An esothoracic electrode for electrophysiological studies

A flexible polythene esothoracic electrode was passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus, were used for bipolar atrial pacing and recording. Ventricular pacing was performed using a cathodic point source on the esothoracic electrode tip; the indifferent electrode (anode) was a high impedance chest pad. Parameters of atrioventricular (AV) nodal function were obtained by atrial pacing. Programmed ventricular stimulation was performed using a standard protocol. Electrophysiological parameters were subsequently determined using an endocardial approach. There was close correlation between measurements of AV node function in 48 subjects: AV Wenckebach Cycle Length (AVWCL) r(2) =.97. The degree of agreement was estimated by the mean difference delta and standard deviation of the difference sigma (AVWCL sigma = 7 ms, delta = 16 ms). Programmed ventricular stimulation was performed in 15 subjects with known or suspected ventricular tachyarrhythmias. In subjects where ventricular tachycardia was induced by using both esothoracic and endocardial approaches, the rate, morphology, and haemodynamic consequences were similar. In several cases, ventricular tachycardia was pace-terminable using overdrive esothoracic ventricular pacing. Electrophysiological parameters determined with this electrode were similar to those obtained with endocardial stimulation.