Free and reverse smooth muscle plasty in rats and goats

Free autologous smooth muscle transplants were performed in 59 Wistar rats from 70 to 90 days old. The free smooth-muscle transplants were prestretched by 0 percent, 100 percent, 120 percent, 150 percent, and 200 percent under resting conditions, and the animals were sacrificed on postoperative days five, 10, 20, 40, and 60, respectively. Five animals died postoperatively. Three of them died with ileus and stenosis after 150 percent prestretching of the transplant. Complications occurred in 11 other animals, and involved ileus in nine due to stenosis or increasing defecation difficulty resulting from post-150-percent-transplant-prestretching-obstruction phenomena. No relaxation reflex was observed manometrically in any of the transplants. Histology confirmed that smooth-muscle necrosis and connective-tissue multiplication increase with increasing prestretching of the transplant. With prestretching of 150 percent or more, the transplant underwent comlete fibrosis. Subsequently anorectal smooth-muscle pedunculated flaps (tunnel grafts) were performed on 20 goats of Syrian and German pedigree. Manometric, histologic, and histochemical results were much better in smooth-muscle transplantation of this nature. Even in these animals, however, increased fibrosis and disintegration of the transplant was shown histologically in all animals with more than 150 percent graft prestretch. After 200 percent prestretch, additional myenteric plexus disintegration was observed and no relaxation could be achieved. Based on these clinical, manometric, and histologic results, smooth-muscle transposition (tunnel graft) can be recommended to improve continence in infants as a non-time-consuming modification of the well-established Rehbein-Romualdi-Kiesewetter pull-through procedure in the high imperforate anus. However, prestretching of the transplanted pedicle flap should not exceed 120 to 140 percent. Supported by the German Volkswagen Foundation research grant.