Measurement of electrical coupling between cardiac ablation catheters and tissue.

Managing cardiac arrhythmias with catheter ablation requires positioning electrodes in contact with myocardial tissue. Objective measures to assess contact and effective coupling of ablation energy are sought. An electrical coupling index (ECI) was devised using complex impedance at 20 kHz to perform in the presence of RF ablation and deliver information about electrical interactions between the tip electrode and its adjacent environment. ECI was derived and compared with clinical judgment, pacing threshold, electrogram amplitude, and ablation lesion depth and transmurality in a porcine model. ECI was also compared with force and displacement using ex vivo bovine myocardial muscle. Mean noncontact ECI was 97.2 ± 14.3 and increased to 145.2 ± 33.6 (p <; 0.001) in clinician assessed (CLIN) moderate contact. ECI significantly improved CLIN's prediction of the variance in pacing threshold from 48.7% to 56.8% ( ). ECI was indicative of contact force under conditions of smooth myocardium. Transmural lesions were associated with higher pre-RF (109 ± 17 versus 149 ± 25, ) and during-RF (82 ± 9 versus 101 ± 17, ) ECI levels. ECI is a tip specific, robust, correlate with contact and ablation efficacy, and can potentially add to clinical interpretation of electrical coupling during electrophysiology procedures.