Evidence for the flutter valve mechanism of the lower oesophageal high pressure zone.

Simultaneous oesophageal manometry and pH monitoring was performed at rest and during abdominal compression in 189 subjects. The force exerted by the high pressure zone (HPZ) and by its intra-abdominal segment was reduced to the same extent in the 102 subjects who refluxed and the 87 who did not. Reflux during abdominal compression occurred in the subjects whose HPZ force fell into a critical range and in whom the contribution by the abdominal segment was reduced to less than 50 per cent of the total force exerted by the HPZ. These results are more in keeping with a mechanical flutter valve theory of lower oesophageal competence than sphincteric reflux control. Furthermore, the results indicate that measurements of oesophageal pressure, length or force in the resting state do not account for reflux or gastrooesophageal competence, but that it is the reserve of pressure, length or force during stress which is responsible.