THE PHRENIC AMPULLA - DISTAL ESOPHAGUS OR POTENTIAL HIATAL-HERNIA

The mechanics of phrenic ampullary emptying were analyzed to determine whether this structure functions in a manner similar to the tubular e sophagus or a hiatal hernia. Simultaneous videofluoroscopy and intralu minal manometry of the gastroesophageal junction were done during bari um swallows in 18 normal volunteers. Esophageal emptying was studied w ithout any external influences, during abdominal compression with a cu ff inflated to 100 mmHg, during a Muller maneuver, and after medicatio n with atropine. The key finding of the study was that ampullary empty ing was distinct from esophageal bolus transport in several ways: the propagation velocity of the clearing wave was slower, the maximal cont act pressures achieved after luminal closure were lower and unaffected by atropine or outflow obstruction, and ampullary emptying was driven by a hydrostatic pressure difference between the ampulla and stomach rather than by a peristaltic contraction. Increased bolus volume sligh tly enlarged the ampulla. Taken together, these findings suggest that ampullary emptying occurs, in part, as a result of the restoration of esophageal length (presumably by tension from the phrenoesophageal mem brane) rather than as a result of an aborally propagated contraction. As such, a normal phrenic ampulla is analogous to a small reducing hia tal hernia. We speculate that overt hernia formation occurs as a resul t of progressive degeneration of the phrenoesophageal membrane.