976-15 Assessment of Pacing Maneuvers to Validate Anterograde Accessory Pathway Potentials

Abstract

Four pacing maneuvers have been proposed to validate anterograde accessory potentials (APP): 1) atrial pacing to induce complete block between the atrial electrogram (Egm) and the APP; 2) atrial pacing to induce complete block between the APP and the ventricular Egm; 3) ventricular pacing to advance the ventricular Egm without altering the timing of the APP; 4) ventricular pacing to advance the APP without altering the timing of the atrial Egm. The purpose of this study was to determine the specificity of these validation techniques by applying them to split Egm's known, based on the location of the recording site, to consist of two atrial components. In 23 patients undergoing an electrophysiology test, a double atrial Egm was recorded in the high, lateral right atrium, mid lateral right atrium, right atrial appendage or the right atrium-inferior vena cava junction. The two atrial Egm components were 54 ± 15 msec apart at baseline. In each patient, critically timed atrial or ventricular premature depolarizations resulted in complete block between the second atrial component and the ventricular Egm, advancement of the ventricular Egm without altering the timing of the second atrial component, and advancement of the second atrial component by 10 – 35 msec without altering the timing of the first component. In no case could complete block be induced between the two components of the atrial Egm. In conclusion, among the four criteria proposed to validate anterograde APP's, the only one which may be specific for an APP is the induction of complete block between the atrial Egm and the APP.