Parts of this study were presented at the annual meeting of the Heart Rhythm Society, Boston, MA, May 2012.
Ablation Effect Indicated by Impedance Fall is Correlated with Contact Force Level During Ablation for Atrial Fibrillation
Article first published online: 19 JUL 2013
© 2013 Wiley Periodicals, Inc.
Journal of Cardiovascular Electrophysiology
Volume 24, Issue 11, pages 1210–1215, November 2013
How to Cite
DE BORTOLI, A., SUN, L.-Z., SOLHEIM, E., HOFF, P. I., SCHUSTER, P., OHM, O.-J. and CHEN, J. (2013), Ablation Effect Indicated by Impedance Fall is Correlated with Contact Force Level During Ablation for Atrial Fibrillation. Journal of Cardiovascular Electrophysiology, 24: 1210–1215. doi: 10.1111/jce.12215
This study was financially supported by Helse Vest, Norway.
- Issue published online: 28 OCT 2013
- Article first published online: 19 JUL 2013
- Accepted manuscript online: 17 JUN 2013 01:39AM EST
- Manuscript Accepted: 7 JUN 2013
- Manuscript Revised: 23 MAY 2013
- Manuscript Received: 4 FEB 2013
- Helse Vest, Norway
- atrial fibrillation;
- contact force;
- catheter ablation;
Contact Force Correlates with Impedance Fall During Ablation
Previous studies have validated the use of impedance fall as a measure of the effects of ablation. We investigated whether catheter-to-tissue contact force correlated with impedance fall during atrial fibrillation ablation.
Methods and Results
A total of 394 ablation points from 35 patients who underwent atrial fibrillation ablation were selected and analyzed in terms of the presence of stable catheter contact in non-ablated areas in the left atrium. A fixed power output (30 W) was applied for 60 seconds. Contact force, impedance fall, and force-direction angle were retrieved and exported for off-line analysis. Qualified points were divided into 5 groups according to the level of contact force (1–5 g, 6–10 g, 11–15 g, 16–20 g, and >20 g). An acute impedance fall was observed in the first 10 seconds followed by a plateau in group I and by a further fall in the other groups. Group V showed a rise in impedance during the last 20 seconds of ablation. Levels of impedance fall at each time point were significantly different among all the groups (P<0.001) except between groups III and IV. There was a significant correlation between contact force and maximum impedance fall (rho = 0.54, P<0.01). Lesions with a force-direction angle of 0–30° had significantly lower contact force and maximum impedance fall than those with angles of 30–60° and 60–135° (P<0.01).
Under stable catheter conditions, contact force correlates with impedance fall during 60 seconds of ablation. Contact force exceeding 5 g produces greater impedance fall, which probably indicates adequate lesion formation. A contact force greater than 20 g may lead to late tissue overheating.