The investigators are looking at a novel approach to measuring gastroesophageal reflux disease (GERD) damage and reducing the need for costly and less optimal testing presently used for diagnostic and treatment purposes. The investigators will be using three custom mucosal impedance (MI) catheters, each designed to measure at slightly different spacing on the esophagus.

During routine esophagogastroduodenoscopy (EGD), consented study participants will have a series of three (3) custom mucosal impedance (MI) catheters with an axial array of sensors positioned along the mucosal wall to directly measure mucosal impedance at various intervals. Each catheter will be manually guided by the physician through the working channel of the endoscope until the sensored tip is visible through the scope camera. The physician will place the sensored rings directly on the mucosa along the lumen. To obtain evaluable data, the sensors must remain in contact with the mucosa at each point for 5 seconds after a stable impedance reading has been captured. This process will be repeated for each of the three prototype catheters in each consented patient in order to determine the optimal catheter/sensor design. The catheters will be attached to a channeled feed that will record measurements on a dedicated computer.

Inclusion Criteria:

• Patients who are undergoing standard of care EGD with or without BRAVO placement;
• Have GERD symptoms and/or have endoscopic esophagitis

Exclusion Criteria:

• Use of acid suppressive therapy within last 10 days;
• Known history of Barrett's esophagus, gastric surgery, alcoholism, significant motility condition

Patients scheduled for an esophagogastroduodenoscoy (EGD) for one of the following reasons: diagnosed with Gastroesophegeal reflux disease (GERD); have a normal esophageal mucosa but an abnormal pH testing (acid measurement); or a normal esophagus and normal pH testing