An RR simulator was developed as part of the Computers in Cardiology Challenge (entry no. 184). The simulator was based on observed physiological changes as they exist in normal subjects.
Mean RR was dependent upon sleep and activity state. Mean RR was randomly chosen to lie within the range 0.6 to 1.2 s. During periods of activity mean RR fell between 0.1 and 0.2 s. The number periods of activity during the wake time ranged from 3 to 7, with durations of 3 to 30 minutes. During the night the number of spontaneous arousals was between 5 to 25 with durations of between 5 and 20 s. Baseline changes were simulated by addition of low frequency sinusoids with periods of 5, 7 and 13 hours.
It is known that the frequency spectrum of normal RR shows a strong 1/f component and a peak at around 0.1 Hz. These were simulated by adding to the mean RR pink noise and a number of random phased sinusiods at around 0.1 Hz.
Variation in RR due to respiration were dependent on sleep and activity states. The frequency of variation ranged from 0.06 to 0.3 Hz and the amplitude of variation from the mean RR ranged from 0.05 to 0.3 s.
A random number of sudden increases in RR to between 1.5 and 2 s were introduced during periods of activity to represent measurement artifacts.
Bowers EJ, Langley P, Drinnan MJ, Allen J, Smith FE, Murray A. Simulation of cardiac RR interval time series. Computers in Cardiology 2002; 29: 233-6.
Ms Emma Bowers, Freeman Unit, Newcastle upon Tyne. Tel: +44 (0)191-223-6161.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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