Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans

OBJECTIVE: The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (MPS) on gastric emptying and pyloric motility. METHODS: Concurrent measurements of gastric emptying and antropyloroduodena l pressures were performed in six volunteers (aged 24-26 yr) who had had py loromyotomy performed in infancy because of IHPS, and in six normal subject s. Subjects were studied on 2 days, once sitting and once in the left later al position. Gastric emptying of 300 mi 25% dextrose labeled with 20 MBq Tc -99m sulfur colloid was measured. Antropyloroduodenal motility was evaluate d with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 mi n, starting 30 min after ingestion of the dextrose. RESULTS: In both body positions, gastric emptying and intragastric distribu tion of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number (p < 0.01) and amplitude (p < 0.02) of isolated pyloric pressur e waves (IPPWs) was greater in the control subjects, whereas basal pyloric pressure was greater in the pyloromyotomy subjects (p ( 0.02). In both grou ps, the rate of gastric emptying in the sitting position was related to the number of IPPWs (r greater than or equal to 0.40, p < 0.05), but not to ba sal pyloric pressure. CONCLUSIONS: These results indicate that, in adults who have had pyloromyot omy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressur e waves are less. In contrast, the overall rate of gastric emptying of a nu trient liquid meal is normal. These observations are consistent with the co ncept that the stomach has the capacity to compensate for changes in pylori c motility to minimize effects on gastric emptying.