Cardiac sympathovagal balance during endoscopic retrograde cholangiopancreatography.

Background and Study Aims: Cardiopulmonary complications have been reported during upper gastrointestinal endoscopy and endoscopic retrograde cholangiopancreatography (ERCP). The aim of this study was to evaluate the sympathovagal response to the stretching of the common bile duct caused by contrast medium injection during ERCP.
Patients and Methods: The 16 patients included in the study were assigned to two groups according to the size of common bile duct. Group A consisted of patients with normal-sized bile ducts, while Group B patients had dilated common bile ducts. The heart rate variability (HRV) technique was used to assess the sympathovagal balance. The HRV data were gathered using the Holter technique, and frequency domain analysis revealed two main spectral components of HRV: low frequency (LF) and high frequency (HF).
Results: In patients with normal-sized bile ducts, contrast injection initiated a rapid increase in the power spectra (ms2) of both the HF and LF components. In patients with dilated common bile ducts, this phenomenon was not observed.
Conclusions: During ERCP, contrast injection into a dilated common bile duct does not stimulate the autonomic nervous system in the same way as it does when the common bile duct is of normal size.