Autonomic responses to heartburn induced by esophageal acid infusion

Background and Aim: Studies have shown that altered visceral perception and lower pain thresholds in patients with symptomatic gastroesophageal reflux disease (GERD) and non-cardiac chest pain. Autonomic changes associated with the perception of heartburn in patients with GERD are poorly understood. Methods: A total of 12 GERD patients (six male, six female; mean age 37.2 +/- 2.7 years) and 12 controls (five male, seven female; mean age 32.8 +/- 2.2 years) were studied. The study protocol included a 20-min water infusion (6 mL/min), and 20-min acid infusion (0.1 N HCl, 6 mL/min). Spectral analysis of heart-rate variability (HRV) was used to assess autonomic functioning. The measured HRV indices included the power in the low-frequency (LF) band (0.04-0.15 Hz) reflecting sympathetic tone, and power in the high-frequency (HF) band (0.15-0.5 Hz) reflecting vagal tone, and the LF/HF ratio as an indicator of sympathovagal balance. Results: The GERD group experienced more heartburn than controls with acid infusion. Between-group comparisons showed no significant changes in LF band power in any period. The HF band power was significantly lower in GERD patients during all infusion periods. The LF/HF ratio was significantly larger in GERD patients. Conclusions: The perception of heartburn induced by esophageal acid infusion is associated with a simultaneous increase in sympathetic modulation in patients with GERD. The autonomic responses with esophageal acid infusion are significantly different between healthy subjects and GERD patients. (C) 2004 Blackwell Publishing Asia Pty Ltd.