Biomechanical and sensory parameters of the human esophagus at four levels

The biomechanical and sensory characteristics of the lower esophageal sphincter (LES) and those of the striated and smooth muscle portions of the esophagus have not been compared in humans. Our aim was to determine sensory perception, cross-sectional area (CSA), and biomechanical parameters at different levels of the esophagus. We studied 11 healthy volunteers, using impedance planimetry. Intermittent balloon distensions (5-60 cmH₂O) were performed at four sites: 1) the LES, 2) 5 cm above LES (distal), 3) 10 cm above LES (mid), and 4) 5 cm below the upper esophageal sphincter (proximal). During these distensions, CSAs, biomechanical parameters, and sensory responses were measured. The mid-esophagus had a higher (P < 0.05) CSA than the distal esophagus. The LES had the smallest CSA (P < 0.05). The LES and the proximal esophagus had greater (P < 0.05) wall tension and were less (P < 0.05) deformable than the mid- or distal esophagus. Sensory thresholds were lower (P < 0.05) in the proximal compared with the mid- or distal esophagus. Biomechanical and sensory parameters are not uniform along the length of the esophagus. The striated muscle portion is more sensitive and less compliant than the smooth muscle portion. These differences could affect the results of balloon distension tests of the esophagus.