Abstract. Atrial conduction disturbances are common substrate for re-entrant atrial arrhythmias. Heterogeneity of structural and electrophysiological properties of atrial tissue creates the possibility for unidirectional block during premature beats and initiation of re-entry. But the correlation between AF severity and degree of atrial conduction within the atria remains unclear. P wave time domain analysis of signal averaged (SA) P wave and recently A wave SA of intraatrial potentials were implied to investigate electrophysiologic properties of atrial myocardium.

The aim of our study was to examine and compare time domain high gain, SA P wave (recorded from conventional and intraatrial leads) in pts with different severity of AF considered for permanent BiAP.

Methods. We performed examinations in 24 pts with atrial conduction disturbances and different frequency of recurrence of arrhythmia (we used Kingma’s division) during implantation of biatrial pacing system. External signals (Ext.) were obtained conventionally from Frank orthogonal leads. Intraatrial signals were recorded separately from right and left atrium, using bipolar pacing atrial leads placed in RAA and CS and ventricular lead temporarily placed in LRA position. Signals gathered during sinus rhythm were filtered and recorded with Codax SAI-IK amplifier, digitized by A/D converter and stored on PC. We analyzed following S.A. ECG (IEGM) parameters: P wave duration (Pdur), root mean square voltages of the last 20 ms of P wave (RMS20) and duration of low amplitude signal < 5mV (LAS5). We considered ALP as positive if Pdur > 125 ms and RMS20 < 2,40 mV.

Results.

Conclusion. SA P wave duration, root mean square voltages of the last 20 ms of P wave (RMS20) and duration of low amplitude signal < 5mV (LAS5) in SA ECG and SA intraatrial IEGM in both external and intraatrial leads do not correlate significantly with severity of atrial fibrillation, with exception for SA P wave duration in external lead. The tendency of differences indicates however that larger cohort of pts should be examined to obtain statistical significance.