A resonant-heating stent for wireless endohyperthermia treatment of restenosis

Abstract This paper reports an electrothermally active stent targeted at the application to endohyperthermia treatment for in-stent restenosis, a common complication that causes failures of stent implantation. The stainless-steel stent designed to function as an electrical inductor is integrated with a flexible capacitor strip to form a passive resonant circuit. This stent-based circuit serves as a frequency-selective wireless heater that is controlled using a tuned radiofrequency (RF) electromagnetic field radiated externally, locally applying thermal stress to the stented site to suppress neointimal hyperplasia, the main cause of in-stent restenosis. The fabricated stent device with the initial diameter of 2 mm is expanded up to 6 mm in diameter to simultaneously deploy the resonant heater circuit and the mechanical scaffolding structure inside an artificial artery using a balloon catheter. The expanded device is revealed to generate electromotive forces close to 1 V and shows heat generation with temperature rise of >30 °C in air when resonated using an RF source power of 320 mW. Temporal and frequency characteristics are evaluated to demonstrate rapid heating ability with strong frequency sensitivity. These results encourage further studies and design optimization towards wireless stent hyperthermia that potentially offers a novel therapeutic path to long-term inhibition and management of in-stent restenosis.