Session PC1.1

The Chaos Theory and Non-Linear Dynamics in Heart Rate Variability in Patients with Heart Failure

G Krstacic*, D Gamberger, A Krstacic, T Smuc, D Milicic

Institute for Cardiovascular Diseases
Zagreb, Croatia

Objective: To evaluate and quantify the non-linear dynamic changes of heart rate variability (HRV) based on chaos theory and fractal analysis in patients with heart failure (HF).
Methods: To investigate the clinical significance of fractal dimension (FD), detrended fluctuation analysis (DFA) and approximate entropy (ApEn), two different groups during 12 months were studied. First, the group of 250 patients with HF (> 40 years old, echo EF LV < 40%, NYHA class II-III and LVIDd > 2.9 cm/m2). They all received standard therapy for heart failure (diuretics, digoxin, ß-blockers, spironolactone, nitrate and ACE-i or ARB's). The control group consisted of 100 randomly selected age matched and sex matched healthy subjects. The patient's group was included in the series after complete non-invasive cardiovascular tests. Series of R-R intervals were obtained from high resolution ECG during 24-hours ECG, and the recording time scale was approximately about 100000 beats. The FD was determined by the range standard analysis. To quantify fractal long-range correlations properties of HRV, the DFA technique, was used. Approximate entropy (ApEn) is a measure and parameter that quantified the regularity or predictability of time, and the creation of information in a time series.
Results: The fractal dimension was significantly higher in patients with HF, while DFA (alpha1)and ApEn were lower than in healthy subjects. The results show existence of crossover phenomena between short time scales estimated by the DFA method. The results show that patients with HF had loss normal fractal characteristics and enhanced regularity in HRV, while patients with standard therapy for HF after 12 months show benefit in HRV.
Conclusions: The measurement of fractal scaling exponent in short-time series, fractal dimension and approximate entropy could give complimentary information on abnormal HR behavior in patients with HF, and positive impact of modern standard treatment of HF patients.

(Abstract Control Number: 159)