Disruption of canine jejunal interdigestive myoelectrical activity by artificial ileocolonic sphincter - Studies of intestinal motor response to surgically fashioned sphincter substitute

We studied the effects of an ileocolonic sphincter substitute on canine small intestine motor activity. Recordings of fasting and postprandial myoelectrical activity were performed in three groups of animals in whom the following procedures had been performed: (1) electrode placement alone, intestinal continuity undisturbed (controls); (2) ileocolonic sphincter substitute fashioned in mid-jejunum; and (3) transection and reanastomosis at a similar location in mid-jejunum. Transection alone resulted in a decrease in slow-wave frequency, a shortening of the period of the interdigestive myoelectrical complex (IDMEC) and a prolongation of phase III of the IDMEC in the jejunum distal to the site of transection. The IDMEC period was also shorter at proximal electrode sites, but the incidence of IDMEC phase III complexes was similar on either side of the transection. However, in those animals in whom a sphincter substitute had been fashioned at the site of the transection, the incidence of IDMEC phase III complexes was significantly suppressed in the proximal intestine; IDMEC phase III frequency per hour (mean±sd transection vs sphincter substitute) was 0.59±0.20 vs 0.23±0.24, P<0.002; 0.61±0.24 vs 0.28±0.30, P<0.006; 0.61±0.24 vs 0.29±0.30, P=0.008, at electrodes 10, 35, and 85 cm proximal to the sphincter substitute, respectively. In addition, the sphincter-substitute animals alone demonstrated, during fasting, recurrent propagated bursts of spike clusters and occasional prolonged spike bursts in electrodes proximal to the sphincter substitute. No significant differences with respect to the pattern of postprandial spike activity were noted between the various animal groups during limited postprandial recordings. None of the animals demonstrated clinical, radiographie, or autopsy evidence of intestinal obstruction. We conclude that placement of a sphincter substitute, of a type advocated for replacement of the ileocolonic sphincter, results in significant disruption of interdigestive myoelectrical activity in the proximal small intestine.