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.

Use of electrical coupling information in AF catheter ablation: a prospective randomized pilot study.

Background: Catheter contact is important for radiofrequency (RF) ablation. Local electrical catheter-to-tissue coupling has been described as a tool to objectively measure contact.

Objective: We hypothesized that pulmonary vein isolation (PVI) ablation using electrical coupling information (ECI) would yield higher rates of PVI than an approach without ECI.

First in human validation of impedance-based catheter tip-to-tissue contact assessment in the left atrium.

Background: In this study, a new method of contact assessment based on the measurement of the local electrical properties at the catheter tip-to-tissue interface was validated in a blinded fashion in vivo in the human left atrium.

Methods: Using a 3-terminal circuit model, local resistance and reactance between catheter tip and tissue surface were measured and combined in an electrical coupling index (ECI). Twelve patients undergoing atrial fibrillation (AF) catheter ablation were included in this study.

Autonomic ganglionated plexi: characterization and effect of epicardial microwave ablation in a canine model of vagally induced acute atrial fibrillation.

Objective: : Autonomic ganglionated plexi (GP) in fat pads near the pulmonary veins may contribute to initiation and maintenance atrial fibrillation (AF). We attempted to localize these plexi in a canine model, and evaluate the efficacy of microwave ablation in eliminating their vagal reflexes.

Methods: : 8 Mongrel dogs (25-31 kg), underwent cervical vagal trunk stimulation to produce AV nodal block and sustained AF.

Direction-dependent conduction abnormalities in a canine model of atrial fibrillation due to chronic atrial dilatation.

Chronic rapid atrial pacing (RAP) leads to changes that perpetuate atrial fibrillation (AF). Chronic atrial dilatation due to mitral regurgitation (MR) also increases AF inducibility, but it is not clear whether the underlying mechanism is similar. Therefore, we have investigated atrial electrophysiology in a canine MR model (mitral valve avulsion, 1 mo) using high-resolution optical mapping and compared it with control dogs and with the canine RAP model (6-8 wk of atrial pacing at 600 beats/min, atrioventricular block, and ventricular pacing at 100 beats/min).