A periodic breathing (PB) pattern is often observed in chronic heart failure (CHF) patients (pts). In order to clarify the role of this abnormal respiratory activity upon heart period variability we investigated, in a group of 20 stable CHF pts (NYHA class II to III, median EF 24%) showing a PB pattern, 1) whether observed data were consistent with the instability hypothesis of PB and 2) the relationship between oscillations of heart period and the contemporary fluctuations of ventilatory and chemoreceptor activity. Univariate and bivariate spectral analysis were performed on short-term resting recordings of instantaneous lung volume (ILV), instantaneous minute ventilation (IMV), heart period (HP) and arterial O2 saturation at the ear (SpO2). A very low frequency (VLF) oscillation around 0.02 Hz, associated with PB, was observed in all signals and contributed to 75% (23 divide 99) (median (range)) of the HP variability. The coherence between ILV and HP was 0.77 (0.3 divide 0.95) and between SpO2 and HP 0.8 (0.4 divide 0.98). A high coherence was also found between IMV and SpO2: 0.9 (0.6 divide 0.98). The median phase lag between IMV and SpO2 was -211° (-240 divide -156), between ILV and HP -205° (-260 divide -180) and between SpO2 and HP 0° (-26 divide 30). The estimated lung-to-ear circulation time was 24.5 s (12.5 divide 36.5). This study definitely confirms that during PB a common rhythm is shared between the respiratory and cardiovascular regulatory system. Taking into account the error introduced by the measuring process, our results are consistent with the hypothesis that periodic breathing of CHF pts originates from an instability of the feedback control system of ventilation. Hence most of the HP variability of these pts simply reflects the abnormal pattern of respiratory activity.
|Number of pages||3|
|Issue number||1 SUPPL.|
|Publication status||Published - 1996|
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