An optimized approach for increasing lesion size in temperature‐controled setting using a catheter with a surface thermocouple and efficient irrigation

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Abstract
Background: We explore an optimized approach for increasing lesion size using a novel ablation catheter with a surface thermocouple and efficient irrigation in a temperature‐control setting.Methods: We conducted radiofrequency applications at various power levels (35 W, 40 W, and 45 W), contact forces (CFs, 10 g/20 g), and durations (60 s/120 s/180 s) in perpendicular/parallel catheter orientations, with normal saline irrigation (NS‐irrigation) and Half NS‐irrigation (HNS‐irrigation) in an ex‐vivo model (Step 1). In addition, we performed applications (35 W/40 W/45 W for 60 s/120 s/180 s in NS‐irrigation and 35 W/40 W for 60 s/120 s/180 s in HNS‐irrigation) in four swine (Step 2), evaluating lesion characteristics and the occurrence of steam pops.Results: In Step 1, out of 288 lesions, we observed 47 (16.3%) steam pops, with 13 in NS‐irrigation and 34 in HNS‐irrigation (p = .001). Although steam pops were mostly observed with the most aggressive setting (45 W/180 s, 54%) with NS‐irrigation, they happened in less aggressive settings with HNS irrigation. Lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. The optimal %impedance‐drop cutoff to predict steam pops was 20% with a negative‐predictive‐value (NPV) = 95.1% including NS‐ and HNS‐irrigation groups, and 22% with an NPV = 96.1% in NS‐irrigation group. In Step 2, similar to the ex‐vivo model, lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. Steam pops were absent with NS‐irrigation (0/35) even with the largest %impedance‐drop reaching 31% at 45 W/180 s. All steam pops were observed with HNS‐irrigation (6/21, 29%). The optimal %impedance‐drop cutoff predicting steam pops was 24% with an NPV = 96.3% including both NS‐ and HNS‐irrigation groups.Conclusions: Rather than using HNS‐irrigation, very long‐duration of radiofrequency applications up to 45 W/180 s may be recommended to safely and effectively increase lesion dimensions using this catheter with NS‐irrigation.
Funding Information
  • Japan Society for the Promotion of Science (20K17074, 22K16068)

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