[Heart rate changes in sleep apnea syndrome].

Sleep apnea syndrome (SAS) is often associated with arrhythmias. The study was performed to clarify the characteristics and mechanisms of the heart rate (HR) changes during and after sleep induced apneas. Thirty-one patients with SAS without definitive heart disease, aged 17-78 years (mean 54.2 years), were examined by electroencephalograms, electrocardiograms, electrooculograms, nasal and oral breathing, thoracic and abdominal respiratory movements and arterial oxygen saturation (SaO2). [Results and Discussion] At the onset of sleep apnea, some showed progressive reductions in HR, followed by abrupt tachycardia on the resumption of breathing. Thirty-one patients with SAS were classified into three Groups (A, B, C). Group A demonstrated that HR changes occurred associated with apnea both in stage REM and in stage non-REM. Group B demonstrated that HR changes occurred associated with apnea only in stage REM. Group C demonstrated that HR changes did not occur associated with apnea. In Group A, apnea frequency and apnea index were higher than those of Group C. In Group A, the lowest SaO2 was lower than that of Group C, total time under 90% of arterial oxygen saturation (SaO2) was longer than that of Group C. There was a good negative correlation between oxygen saturation and HR changes. Further, HR changes were augmented by arousal response. This might be related to the arousal response as well as to the cardiostimulatory effects of hypoxia associated with increased ventilation. The arousability in response to apneas might be important in HR changes. In SAS, the degree of HR changes was related to apnea frequency, apnea index, apnea length and sleep stage.(ABSTRACT TRUNCATED AT 250 WORDS)