Recording of left atrial potentials from pulmonary artery in man

Atrial activation mapping in sinus rhythm in the clinical electrophysiology laboratory: observations during Bachmann's bundle block

INTRODUCTION

The high posterolateral right atrium (RA) is considered the "sinus node area," but we lack information on endocardial atrial activation in sinus rhythm. We studied RA and left atrial (LA) endocardial activation in the electrophysiology laboratory.

METHODS AND RESULTS

Thirty-five patients (21 men) aged 47 +/- 16.4 years (mean +/- SD) underwent RA mapping (22.2 +/- 3.8 points). In 21 patients, LA activation was mapped (11.1 +/- 3.9 points) through the coronary sinus (CS), right pulmonary artery, and/or a patent oval foramen. Fourteen patients had atrial arrhythmias, and 3 an ECG pattern of Bachmann's bundle block. Endocardial RA activation preceded P wave in 5 (-14 +/- 4.2 ms), coincided in 11, and followed P onset in 18 (16.7 +/- 6.6 ms). Location of the zero point varied from the superior vena cava to the low RA and from lateral to paraseptal RA. In 19 patients, activation started simultaneously in 2 to 5 points located >or=1 cm apart. RA activation was descending in most, but in 3 with low onset there was collision in the anterior and septal walls. In 15 of 21 patients, descending LA activation dominated, ending in the mid CS in 12, proximal CS in 1, and simultaneously throughout the CS in 2. In 3 with Bachmann's bundle block, CS activation was ascending and in 2 double potentials were recorded from the LA roof.

CONCLUSION

During stable sinus rhythm, RA activation can start in different areas or simultaneously over large areas resulting in different activation patterns, both in the RA and the LA. LA activation is predominantly descending, but in Bachmann's bundle block it becomes ascending, and double potentials suggest a location of block in the LA roof.

Electrophysiologic effects of intravenous dipyridamole

We evaluated the electrophysiologic effects of dipyridamole given intravenously to 24 patients during intracardiac electrophysiologic study. Electrophysiologic parameters were measured before and 5 minutes following infusion of 0.5 mg/kg of dipyridamole. The drug significantly shortened the sinus cycle length by 26 per cent (P less than 0.001), sinuatrial conduction time by 15 per cent (P less than 0.01), maximal sinus node recovery time by 21 per cent (P less than 0.001), atrial and atrioventricular nodal effective refractory period by 8 and by 11 per cent, respectively (both P less than 0.01), ventricular effective refractory period by 4 per cent (P less than 0.001), paced cycle length to atrioventricular nodal Mobitz type II block by 5 per cent (P = 0.046), and QT interval during sinus rhythm by 10 per cent (P less than 0.01). After dipyridamole, the PA interval increased by 16 per cent (P less than 0.001), the AH interval by 11 per cent (P less than 0.01), and the corrected QT interval by 5 per cent (P less than 0.01). During retrograde conduction we observed a shortening of the ventriculoatrial interval by 6 per cent (P = 0.036), retrograde atrioventricular nodal effective refractory period by 5 per cent (P less than 0.001), paced cycle length to atrioventricular nodal Wenckebach and atrioventricular nodal Mobitz type II block both by 8 per cent (P less than 0.01). We conclude that intravenous dipyridamole increases sinus node automaticity and reduces atrial, atrioventricular nodal and ventricular refractory periods, prolongs intra-atrial and atrioventricular nodal conduction, but does not produce any changes in His-Purkinje system conduction times.(ABSTRACT TRUNCATED AT 250 WORDS)