Esophageal shortening during swallow

(A) Before swallow - Clip B marks the position of the squamocolumnar junction (SCJ), 35 mm distal to the anchor point on the vertebral body; clip A is affixed to the esophageal mucosa 31 mm proximally. Clip movements are referenced to point V on the vertebral column.
(B) At the time of maximal esophageal shortening during swallow, clip B is 20 mm distal to point V and the distance between clips A and B is reduced to 22 mm, indicative of 29 percent shortening.
(C) As elongation proceeds, first both clips descend, after which clip B descends, stretching the A-B segment back to its initial length.
(D) After swallow recovery to normal.