AUGMENTED VERY-LOW FREQUENCY COMPONENT OF HEART-RATE-VARIABILITY DURING OBSTRUCTIVE SLEEP-APNEA

After documenting the presence of obstructive sleep apnea syndrome (OS AS) through polysomnographic monitoring, we performed simultaneous amb ulatory recordings of electrocardiogram, oronasal airflow, and pulse o ximetry on 12 OSAS patients with normal autonomic nervous function for a period of 24 hours. The power spectrum of heart rate variability wa s investigated before and during treatments using dental appliances. F requency domain analysis showed that the very low frequency component of heart rate (0.008-0.04 Hz) was increased in OSAS patients and that a very low frequency peak appeared during episodes of obstructive slee p apnea. The increase in very low frequency identification was synchro nized with episodes of absence of air exchange or hypoxemia (decreased arterial oxygen saturation) that occurred repeatedly at a cycle lengt h of 25-120 seconds in our subjects. Frequency domain analysis of hear t rate variability before and during prosthetic mandibular advancement treatment showed that only the very low frequency was significantly d ecreased during prosthetic mandibular advancement treatment, whereas t he other frequencies, i.e. high, low, and ultralow frequency component values, showed no significant changes. Time domain analysis of heart rate variability before and during prosthetic mandibular advancement t reatment showed no significant changes in any of these parameters. Fre quency domain analysis of heart rate variability during nocturnal slee p, especially investigation of very low frequency and very low frequen cy peak, can be a noninvasive low-cost approach to diagnose and even b etter monitor subjects undergoing treatment at home, particularly cons idering that R-R intervals can be extracted from pulse oximetry and th at analysis software programs are already commercially available.