EFFECT OF LEVEL OF CIRCULAR MYOTOMY ON ESOPHAGEAL FUNCTION IN A PIGLET MODEL

Oesophageal continuity is often difficult to oesophageal atresia, and a circular myotomy may be required to achieve oesophageal anastomosis. This study compared the effects of upper and lower segmental circular myotomy on oesophageal stricture formation, oesophageal motility, and the development of gastro-oesophageal reflux (GOR) in a piglet model. Group I underwent mid-oesophageal resection with upper segment myotom y (14); group II mid-oesophageal resection with lower segment myotomy (8); and group III oesophageal transection and anastomosis without res ection (6). Normal motility data were obtained from 8 unmanipulated pi glets. The incidence of stricture formation was high in all operated g roups. Pseudodiverticula developed in all piglets after proximal myoto my, but not after transection or distal myotomy. Lower oesophageal sph incter pressure and mean amplitude of upper oesophageal contractions w ere similar after operation in all groups and in controls. GOR (number of reflux episodes/24 h, number of episodes of reflux lasting more th an 5 min, and fraction of time pH less than 4.0) was worse after opera tion compared to controls. Within each group most manometric parameter s and GOR worsened with time. We found no evidence that the level of c ircular myotomy (upper or lower) resulted in any significant differenc e in stricture rate, oesophageal motility, or severity of GOR. Given t he difficulty of performing an upper myotomy in long-gap atresia, wher e the upper segment is often very short and pseudodiverticulum formati on is common, a lower-segment circular myotomy would appear to be a re asonable alternative.