REGIONAL RIGHT AND LEFT ATRIAL ACTIVATION PATTERNS DURING SINGLE-SITEAND DUAL-SITE ATRIAL-PACING IN PATIENTS WITH ATRIAL-FIBRILLATION

We examined the activation of the right atrium and left atrium by paci ng from different atrial sites using several single- and dual-site atr ial pacing modes in patients with atrial fibrillation or flutter. We a lso analyzed the effect of these pacing modes on fixed coupled extrast imuli in this population. Patients underwent detailed mapping of regio nal right atrial (RA) and left atrial (LA) sites. Bipolar pacing was p erformed individually from the high sight atrium, coronary sinus ostiu m, and the distal coronary sinus, and simultaneously from the high rig ht atrium and coronary sinus ostium (dual-site RA pacing) or high righ t atrium and distal coronary sinus (biatrial pacing). Extrastimuli wer e delivered from the high right atrium at fixed coupling intervals of 350 and 250 ms. Twenty patients with atrial fibrillation were studied. P-wave duration during pacing was significantly abbreviated by both d ual-site RA and biatrial pacing (p <0.001 vs high RA pacing, respectiv ely) but not by any other single-site atrial pacing method. Both dual- site atrial pacing modes also significantly abbreviated P wave duratio ns for closely coupled high RA premature beats (p <0.001) in contrast to high RA pacing. During the basic pacing drive and for high PA extra stimuli, RA activation at the crista terminalis and atrial septum was comparable in sinus rhythm, high RA pacing, and in both dual-site atri al pacing methods, but was significantly delayed by coronary sinus ost ial and distal coronary sinus pacing. In contrast, proximal coronary s inus activation was delayed with high RA pacing compared with all othe r pacing modes, and high PA extrastimuli encountered seduced conductio n delay at this location with dual-site atrial pacing modes. LA activa tion was advanced superiorly by bath single-site coronary sinus pacing methods and both dual-site atrial pacing techniques. Inferior and lat eral LA activation was advanced by all pacing modes using a coronary s inus pacing site. However, earlier activation of LA sites occurred for high IRA premature beats after both dual-site pacing methods (p <0.05 ) compared with single-site pacing modes. incremental conduction delay at different atrial regions for closely coupled high RA extrastimuli ranged from 33% to 120% during high RA pacing and was significantly at tenuated cat multiple IRA and LA sites by dual-site PA and biatrial pa cing. Distinct global, as well as regional electrophysiologic effects, may mediate the variable antiarrhythmic effects of different and nove l atrial pacing methods. (C) 1998 by Excerpta Medica, Inc.