Catheter-Integrated Fractal Microelectronics for Low-Voltage Ablation and Minimally Invasive Sensing

Pulse field ablation (PFA) has become a popular technique for treating tens of millions of patients with atrial fibrillation, as it avoids many complications associated with traditional radiofrequency ablation. However, currently, limited studies have used millimeter-scale rigid electrodes modified from radiofrequency ablation to apply electrical pulses of thousands of volts without integrated sensing capabilities. Herein, we combine fractal microelectronics with biomedical catheters for low-voltage PFA, detection of electrode-tissue contact, and interventional electrocardiogram recording. The fractal configuration increases the ratio of the microelectrode insulating edge to area, which facilitates the transfer of current from the microelectrode to the tissue, increasing the ablation depth by 38.6% at 300 V (a 10-fold reduction compared to current technology). In vivo ablation experiments on living beagles successfully block electrical conduction, as demonstrated by voltage mapping and electrical pacing. More impressively, this study provides the first evidence that microelectrodes can selectively ablate cardiomyocytes without damaging nerves and blood vessels, greatly improving the safety of PFA. These results are essential for the clinical translation of PFA in the field of cardiac electrophysiology.