Regional heterogeneity of right atrial repolarization. Monophasic action potential mapping in swine.

Abstract Objectives. To establish a set of reference values for regional dispersion of repolarization of the right atrium in the in situ heart of pigs and to see if the global dispersion of repolarization could be estimated from regional mapping. Design. Monophasic action potential (MAP) were sequentially recorded from 28 ± 3 sites in seven different regional areas of the right atrium: lateral, anterior and posterior wall, septum, sinoatrial node (SAN), appendage, and near the tricuspid annulus (TA) in 10 healthy pigs using the CARTO mapping system. Results. The activation time (AT), MAP duration (MAPd) and end of repolarization time (EOR) of the whole right atrium were 68 ± 7, 239 ± 20 and 270 ± 23 ms, respectively. There were no significant differences on MAPd and EOR among the seven regional areas, nor between each of the regional and global values. The global dispersions of the MAPd and EOR were 75 ± 19 and 103 ± 13 ms, which were significantly greater than those obtained from any of the seven regional areas and those between two remote regions, SAN vs. TA and SAN vs. appendage regions. Conclusions. The data of regional and global dispersion of repolarization in healthy pigs can serve as reference values for evaluation of increased dispersion of repolarization. The global dispersions of MAPd and EOR in the right atrium were poorly estimated from regional mapping, suggesting the importance of global mapping in evaluating the dispersion of atrial repolarization.