Implantable medical device that lowers blood pressure

Apr 3 2005

Doctors at the University of Rochester Medical Center are the first in the nation to implant an investigational medical device that lowers blood pressure by activating the body's natural blood pressure regulation systems.

The landmark procedure, performed yesterday, is part of a Phase II clinical research trial to be conducted by a limited number of medical centers in the United States. Called the Rheos Trial, it is funded by CVRx Inc. of Minneapolis. Karl A. Illig, M.D., chief of the Division of Vascular Surgery, is principal investigator for the Rochester trial site. Cardiologist John D. Bisognano, M.D., Ph.D., associate professor of Medicine, who has been involved in development of this technology, and nephrologist James A. Sloand, M.D., associate professor of Medicine, serve as primary co-investigators.

"The Rheos System works by electrically activating the baroreflex system based in the carotid arteries in the neck, regulating blood pressure in a manner similar to a pacemaker regulating heart rhythm," Illig says. "Low-level electrical stimulation to this area sends signals to the brain, 'telling' it to take action to lower blood pressure through a variety of mechanisms, including blood vessel dilatation, heart rate reduction, and promotion of fluid excretion by the kidneys. In this way, the Rheos System provides a physiologic approach to reducing high blood pressure by allowing the brain to direct the body's own control mechanisms."

"This device, if found effective, would offer a way to lower blood pressure in patients who have not been able to control their blood pressure with medications, and could conceivably reduce the need for pressure-lowering medications in patients with lesser degrees of hypertension," Illig says.

The Rheos system consists of a battery-powered implantable generator, which is inserted under the skin near the collarbone, and two carotid sinus leads, which run from the generator to the left and right carotid sinus in the neck. While implantation is slightly more involved, the general principle is quite similar to the implantation of cardiac pacemakers.

Following the Phase II trial, if results continue to be good, a larger, nationwide trial will begin.

Trial patients receive the device as part of a minimally invasive surgical procedure, followed typically by a one- or two-night stay in the hospital. The device initially will be tested for effect in the operating room and then turned off for one month, to ensure there are no health problems associated with the implant. At one month, a graduated scale of stimulation will be applied until the best possible blood pressure response is achieved. Patients will be evaluated on a regular schedule until the device receives FDA approval, and generally will be followed for life.

"Findings from this study could have a significant impact on how we are able to treat hypertensive patients in the future," Illig says. "We are honored that the University of Rochester can be at the forefront of this technology."

Illig, Bisognano and Sloand are conducting the trial with vascular surgeons Mark Davies, M.D., Ph.D., Jeffrey Rhodes, M.D., Cynthia Shortell, M.D., and Michael Singh M.D.