Selective vagotomy of the canine oesophagus--a model for the treatment of hiatal hernia.

Abstract

M. H. (1976). Thorax, 31,[185][186][187][188][189]. Selective vagotomy of the canine oesophagus-a model for the treatment of hiatal hernia. Hiatal herniation caused by contraction of the longitudinal muscle of the oesophagus has been prevented by disconnecting the local vagal nerve supply while preserving the vagal connections to more distant organs. A selective oesophageal vagotomy above the lung hilum may prove an effective adjunct to orthodox hiatal hernia repair in man.Repair of hiatal hernia as a treatment for oesophageal reflux remains unsatisfactory in up to 22% of cases (Mustard, 1970), usually because of a recurrence of the hernia.The results are even less favourable in the presence of oesophageal shortening (Skinner and Belsey, 1967). Botha (1962) and Johnson (1968) have pointed out that shortening may be caused by vertical traction from the longitudinal muscle of the oesophagus. Davidson (1972) and Mullard (1972) have described myotomies of this muscle as an adjunct to orthodox hiatal hernia repair, so as to obtain more permanent reduction of the hernia. Such techniques, however, are theoretically prone to oesophageal perforation, submucosal ischaemia, and diverticulum formation. Weakening of the longitudinal muscle by disconnecting its motor nerve supply, the vagus, appeared to be potentially safer and to offer prospects of a more radical effect.A logical approach to this problem, not previously reported, was to assess the weakening effect of dissociating different sections of the vagus from the oesophagus while preserving the vagal connections with more distant organs.The dog was chosen as the experimental model because the vagal bundles over the oesophagus are easily identifiable and the longitudinal muscle is well developed, which would make for clarity of dissection and for large differences in experimental response. MATERIAL AND METHODSFasting adult mongrel dogs of mean weight 207 kg were anaesthetized using 200 mg thiopentone sodium intravenously, intubated with a cuffed endotracheal tube, and ventilated with a Bird Mark 2 ventilator using halothane 1-5% and oxygen at 2 1/min. A mean of 3000 ml of 0-9% sodium chloride was administered intravenously to replace blood and fluid losses. Each dog was killed at the end of the experiment. One side of the whole intrathoracic oesophagus was exposed by reflecting a large chest wall flap consisting of one side of the sternum and the fourth to eighth ribs, and removing the ipsilateral lung. Kymographs were attached to the oesophagus at three points-at the level of the hiatus, at the lower border of the hilum, and at the upper border of the aortic arch. The kymographs were connected by a system of pulleys to record longitudinal movements (Fig. 1).The pressures in the lower oesophagus and stomach were measured by means of a continuously infused 3-lumen oesophageal tube connected to three Model P23 De Statham transducers, and recorded on a Devices M4 4-channel recorder. The fourth channel was adapted to record heart rate from a Devices ECG unit and a Devices...