The variability of the fasted duodenal contractile pattern and the patterns of contraction during the fed phase was examined in normal volunteers. Prolonged recordings from the duodenum and proximal jejunum were achieved using a series of transducers mounted on a 2.3-mm catheter. A total of 58 interMMC intervals and the response to 18 meals was examined. There was marked inter- and intrasubject variability in the fasted state, even within one study. The phase II pattern was examined in detail and propagated single peaks, propagated clusters, and repeated propagated clusters are described. Single peaks could be propagated as rapidly as 16 cm/sec. Single peaks were propagated more rapidly than propagated multiple peaks. During phase III, duodenal contractions occurred at 11.3 ±0.09/min and jejunal contractions at 10.73±0.15/min. The rate of progression of the onset of phase III was 0.145±0.015 cm/sec. The effect of the caloric content of the meal was examined by determining the effect of 150-kcal, 300-kcal, and 600-kcal meals on the fed pattern. Increasing caloric content increased the duration of the fed pattern but had no effect on the total or normalized motility index or on the change in motility index over time during the fed pattern. The types of contractions seen during the fed pattern are described. Propagated clusters over at least 16 cm are common during the fed phase in normals, with 10% of all contractions seen during the fed phase being propagated over 28 cm. No difference in the patterns of contractions or their propagation was seen with the different caloric contents of the meals. These studies demonstrate the variability of the normal fasted pattern and demonstrate the motor equivalents of a variety of myoelectric patterns that have been described. A method of analyzing the fed pattern is described.
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