Human duodenal myoelectric activity after operation and with pacing

We sought to determine the influence of operation on the pattern of human duodenal myoelectric activity and to assess whether electrical pacing might correct any postoperative disturbances. Three pairs of temporary bipolar serosal electrodes were placed on the duodenums of ten patients undergoing cholecystectomy. Electrical recordings were obtained daily until the patients' discharge, at 3 to 7 days, after operation. On each postoperative day, a regular rhythmic pattern of pacesetter potentials (PPs) was detected in all patients. The PP frequency (mean ± SEM) was greater at the proximal electrode than at the distal electrode on the first postoperative day (12.3 ± 0.1 cpm vs 11.9 ± 0.1 cpm, p < 0.01) and on the day of feeding (12.0 ± 0.2 cpm vs 11.6 ± 0.2, p < 0.01). Spontaneous periods when spike potentials accompanied each PP (phase III of the migrating myoelectric complex), were found in only one patient on the day after operation, while they were recorded in five patients after 3 to 7 days, when postoperative ileus had resolved (p < 0.05). Pacing with electric pulses (50 msec, 5 to 15 mA, 11 to 13 cpm) did not alter the pattern of duodenal PPs or entrain them in the duodenum of any patient at any time after operation. In conclusion, the pattern of duodenal pacesetter potentials changed little during the period of postoperative ileus, while the incidence of phase IIIs of the migrating myoelectric complex was greatly decreased. The fact that the proximal duodenum exhibited a frequency gradient of PPs at all times, as opposed to a frequency plateau, may explain the failure of extrinsic electrical stimuli to entrain the human duodenum.