Magnetic Sphincter Augmentation for Gastroesophageal Reflux Disease

The continuous search for the ideal antireflux procedure reflects a widely held perception among surgeons, gastroenterologists, and patients that therapy for gastroesophageal reflux disease (GERD) remains unsatisfactory. About 30% to 40% of patients are resistant or only partial responders to proton pump inhibitor (PPI) therapy, and even high-dose escalation may be inadequate to maintain individuals in a symptom-free state with a mechanically defective lower esophageal sphincter (LES). Additionally, there are growing concerns over the long-term effects of chronic acid suppression. Many patients suffer from persistent nonacid reflux and nocturnal acid breakthrough, and may progress to serious complications of the disease, such as volume regurgitation with pulmonary aspiration and Barrett metaplasia, the leading risk factor for esophageal adenocarcinoma. A large European open cohort multicenter study showed that about 10% of patients under routine medical care progressed to Barrett esophagus in 5 years of follow-up. Recent literature also indicates that chronic acid suppression with PPIs can reduce the absorption of vitamin B ₁₂ and magnesium, the effectiveness of medications such as clopidogrel, and increase the risk of Clostridium difficile infection. Other consequences of prolonged PPI therapy include hypergastrinemia, enterochromaffin-like cell hyperplasia, and parietal cell hypertrophy, leading to rebound acid hypersecretion. Finally, there is some evidence suggesting that chronic acid suppression may be associated with an increased incidence of gastric cancer.

The laparoscopic Nissen fundoplication is the current surgical gold standard for the treatment of GERD. It is a safe, effective, and durable antireflux procedure when performed in specialized centers. A multicenter European trial comparing medical therapy with total or partial fundoplication performed in selected centers by expert surgeons showed that 92% of medical patients and 85% of surgical patients remained in remission at 5 years of follow-up. However, despite remarkably low morbidity and mortality rates, the operation is underused due to the perception of long-term side effects and fear of failure, which impacts referral patterns. Also, wide variability in clinical outcomes related to interindividual surgical expertise and/or technical modifications have limited the adoption of this procedure especially in patients with early GERD. Patients undergoing a Nissen fundoplication are especially at risk for potential side effects of the procedure such as bloating, the inability to belch and vomit, and the occurrence of persistent dysphagia that may occasionally require revisional surgery. These are the main reasons why gastroenterologists tend to limit their referrals for fundoplication only to patients with long-lasting severe disease and large hiatal hernias. A downward trend in the use of surgical fundoplication has been noted in the United States over the past decade. The decline in surgical volume has been attributed to the perceived risk of fundoplication failure, to the availability of over-the-counter PPI and endoscopic therapies, and to the rise of bariatric surgery.

The limitations of both PPI therapy and fundoplication have left many patients and clinicians in the equivocal position of tolerating a lifetime drug dependence with incomplete symptom relief, or undertaking the risk of a surgical procedure that alters gastric anatomy, may have considerable side effects, and may deteriorate over time. The Linx Reflux Management System (Torax Medical, St. Paul, Minnesota) is a US Food and Drug Administration–approved device designed to provide a permanent solution to GERD by augmenting the LES barrier with a standardized laparoscopic procedure.

Magnetic Sphincter Augmentation

The Linx is a simple mechanical device designed to augment the physiologic barrier to reflux by magnetic force. The device consists of a series of biocompatible titanium beads with magnetic cores hermetically sealed inside. The beads are interlinked with independent titanium wires to form a flexible and expandable ring. At rest, each bead is in contact with adjacent beads. The beads can move independent of the adjacent beads, creating a dynamic implant that does not compress the esophagus and does not limit its range of motion upon swallowing, belching, and vomiting ( Fig. 20.1 ). For reflux to occur, the intragastric pressure must overcome the resistance to opening of both the patient's native LES pressure and the magnetic bonds of the device. The Linx is manufactured in different sizes and is capable of nearly doubling its diameter when all beads are separated. The magnetic attraction force to be counteracted to allow bead separation is independent of the number of beads contained in the device. The Linx device, while augmenting the LES, allows for expansion to accommodate a swallowed bolus or the escape of elevated gastric pressure associated with belching or vomiting. Once healing is complete after the implant, the device is encapsulated in fibrous tissue but is not incorporated in the esophageal wall ; this makes it possible to remove the device without damage to the esophagus. The Linx has recently received magnetic resonance imaging (MRI) approval for scanning in systems up to 1.5 Tesla.