Thermal Profile of Contact Force Dependent Pulse Field Electroporation Beyond Calcium Electroporation at the Koch...

Contact force (CF)-dependent pulse field electroporation (PFE) may generate tissue heating, affecting junctional rhythm at the triangle of Koch (ToK) in a clinical setting. PFE may also disrupt calcium homeostasis, causing calcium electroporation (CE) for some Joule heating. The impact of CF on PFE and CE for electrode temperature (ET) at the ToK has not been validated.

A CF-sensing catheter with an ET probe was positioned perpendicularly on dissected ToK from 12 swine. PFE was applied in four groups: low CF-calcium chloride (CC, 5.0 mM; LCF-CC, 2-10 g), high CF-CC (HCF-CC, 11-50 g), LCF-saline solution (SS; CF-SS, 2-10 g), and HCF-SS (11-50 g). ET changes derived from (LCF-CC minus LCF-SS) and (HCF-SS minus LCF-SS) was operationally defined as dominant CE (DCE) and PEF (DPFE) components, respectively.

Fewer time-temperature curves with straight, abrupt surge (AS) followed by sudden descent (SD) were observed in LCF-CC versus other groups (p < 0.001). The delayed AS-maximal temperature (MT) curve is almost absent in the LCF-SS versus LCF-CC group (6.3% vs. 70.3%, p < 0.001). The highest △AS-MT was detected in HCF-CC and LCF-CC groups (4.3 ± 0.7°C vs. 4.3 ± 1.0°C, p = 0.37). △△AS-MT was larger from DCE than the DPFE effect (1.1 ± 1.0°C vs. 0.4 ± 0.4°C, p < 0.001). Although △SD-MT was similar in DCE and DPFE groups (p > 0.05), △△SD-MT (resistance to △SD-MT) was more prominent in DCE (0.2 ± 0.5 vs. -0.1 ± 0.5, p < 0.05). More extensive △SD-MT/duration was synchronously changed with short duration in LCF-CC or HCF-SS versus HCF-CC, and DCE group (p < 0.05).

The in vitro model showed biphasic ET changes (initial rise followed by decline) correlated with CF-dependent CE and PFE. CF significantly modulated ET dynamics while maintaining safe thermal thresholds. Further studies should clarify how this biphasic pattern affects junctional rhythm generation in vivo conditions.