The company that invented the heart pacemaker is employing the same technology to trick obese patients into thinking their stomachs are full.

And Medtronic Inc., the world’s biggest maker of medical devices, is not the only medical technology company trying to tap into the $100 billion obesity market.

While Medtronic is trying to develop a battery-powered gastric pacemaker that causes the stomach to contract, sending signals of satiety to the appetite center in the brain, a small start-up also is working with the famed Mayo Clinic on a device that uses electricity to paralyze the stomach, reducing or stopping contractions that churn food as part of the digestion process.

Doctors and companies across the United States are looking at various technologies to combat obesity, including brain stimulation. These methods, though not completely understood by doctors, may be preferable to bariatric surgery since device-based treatments are reversible and have fewer side effects.

Despite failures so far of some devices in clinical trials, companies are pushing ahead, convinced that medical devices hold the key to battling obesity.

Medtronic said it remains committed to solving obesity, largely untapped by the medtech sector, even though its implantable gastric stimulator, or IGS, failed to prove effective in a clinical trial in achieving excess weight loss after 12 months, said the new chief of the company’s neurological business, Dr. Richard Kuntz.

Kuntz said the market for all therapy related to obesity is $100 billion; the market for the severely obese is $5 billion to $10 billion.

“We think that’s conservative ... we think we could grow that market very quickly,” Kuntz said in a recent interview from the company’s headquarters in Minneapolis, Minnesota.

Medtronic’s stopwatch-size IGS, which the company acquired through its $260 million purchase of Transneuronix last year, is implanted under the skin of the abdomen with electric wires placed on the wall of the stomach.

The device “paces” the stomach by delivering small electrical currents that cause the stomach to contract.

Kuntz said he was not too discouraged by the trial’s failure because there are still questions about the settings that should be used on the implants, such as how much voltage should be delivered and the frequency of stimulation.

Kuntz, a cardiologist by training, said Medtronic would also look at its deep brain stimulation technology - which uses tiny electrodes implanted in specific areas of the brain to affect behavior, movement and other functions - as a possible treatment for obesity.

Brain stimulation technology is currently approved in the United States to treat movement disorders such as Parkinson’s disease and is being studied to treat obsessive-compulsive disorder and severe depression.

“If we can salvage IGS, that’s probably our fastest way to that market,” Kuntz said, adding that it could be as soon as three or four years from now.

In another laboratory in Minneapolis - a city once dominated by flour mills that has evolved into a hotbed for medical technology - medtech start-up Enteromedics Inc. is working with the Mayo Clinic on its own implantable device to fight obesity.

START-UP TAKES ANOTHER APPROACH

But rather than stimulating the stomach like Medtronic’s IGS device, privately-held Enteromedics is trying to inhibit nerve function by using electrical currents to block the Vagus Nerve, one of five cranial nerves.

The device, called Maestro, is also inserted beneath the skin of the abdomen, with connecting electrical leads placed on the stomach. The electrical pulses block the Vagus Nerve and paralyze the stomach, stopping contractions that churn food as part of the digestion process, said William Sandborn, one of the gastroenterologists at the Mayo Clinic working with Enteromedics.

“The way the device is used is still evolving,” Sandborn said, noting that the initial trial included only 15 patients.

The goal is to slow digestion so that the patient feels sated longer. The device also shuts down the pancreas and the secretions of digestive enzymes. The process effectively causes the patient to absorb less food, and thus calories, Sandborn said, noting that is partly the reason gastric bypass surgery works.

Mark Knudson, president and chief executive of Enteromedics - a company with just 40 employees, some of them from Medtronic - said he hopes to announce clinical results from human trials this year.

The only approved medical device that addresses obesity is the Lapband, owned by Allergan.

Bariatric surgery, including gastric bands like the Lapband, is the only effective permanent solution, doctors say. A commercially available implantable device may be years away from being approved in the United States, they say.

Mitchell Roslin, chief of obesity surgery at New York’s Lenox Hill Hospital, led the clinical trial testing Cyberonics Inc.‘s Vagus Nerve Stimulation to treat obesity, which also failed to meet its goals.

Roslin said he believes the future of treating obesity will lie in devices, but today there is not enough data.

“It’s not ready for prime time,” he said.

“When we eat, and there’s a feeling of being full, the nerves are stimulated. We can stimulate the stomach with the Vagus nerve, but we only know how to turn it on. We don’t know what we’re communicating ... and so we only have random success,” Roslin said.

Neurosurgeon Ali Rezai of the Cleveland Clinic is investigating other possible indications for deep brain stimulation.

“We know where the feeding and satiety centers are in the brain ... but at this point, there’s no real data.

“As imaging advances, we’ll increasingly be able to pinpoint problems, and it will lead to a new era of how we treat these problems,” he said.

Rezai said doctors are using magnetoencephalography, or MEG, to view real time electrical activity in the brain.