Although bariatric surgery procedures yield significant weight loss for patients struggling with obesity, the procedures aren't without considerable risk. These procedures include banding, which is the placement of a band around the top part of the stomach to reduce its capacity, or bypass procedures which reroute food and remove part of the stomach.

Complications occur at a somewhat high rate from these procedures as a study of insurance claims of 2522 who had undergone bariatric surgery revealed 21.9% complications during the initial hospital stay but a total of 40% risk of complications in the subsequent six months.

But Mayo Clinic (Rochester, Minnesota), in collaboration with EnteroMedics (St. Paul, Minnesota), is developing a new implantable device-based therapy called VBLOC, or vagal blocking therapy, that is being touted as a safer alternative to bariatric procedures.

VBLOC went through a six-month, open-label trial involving three medical centers in Australia, Mexico and Norway.

The 31 obese participants who received the vagal nerve blocking device, also called VBLOC vagal blocking therapy, lost an average of nearly 15% of their excess weight. A quarter of the participants lost more than 25%, and three patients lost more than 30%, according to findings published in the recent issue of the journal Surgery.

Michael Camilleri, MD, a gastroenterologist who helped design the study and is one of the Mayo Clinic researchers whose previous work and know-how contributed to development of the device, said in a press release that "for this study, we wanted to get an initial assessment of whether blocking the vagus nerve electrically could cause obese patients to feel full after a normal-sized meal. Patients were not put on any restricted diets or given counseling that typically accompanies gastric banding or bypass. We wanted to determine how much weight loss could be attributed to the device alone."

The VBLOC therapy is similar to a heart pacemaker, but instead of stimulating a normal, regular heartbeat, it uses high-frequency electricity to block the nerve impulses between the brain and the stomach and pancreas. A pacemaker continuously monitors the heart and regulates its beating.

But the patient flips a switch to activate the VBLOC device when the system is worn during the daytime hours so that the blocking signal can influence how the stomach functions and food is digested following a meal.

The vagal nerves begin in the brain and extend to multiple organs and regions of the digestive system. Each vagus nerve provides direct two-way communication between the brain and the digestive system without the additional spinal cord processing of impulses that is typical for most other human nerves.

The vagal nerve trunks are nearly 3 mm to 4 mm in diameter and course along the anterior (front) and posterior (back) of the esophagus before they branch out from the esophagus to the stomach, pancreas, duodenum and gall bladder.

Here's a breakdown of how the device works.

The lead wires are implanted in the abdomen laparoscopically, with electrodes attached to the vagal nerves and the neuroregulator, a pacemaker-sized device, is implanted just under the skin. While gastric bypass involves removing portions of the digestive tract and rerouting the flow of food and, therefore, is not reversible, the VBLOC delivery system can be removed if desired, and previous studies in animals have indicated that it does not damage or permanently affect the vagal nerves.

Also with VBLOC, there is no distortion of digestive system anatomy as is the case with both gastric bypass and gastric banding, and to date there have been no significant issues related to food intolerance, nausea or vomiting as is common with both bypass and banding.

Camilleri was involved in designing the study, but because Mayo Clinic physicians and scientists participated in the development and preclinical testing of the device, the initial clinical research was conducted elsewhere to avoid having results affected by a conflict of interest.

The participating centers for the initial study were Flinders Medical Centre (Adelaide, Australia) Instituto National de la Nutricion (INNSZ; Mexico City); and St. Olav's University Hospital (Trondheim, Norway).

He said a follow-up double-blinded study, which will involve up to 300 patients at multiple medical centers, including a limited number from Mayo Clinic, will be important for gauging the device's true effectiveness.

"After the pivotal study is completed, those who had the sham' treatment will have their devices turned on so they can experience the benefits," Camilleri said. "And unlike the first study, participants also will have access to behavioral counseling and dietary modifications, which will lead to a more realistic comparison of the magnitude of weight loss through vagal blockade as compared with bariatric surgery."

He added, "The findings published this month are promising, but the next study will tell us whether VBLOC therapy is a viable alternative to gastric bypass or gastric banding, and for which patients."

EnteroMedics is a development-stage medical device company focused on the design and development of devices that use neuroblocking technology to treat obesity.

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