Abstract
Prolongation of the QT interval has been associated with increased vulnerability to ventricular arrhythmias and implicated as a mechanism for the Sudden Infant Death Syndrome (SIDS). Since QT prolongation may result from imbalance of the cardiac sympathetic tone and since autonomic activity varies with stage of sleep, this study was performed to determine the effect of sleep stage on the QT interval.
Twenty QT intervals selected at random from the middle periods of REM and Quiet sleep were measured in 8 normal babies studied at monthly intervals for the first four months of life. An accuracy of 2.0 msec, or better was achieved by using a time-base expansion of the ECG and computer averaging of the digitized signal. Sleep staging was done visually using a C4-A1 EEG lead, a single bipolar EOG lead and submental EMG. The QT index (QTc= RR) was significantly greater during Quiet sleep (mean=0.445; SD=0.016) than during RDM sleep (Mean=0.437; SD=0.014)(p<0.001). These results suggest that, contrary to recent speculations, 1) imbalance of the cardiac sympathetic tone is greater in Quiet than in REM sleep in normal infants, and 2) the ventricles may be more susceptible to potentially lethal arrhythmias in Quiet sleep than in REM sleep.
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Hajddad, G., Law, HF., Krongrad, E. et al. EFFECT OF SLEEP STAGE ON THE QT INTERVAL IN NORMAL INFANTS. Pediatr Res 11, 534 (1977). https://doi.org/10.1203/00006450-197704000-00985
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DOI: https://doi.org/10.1203/00006450-197704000-00985