ANATOMICAL RELATIONSHIP BETWEEN CRURAL DIAPHRAGM AND LOWER ESOPHAGEALSPHINCTER - AN ELECTROPHYSIOLOGICAL STUDY

We performed electrophysiological studies in 12 normal, healthy subjec ts to determine the relative locations of the lower oesophageal sphinc ter, crural diaphragm and squamocolumnar junction. Oesophagogastric ju nction pressure, crural diaphragm electromyogram and mucosal potential difference were measured using a specially designed catheter. This ca theter had a side hole to measure pressure and electrodes placed aroun d the side hole for crural diaphragm electromyogram recordings. Mucosa l potential difference was measured at the side hole that measured pre ssure. Recordings were obtained using a motorized rapid pullthrough at a constant speed of 0.85 cm/sec. Rapid pullthroughs were performed un der the following conditions: (a) end expiration (diaphragm relaxed), (b) during a sustained maximal contraction of the diaphragm, and (c) d uring 50% of maximal diaphragmatic contraction. Our results show that the lower oesophageal sphincter is 4.4 cm in length, 2 cm of which is located in the abdomen. The crural diaphragm is 1.7 cm in length and s urrounds the proximal half of the lower oesophageal sphincter. The squ amocolumnar junction is located in the upper half of the lower oesopha geal sphincter in the majority of subjects. The relative location of t he lower oesophageal sphincter to the crural diaphragm does not change during diaphragmatic contraction. We conclude that a part of the lowe r oesophageal sphincter is located in the abdomen. The intra-abdominal location of the lower oesophageal sphincter may be important for its anti-reflux barrier function.