Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function.
OBJECTIVE
Dual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function.


METHODS
Twelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction >or=50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system.


RESULTS
In patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test).


CONCLUSIONS
Compared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function.
Ferro
Adele
A
Department of Biomorphological and Functional Sciences, Institute of Biostructure and Bioimages of the National Council of Research, University Federico II, Naples, Italy.
Duilio
Carlo
C
Santomauro
Maurizio
M
Salvatore
Marco
M
Cuocolo
Alberto
A
D000368:Aged; D001794:Blood Pressure; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005080:Exercise Test / Q000379:methods; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods*; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000628:therapy*; D016138:Walking