In a previous study we determined the rectal pacing parameters needed for r
ectal evacuation in patients with rectal inertia. Here we investigated the
effect of rectal pacing on rectal myoelectric activity, motility, and evacu
ation in ten patients with constipation due to rectal inertia. A pacemaker
was implanted in a subcutaneous pocket above the inguinal area, with a lead
threaded in the anal submucosa to be hooked at the rectosigmoid junction.
The effect of rectal pacing on rectal electric activity was investigated by
inserting two recording electrodes to the rectal mucosa. The patients were
then trained for home pacing. No waves were recorded from the rectum at re
st. On rectal pacing, slow waves or pacesetter potentials (mean frequency 2
.3+/-1.1 cpm, amplitude 0.86+/-0.1 mV, velocity 3.4+/-1.6 ms) were register
ed after a latency period of 5.2+/-1.6 min. Rectal evacuation, on pacing, o
ccurred in seven of the ten patients. The three who showed no significant r
esponse exhibited low wave parameters. Three of seven patients were able to
evacuate spontaneously without pacing after having performed daily pacing
for 5-6 months. The pacemaker was removed in six patients (three failures a
nd three after spontaneous defecation). Thus rectal pacing succeeded in ind
ucing rectal evacuation in 70% of the patients. The procedure failed in thr
ee patients. Three had spontaneous defecation after a few months of rectal
pacing. No complications were encountered, and the method was tolerated and
acceptable. Further studies on a large group of patients are required.