Clinical utility of local impedance monitoring during pulmonary vein isolation

Abstract

Introduction: A novel ablation catheter that can measure local impedance (LI) was recently launched. We aimed to explore target LI measurements at each radiofrequency application (RFA) for creating sufficient ablation lesions during pulmonary vein (PV) isolation. Methods: This prospective study included 15 consecutive patients scheduled to undergo an initial ablation of paroxysmal atrial fibrillation (AF). Circumferential ablation around both ipsilateral PVs was performed using a 4-mm irrigated ablation catheter with an LI sensor. Point-by-point ablation was used with a 4-mm inter-ablation-point distance. Operators were blinded to LI measurements during the procedure. Creation of sufficient ablation lesions was assessed by the absence of a conduction gap. Results: After first-pass encircling PV antrum ablation, left atrium to PV conduction remained in 12 of 30 (40%) ipsilateral PVs. Mapping using the mini-basket catheter identified 48 ablation points through which the propagation wave entered the PV. At ablation points with a gap, the LI drop during RFA was half that at points without a gap (12 ± 7 vs. 23 ± 12 ohm, p<0.001). The GI drop did not differ between ablation points with and without a gap (12 ± 7 vs. 14 ± 10 ohm, p=0.10). An LI drop of 15 ohm predicted sufficient lesion formation without a gap with a sensitivity of 0.71, specificity of 0.81, and predictive accuracy of 0.75. Conclusion: A target LI drop of 15 ohm at each RFA with a 4-mm distance between adjacent ablation points may facilitate creation of sufficient ablation lesions during PV isolation

The correlation between local impedance drop and catheter contact in clinical pulmonary vein isolation use

“…As previously described, a nonstimulatory alternating current (5.0 μA, 14.5 kHz) was delivered between the tip and the proximal ring to create a local potential field. [7][8][9][10] Voltage was measured between the tip electrode and the distal ring. LI was calculated by dividing the voltage by the nonstimulatory current.…”

“…Several studies have reported that the magnitude of LI drop predicted acute PVI segment block, which is similar to our results. 7,8 Das et al 7 reported that the optimal LI drop cut-off value for the anterior/roof segments and that for the posterior/inferior segments were 16.1 and 12.3 Ω, respectively. Masuda et al 8 reported that LI drop of 13.4 Ω predicted acute PV-LA conduction block.…”

“…7,8 Das et al 7 reported that the optimal LI drop cut-off value for the anterior/roof segments and that for the posterior/inferior segments were 16.1 and 12.3 Ω, respectively. Masuda et al 8 reported that LI drop of 13.4 Ω predicted acute PV-LA conduction block. However, these LI drop cut-off values were relatively lower than our results (23.0 Ω).…”

“…5,6 In addition, in clinical studies, the efficacy of monitoring LI drop during RF application has been reported. [7][8][9] Recently, a novel ablation catheter which can monitor both LI and contact parameters including CF and CA (IntellaNav StablePoint;…”

“…A recent study in animal model described that local impedance (LI) drop during RF application was more associated with the lesion size than generator impedance drop 5,6 . In addition, in clinical studies, the efficacy of monitoring LI drop during RF application has been reported 7–9 …”