Differing effects of adaptive servoventilation and continuous positive airway pressure on muscle sympathetic nerve activity in patients with heart failure.

BACKGROUND Long-term adaptive servoventilation (ASV) increases cardiac function more effectively than continuous positive airway pressure (CPAP), possibly via alleviation of sympathetic overactivation. The present study evaluated the effect of ASV and CPAP at comparable pressure on muscle sympathetic nerve activity (MSNA) in patients with heart failure (HF) and with or without periodic breathing (PB). METHODS AND RESULTS A total of 57 patients with HF (ejection fraction <0.45) were randomized to receive CPAP (n=28) or ASV (n=29). Respiratory profiles and MSNA were continuously monitored before and during CPAP and ASV (30min) at pressures of 6.5 and 6.6cmH2O, respectively. The severity of respiratory instability was determined using the coefficient of variation of tidal volume (CV-TV). Although heart rate and blood pressure remained unchanged, only ASV improved CV-TV. MSNA decreased in the ASV (P<0.001), but not in the CPAP group. The change in CV-TV independently predicted changes in MSNA (P<0.001). Device type and PB significantly interacted with changes in MSNA (P<0.05) and ASV exerted sympathoinhibitory effects in patients with PB, whereas CPAP did not. A sympathoinhibitory effect in patients without PB was not evident in either treatment arm. CONCLUSIONS ASV probably exerts its sympathoinhibitory effects in patients with HF and PB through pressure support.