(This story has been posted on The Wall Street Journal Online's Health Blog at http://blogs.wsj.com/health.) By Christopher Weaver A new medical device with the promise to relieve an otherwise untreatable form of high-blood pressure has made its first forays into the U.S. in recent weeks, as major medical centers begin testing the procedure, WSJ reported. Patients have high hopes for the clinical trial, coupled in some cases with frustration: Because the device is the first with that might ease stubborn hypertension that doesn't respond to drugs, those who don't make the cut have few other options. The device, made by Medtronic, burns nerves that run along the renal arteries to the kidneys, disrupting signals from the organs that are linked to elevated blood pressure. In sharp contrast to many devices -- widgets or incremental improvements to existing therapies -- Medtronic's so-called renal denervation product breaks new physiological ground, says Mike Carusi, an early investor in the technology with Advanced Technology Ventures. Only about 300 patients in Europe and Australia have participated in trials so far. Although the data covers only a narrow group, the results have been promising. Systolic blood pressures have dropped by 20 to 31 mmHg in various studies, and complications have been rare. Medtronic's trial, which could lead to U.S. approval in 2014, focuses on patients with extremely high blood pressure who don't benefit from at least three of the many hypertension medications on the market. "They don't have any other identifiable, treatable causes" of high blood pressure, says Keith Benzuly, a cardiologist at Northwestern Medicine in Chicago who is participating in the trial. That's been frustrating for patients, sometimes for years. "I started out with one medicine, and it wasn't working, so they added another one," says Carolyn Campas, 59, of Chicago. "These are pills I take every day. They have a lot of side effects: nausea, dizziness, fatigue. Campas, a Northwestern patient, is still being screened for the trial, which will ultimately include 530 patients. Of those, about two-thirds will receive the renal denervation procedure, while the remaining third will receive a simulated procedure. Patients receiving the simulation are blindfolded and wear ear plugs so they can't discern whether the treatment is real or not. Campas says she was thrilled at the opportunity to join the study, even if she doesn't receive the actual treatment right away. "There was nothing else I could do." The Mayo Clinic in Minnesota, which is also participating in the trial, has been getting enthusiastic calls from would-be participants. But screening out the folks that are eligible has proven difficult, says Karen Miller, a clinical trial coordinator there. "It's much more complex than other studies we do," she says. Patients must have systolic blood pressure that hovers above 160 mmHg despite taking at least three anti-hypertensive medicines. That limits the trial to only those with the most serious blood pressure problems. The procedure itself involves threading a catheter from an artery in the groin to the renal arteries, the main approach to the kidneys. Before delivering the treatment, doctors perform an angiogram, an imaging technique, to make sure the patient's anatomy is appropriate. Less invasive than surgery, it still has risks, which are a turn off for some patients. However, says Mayo's Miller, "their high blood pressure is a huge risk, too," and few patients have been deterred by the risks of the therapy. Patients who won't receive the denervation procedure will be able to have the treatment free of charge after six months, the period in which prior, smaller studies showed peak results. "It is a sign of confidence," says Issam Moussa, a Mayo doctor based in Florida, citing the promise of the European trial data. A lot of patients would feel very uncomfortable about the study if they have no chance of getting the treatment, he says. -For continuously updated news from The Wall Street Journal, see WSJ.com at http://wsj.com.