Recovery Assessment of Open-heart Cardiac Surgery Patients Using Heart Rate Variability Parameters

Surgical operation causes short-term stress changing the balance of the autonomic nervous system (ANS). The ANS activity can be assessed through heart rate variability (HRV). This work aims to evaluate the recovery process of open-heart cardiac surgery patients under two post-surgery physiotherapy interventions using HRV parameters. Ten-minute ECG recordings were performed on 17 open-heart cardiac surgery patients pre-operatively (PREOP) and during three consecutive post-operative days (POD1, POD2 and POD3). The recovery process was promoted using two different physiotherapy techniques: positive expiratory pressure (PEP, N = 9) and inspiratory training (IMT, N = 8). Common HRV parameters (SDNN, LF power and SD1) were calculated for each patient and statistical analyses were performed. The results show significant differences between HRV parameters pre- and post-operatively, and there was a reduction of all three investigated HRV parameters in the POD1 for both groups. HRV parameters average values increased between POD1 to POD3 for both intervention groups indicating that patients were eventually starting to recover from the surgery. Statistically significant difference between PEP and IMT interventions was not discovered (e.g., p = 0.54 for SDNN, PREOP vs. POD3). Based on the results, all studied HRV parameters are potential indicators of the short-term recovery after cardiac surgery.