Gastroparesis (GP) is describing a condition when stomach does not empty as fast as it should. This fact creates the situation, when food stays in the stomach for a long time and it causes symptoms of nausea, vomiting, loss of appetite, bloating, inability to finish normal size meal and abdominal pain. There are not many drugs available to treat this condition and majority of gastroparetic patients are not responding well to them after they are on it for some time. Many investigators are able to implant Gastric Stimulator System (GES) under FDA approved status of Humanitarian Device Exemption (HDE) definition. In the last few years it became possible to add another surgical procedure, which is called pyloroplasty (making bigger opening on the end of stomach), may help even more as it is also increasing the rate of the emptying of the stomach. Therefore this study is proposing to evaluate if GES in combination with pyloroplasty is much better than pyloroplasty alone. For this reason, two of these procedures will be introduced surgically at the same time, but GES devices will not be turn ON in half of these participants for 3 months. After that time all subjects will have their devices turned ON. All subjects will be asked to evaluate their symptoms of gastroparesis and their quality of life during clinical visits, and investigators will conduct pathological analyses of tissue obtained during surgery.

GES system (Enterra Therapy) involves surgical implantation of a pulse generator in the abdominal wall and 2 electrodes into the muscularis propria of the stomach. Well established procedure, called pyloroplasty, will be performed during the implantation of GES system, therefore all participants will have both surgeries done at the same time. Half of them will be randomized to keep GES ON after surgery, and other half will have GES turned OFF for 3 months.

Both groups will be followed for additional 3 more months. Study related questionnaires and diagnostic/ clinical tests will be obtained at all points of interest of this study.

Inclusion Criteria:

• Documented diagnosis of GP for > 1 year and refractoriness to anti-emetics and prokinetics; more than 7 emetic episodes per week;
• Delayed GE (gastric retention greater than 60% at 2 h and/or greater than 10% at 4 h) based on a 4-h standardized radionuclide solid meal test

Exclusion Criteria:

• Organic or pseudo-obstruction, primary eating or swallowing disorders, positive pregnancy test result, psychogenic vomiting, peritoneal dialysis, drug dependent, morbid obesity, active malignancy

Patient and clinical investigators are going to be blinded in regards to the status of GES (if it is ON or OFF) for 3 months after surgery. One non-clinical investigator is assigned to serve as un-blind person , who is going to generate a master list of participants by dividing them into two groups based on their etiologies (diabetic or idiopathic). All effort would be to include similar numbers of idiopathic and diabetic patients in each intervention group based on a block randomization method, allowing for GES to be turned ON at the surgery, or it will stay OFF for the 3 month during the blind portion of the study.