Stimulation and characteristics of secondary oesophageal peristalsis in normal subjects

The study evaluates the triggering and characteristics of secondary oesophageal peristalsis in 25 healthy volunteers. Secondary peristalsis was stimulated by rapid intraoesophageal injection of boluses of air and water, and by a five second oesophageal distension with a balloon. Air and water boluses triggered secondary peristalsis that started in the proximal oesophagus regardless of injection site. Response rates were volume dependent with 83% of the 20 ml air boluses triggering secondary peristalsis compared with 2% for the 2 ml water bolus (p < 0.0001). Response rates for air and water were similar for equal bolus volumes and were not influenced by the site of injection. In contrast, balloon distension usually induced a synchronous contraction above the balloon, with secondary peristalsis starting below the balloon after deflation. The peristaltic response rate to balloon distension was also volume dependent and the middle balloon was more effective in triggering secondary peristalsis than either the upper or lower balloons (p < 0.001). Secondary peristaltic amplitude was less than that of primary peristalsis (p < 0.001). Secondary peristaltic velocity with a water bolus was slower (p = 0.001) than that of primary peristalsis. Intravenous atropine significantly reduced secondary peristaltic responses to all stimuli. There was also a significant reduction in pressure wave amplitude for air stimulated secondary peristalsis while those for the water responses were similar. Secondary peristaltic velocity with air and water boluses was not changed by atropine. The reproducibility of testing secondary peristalsis was examined six volunteers and did not show any significant differences on separate test days in response rate and peristaltic amplitude or velocity. It is concluded that in normal subjects, secondary peristalsis can be more reliably triggered by intraoesophageal air or water infusion than balloon distension. Secondary peristaltic amplitude and velocity are stimulus but not site or volume dependent and propagation is partially mediated by cholinergic nerves.