Differences in pacing from the atrial appendage and the lateral atrial free wall on left ventricular filling and haemodynamics during DDD pacing.

INTRODUCTION: Atrioventricular sequential pacing involves stimulation from electrodes in the right atrium, generally the atrial appendage (RAA) and the right ventricular apex. The appendage, however, may be unsuitable if a stable position cannot be achieved. The aim of this study was to assess the haemodynamic consequences of different atrial stimulation sites during DDD pacing.
METHODS: In 12 consecutive patients (mean age 67 +/- 7 years) who underwent DDD pacemaker implantation, an additional temporary bipolar pacing electrode was positioned on the right atrial free wall. Pacing was performed alternating from the two locations at 85, 100 and 120 beats per minute (bpm). Paced atrioventricular delay was set at 180 ms. Cardiac output and mitral inflow measurements were performed using Doppler echocardiography.
RESULTS: Pacing at 85 and 100 bpm resulted in a significantly higher A-peak velocity from the RAA compared with the right atrial free wall. Cardiac index was consistently higher from the RAA location (2.4 +/- 1.2 vs 2.1 +/- 0.91. min-1 m-2 at 85 bpm, 2.71 +/- 1.4 vs 2.35 +/- 1.11. min-1 m-2 at 100 bpm and 2.94 +/- 1.5 vs 2.61 +/- 1.41. min-1 m-2 at 120 bpm, P < 0.05).
CONCLUSION: Stimulation from the RAA was superior to stimulation from the right atrial free wall with respect to left ventricular filling and cardiac output. Compared with stimulation from the right atrial free wall, RAA pacing resulted in an increase of 10-15% in cardiac output.