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Impedance decrement indexes for avoiding steam‐pop during bipolar radiofrequency ablation: An experimental study using a dual‐bath preparation
Author(s) -
Saitoh Osamu,
Oikawa Ayaka,
Sugai Ayari,
Chinushi Masaomi
Publication year - 2020
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/jce.14764
Subject(s) - medicine , ablation , electrical impedance , radiofrequency ablation , ohm , ventricle , biomedical engineering , nuclear medicine , cardiology , electrical engineering , engineering
This experimental study was conducted to explore impedance monitoring for safely performing bipolar (BIP) radiofrequency (RF) ablation targeted to arrhythmia focus. Methods and Results Using a newly designed dual‐bath experimental model, contact‐force‐controlled (20‐g) BIP ablation (50 W, 60 s) was attempted for porcine left ventricle (17.0 ± 2.7 mm thickness). BIP ablation was successfully accomplished for 60 s in 75 of the 89 RF applications (84.3%), whereas audible steam‐pop occurred in the other 14 RF applications (15.7%). Receiver operating characteristic analysis demonstrated the optimal predictive values regarding the occurrence of steam‐pop as follows; thinner myocardial wall (≤14.8 mm), low minimum impedance (≤89 ohm), greater total impedance decrement (TID) (≤ −25 ohm) and %TID (≤ −22.5%). Greater impedance decrement was not observed immediately preceding the occurrence of steam‐pop but appeared around 15 s before. Four steam‐pops happened before reaching the optimal predictive values of minimum impedance, whereas all 14 steam‐pops developed 11.5 ± 9.2 and 8.1 ± 8.1 s after reaching the optimal predictive values of TID and %TID, respectively. Total lesion depth (endocardial plus epicardial) was 10.7 ± 1.2 mm on average, and was well correlated with TID and %TID. Transmural lesion through the myocardial wall was created in 22 RF applications. Conclusion Relatively thinner areas of the myocardium are likely to be at greater risk for steam‐pop during BIP RF ablation. Lowering the RF application energy to reduce the impedance decrement may help to lessen this risk.