Numerical Investigation of a Dual-Mode Shape Memory Alloy Stent Enabling Secondary Expansion via Focused Ultrasound: A Potential Strategy for Correcting In-Stent Restenosis

Coronary stent implantation is an invasive procedure performed to correct atherosclerosis. The aftermath of this procedure is identified with neointimal hyperplasia, which contributes to in-stent restenosis (ISR), and thus remains a significant clinical challenge. This study introduces a novel, noninvasive conceptual approach for addressing ISR through the thermal activation of shape memory alloy (SMA) stent using focused ultrasound (FU) in a controlled manner to restore luminal patency. COMSOL Multiphysics and ABAQUS finite element software were employed to perform the numerical modeling to simulate the thermal and mechanical responses of the SMA stent integrated into the arterial wall. After 15 s of insonation, the temperature within the tissue layers rises from 37°C to 42.63°C. Surface temperature rise plot confirms that heat is directed at the target region (focal zone) with minimal heating effect to the surrounding tissues. Minor increases in stress development in both the stent and artery observed were within acceptable limits, which indicates mechanical integrity and a low chance of increasing mechanical damage via stretching to the tissue. This development offers a viable alternative to reintervention, providing precise, patient-specific, and ultrasonically guided therapy for ISR.