Evolution in time and scales of the stability of heart interbeat rate

¹ SATMEX - Av. de las Telecomunicaciones S/N CONTEL Edif. SGA-II, México, D.F. 09310, México
² Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional Av. IPN No. 2580, Col. Ticomán, México D.F. 07340, México
³ Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional Edif. No. 9, U.P. Zacatenco, México D.F., 07738, México

^a ricardohdzpz@gmail.com

Received: 14 August 2010
Accepted: 7 December 2010

Abstract

We approach heart interbeat rate by observing the evolution of its stability on scales and time, using tools for the analysis of frequency standards. In particular, we employ the dynamic Allan variance, which is used to characterize the time-varying stability of an atomic clock, to analyze heart interbeat time series for normal subjects and patients with congestive heart failure (CHF). Our stability analysis shows that healthy dynamics is characterized by at least two stability regions along different scales. In contrast, diseased patients exhibit at least three different stability regions; over short scales the fluctuations resembled white-noise behavior whereas for large scales a drift is observed. The inflection points delimiting the first two stability regions for both groups are located around the same scales. Moreover, we find that CHF patients show lower variation of the stability in time than healthy subjects.