Passive Monitoring to Active Regulation: Closed-Loop Piezoelectric Theranostic Platform Enabling On-Demand Vagus Stimulation for Terminating Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia (IST), characterized by unexplained acceleration of sinus rhythm, poses significant diagnostic and therapeutic challenges due to its paroxysmal and limited treatment options. This study proposes a closed-loop theranostic platform (TP-IST) based on an implantable piezoelectric fiber patch (iPFP) for on-demand vagus nerve stimulation for real-time monitoring of heartbeat and terminating IST, achieving a shift from traditional passive monitoring to revolutionary active regulation. Due to the enhanced piezoelectric response of the hot-press-treated piezoelectric fibers, the iPFP exhibits outstanding sensing performance, which can capture the heartbeats and generate synchronized electrical signals. The implantable real-time transceiver (iRT) processes electrical signals and releases vagus nerve stimulation on demand to terminate tachycardia. Prolonged TP-IST intervention inhibits the function and neural activity of the right stellate ganglion (RSG) by downregulating the expression of c-fos and nerve growth factor (NGF) in the sympathetic neurons, thus attenuating the severity of sympathetic-induced IST. Biocompatibility assessments confirm minimal cytotoxicity (cell viability >90%) and negligible tissue inflammation postimplantation. Experimental results in the large animal model suggest that the developed TP-IST exhibits excellent effectiveness and safety in terminating IST. This work is expected to enrich the treatment of cardiac arrhythmia and provide innovative guidance for cardiovascular disease management.