Abstract
Purpose
Contact force (CF) catheters are useful to address proper contact during ablation. However, interactions between the ablation process, or its associated irrigation flow changes, with the CF sensing may translate into unexpected CF value fluctuations. We aimed to test for unintentional CF value variations during radiofrequency applications at a fixed applied force, with two commercially available catheters (TactiCath™ and SmartTouch™), and to evaluate its theoretical clinical significance by correlating CF-derived automatic ablation algorithms (force-time integral and lesion index) and actual lesion size at two standard CF values.
Methods
Four series of 20 perpendicular epicardial ablations (20 W, 60 s, 17 ml/min) were performed on porcine left ventricle submerged in 37 °C saline. Catheters were mechanically fixed at a constant position and evaluated at 10 and 20 g. CF values were digitally analysed before each application changing irrigation rate (2–17–30 ml/min), and during ablation. Finally, lesions were quantified.
Results
Increasing irrigation before ablation led to a slight but significant CF decrease. During ablation, CF showed a reproducible pattern: fast initial decrease, subsequent increase until higher-than-initial values and final plateau phase (CF variation up to 69% at 10 g). CF variability was significantly higher at 10 g and using TactiCath™. There were no major differences in lesion size between catheters at the same initial CF. CF only correlated mildly to lesion measures, and automatic algorithms globally failed to predict lesion size.
Conclusions
CF measured values spontaneously vary during ablation following a predictable pattern (initial decrease, subsequent increase and final plateau). This is especially remarkable applying lower CF.
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Acknowledgments
We would like to thank Jaime To and Carlos Macian for their assistance during the experiments.
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Dr. Eduardo Franco has received consulting fees from Biosense Webster. Dr. Javier Moreno receives consulting fees from Biosense Webster and St Jude Medical. The rest of the authors declare no conflicts of interest.
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Supplementary Video 1
Typical response of SmartTouch to irrigation rate variations. In this example (not included in the data presented in this paper, and using a different protocol), we increased irrigation rate to 17 ml/min, and then abruptly stopped irrigation. Irrigation increase led to non-significant contact force changes, but irrigation stop led to an important decrease in contact force values. (MP4 36,005 kb)
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Franco, E., Rodríguez Muñoz, D., Matía, R. et al. Contact force-sensing catheters: performance in an ex vivo porcine heart model. J Interv Card Electrophysiol 53, 141–150 (2018). https://doi.org/10.1007/s10840-018-0435-y
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DOI: https://doi.org/10.1007/s10840-018-0435-y