Objective: To discover whether the human stomach contracts every 20 seconds or not.
Design: Manometric study.
Setting: Teaching hospital, Belgium.
Subjects: 10 healthy volunteers, and 31 patients who had had the whole stomach denervated and pulled up to the neck for oesophageal replacement.
Interventions: Analysis of selected strips of manometric tracings obtained with intraluminal perfused catheters. 13 patients were given erythromycin (1g/day) by mouth.
Main outcome measures: Estimation of the rate and frequency distribution according to amplitude of intraluminal pressure waves with the vertical axis of the tracings scaled up to reflect contractions within the gastric wall.
Results: Microwaves (<9 mmHg) that came in between conventional macrowaves (>9 mmHg) were found, showing that the human stomach undergoes mechanical activity (amplitude ranging from 0.2-310 mmHg) at the pacemaker's rate which varied from 2.43 to 3.60 cycles/minute from one subject to another. Phase I of the interdigestive motor complex contained microwaves only, phase II and the fed pattern consisted of a mixture of microwaves and macrowaves, and phase III contained macrowaves only. The fasting rate of mechanical activity was lower in patients who were given erythromycin than in those not given erythromycin (p = 0.003) and in healthy volunteers (p = 0.002), and it increased significantly after a meal (p < 0.0001). Microwaves in strips in which they were the most prominent were of higher amplitude in patients than in healthy volunteers (median: 3.5 compared with 2.5 mmHg; p < 0.0001).
Conclusions: The human stomach has mechanical activity at the rate at which the pacemaker generates electrical slow waves. The classic phases of the gastric motor activity seem to differ from each other by the frequency distribution of pressure waves according to amplitude rather than by the contraction rate. Weak mechanical activity is much more readily detectable after the stomach has been denervated and tailored for oesophageal substitution.