Design of a Tetrapolar Probe for Electrical Characterization of the Left Atrial Appendage From 0.1 Hz to 100 kHz

Recently, nonthermal pulsed field ablation using electroporation has generated a lot of interest as a potential treatment for atrial fibrillation (AF). The electrical properties, especially the conductivity of cardiac tissues, are used in the treatment planning of nonthermal pulsed field ablation. However, there is no standard approach to measure conductivity, particularly for the left atrial appendage (LAA). Electrical conductivity characterization studies, focusing on cardiac tissues, have used different probe typologies with different electrode sizes. Furthermore, no study has investigated the effect of the probe design on the acquired conductivity. In this study, common leading probe typologies with different electrode sizes are compared in terms of accuracy and measurement repeatability. Using liquid phantoms, differences in terms of measurement accuracy and repeatability are observed between the probe designs that suggest that the measurement probe design influences the data acquisition quality. Based on these results, a custom probe design is proposed suitable for the characterization of the conductivity of the LAA. The probe is tested using ten ex vivo bovine tissue samples between 0.1 Hz and 100 kHz. The mean conductivity of the LAA acquired from the ten samples is 2.5 mS/cm with a standard deviation (SD) of 0.24 mS/cm, which is in line with the conductivity of cardiac tissues in the literature. The conductivity values of the LAA may be useful in electroporation treatment planning. Furthermore, this study suggests that adapting the probe design to the tissue under study can be important.