An <i>in silico</i> structural approach to calcified nodules using a viscoelastic model: bridging mechanics and intervention with prolonged inflation

Calcified nodules (CNs) are challenging lesions in percutaneous coronary intervention (PCI), often requiring repeated interventions after balloon angioplasty. The biomechanical behavior of CNs remains poorly characterized, limiting the development of optimized strategies. This study aimed to evaluate the time-dependent mechanical response of CNs using a viscoelastic finite element model. A coronary artery segment with a protruding CN was modeled, with distinct material properties for the vessel wall and nodule. A Voigt-type viscoelastic model was applied, and internal pressure was simulated on both the luminal and nodule surfaces. Simulations were performed for short (15 s) and prolonged (120 s) inflation durations. The results demonstrated that the calcified region exhibited viscoelastic creep, with displacement accumulating over time under constant pressure. Notably, prolonged inflation led to a greater increase in luminal area compared to short inflation. These findings suggest that CNs deform gradually due to time-dependent mechanical behavior, and that prolonged balloon inflation may facilitate improved luminal expansion. This study provides a mechanics-informed rationale for incorporating inflation duration into PCI strategy for CNs.