DYNAMIC IMAGING OF OBSTRUCTED OPOSSUM ESOPHAGUS - FROM ALTERED LOAD TO ALTERED CONTRACTILITY

We studied by barium contrast the dynamics of experimental obstruction in the opossum esophagus. Immediately after banding the gastroesophag eal junction, entrapment of the bolus between the band and the perista ltic contraction led to esophageal bulging, forceful retropulsion of t he bolus at the band, and the repeated triggering of peristaltic contr actions by the retropelled bolus. In ensuing weeks, triggering of cont ractions became more difficult and contractions led to bizarre ''corks crew'' movements of the increasingly distended and tortuous esophagus. A tight contraction ring that moved very slowly retrograde was occasi onally observed in the chronically distended esophagus. Computer-assis ted analysis showed that the area and Perimeter of the bolus were abno rmally large in chronic obstruction and that during its passage throug h the esophagus the compactness of the bolus increased no longer. Conf igurational analysis of the cone that the peristaltic contraction shap es at the tail of the barium column showed this to narrow progressivel y on passage through the normal esophagus and, paradoxically, to widen in both acute and chronic obstruction.