Pyloric motor abnormality in patients with infantile hypertrophic pyloric stenosis

There are no published data of manometric studies of pyloric motor function in patients with infantile hypertropic pyloric stenosis (IHPS). The present study attempted to examine the characteristics of motor abnormality of the pylorus in five children with IHPS. Using a transducer-built-in manometric catheter cannulated through the pylorus under fluoroscopy, the pressure in the pyloric canal was recorded continuously over 3 h during fasting. Clusters of high-amplitude spastic contractions of over 300 mmHg were recorded at intervals. The frequency was 1-3/min (mean 1.7 cpm) and the duration was 7-15 s. These periodic spastic contractions were suppressed temporarily for 20-30 min after intravenous injection of 0.01 mg/kg atropine. After pyloromyotomy, these spastic contractions decreased remarkably in amplitude, but there were no changes in frequency. It is concluded that the underlying motor abnormality observed in hypertrophied pyloric muscle is clusters of high-amplitude contractions, although more precise measurements of basal pyloric pressure are needed to explore the pathophysiology of IHPS in detail. The effect of pyloromyotomy may be related to the decrease in high-amplitude contractions.