New insights on the origin of the VLF cardiorespiratory rhythm in chronic heart failure patients

Abstract

In this study the authors investigated in a group of 14 chronic heart failure (CHF) patients showing a periodic breathing (PB) pattern: 1) the phase relationship between ventilation and arterial O/sub 2/ saturation to verify the respiratory control instability hypothesis of PB; 2) the relationship between these signals and heart period (HP) variability. A clear very low frequency (VLF) oscillation around 0.02 Hz, associated with PB, was observed in the instantaneous lung volume (ILV), instantaneous minute ventilation (IMV), O/sub 2/ saturation at the ear (SpO/sub 2/) and HP signals. The coherence between signals was on average >=0.8, thus confirming that during PB a more general cardiorespiratory rhythm takes place. The median phase lag between IMV and SpO/sub 2/ was -206/spl deg/ (IMV leads); between ILV and HP was -202/spl deg/ (ILV leads). SpO/sub 2/ and HP were almost synchronous. The authors' findings are consistent with and clearly support the instability hypothesis for PB. As concerns the link between respiratory and HP oscillations the authors' results point out that, besides central coupling and lung stretch receptors feedback, an important role in the linkage between respiratory and cardiovascular regulation might be played by arterial chemoreceptors.