Novel Measure of Local Impedance Predicts Catheter–Tissue Contact and Lesion Formation. (April 2018)

• Record Type: Journal Article
• Authors: Sulkin, Matthew S.; Laughner, Jacob I.; Hilbert, Sebastian; Kapa, Suraj; Kosiuk, Jedrzej; Younan, Paul; Romero, Iñaki; Shuros, Allan; Hamann, Jason J.; Hindricks, Gerhard; Bollmann, Andreas
• Is Part Of: Circulation. Volume 11:Number 4(2018)
• Publication Date: 2018-04
• Subjects: cardiac arrhythmias -- catheter -- swine -- therapy -- tissue; Arrhythmia -- Periodicals; Heart -- Electric properties -- Periodicals; 616.128
• DOI: 10.1161/CIRCEP.117.005831
• Languages: English
• ISSNs: 1941-3149

Abstract

Abstract : Background: Coupling between the ablation catheter and myocardium is critical to resistively heat tissue with radiofrequency ablation. The objective of this study was to evaluate whether a novel local impedance (LI) measurement on an ablation catheter identifies catheter–tissue coupling and is predictive of lesion formation. Methods and Results: LI was studied in explanted hearts (n=10 swine) and in vivo (n=10; 50–70 kg swine) using an investigational electroanatomic mapping system that measures impedance from an ablation catheter with mini-electrodes incorporated in the distal electrode (Rhythmia and IntellaNav MiFi OI, Boston Scientific). Explanted tissue was placed in a warmed (37 °C) saline bath mounted on a scale, and LI was measured 15 mm away from tissue to 5 mm of catheter–tissue compression at multiple catheter angles. Lesions were created with 31 and 50 W for 5 to 45 seconds (n=90). During in vivo evaluation of LI, measurements of myocardium (n=90) and blood pool (n=30) were guided by intracardiac ultrasound while operators were blinded to LI data. Lesions were created with 31 and 50 W for 45 seconds in the ventricles (n=72). LI of myocardium (119.7 Ω) was significantly greater than that of blood pool (67.6 Ω; P <0.01). Models that incorporate LI drop (ΔLI) to predict lesion size had better performance than models that incorporate force-time integral ( R 2 =0.75 versus R 2 =0.54) and generator impedance drop ( R 2 =0.82 versus R 2 =0.58). Steam pops displayed a significantly higher starting LI and larger ΔLI compared with successful radiofrequency applications ( P <0.01). Conclusions: LI recorded from miniature electrodes provides a valuable measure of catheter–tissue coupling, and ΔLI is predictive of lesion formation during radiofrequency ablation. Abstract : Supplemental Digital Content is available in the text.