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Determinants of Impedance Rise During Catheter Ablation of Bovine Myocardium with Radiofrequency Energy
Author(s) -
RING MICHAEL E.,
HUANG SHOEI K. STEPHEN,
GORMAN GRACE,
GRAHAM ANNA R.
Publication year - 1989
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1989.tb06155.x
Subject(s) - medicine , catheter , electrical impedance , ablation , biomedical engineering , saline , catheter ablation , anesthesia , cardiology , surgery , electrical engineering , engineering
Recently, radiofrequency (RF) energy has been used as an alternative energy source to direct‐current (DC) electricity for catheter ablation of recurrent tachyarrhythmias. Since delivered energy is inversely related to impedance, factors that cause impedance rise during catheter ablation impede the ability to ablate tissue. To elucidate some of the factors responsible for impedance rise during RF (750 kHz) catheter ablation using a constant voltage RF generator, the effects of the following variables on impedance were studied in an in vitro bovine heart model: power setting (10–70 W), pulse duration (10–60 sec), catheter contact pressure (5‐1 20 gm), repeated applications (2–4), and immersion media (saline vs citrated blood). Baseline impedance in blood was twice that of saline (190 vs 80 ohm) and rises in impedances occurred more rapidly in blood for the same energy settings. Increased power settings (≥ 30 W) and pulse duration (≥ 30 sec at 20 W) were associated with impedance rises in blood medium. Typically, impedance rises in blood were associated with blood coagulum on the catheter electrodes. Impedance rises in both saline and blood media were also associated with tissue charring and endocardial surface disruption. Once a rise in impedance occurred at the ablation site, repeated applications to the same site resulted in a more rapid rise in impedance. Catheter contact pressure of 80 gm or more also resulted in rapid impedance rise. These data suggest that factors other than set power and duration may also contribute to impedance rises during RF ablation. These Endings may have important clinical implications in performing catheter ablation with RF energy.