Electrically stimulated colonic reservoir for total anorectal reconstruction

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Abstract
Total anorectal reconstruction after abdominoperineal excision of the rectum has failed to achieve perfect continence. Electrically stimulated reservoir evacuation in combination with an electrically stimulated gracilis neoanal sphincter might improve results. A J pouch was constructed in an isolated colonic loop of seven dogs. Bipolar square wave pulses were delivered via two intramural stainless steel electrode pairs at 10 Hz. Stimulation parameters were varied to achieve adequate contraction. Serosal strain gauges recorded spontaneous and stimulated pouch motility. Evacuation was quantified by a volume displacement technique and observed fluoroscopically. Recordings were performed for a median of 3 (range 1–11) months. At 10 Hz and 0·5 ms pulse width, stimulation was required for 2 min and at voltages of 15 V (n = 4), 18 V (n = 1) and 20 V (n = 2) to obtain a contraction of amplitude comparable to that of a spontaneous contraction. Suprathreshold stimulation invariably resulted in colonic pouch contraction. The mean(95 per cent confidence interval (c.i.)) stimulus-response latency was 25·5(1-9) s. The mean(95 per cent c.i.) intraluminal pressure generated during stimulation was 114±1(17±0) cmH2O and 64±6(12±0) cmH2O during spontaneous activity (P<0±001). In conclusion, electrical stimulation via intramural electrodes produced contraction generating sufficient intraluminal pressure to effect evacuation of a canine colonic pouch. This has potential for incorporation with an electrically stimulated neoanal sphincter in total anorectal reconstruction to improve evacuation and continence.