviors under transient impacts, including strain hardening, rate-dependent strengthening, and stress relaxation. Sequential jet impacts induce cumulative stress through strain hardening, with multi-bubble synergy achieving significantly higher stresses than single-bubble impact. Optimal bubble radius distributions enable amplified normal/shear stresses within thrombi – double bubble impact sequences generate 6.02 MPa maximum normal stress, surpassing thrombus tensile strength, versus 1.45 MPa from single bubble impact. Key quantitative relationships between bubble cluster parameters, dimensionless distance, thrombus mass, and stress accumulation provide optimization guidelines for ultrasound thrombolysis. Notably, controlled multi-bubble jet impact sequences with attenuated pressure peaks demonstrate enhanced therapeutic potential through cumulative mechanical effects rather than single high-intensity impacts.
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