Coronary artery bypass grafting (CABG) with cardiopulmonary bypass has been associated with more frequent occurrence of arrhythmic events than surgery performed without CABG. We explored the effects of arrested- and beating-heart revascularization procedures on the dynamics of ventricular repolarization and on increased postoperative arrhythmic events. Postoperative arrhythmic events were significantly more frequent in both groups. One week postoperatively these events were significantly more frequent in the on-pump group.
Non-linear analyses of heart rate dynamics reveal subtle changes not evident from conventional heart rate variability measures. In 67 patients revascularized with beating-heart technique, fractal dimension and detrended fluctuation analyses were obtained from 24-hour Holter and 15-minute high-resolution ECG recordings pre and postoperatively. We found strong correlations of non-linear indices between 24-hour and 15-minute recordings (0.54–0.77, p < 0.001), unaffected by proportion of artifacts.
Patients experiencing postoperative deterioration of ventricular arrythmia already have impaired autonomic regulation before surgery. Higher postoperative values of the low fractal dimension index indicate that sympathetic predominance with or without concomitant vagal withdrawal is the underlying neurogenic mechaism contributing to ventricular arrythmia.