Figure 18 - Esophagogastric junction high pressure zone relative to the diaphragmatic hiatus.

Length and position of EGJ high pressure zone relative to the diaphragmatic hiatus among groups of normal subjects (group 1), subjects in whom the squamocolumnar junction (SCJ) was 0 to 2 cm above the diaphragm at rest (group 2), and subjects in whom the SCJ was >2 cm above the diaphragm at rest (group 3). Subject groups were defined by radiographically imaging an endoscopically placed metal mucosal clip. The horizontal bars depict the average limits of the high-pressure zone within each subject group (mean standard error in centimeters). The position of the respiratory inversion point (RIP) is constant among subject groups, whereas the position of the SCJ is progressively more cephalic in groups 2 and 3. Similar to the type IV patients in Figure 9, the group 3 subjects in this investigation had a patulous hiatus and no detectable high-pressure zone at the diaphragmatic hiatus. Thus, the net effect was of shortening the high-pressure zone and positioning the SCJ relatively distally within the high-pressure zone such that it likely would be visible endoscopically from a retroflexed view. (Source: Kahrilas et al.,⁹ with permission from American Gastroenterological Association.)