Impedance Monitoring During Radiofrequency Catheter Ablation in Humans

Abstract

Radiofrequency catheter ablation of accessory pathways and the atrioventricular junction often requires multiple applications of energy. The inability to determine the effects of any given application on the underlying tissue may contribute to this problem. In the present study, impedance was monitored in 20 patients undergoing radiofrequency catheter ablation, and the relationship between an initial decrease in impedance and subsequent effects were examined. An initial fall in impedance of more than 10 omega was 78% sensitive and 88% specific for predicting subsequent evidence of tissue heating (interruption of conduction or an abrupt rise in impedance due to coagulum formation). In contrast, initial values of voltage, current, or impedance did not distinguish between effective and ineffective applications of radiofrequency energy. Continuous monitoring of impedance may facilitate radiofrequency catheter ablation.

Saline-Cooled Versus Standard Radiofrequency Catheter Ablation for Infarct-Related Ventricular Tachycardias

“…Therefore, we compared only the maximal values among systems, recognizing that this is only a crude indication of the energy applied. Methods for standard RF energy application guided by temperature 15,16 or impedance monitoring have been well defined, and both methods yielded similar effects in the present study. The optimal manner of energy titration for cooled RF application has not been clearly defined.…”

Impedance and Temperature Monitoring Improve the Safety of Closed‐Loop Irrigated‐Tip Radiofrequency Ablation

“…The impedance fall that occurs during RF ablation has been postulated to be caused by an increase in tissue temperature, 7,8,10,12 but some authors have detected irreversible changes in components of the impedance 11 . Data recorded during repeated ablations at the same site suggested that the impedance drop occurring during radiofrequency ablation in cardiac tissue appeared to be due to reversible factors (e.g., temperature) rather than irreversible changes.…”

“…The safety and efficacy profile of fixed power 3 and temperature control 4,5 during irrigated‐tip catheter ablation have been investigated previously. Titration of RF power using the drop‐in impedance during ablation has been proposed as an alternative strategy to temperature‐controlled or fixed‐power ablation protocols 6–8 . The impedance drop during radiofrequency (RF) ablation has been postulated to be secondary to increased myocardial tissue temperature 7,9,10 .…”

Predictive Factors for Efficacy of Catheterbased Renal Denervation with Standard Ablation Catheter in Refractory Hypertension

“…Standard ablation catheter with 4 mm head end used in our study was supposed to make larger contact area as previously referred and in the use of it, good catheter contact could result in effective tissue heating and durable ablation lesions. Early study revealed the relationship between the initial impedance change and tissue heating, and indicated that an initial fall in impedance beyond 10 ohms would predict interruption of accessory pathways' conduction [20]. Until now, impedance decrease has even been an indicator of good catheter contact as evidenced by force sensing catheterization technique [21].…”