Electronic B.P. Monitor

High blood pressure can be a very serious condition, and is usually controlled via medication along with lifestyle changes. For approximately 35 percent of patients, however, that medication doesn't work in the long run. That's why a team of researchers from Germany's University of Freiburg are developing an implantable electronic cuff, that may one day control peoples' blood pressure via electrical pulses within the neck.

In tests on rats, the cuff has been implanted in the vagus nerve. In both rats and humans, the vagus nerve extends from the brain stem into the thorax and abdomen, running through the neck along the way. It relays signals that control unconscious body procedures such as heart rate, digestion and breathing.

Using a technique known as BaroLoopTM, the cuff is able to determine which of its 24 electrodes is closest to the nerve fibers responsible for transmitting the blood pressure signal from the brain to the heart. It then activates that electrode, to selectively stimulate only those fibers. As a result, it is able to "overwrite" the brain's faulty signal, lowering the blood pressure to a safe level.

Because no other nerve fibers are stimulated, no other bodily functions are affected. In the rat trials, the animals' mean blood pressure was decreased by 30 percent, while their heart rate and respiratory rate remained largely unchanged.

The current prototype uses leads that extend out of the body, but the scientists are now working on producing a completely implantable device. Because of the stringent safety standards that such implants must meet, however, the finished product isn't expected to be available for at least 10 years.