The EndoStim LES Stimulation System is an investigational device intended to improve the LES pressure and restore Lower Esophageal Sphincter (LES) function in individuals suffering from Gastroesophageal Reflux Disease (GERD).

EndoStim has developed an investigational medical device specifically designed to deliver electrical stimulation to the LES and has completed two clinical feasibility studies using an external version of the EndoStim stimulation system in fifteen subjects. In these two short-term studies, electrical stimulation resulted in significant increases in LES pressure.

This study will further evaluate the safety of the procedure and its feasibility for use in this group of patients.

Inclusion Criteria:

• Subject is between 21 - 70 years of age.
• Subject has a history of heartburn, regurgitation or both for > 12 month prompting physician recommendation of continual daily use of PPI before study entry.
• Baseline GERD HRQL heartburn score following 10-14 days off PPI which is ≥ 20 and at least 10 points higher than the on PPI score
• Subject who are on standard medical therapy for 12 months or longer and experience discomfort or who are otherwise dissatisfied with GERD symptoms
• Subjects with a GERD condition that in the opinion of the PI justifies a minimally invasive reversible procedure prior to attempting anatomical change such as Nissen fundoplication
• Subject has an American Society of Anesthesiologists (ASA) Physical Status Classification I or II (or comparable local classification if any).
• Subject has exhibited excessive lower esophageal acid exposure during 24-hour pHmetry of antisecretory therapy performed within 6 months of screening visit; pH < 4 for > 5% of total time.
• Subject has a resting LES end expiratory pressure > 5mm Hg and < 15 mm Hg on a high resolution manometry within 6 months of enrollment.
• Subject has esophagitis ≤ Grade C (LA classification) on upper endoscopy within 6 months of enrollment.
• Subject has esophageal body contraction amplitude > 30 mmHg for > 50% of swallows and > 50% peristaltic contractions on high resolution manometry.
• Subject has signed the informed consent form and is able to adhere to study visit schedule.

Exclusion Criteria:

• Subject has any non-GERD esophageal motility disorders.
• Subject has gastroparesis.
• Subject has any significant multisystem diseases.
• Subject has an autoimmune or a connective tissue disorder (e.g. scleroderma, dermatomyositis, Calcinosis-Raynaud's-Esophagus, Sclerodactyly Syndrome (CREST), Sjogren's Syndrome, Sharp's Syndrome), requiring therapy in the preceding 2 years.
• Subject has Barrett's epithelium (> M2; > C1) or any grade of dysplasia.
• Subject has a hiatal hernia larger than 3 cm.
• Subject has a body mass index (BMI) greater than 35 kg/m2.
• Subject has Type 1 diabetes mellitus
• Subject has uncontrolled Type 2 diabetes mellitus (T2DM) defined as HbA1c > 9.5 in the previous 6 months, or has T2DM for > 10 years.
• Subject has a history of suspected or confirmed esophageal or gastric cancer.
• Subject has esophageal or gastric varices.
• Subject has significant cardiac arrhythmia or ectopy or significant cardiovascular disease.
• Subject has an existing implanted electrical stimulator (e.g., pacemaker, AICD).
• Subject requires chronic anticoagulant therapy.
• Subject has dysphagia or esophageal peptic stricture, excluding Schatzki's ring.
• Subject of child-bearing potential who is pregnant or intends to become pregnant during the trial period.
• Subject is currently enrolled in other potentially confounding research.
• History of any malignancy in the last 2 years.
• History of previous esophageal or gastric surgery, including nissen fundoplication.
• Subject has any condition that, at the discretion of the investigator or sponsor, would preclude participation in the trial.