Some Considerations on the IPFM Model for the Heart Rate Variability Analysis

O Meste

, G Blain

, S Bermon

University of Nice-Sophia Antipolis, Lab. I3S, France

University of Nice-Sophia Antipolis, Medical school, Lab. of Physiology, France

Abstract

The arch or inverted arch signals are characterizingpatterns of the Respiratory Sinus Arrhytmia. The abilityof any model in generating these patterns can be a goodcriteria for their selection. We show that using the tidalvolume signal as the input of the model, an alternative tothe IPFM can be proposed. The relevance of our model isshown with synthesized and real signals.

1. Introduction

It is commonly admitted that the IPFM model is apossible model for the generation of the R waves timeoccurrences . The use of the outputs s for the frequencyanalysis of the heart rate variability has been studied indetail in several papers. The latest [1], [2] gives somerecommendation in using these outputs in order to reduceor cancel the distortion of the spectrum. The problem ofthe choice for the model input is not usually addressedand is simplified using a single or a sum of cosines butnot a real physiological signal, the respiration for instance.Since the Respiratory Sinus Arrhytmia (RSA) is one ofthe most important component of the heart rate variabilityit is straightforward that effort should be made in takingthe respiration as an input of the model. In the last CinCwe have proposed [3] a model for the generation of the Rwaves:

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#$#

(1)%'&

(

*),+ -/.021

where 3 is an external modulation. It willbe shown in the following paper that similarly to the IPFMmodel a time occurrences generator, called PFM model, canbe deduced from the expression (1). The condition for thecorrect use of the heart period signal defined as (4 5 6

7

98

will be also given. The aim of this communicationis to compare these two models regarding their ability tomimic the RSA when a real or a synthetic respiration signalis used as the input of the model.

It has been shown that the repetitive pattern of theRSA can exhibit different shapes [4] depending on thesubjects and experimental conditions. These shapes couldbe compared to arch or inverted arch and will be designatedconsequently. Since this shape analysis is a step forwardcompared to classical frequency analysis we will checkwhether the PFM or the IPFM can exhibit these patternsunder some artificial experimental conditions. We willclose this communication presenting a real case. Thiscase compares the outputs obtained from the two models,using the recorded respiration volume as the input, to themeasured heart period signal from the real ECG signal.

2. Models definitions and properties

Starting from the R-waves generator defined by (1) andassuming that the maximum of ) correspond to thetime occurrence of interest $ , it is clear that the s arethe solution of the equation:

:

;

=>:>@ . The proposed solution of this equationis: