PERIOPERATIVE MYOCARDIAL-ISCHEMIA IS ASSOCIATED WITH A PROLONGED CARDIAC VAGAL DYSFUNCTION AFTER NONCARDIAC SURGERY

Background: Heart rate variability (HRV), a measure of cardiac autonom ic balance seems to be linked to coronary artery disease (CAD). impair ed vagal input facilitates the generation of fatal arrhythmias and has a great impact on morbidity and mortality. The purpose of this study was to determine the relationship between perioperative HRV and the in cidence of silent myocardial ischemia (SMI) and ventricular dysrhythmi as in CAD-patients undergoing non-cardiac surgery. Methods: 31 patient s were studied by continuous Holter electrocardiography preoperatively and again on the evening before surgery until postoperative day 3. Th ree frequency and one time domain measures of HRV (TP, 0.01-1.00 Hz: t otal power of the amplitude spectral plot; LF, 0.04-0.15 Hz: low-frequ ency power; HE 0.15-0.40 Hz: high-frequency power; MeanRR: mean of all coupling RR-intervals between normal beats) as well as ischemic event s and ventricular couplets and runs were computed. Results: Depending on the presence of ischemic episodes, each patient was assigned to eit her the no SMI-group (13 pts) or the SMI-group (18 pts). MeanRR, TP an d LF significantly declined in both groups over time. The parasympathe tically dominated index HE however, only decreased in the SMI-group. N ormalized HF power (HF/TP) even increased in the no SMI-group resultin g in a postoperative decrease in LF/HF ratio. TP, LF and HF inversely correlated with ischemia parameters whereas HF/TP and HF/LF ratio corr elated with the number of ventricular couplets. Incidence and severity of SMI significantly increased after surgery. Conclusion: Postoperati vely, a prolonged vagal withdrawal occurred in CAD-patients exhibiting perioperative SMI. Whether the increased incidence of SMI after surge ry in conjunction with the observed parasympathetic derangement contri butes to adverse cardiac outcome still has to be determined.