Reliability of spectral analysis of the heart rate variability signal from a commercial Holter system

Power spectral analysis of the heart rate variability signal coming from a traditional Holter recording, might be contaminated by several sources of error. The authors performed a statistical characterization of the measurement error (ME) of some common spectral parameters obtained analyzing the 24-hour R-R intervals list generated by a commercial Holter system. Two ECG signals with known modulation of the R-R interval were generated into a PC and fed to three Holter recorders successively equipped with four different tapes. One ECG signal had `normal´ variability (var=2376 msec<sup>2</sup>), while the other `reduced´ variability (var=86 msec²). Twenty-four 10 minute recordings were analyzed on each tape. For each investigated parameter the ME was computed subtracting its true value obtained before Holter recording from its value estimated from the Holter generated R-R list. It was found that the investigated Holter equipment can affect power spectral estimates on the reduced variability tachogram