We propose a simple normalized index (i.e. the percentage of positive variations between two successive sample, PV%) and a procedure based on surrogate data to detect irreversible time series. This index was applied to short term heart period variability series (~300 cardiac beats) derived from 10 young healty humans at rest (R), during head-up tilt(T) and controlled respiration at 10, 15 and 20 bresths/minute (R10, R15, and R20). We found that heart period variability is time irreversible in 30%, 60%, 60%, 60% and 40% of the subjects at R, T, R10, R15 and R20 respectively. Mostly during T, R10, R15 and R20 the values of PV% indicate the presences of bradycardic runs (i.e. sequences characterized by heart period lengthening) lasting less than tachycardic ones, thus indicating a specific asymmetry of the temporal features present in the heat period variability series.
Time reversibility in short-term heart period variability / A. Porta, S. Guzzetti, N. Montano, T. Gnecchi Ruscone, R. Furlan, A. Malliani. - In: COMPUTERS IN CARDIOLOGY. - ISSN 0276-6574. - 33:(2006), pp. 4511792.77-4511792.80. (Intervento presentato al convegno Computers in cardiology tenutosi a Valencia nel 2006).
Time reversibility in short-term heart period variability
A. PortaPrimo
;N. Montano;R. FurlanPenultimo
;A. MallianiUltimo
2006
Abstract
We propose a simple normalized index (i.e. the percentage of positive variations between two successive sample, PV%) and a procedure based on surrogate data to detect irreversible time series. This index was applied to short term heart period variability series (~300 cardiac beats) derived from 10 young healty humans at rest (R), during head-up tilt(T) and controlled respiration at 10, 15 and 20 bresths/minute (R10, R15, and R20). We found that heart period variability is time irreversible in 30%, 60%, 60%, 60% and 40% of the subjects at R, T, R10, R15 and R20 respectively. Mostly during T, R10, R15 and R20 the values of PV% indicate the presences of bradycardic runs (i.e. sequences characterized by heart period lengthening) lasting less than tachycardic ones, thus indicating a specific asymmetry of the temporal features present in the heat period variability series.Pubblicazioni consigliate
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