Friday, September 09, 2005

Gastric Pacemaker for Gastroparesis --- A Positive Report

Every once in a while, a new therapy is offered for a difficult problem that has some real promise. Such is the case, I think, with a new device for use in patients with severe gastroparesis, which results in nausea, vomiting, and sometimes dependence on nutritional support (with a feeding jejunostomy). Gastroenterologists struggle caring for the patient with severe gastroparesis, most often due to diabetes but occasionally idiopathic (more info on diabetic gastroparesis can be found here, here, and here). There are occasional patients for whom no medical therapy works well, including alteration of dietary habits or prokinetic medications (Reglan); some are eventually even referred for gastrectomy.

A new device is available which in early trials seems to be very promising -- basically, it is a pacemaker for the stomach. Marketed by Medtronic, the Enterra Therapy Gastric Electrical Stimulation device is designed to provide low voltage electrical impulses to the stomach, restoring some semblance of normal gastric motility.
The two electrodes are placed into the stomach wall and are connected to the neurostimulator, which is then placed into a subcutaneous pocket in the abdominal wall. The procedure can be performed laparoscopically in most patients.

Interestingly, this device received a humanitarian device exemption for use in these patients on the basis of a single case report and a multinational, multi-institutional trial, both of which had promising results. Because there are relatively few patients with severely debilitating gastroparesis, accrual of large numbers of patients in trials has been slow. A recent US report from USC (Archives of Surgery, Sept. '05; not available online yet) gives results of 29 patients treated with the Enterra gastric pacemaker --- and they were quite promising:

  1. Median hospital stay of 3 days
  2. All patients tolerated an oral diet at discharge
  3. Symptom control (i.e., nausea and vomiting) was excellent to good in 19 out of 27 patients with follow-up
  4. Nutritional support was discontinued in the 19 patients dependent on supplemental feeding preoperatively
  5. Median BMI showed statistically significant improvement
  6. Gastric emptying rate was shown to be significantly improved
(Mason, RJ, et al. Gastric Electrical Stimulation: An Alternative Surgical Therapy for Patients with Gastroparesis. Arch Surg. 2005; 140:841-848)

There is no questions that these patients are quite challenging and time-consuming for gastroenterologists. Hopefully, this device will be a good alternative for many, especially those with diabetic gastroparesis. This study has its limitations -- it was uncontrolled and retrospective -- and the device is quite expensive, so there is no reason to adopt its use without reservation just yet. However, in the next few years, I would expect there will be some reasonable delineation of which patients will, or will not, benefit from gastric pacing -- diabetics, pancreatic malignancy, post-vagotomy, etc.