Passive Monitoring to Active Regulation: Closed-Loop Piezoelectric Theranostic Platform Enabling On-Demand Vagus...

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.