It has been observed that repeated acid infusions induce stronger symptoms (symptom hypersensitivity).
In this study, researchers from San Diego, California, assessed whether symptom hypersensitivity is associated with esophageal contractile hypersensitivity.
Subjects with chronic heartburn symptoms underwent simultaneous pressure and ultrasound imaging of esophagus.
The team infused normal saline and 0.1 N HCl sequentially into the esophagus. They then scored subjects’ heartburn symptoms on a 1 to 10 scale.
|Acid infusion induced heartburn.|
|AJP Gastrointestinal and Liver Physiology|
The team also repeated the infusions in 10 subjects with a positive Bernstein test.
The researchers measured esophageal contraction amplitude and duration, and muscularis propria thickness.
The team determined that acid infusion induced heartburn.
In addition, esophageal contractions had higher amplitudes and longer duration during acid infusion. Average muscle thickness was greater during acid infusion than saline infusion.
The team identified sustained esophageal contractions during acid infusion.
The researchers established that a second acid infusion (acid-2) induced heartburn with shorter latency and stronger severity than the first acid infusion (acid-1).
Furthermore, contraction amplitudes, average muscle thickness, and contraction duration were higher during acid-2 than acid-1.
Dr Vikas Bhalla and colleagues concluded, “Our data show that acid infusion into esophagus induces esophageal hypersensitivity and that a close temporal correlation exists between symptom hypersensitivity and contractility hypersensitivity”.