Background: Analysis of R-R interval variability (RRIV) provides information about cardiac autonomic function. Coronary artery bypass grafting (CABG) causes marked attenuation of RRIV. We analyzed RRIV with an alternative method using electromyography (EMG) in patients undergoing CABG.

Methods: The study included 19 consecutive patients (6 females, 13 males; mean age 57.8±10.2 years) undergoing CABG. R-R interval variability was assessed by EMG studies during quiet and deep breathing before, and one and two months after surgery.

Results: Compared to preoperative values, the mean RRIV values were significantly lower during quiet and deep breathing after one (R-R, quiet, p=0.001; R-R, deep, p=0.009) and two (R-R, quiet, p=0.001; R-R, deep, p=0.006) months of CABG. The mean RRIV values one month after surgery were significantly lower than those obtained two months postoperatively (R-R, quiet, p=0.01; R-R, deep, p=0.001). No correlations were found between RRIV and the following: age, gender, hypertension, smoking, total cholesterol, triglyceride, body mass index, duration of surgery, duration of cardiopulmonary bypass, cross clamp time, mechanical ventilation time, and intensive care unit stay.

Conclusion: Our data showed that CABG is associated with significant attenuation of RRIV within the first two postoperative months, with partial improvement in the latter. Analysis of RRIV with the use of EMG is an alternative method in patients undergoing CABG. It is not a timeconsuming procedure, is easily performed in the EMG laboratory, and is a simple way of reflecting the autonomic function of the heart.

Keywords : Arrhythmia; autonomic nervous system; coronary artery bypass; electrocardiography; electromyography; heart rate; neural conduction; postoperative complications; respiration