Holter ECG monitoring of sympathovagal fluctuation during bronchoscopy.

BACKGROUND AND AIMS The changes of autonomic nervous activity during bronchoscopic procedures are closely related to the development of cardiovascular complications. We aimed to evaluate the changes of autonomic nervous activity during bronchoscopic procedures using R-R interval variability from electrocardiograms (ECGs) obtained during diagnostic bronchoscopy. METHODS Twenty-four patients who underwent bronchoscopy were included. Continuous ECG was recorded prior to, during and after the bronchoscopic procedure. Time and frequency domain analyses of heart rate variability were performed. RESULTS Heart rate increased significantly after pre-medication compared with that before pre-medication and increased further during bronchoscopy. The coefficient of variation (CVRR ) values after pre-medication and during bronchoscopy were significantly higher than those before pre-medication (P = 0.031 and P = 0.041, respectively). The low frequency (LF) power decreased during bronchoscopy. LF powers obtained after bronchoscopy were significantly lower than those obtained before bronchoscopy (P < 0.041). The high-frequency (HF) power was found to be decreased during bronchoscopy. In particular, HF powers obtained after bronchoscopy were significantly lower than those obtained before bronchoscopy (P < 0.019). Although the LF/HF ratios increased after pre-medication, they decreased temporarily during the bronchoscope insertion. CONCLUSIONS This study shows for the first time that Holter ECG monitoring during diagnostic bronchoscopy was associated with activation of cardiac sympathetic and withdrawal of cardiac parasympathetic regulation, which may contribute to the occurrence of cardiac events during bronchoscopic procedures. So, Holter ECG monitoring during bronchoscopic procedures may confer reduction in cardiovascular events.