Objective: 

The aim of this study is to evaluate Heart Rate Variability (HRV) as an important marker of autonomic nervous system (ANS) modulation before and after coronary artery bypass graft (CABG) surgery in patients (n=10) with the diagnose of coronary artery disease (CAD).

Methods: 

Five minute electrocardiography (ECG) epochs were recorded before and 4–5 weeks after the surgery by using MITSAR recording system in order to calculate Heart rate (HR) data. Spectra of HR were divided into low (LF: 0.02–0.05Hz)- and high (HF: 0.2–0.35 Hz)-frequency bands. All statistical analyses were performed with t-test by using SPSS-PC 16.0.

Results: 

The average values of LF and HF band powers of HRV data were decreased after the surgery without any statistically significance (LF: p=0.47, HF: p=0.81). The decrease in LF/HF ratio after surgery was statistically significant (p= 0.04).

Conclusions: 

Reduced LF/HF (marker of sympathovagal balance as a measurement of HRV) indicates higher parasympathetic activation after surgery. Although the preliminary results point the effects of CABG surgery on ANS modulation of heart rate, to increase reliability of the results, more patients and recordings in later periods (6–12 months after surgery) would be beneficial. The present work was supported by the Research Fund of Istanbul University. Project No. 6285