For more than a dozen years Buz Harrison, a Nashville-based media producer, has been plagued by gastroesophageal reflux disease (GERD).

The frequent leakage of stomach acid into his esophagus damaged his vocal cords to the point that he had to drop out of his church choir. He's tried acid-blocking medications. "But I can still feel that burning sensation," he said.

Harrison, 61, recently became one of the first three subjects at Vanderbilt University Medical Center (VUMC) to participate in a clinical trial of an implantable neurostimulator made by EndoStim, a medical device company based in Dallas and the Netherlands.

As many as 100 million Americans suffer from reflux disease, said Michael Vaezi, MD, PhD, professor of Medicine and director of the Vanderbilt Swallowing and Esophageal Disorders Center who is leading the study. Nearly a third of them continue to experience symptoms despite medical treatment.

Reflux often results from a weak or dysfunctional lower esophageal sphincter (LES) muscle between the stomach and esophagus. Implanted under the skin, the EndoStim device sends intermittent electrical pulses -- too low to be felt -- via electrodes to the LES. The goal is to strengthen the muscle and thus reduce reflux.

Called the Lower Esophageal Sphincter Stimulation for GERD (LESS GERD) trial, the study is randomized and double-blinded, meaning that half the subjects will be randomly assigned to a control group in which the device initially will not transmit electrical signals.

Neither the subjects nor the researchers will know which group they're in. After six months, the device will be turned on in the control group.

Approximately 25 subjects are being recruited for the Vanderbilt trial, which is expected to take about a year to complete. If the neurostimulator works in Harrison's case, it may not take that long for him to get back to singing in the choir.

"Once you stop the acid that's coming up," Vaezi said, "the vocal cord is amazing in its ability to heal itself."

For more information about the LESS GERD trial, contact Tina Higginbotham, MPA, in the Division of Gastroenterology, Hepatology and Nutrition at tina.higginbotham@vanderbilt.edu.