Mechanism of action of antireflux procedures

Background: To define the clinical role of antireflux surgical procedures a proper understanding of their mode of action is required. The aim of this study was to investigate the impact of total or posterior partial fundoplic ation on the function of the lower oesophageal sphincter (LOS) in the basal state as well as during stimulation. Methods: Patients with chronic reflux (n = 24) were randomized either to a total fundic wrap or to a posterior partial (Toupet) fundoplication. Basal LOS function was investigated as well as the response to inhibitory stimuli 4 years after operation. Inhibitory stimulation was elicited by water swal lows and by gas distension (750 ml air insufflation into the stomach). Results: Basal LOS tone was substantially higher (P = 0.01) after a total t han a partial wrap, as was the nadir pressure after water swallows (10.1 ve rsus 3.4 mmHg). Body position did not affect this difference. Transient LOS relaxations occurred only occasionally in the basal state. The frequency o f transient LOS relaxation increased somewhat during the first 10 min of st omach distension with more occurring in patients who underwent a Toupet pro cedure. Common oesophagogastric cavities were more often seen in this latte r group of patients after gas distension of the stomach. Conclusion: These physiological observations on the LOS after total and pos terior partial fundoplication explain the observed clinical differences in favour of the latter operation. The partial fundoplication seems to restore the physiology of the gastro-oesophageal junction more adequately, allowin g air to be vented from the stomach without jeopardizing the antireflux bar rier.