Variability of QRS-shape and heart rate in magneto/electrocardiograms of healthy subjects and risk patients

Bandlimited frequency components are used to estimate the variability of QRS-shape and heart rate. Utilising complex binomial filters, the applied signal processing method allows to analyse envelope and phase (current frequency) of the bandpass signal independently of each other. A beat-to-beat analysis of envelope and current frequency of the entire QRS interval gives an estimate of the QRS variability. A short term heart rate variability is calculated in terms of the heart frequency deviation of the continuously filtered cardiac signal which is determined by the bandwidth of the envelope spectrum in the vicinity of the mean beat frequency. Mean-to-standard deviation ratio of the envelope and current frequency and the heart frequency deviation are combined to a parameter that separate cardiac signals of patients suffering from ventricular arrhythmia from cardiac signals of healthy persons