July 13, 1998 By Melanie Fridl Ross
GAINESVILLE, Fla.---For the first time in Florida, University of Florida surgeons have implanted a small abdominal pacemaker in two women whose stomachs do not readily empty after they eat, a fairly common gastric disorder whose symptoms can make mealtime a nightmare.
Similar to the heart, which beats an average of 60 to 70 times each minute at rest, the muscular stomach gives off its own rhythmic impulses about every 20 seconds. This process mixes food with digestive juices, converting it into a thick fluid before it travels to the small intestine.
Patients with gastroparesis - which literally means "weak stomach" - may feel full after just a few bites of food. Worse yet, they frequently suffer from severe nausea and vomiting, and often experience substantial weight loss and related nutritional problems, said Dr. Charles A. Sninsky, a professor of medicine in the division of gastroenterology, hepatology and nutrition at UF's College of Medicine and chief of the gastrointestinal section at the Gainesville Veterans Affairs Medical Center.
On June 10, UF surgeons operated on an Orlando woman, 45, and a Tampa woman, 43, to implant the pacemaker. The condition is one of the more common reasons patients are referred to the gastrointestinal unit at Shands hospital at UF, and frequently is seen in young women and patients with diabetes, Sninsky said.
"Most people empty 50 percent of their stomach contents within 80 minutes. That varies depending on the amount of calories taken in," he said. "You can imagine the larger the amount of calories ingested and the larger the amount of fat in a meal, the longer it takes your stomach to empty. The people we're talking about don't empty their stomach for three or four hours - or not at all."
UF researchers are studying whether the small pacemaker, implanted in the abdominal wall, can reduce the disorder's life-altering symptoms. A second focus is to determine whether the device can train the stomach to empty more quickly.
"The goal is to improve the quality of life by decreasing nausea and vomiting and allowing them to eat," Sninsky said. "They then might be able to take in a caloric load that would allow them to stabilize their weight."
UF surgeons are operating on patients 18 and older whose symptoms have not responded to medication. During the operation, they thread two wires from the pacemaker to the stomach's surface. The device sends impulses to the stomach and stimulates it to contract 12 times a minute, said Dr. Michael Hocking, a professor of surgery at UF.
The pacemaker, manufactured by Minneapolis-based Medtronics, can be programmed externally using a magnet.
Half the study participants will have their pacemaker activated shortly after the surgery; the others will have it switched off. Patients will not know which group they are in. After six weeks, those whose pacemakers were on will have them turned off, and vice versa.
Participants will keep daily diaries detailing the symptoms they experience. After three months, patients can have the pacemaker turned on or off, depending on their preference. Researchers will track about 100 patients worldwide for up to a year.
"While most patients can be managed with medications, we see individuals whose medications work for awhile but then stop," Sninsky said. "We often have to rotate different medicines to find one that will work. In addition, there is a subset of patients who fail to respond to all medications and who must go to total parenteral nutrition or hyperalimentation (tube feedings), which can cost as must as $100,000 a year and pose certain risks, such as infection and other complications. We're looking for an alternative that will improve their quality of life and their nutritional status while decreasing their symptoms and allowing them to eat."
Many animal studies in recent years have shown that gastric pacing is beneficial, Hocking said.
A small pilot study of the pacemakers involving one U.S. center as well as a handful of European centers found marked improvement in patient symptoms, even though the rate of stomach emptying did not change dramatically, he said.
"There is some suggestion this may alter the nerve impulses from the stomach so patients have fewer symptoms, like an electronic form of acupuncture," Hocking said.
Should the device prove promising, it also could be tested as a treatment for other problems or as a method of speeding the recovery of gastric function after surgery, he said.
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