A Unique Longitudinal Muscle Contraction Pattern Associated With Transient Lower Esophageal Sphincter Relaxation

Background & Aims: Contraction of the longitudinal muscle of the esophagus may play a role in the relaxation and opening of the lower esophageal sphincter (LES). The goal of our study was to determine the pattern and precise temporal correlation between local longitudinal muscle contraction (LMC) of the esophagus during peristalsis and transient LES relaxation (TLESR). Methods: Esophageal pressures and high-frequency intraluminal ultrasound imaging of the esophagus were recorded in 24 healthy subjects during swallow-induced peristalsis and spontaneous TLESR. Intraluminal multiple impedance recordings were obtained to determine the relationship between “common cavity pressure” and gastroesophageal reflux (GER). Results: During swallow-induced peristalsis, there is simultaneous contraction of circular and longitudinal muscles of the esophagus. On the other hand, TLESR is associated with a distinct pattern of LMC in the esophagus that has the following characteristics: (1) it is restricted to the distal esophagus; (2) it begins before the onset of TLESR and spreads in a retrograde manner; (3) it is generally stronger than the swallow-induced contraction; and (4) it is sustained during the entire duration of TLESR. The increase in esophageal pressure during TLESR is temporally correlated with the contraction of the LM of the distal esophagus, rather than with the impedance recorded GER. Conclusions: We propose that the LMC of the distal esophagus may play an important role in the relaxation of LES and induction of GER.

Abbreviations used in this paper: HFIUS, high-frequency intraluminal ultrasonography, LMC, longitudinal muscle contraction, TLESR, transient lower esophageal contraction