In vivo assessment of catheter-tissue contact using tissue proximity indication and its impact on cardiac lesion formation in pulsed field ablation
Yasuo Okumura, Ryuta Watanabe, Koichi Nagashima, Yuji Wakamatsu, Eric Byun, Qi Chen, Tara Gomez
Abstract
BACKGROUND: No evidence exists regarding whether tissue proximity indication (TPI), an impedance-based contact indicator, can improve in vivo lesion formation and durability during pulsed field ablation (PFA). OBJECTIVE: This in vivo study investigated the relationship between catheter-tissue contact and lesion formation. METHODS: In 5 porcine subjects, PFA applications were delivered at 35 atrial target sites using the VARIPULSE variable-loop circular catheter with the CARTO 3 mapping system. We compared acute ablative low-voltage zones (LVZs; <0.5 mV), chronic LVZs, and pathologic lesions between no/minimum contact (TPI-negative/flickering TPI-positive status) and consistent tissue contact (consistent TPI-positive status) for typical clinical scenarios and tissue tenting (TPI-positive status with electrodes extensively away from the 3-dimensional mapping surface) for safety margin. Ultrasound imaging also confirmed contact category assessments. RESULTS: Acute and chronic LVZs were significantly larger with consistent contact compared with no/minimum contact, including pathologic lesion length (36.0 ± 12.5 mm vs 17.4 ± 15.2 mm; P = .002) and maximum width (10.3 ± 2.7 mm vs 5.7 ± 5.1 mm; P = .035); results with tenting (length: 34.6 ± 11.7 mm; width: 11.3 ± 1.9 mm) were comparable to consistent contact. Lesion transmurality was achieved in all lesions with consistent contact or tissue tenting but only in 54.5% with no/minimum contact (P = .001 for each). The TPI-based electrode contact distance, measured as the cumulative length of the multielectrode catheter tip positive for TPI, significantly correlated with lesion length, maximum width, and transmurality. CONCLUSION: Consistent TPI-based contact during PFA was strongly associated with distinct chronic transmural lesions, emphasizing the importance of tissue contact in optimizing circumferential lesion formation with circular PFA catheters.