Implanted medical device aims to lower blood pressure
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.
