Diseases of the Esophagus (1997) 10, I 15-1 18 © 1997 International Society for Diseases of the Esophagus / Pearson Professional Ltd ORIGINAL ARTICLE Mechanical effect of the Angelchik prosthesis on the competency of the gastric cardia: pathophysiologic implications and surgical perspectives L. Bonavina*, T. DeMeester 1 ^, R. Mason 1 ^ H. J. Stein*, H. Feussner*, A. Evander + From the Departments of Surgery: *University of Milan, Milan, Italy; fUniversity of Southern California, Los Angeles, USA; $Technische Universitdt Munchen, Munich, Germany SUMMARY. The Angelchik prosthesis appears to be effective in preventing gastroesophageal reflux, although its precise mechanism of action remains controversial. In a unique in vitro model, 10 freshly harvested canine esopha- gogastric specimens were tested for their ability to remain competent against challenges of intragastric pressure under controlled conditions of intra-abdominal pressure, longitudinal esophageal tension, lower esophageal sphinc- ter pressure and overall length and circumference of the cardia (measure of gastric dilatation). Competency of the specimen was assessed by stepwise variation in the overall length of the sphincter, while keeping constant intra- abdominal pressure (20 cm H 2 0), intragastric pressure (20 cm H 2 0), esophageal tension (physiologic), lower esophageal sphincter pressure (15 cm H 2 0) and degree of gastric dilatation (3 cm). With each specimen serving as its own control, the effect produced by the application of an Angelchik prosthesis was evaluated. Results consistently demonstrated that at any lower esophageal sphincter length the percent of competency was increased when the pros- thesis was applied (P < 0.01). The findings indicate that the Angelchik prosthesis controls reflux by preventing unfolding of the lower esophageal sphincter when challenged by intragastric pressure. INTRODUCTION Improvement of the function of the cardia rather than simple reduction of the herniated stomach by crural repair has gained the attention of surgeons since it was realized that the symptoms of hiatal hernia are linked to the occurrence of gastroesophageal reflux. 1 Various antireflux procedures have been designed over the past half-century to restore competency of the cardia in patients with abnormal esophageal acid exposure, namely the Nissen, Belsey, Toupet, Dor and Hill opera- tions. The Nissen fundoplication has proven most effec- tive in long-term follow-up, but a number of side-effects and complications have been reported, indicating that standardization of surgical technique is a critical factor. 2 In 1979, Angelchik and Cohen introduced a prosthetic device, the Angelchik antireflux prosthesis (AAP), designed to improve competency of the cardia by simpli- fying and standardizing the surgical procedure. 3 Although little is known about the mechanism of action of the pros- thesis, several clinical studies have demonstrated the effi- cacy of this device in controlling gastroesophageal reflux. Corrrespondence to: Dr Luigi Bonavina, Istituto di Chirurgia Generale e Oncologia Chirurgica dell'Universita, Ospedale Maggiore Policlinico, IRCCS, Via F. Sforza 35, 201122 Milan, Italy. Two prospective randomized trials comparing the AAP with the Nissen fundoplication have shown comparable results. 4,5 Moreover, the feasibility of laparoscopic place- ment of the AAP has been demonstrated. 6 The aim of this study was to investigate in vitro the role of the mechanical components of the antireflux barrier and the effect of the AAP on competency of the cardia. MATERIALS AND METHODS Ten esophagogastric specimens were excised from anesthetized dogs through a left thoracotomy. Prior to dissection of the esophagus and the hiatus, two silk stitches were placed as markers at the insertion of the phrenoesophageal ligament and on the esophageal wall 5 cm above. This was done in order to reproduce in vitro the physiologic length and tension of the specimen. The specimens were stored in saline solution at 4°C for up to 1 h before starting the experiment. The in vitro model used for the study represents a further modification of that previously described by DeMeester and coworkers in 1979 7 (Fig. 1) and was designed to simulate flow from the stomach through the cardia into the esophagus. The excised specimen was mounted within a cham- ber representing abdominal cavity. The specimen, 115 Downloaded from https://academic.oup.com/dote/article/10/2/115/4371468 by guest on 17 February 2023