The Angelchik prosthesis behaves as a fundoplication.

It is not known why the Angelchik prosthesis prevents gastro-oesophageal reflux. A review of 53 barium meal examinations in 39 patients with the prosthesis showed that in 43 examinations the prosthesis was below the diaphragm. In 38 of these a small knuckle of stomach had herniated through the prosthetic ring alongside the oesophagus, forming a small intra-abdominal para-oesophageal hernia. Radiological reflux occurred in only one patient with such a hernia. In the remaining five examinations where the prosthesis was correctly situated in the abdomen, there was no hernia within the prosthetic ring and reflux occurred in three. In ten examinations the prosthesis had migrated into the mediastinum. None of these showed a hernia and reflux occurred in eight. It is suggested that the Angelchik prosthesis results in the formation of a small para-oesophageal hernia within a loosely fitting ring within the abdomen and this is a requirement for the success of the Angelchik prosthesis. Radiographically the intra-abdominal para-oesophageal hernia inside the prosthesis results in buttressing of the intra-abdominal oesophagus in a manner similar to a fundoplication.