Systemic arterial pressure oscillations during periodic breathing in chronic heart failure patients

Periodic breathing (PB) has a high prevalence in chronic heart failure (CHF) patients with mild to moderate symptoms and poor ventricular function. In this work we analyzed by spectral techniques the fluctuating pattern of systolic (SAP) and diastolic (DAP) arterial pressure and their relationship with contemporary ventilatory activity during this abnormal respiratory pattern. Supine resting recordings (8 min) of lung volume (LV), SAP and DAP were obtained from 20 CHF patients showing stable PB. Spectral components in the very low frequency band (VLF, 0.01÷0.04 Hz), low frequency band (LF, 0.04÷0.15 Hz) and high frequency band (HF, 0.15÷0.45 Hz) as well as the coherence and phase spectrum for the relationship LV-SAP and LV-DAP were estimated. All signals showed a clear narrowband component at about 0.02 Hz which was markedly dominant in SAP and DAP (86% and 72% (median values) of total power) and much lower in LV (38%). The power of the LF component was negligible (3.3%, 5% and 2.6% for SAP, DAP and LV). Around the VLF and HF peaks we found a high coherence both for LV-SAP (0.76, 0.88) and LV-DAP (0.76, 0.80). The phase delay was -56° and -71° for LV-SAP and -28° and -87° for LV-DAP. These results demonstrate that during PB most of SAP and DAP variability reflects the abnormal pattern of respiratory activity. The marked increase of the gain LV-SAP and LV-DAP in the VLF band with respect to the HF band suggests that neural mechanisms such as chemoreceptor and cardiopulmonary receptor reflexes may contribute to the VLF modulation of arterial pressure induced by respiration.