Implantable Knitted Fabric Structured Electrode for Monitoring and Treatment of Cardiac Arrhythmias

Arrhythmia is one of the most common complications during open-heart surgery and poses a serious threat to patient safety if not promptly treated. However, most recently developed implantable electrocardiogram sensors for arrhythmia monitoring and treatment adopt 2D thin-film structures, which are non-breathable and hinder metabolic exchange processes at the cardiac surface. Here, a highly breathable and mechanically adaptive knitted fabric structured cardiac electrode for real-time arrhythmia monitoring and radiofrequency ablation therapy is reported. The electrode is fabricated from nylon fibers coated with gold-shelled silver nanowires via computer-controlled flat knitting techniques. This knitted structure has an ultralow Young's modulus (9.31 kPa), significantly minimizing mechanical interference with cardiac motion. Moreover, the electrode passively stretches during diastole and actively retightens during systole, dynamically conforming to the beating heart, allowing for stable monitoring of the heart's surface for 12 h. The use of nanowires imparts excellent electrical properties, with the electrode impedance being only ≈1/3 that of dense silver wires at 1000 Hz, enabling high-fidelity signal recording and low-voltage ablation. Moreover, the electrode retains stable electrical performance after 500 000 cycles of dynamic strain. In vivo biocompatibility tests validate the safety of the device. In a mouse model, the electrode successfully localizes the origin of abnormal electrical signals during atrial fibrillation and guides effective radiofrequency ablation to restore sinus rhythm, demonstrating strong potential for clinical translation.