Gastric Electrical Stimulation

Humanitarian Device

The Enterra neurostimulator received humanitarian device exemption (HDE) approval from the U.S. Food and Drug Administration (FDA) in 2000. HDE status allows Medtronic, Inc. to provide the Enterra System for the treatment of chronic intractable (drug-refractory) nausea and vomiting secondary to gastroparesis of diabetic or idiopathic origin. However, the effectiveness of gastric electrical stimulation for this use has not been demonstrated. Because of the HDE status, the system must be implanted in a medical center whose institutional review board (IRB) has approved use of the device.

Indications

GES is indicated for use in the treatment of chronic, intractable (drug refractory) nausea and vomiting secondary to gastroparesis of diabetic or idiopathic etiology.

Contraindications

Patients whom the clinician determines are not candidates for surgical procedures and/or anesthesia due to physical or mental health conditions.

Do not use shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy (all now referred to as diathermy) on patients implanted with a neurostimulation system. Energy from diathermy can be transferred through the implanted system and can cause tissue damage at the location of the implanted electrodes, resulting in severe injury or death.

Diathermy is further prohibited because it can also damage the neurostimulation system components resulting in loss of therapy, requiring additional surgery for system explantation and replacement.

Injury or damage can occur during diathermy treatment whether the neurostimulation system is turned "on" or "off." Advise your patients to inform all their health care professionals that they should not be exposed to diathermy treatment.

Treatment & Diagnosis

About Gastroparesis

Gastroparesis is a neuromuscular stomach disorder in which food empties from the stomach more slowly than normal. In most people, undigested food moves from the stomach into the duodenum and small intestine within two to four hours after eating.

In contrast, patients who have gastroparesis will retain significant amounts of food in the stomach hours after eating or longer. Patients with gastroparesis experience a variety of upper gastrointestinal symptoms including chronic nausea, frequent vomiting, early satiety, abdominal bloating, and abdominal pain. These symptoms prevent the patient from eating normally and may lead to dehydration, weight loss, and eventual life-threatening electrolyte imbalances and malnutrition.

Moreover, delayed stomach emptying interferes with oral drug absorption and, in patients with diabetes mellitus, prevents effective control of blood glucose levels.

Impact of Gastroparesis on Patients

Gastroparesis is a debilitating condition because of chronic nausea and vomiting and the severity of abdominal discomfort. If vomiting episodes cannot be controlled through dietary modification or medication, then dehydration, significant weight loss, and poor nutrition are inevitable.

Nutritional support via a surgically inserted feeding tube or indwelling intravenous catheter may be necessary if sufficient caloric intake cannot be maintained. These methods of nourishment carry the risk of infection in an already compromised individual.

Etiology of Gastroparesis

In a survey of 146 patients with documented chronic gastroparesis, it was found that approximately¹:

• 35.6% had idiopathic gastroparesis
• 29% had diabetic gastroparesis
• 35.4% had gastroparesis of other origins

About Gastric Stimulation

Gastric stimulation may reduce the symptoms of chronic intractable (drug refractory) nausea and vomiting due to gastroparesis of diabetic or idiopathic origin. Often, a combination of therapies is needed to adequately control symptoms.

Rate of improvement varies from person to person and can be immediate or gradual. A baseline comparison is important for patient monitoring and is useful when a patient experiences a flare-up of nausea and vomiting and underestimates the degree of improvement s/he has undergone.

Gastric stimulation potential benefits to patients:²

• Significant reduction in weekly vomiting
• Improvements in health-related quality of life measures and other symptoms

What it is indicated for

The Enterra Gastric Neurostimulation System is indicated for the treatment of chronic intractable (drug-refractory) nausea and vomiting secondary to gastroparesis of diabetic or idiopathic etiology. The effectiveness of this device for this use has not been demonstrated.

How It Helps Treat Gastroparesis

Gastric stimulation is a reversible therapy that involves electrical stimulation of the lower stomach (antrum). Electrical stimulation is accomplished via a fully implantable system that consists of two unipolar intramuscular leads and a neurostimulator.

The results of a Medtronic-sponsored clinical study called WAVESS—Worldwide Anti-Vomiting Electrical Stimulation Study indicate that electrical stimulation of the stomach reduces vomiting frequency in most patients with diabetic or idiopathic gastroparesis. Study results indicate that symptoms of nausea and vomiting were reduced and health-related quality of life improved at 6 and 12 months post-implant, compared to baseline values.¹

Thirty-three (33) patients with chronic gastroparesis were enrolled in WAVESS (17 of diabetic origin and 16 of idiopathic origin). Symptoms were compared between baseline and 6 and 12 months.

At both follow-ups and for both patient groups, the median weekly vomiting episodes were significantly reduced:

• At 6 months after implant, the median vomiting frequency declined 80% for the diabetic group (n=13) and 88% for the idiopathic group (n = 14).
• At 12 months after implant, the median vomiting frequency declined 63% for the diabetic group (n=11) and 83% for the idiopathic group (n = 13).