Rectal pacing in patients with constipation due to rectal inertia: technique and results.

In a previous study we determined the rectal pacing parameters needed for rectal evacuation in patients with rectal inertia. Here we investigated the effect of rectal pacing on rectal myoelectric activity, motility, and evacuation 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 rest. 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 registered after a latency period of 5.2+/-1.6 min. Rectal evacuation, on pacing, occurred in seven of the ten patients. The three who showed no significant response 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 and three after spontaneous defecation). Thus rectal pacing succeeded in inducing rectal evacuation in 70% of the patients. The procedure failed in three 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.