Heart Rate Variability for Prediction of Perioperative Events

Hypotension and bradycardia following induction of anesthesia may result in insufficient organ perfusion. Patients with underlying cardiovascular disease are at high risk of perioperative cardiovascular events and death. Hemodynamic variables are controlled by the autonomic nervous system reflected by Heart Rate Variability (HRV). Several authors demonstrated depressed long-term HRV in patients with underlying cardiovascular disease. Depressed 24 hours HRV proved to be highly predictive for cardiovascular morbidity and mortality Recently, short-term analysis was demonstrated to be a reliable tool to predict hypotension after spinal anesthesia. No data are available, however, with respect to preoperative HRV values and incidence of postoperative cardiovascular events. To investigate the prognostic value of HRV in patients with underlying cardiovascular disease. Hypothesise i) differences in pre-operative HRV are present in patients with underlying cardiovascular disease, ii) depressed preoperative HRV indicates high risk of post-operative cardiac ischemia, iii) depressed preoperative HRV is associated with longer postoperative hospital stay and adverse cardiac events after hospital discharge.

First, patients are assigned to one of two groups depending on the presence or absence of postoperative cardiac ischemia; second, a predictive model will be built to confirm our findings prospectively in another group of patients.

Patients: 100 patients (ASA physical status class II - IV) scheduled for general anesthesia. Inclusion criteria:evidence of high perioperative cardiovascular risk based on the Revised Cardiac Risk Index (RCRI >3).Exclusion criteria: lack of sinus rhythm, emergency cases, postoperative admission to an intensive care unit and age under 18 years. Time and frequency domain parameters of HRV will be recorded at the day of surgery before induction of anesthesia. Cardiovascular events and outcome will be analyzed.