Treatment of irritable bowel syndrome with colonic pacing: evaluation of pacing parameters required for correction of the "tachyarrhythmia" of the IBS

BACKGROUND/AIMS: A recent study of the electromyographic (EMG) activity of irritable bowel syndrome (IBS) has shown that the frequency, amplitude and conduction velocity of the slow waves (SWs) of the sigmoid colon (SC) were significantly higher in IBS patients than in the healthy volunteers. The SW rhythm was irregular. A "tachyarrhythmic pattern" was characteristic of the IBS. The SC pressure in the IBS was also significantly higher than that of the healthy controls. We suggested that the cause of IBS is related to an aberrant focus in one or more of the colonic pacemakers which possibly triggers abnormal impulses to the colon. We hypothesized that stimulation of the pacemaker which delivers electric waves to the SC, may correct the abnormal electric waves and eliminate the IBS symptoms. In this communication we tried to define the adequate pacing parameters necessary for normalization of the tachyarrhythmic pattern of the electric waves in IBS. METHODOLOGY: Nineteen subjects with IBS were divided into a study group (age 48.6+/-9.8 years; 7 women, 4 men) and a control group (age 47.6+/-9.2 years; 5 women, 3 men). The study also included 8 healthy volunteers (47.9+/-9.7 years; 5 women). Three 28-gauge cardiac pacing electrodes were used: one for pacing applied to the pacemaker at the colosigmoid junction (CSJ) and 2 for recording applied to the SC mucosa. In the study group, the CSJ electrode was stimulated using an electrical stimulator which delivered a constant current. The optimal pacing parameters had been determined after repeated trials with different variables. In the control group, recording was done without pacemaker activation. The SC pressure was measured by a 10-F saline-perfused tube. RESULTS: In the healthy volunteers, the basal SWs were regular and followed or superimposed by action potentials (APs). Pacing produced a significant increase in the SW variables and SC pressure; the latency was 20.3+/-3.6 s. The study and the control group exhibited a basal tachyarrhythmic pattern and a significantly higher SC pressure than the healthy volunteers. Pacing of the study group effected lowering of the SW variables and SC pressure which did not show a significant difference against those of the healthy volunteers at rest. The optimal pacing parameters comprised an amplitude of 6 mA, a pulse width of 150 ms and a 25% higher frequency than that of the already recorded basal colonic waves. The control group showed no change in the tachyarrhythmic pattern. CONCLUSIONS: CS pacing parameters were identified and succeeded in normalizing the tachyarrhythmic pattern of the IBS. We suggest that this method be used for the treatment of patients with IBS when other measures have failed to cure the condition.