Gastric Electrical Stimulation for Chronic Gastroparesis

Jameson Forster

Indications/Contraindications

As a transplant surgeon who 13 years ago happened to become involved in placing gastric electrical stimulators for the treatment of gastroparesis, I have been impressed that the patients who suffer from this disease are as much psychologically impaired as they are nutritionally impaired. They are afraid of eating and scared to be anywhere but in a hospital bed; to later see these patients walking down the hospital hallway, well dressed, smiling, and engaged in life, all because they can now eat is astounding and gratifying. I have learned that being able to eat is an important part of being human. Gastroparetics suffers from nausea, vomiting, bloating, abdominal pain, weight loss, and early satiety. The disease is defined as having >10% of a standard meal remaining in the stomach after 4 hours. There needs to be an anatomically normal stomach, normal thyroid function, and no small bowel obstruction. The condition is frequently associated with diabetes mellitus of 20 years or more duration but may develop from unknown causes (idiopathically) or following abdominal surgery.

Since the gastric electrical stimulator does not cause gastric contractions, I have felt that we should not use the term “pacemaker,” even though the device resembles a cardiac pacemaker. To actually pace the stomach, one needs to use a pulse lasting 1,000-fold longer, which can only be accomplished with an external power source.

A surgeon should not venture out alone in this endeavor but be an integral part of a multidisciplinary team that cares for these complicated patients. The other members should include gastroenterologists, with an interest in motility disorders, dietitians, psychologists, psychiatrists, pain specialists, and nurse practitioners. Conditions that often mimic gastroparesis but require a significantly different approach include rumination syndrome, conditioned vomiting, regurgitation, gallbladder dyskinesia, gastric outlet obstruction, and severe constipation. Medical treatment includes Erythromycin, Reglan, Domperidone, Tegaserod, Bethanechol, phenothiazines, ondansetron, tricyclic antidepressants, and antihistamines.

Surgeons have previously played only a minor role, since any resections short of total gastrectomy have proven ineffective in promoting gastric emptying or reducing nausea and vomiting. Pyloroplasties, gastrostomies, and/or subtotal gastric resections do not help. A jejunostomy feeding tube may allow a malnourished patient to be safely fed without the expense and risk associated with total parenteral nutrition (TPN).

Preoperative Planning

Patients should have recently documented normal esophagogastroduodenoscopy (EGD) and colonoscopy. An abdominal ultrasound should be obtained to rule out gallstones and a biliary scan with measurement of the gallbladder ejection fraction is appropriate, if there is a suggestion of biliary colic. Thyroid function studies are also required. Since postoperative infections are difficult to treat, prevention is the key. For patients with a history of infections, I suggest nasal swabs to make certain MRSA is not present and treatment with Bactroban if positive. Showers with chlorhexidine soap for a week prior to surgery are recommended. Ioban skin drapes are used during the operation so that neither the stimulator nor the electrodes come in contact with the skin; cefazolin as the preoperative intravenous antibiotic and for 24 hours postoperative is essential; a subcuticular closure with a running absorbable suture, dressed with dermabond, which seals and protects the skin from postsurgical infection, ends the case. Some patients may benefit from pyloroplasty, in an effort to improve gastric emptying which is not improved by the stimulator; others who come to surgery severely malnourished are often supplemented by placement of a feeding jejunostomy.

We have seen two early postoperative deaths in our series, for a mortality of about 1%, one elderly woman died from a pulmonary embolism and the other, also an elderly woman, died from a cardiovascular event. Morbidity includes no improvement in symptoms, migration of the device requiring reoperation, 10% incidence of infection, and a limited (7 to 8 years) battery life requiring replacement.

Surgery

The patient is placed supine. After sufficient endotracheal anesthesia is established, nasogastric (NG) tube and Foley catheter are placed. Preoperative antibiotics are given and the lower chest and abdomen are prepped with chlorhexidine. The patient is draped using an Ioban Incise Drape. A small upper midline incision is made, approximately 5 cm in length. Once in the abdomen, exploration is done. The stomach is identified and the pylorus is located. If there was a prior cholecystectomy, the pylorus is usually adherent to the gallbladder bed and needs to be mobilized. Only when the pylorus is freed, can one properly measure along the greater curvature. Using a plastic ruler, we measure along the greater curvature and mark the stomach at 9.5 and 10.5 cm proximal to the pylorus, stretching the stomach as much as possible (Fig. 36.1). The
needles of each electrode are inserted tangentially through the gastric wall, radially inward, deep enough so that the needle is in the gastric muscle and not visible through the serosa. The two needles are placed a centimeter apart and coursing for at least a distance of 1 cm within the muscle (Fig. 36.2

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