Wave propagation in the atrial myocardium: dispersion properties in the normal state and before fibrillation.

The formalism of wave propagation in passive media is applied to the spread of the electrical excitation in the human atrial myocardium. From an analog of the classical dispersion dependence that is obtained by wavelet decomposition a precursor parameter is calculated that serves to predict fibrillation already before its onset.

High-frequency oscillations of the heart rate during ramp load reflect the human anaerobic threshold.

The aim of this study was to analyze the dynamic behavior of the high-frequency component (HF > 0.15 Hz) of heart rate variability (HRV) and the respiratory frequency in relation to the anaerobic threshold (AT). Twenty-two healthy subjects [mean (SD) age: 24 (6) years, height: 175 (10) cm, body mass: 65 (11) kg] completed a ramp load, with increments of 20 W x min(-1), on a cycle ergometer.