By Ramsey Hachem, M.D.
Washington University School of Medicine Barnes-Jewish Hospital
Division of Pulmonary and Critical Care
July, 2006
Most of us have experienced acid reflux or heartburn at some point. For many, this is a rare symptom that is only brought on by a heavy meal or spicy food. On the other hand, many otherwise healthy people have frequent acid reflux symptoms that affect their eating habits and lifestyles. Gastroesophageal reflux disease, or GERD, is defined as symptoms of injury to the esophageal mucosa produced by abnormal reflux of stomach contents into the esophagus. Under normal conditions, the stomach makes acid to initiate digestion, and when this acid refluxes into the esophagus it may cause heartburn, the cardinal symptom of GERD. Other common symptoms include regurgitation, the return of stomach contents to the back of the throat without retching or vomiting, chest pain, and a constant sensation of a lump in the back of the throat.
Aside from these troubling symptoms, GERD can cause more serious complications. As the esophageal mucosal irritation heals, a stricture narrowing the lumen of the esophagus may form. The development of Barrett’s esophagus is a more ominous complication because it may predispose to esophageal cancer. Barrett’s esophagus is characterized by an abnormal intestinal-type epithelium that replaces the normal esophageal epithelium, and this can be visualized with endoscopy. In addition, there are some extra-intestinal complications that may arise because of acid reflux. The airway is just anterior to the esophagus in the larynx (or back of the throat), and acid refluxed up to the back of the throat can easily trickle into the airway past the vocal cords. Indeed, GERD has long been associated with asthma. It is proposed that stomach acid refluxes up the esophagus, is aspirated silently into the airway, and irritates the small airways causing bronchoconstriction and asthma symptoms. Furthermore, many patients with idiopathic pulmonary fibrosis (IPF) have abnormal esophageal function or symptomatic GERD, and some have proposed that silent aspiration of stomach acid into the lungs may either cause IPF or exacerbate it.
So, what impact does GERD have after lung transplantation? It is apparent that after transplantation, patients are more likely to have acid reflux than before surgery. Weight gain after transplantation is common, and this is a well recognized risk factor for GERD because it increases abdominal pressures. In addition, delayed gastric emptying, or gastroparesis, is a common complication after lung transplantation. This may result from injury to the vagus nerve, which runs through the middle of the chest and innervates the stomach. A distended stomach is more likely to reflux its contents into the esophagus. Indeed, many lung transplant recipients complain of acid reflux in the first few months after surgery.
But, is GERD after lung transplantation just a nuisance or can it be something more serious? The answer is not clear, however, researchers at Duke University have suggested that there may be a link between GERD and chronic rejection after lung transplantation. The idea is that stomach acid or stomach contents in general may be silently aspirated into the airways and irritate the small airways in the same way that GERD may exacerbate asthma. Injury to the small airways, or any part of the lung for that matter, after lung transplantation may trigger the immune response and initiate a cascade of events that leads to the small airway scarring that is recognized as obliterative bronchiolitis, or chronic rejection. Thus, the Duke University researchers have proposed that for some patients, surgical treatment for GERD may prevent the development of chronic rejection or slow its progression. The surgery is called fundoplication, and it involves wrapping the top part of the stomach around the esophagus to prevent the reflux of stomach contents into the esophagus. In a way, this acts as a one-way valve allowing the food bolus to pass from the esophagus into the stomach but preventing reflux back into the esophagus.
Surgical treatment for GERD after lung transplantation is a promising approach to the management and prevention of chronic rejection, but it is not yet the standard of care. There are many questions regarding the ideal timing of surgery and the severity of GERD that should warrant surgical therapy that are yet to be answered. But, perhaps the most important question is whether the surgical treatment for GERD truly prevents or slows the progression of chronic rejection. While these questions are addressed, the first lines of therapy for GERD should be instituted; these include behavioral modifications (weight loss, reducing caffeine and alcohol intake, avoiding late meals, and elevating the head of the bed) and medical therapy to reduce acid production in the stomach. For now, surgical therapy should be considered for patients who have persistent symptoms of acid reflux despite behavioral modifications and medical therapy and for those who have evidence of aspiration of stomach contents into the airways.