"Awakenings": electrocardiographic findings in central sleep apnea.

Central sleep apnea is an important but frequently missed clinical diagnosis. The purpose of this clinical case series is to demonstrate that in a subset of patients with central sleep apnea, inpatient telemetry ECG recordings may reveal a consistent relationship between changes in sinus rate, AV conduction, and the presence and rate of respiratory artifact that should raise the clinical suspicion of central sleep apnea. In the three presented cases, marked sinus bradycardia or AV block was followed by the simultaneous occurrence of abrupt acceleration of heart rate and the appearance of rapid micro-oscillations consistent with respiratory artifact. These changes suggested central sleep apnea characterized by bradycardia during the apneic spells followed by awakening of the breathing center and postvagal tachycardia. In each case, central sleep apnea was confirmed by visual observation of the patient, documentation of arterial desaturations during episodes of bradycardia, and in two, by a subsequent sleep study. Physicians should be aware of the potential and significance of these electrocardiographic disturbances in patients with central sleep apnea.