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Comparison Between Three Time Series of Rr Intervals Registered in Three Different Periods Using Heart Rate Variability Analisys

Jesus Paulo C; Santos Luciano M; Paula Wagner D, Carvalho Hervaldo S; Junqueira Jr Luiz;

University of Brasilia Department of Internal Medicine. Division of Cardiology
70910-900, Brasilia, DF - Brazil.
Tel: 55 (002161) 307-2274, Fax: 55 (002161) 344-0384



Introduction: In the clinical evaluation of the cardiac autonomic function based on Heart Rate Variability (HRV) the effects related to the period of time to acquire the electrocardiographic signal have not been properly characterized.
Objective: To compare the influence of three different time series of RR intervals – 2 minutes and 5 minutes of electrocardiographic acquisition and the number of 256 RR intervals (RRint) – in the temporal and spectral indexes of HRV obtained with this series.
Subjects and Methods: We studied 31 healthy individuals (19 M, 2 F – median age of 28 years – minimum = 45 and maximum = 19). RRint series were sequentially obtained from the ECG registered (DII, 25 mm/s), in supine position, during 5 minutes, with a graphical mark at 2 minutes; the 256 RRint were obtained by counting them since the beginning of registration. The differences were compared by Kruskal-Wallis test (using, if necessary, the Student-Newmann-Keuls [SNK] test as a discriminator), at a p < 0.01.
Results: No statistical differences were verified in comparing the temporal indexes (mean and coefficient of variation) in the three time series of RRint (p = 0.52 – 0,99). In the spectral indexes we observed statistical difference only in the total power (p < 0.001), using the SNK we observed that the comparison between the time series of 2 minutes and 5 minutes and that the 256 RRint and 5 minutes showed statistical differences (p<0.05), but the comparison between the time series of 2 minutes and 256 RRint did not show any difference ( p > 0,05).
Conclusion: The comparison between this 3 different time series of RRint did not show critical differences in the HRV analysis, this suggests that HRV can be done with any of this short term time series, but it seems preferable to use the series of 256 RRint and/or of 5 minutes of duration. (CNPq, FAPDF).


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