Table 2. Effects of CABG on Heart Rate Variability (HRV) and Heart Rate (HR) Dynamics

Analyses of standard deviation of all R-R intervals (SDNN), average R-R interval, low frequency (LF), high frequency (HF), approximate entropy (ApEn), and Poincaré plot were performed on 1,000-beat segments, and short-term (α¹) and intermediate-term (α²) correlation properties (DFA) were performed in segments of 8,000 beats. Very low frequency of spectral power (VLF), ultra low frequency band (ULF), and scaling exponent of the power law relationship (β-slope) were analyzed in epochs of 24 h. Significance levels were tested with Wilcoxon matched pairs test. Values are means (median) ± SD (range).

*P = 0.05 versus  baseline (preoperative value).

†P < 0.01 versus  baseline.

‡P < 0.001 versus  baseline.

P  values are after Bonferroni correction.

SD1 = instantaneous beat-to-beat HRV; SD2 = continuous long-term HRV; CABG = coronary artery bypass graft; DFA = detrended fluctuation analyses.