A new Mayo Clinic study suggests that video capsule endoscopy (CE), a procedure that uses wireless technology in diagnosing intestinal disease, is safe for patients with heart devices. Wireless electrical gadgets, such as cell phones, have been shown to interfere with implanted heart devices, including pacemakers and defibrillators. This risk has led medical experts to speculate that capsule endoscopy could similarly cause heart devices to fail.
As a result, the noninvasive procedure has been contraindicated by the U.S. Food and Drug Administration (FDA) for patients with cardiac devices. Contraindication means an increased risk may be involved.
Generally, the topic has remained in the subject of speculation, although several small studies have found no interference with cardiac devices, and no clinical reports have surfaced linking CE to problems with them.
The study concludes that performing a video capsule endoscopy on patients who have cardiac devices appears safe, and, conversely, the cardiac implants don't impair capsule endoscopies.
"Ours is the largest study of its kind, with 84 patients (91 capsule studies), and we found no complications from the capsule endoscopy," says Jonathan Leighton, M.D., chair of the Division of Gastroenterology at Mayo Clinic in Arizona and senior author of a report on the research.
"The size of the study population should give physicians confidence to use the procedure," says Dr. Leighton. Mayo physicians perform capsule endoscopy routinely, averaging from two to five cases a week at the Arizona site.
In the study, Lucinda Harris, M.D., Stephanie Hansel, M.D., reviewed the medical records of 84 patients who underwent CE and had implantable cardiac devices -- cardiac pacemakers, defibrillators or left ventricular assist devices -- at Mayo Clinic's campuses in Arizona and Rochester, Minn.
The patients' average age was 73, and 69 percent had pacemakers. In a large majority of cases (74 percent), the reason for performing the CE was to locate gastrointestinal bleeding. In each case, the capsule explored the entire length of the small bowel. Assessments after the procedure revealed no interference with the implanted cardiac devices.
Approved by the FDA in 2000, capsule endoscopy uses a tiny wireless camera to examine the inside of the digestive tract. The patient swallows a vitamin-sized capsule containing a battery-driven camera that travels through the intestines, taking thousands of pictures. It then transmits them to an external receiver from areas deep inside the small bowel previously accessible only through surgery. The device is later excreted through the colon.
The use of capsule endoscopy has solved a long-term problem for doctors: visualizing the midsection of the small intestine, which can measure 20 feet in length. Standard endoscopy, done through the mouth or the rectum, can't penetrate deeply enough and requires anesthesia. Now, CE is used to visualize the entire small intestine. Most commonly, it is used to find the source of unexplained bleeding. The procedure is also used to detect the causes of anemia, abdominal pain and certain intestinal diseases.
Because cell phones, microwave ovens and other wireless appliances have affected heart devices, physicians were concerned that the radiofrequencies used in CE may potentially interfere with the radiofrequency of heart devices. But in the study, the only research complication occurred when a capsule's receiver stopped working for reasons unrelated to a heart device, according to Dr. Harris, a Mayo gastroenterologist and first author on this study.
"There were no problems with the devices interacting," says Dr. Harris. "The data is now out there. We are coming to the point where we know this is a relatively safe procedure. She was scheduled to report on the project Monday, Oct. 26, at a meeting of the American College of Gastroenterology in San Diego.
Affirming the procedure's safety when heart devices are present mainly benefits elderly patients, who are the most prone to have implanted devices (primarily pacemakers) and to experience unexplained intestinal bleeding from illnesses or blood-thinning medications.
Mayo doctors plan to continue using capsule technology on patients with implants. But even with the positive results of the study, they will continue to do CE as an inpatient procedure.
"If it were not contraindicated by the FDA, we would do it as outpatient, and it would reduce costs, just as safely," says Dr. Leighton.
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