Lack of sustained vagal control of gastric mucosal blood flow. Why vagotomy is not effective in preventing recurrent hemorrhage from stress ulcers.

Vagotomy with drainage or resection has been advocated for control of hemorrhage from stress-related gastric erosions despite the high rate of associated rebleeding. The object of this study was to evaluate the effect of truncal and selective vagotomy on gastric mucosal blood flow under both normotensive and ischemic conditions to ascertain why rebleeding occurs. Fifteen miniature swine were divided into three groups according to the surgical procedure they underwent: (1) pyloroplasty alone, (2) truncal vagotomy and pyloroplasty, and (3) selective vagotomy and pyloroplasty. Four weeks postoperatively the animals were studied in three phases--during a normotensive period, during 5 minutes of shock (50 mm Hg), and during 90 minutes of shock (50 mm Hg). Cardiac output and mean arterial pressure values as well as gastric mucosal blood flow (measured by 15 microspheres) were determined during each phase. The following values were similar in all three groups: shock-related decreases in cardiac output and mean arterial pressure (60% decrease), total gastric mucosal blood flow during normotension, and gastric mucosal blood flow decreases at 5 and 90 minutes of shock (60% decrease). Identical reductions in gastric mucosal blood flow occurred in the gastric fundus, corpus, and antrum as well. These results demonstrate that the elimination of gastric vagal tone does not alter either the normotensive gastric mucosal blood flow or the gastric mucosal vascular response to ischemia and suggest that there is no physiologic basis for the long-term protective effect of vagotomy in preventing either rebleeding or the gastric mucosal ischemia that may lead to stress ulcers. These factors may explain the high failure rate associated with this procedure.