The idea behind Enteryx is simple. Inject a bulking agent into the walls of the oesophagus near the junction with the stomach to enhance the lower oesophageal sphincter.
Patient trials were commenced in 2002 with great hopes. It was approved by FDA in America in April 2003.
In September 2003 a research paper published in the American Journal of Gastroenterology [r-xxxv] concluded: "Enteryx implantation allows most patients to discontinue PPI therapy, improves their symptoms, and reduces esophageal acid exposure. The effects of implantation are long-lasting, and morbidity is transient and minimal. The procedure requires basic endoscopic skills and seems to provide a useful option in the effective clinical A bulking agent is injected via endoscope management of GERD."
A paper published in Gastrointestinal Endoscopy in 2005 [r-xxxvi] stated: "In conclusion, this report encompasses a large cohort of patients with PPI-dependent GERD treated with Enteryx implantation into the distal esophagus. The findings indicate that Enteryx is a safe, effective, and durable endoluminal therapy for the majority of treated patients." However, the same publication reported a case study where complications had occurred. [r-xxxvii]
In October 2005, the FDA issued a Preliminary Public Health Notification [r-xxxviii] and the manufacturers recalled the device.
The Journal of Radiology Case Reports in 2014 published an account whereby the bulking agent had been injected into the visceral artery. [r-xxxix]
It noted: "Endoscopic injection of Enteryx into the lower esophageal sphincter carries the risk of inadvertent intravascular injection and migration of the polymer into visceral arteries. Although the product has been withdrawn from the market, similar products may be developed in the future and operators need to be aware of the potential complications of such injection and the risks of intravascular embolization. A test in which contrast is injected before the polymer mixture can help ascertain the location of injection and improve the safety of the procedure."
The Gatekeeper procedure:
1. The oesophagus wall is aspirated. 2. Normal saline is injected into the sub-mucosal layer. 3. A pocket is created in the sub-mucosal layer. 4. The prosthesis is implanted in the pocket. 5. View after completion of the operation.
Instead of injecting a polymer like Enteryx, Gatekeeper placed a hydrogel rod just under the surface of the oesophagus.
However problems occurred with the prosthesis remaining in situ. The device never received approval from NICE whose guidance on the procedure in 2007 [r-xl] stated "There is limited evidence of short-term efficacy on endoscopic augmentation of the lower oesophageal sphincter using hydrogel implants for the treatment of gastro-oesophageal reflux disease (GORD). This evidence also raises concerns about the procedure's safety. Therefore, this procedure should not be used without special arrangements for consent and for audit" and it is no longer available.