A group of scientists from Germany have developed an implantable device that successfully lowered rats’ blood pressure by 60 percent, thanks to a set of electrical signals fed through the animals’ brains and major organs.
The new study, published in the Journal of Neural Engineering, offers an experimental strategy for treating hypertension in humans that uses the body’s own sensors, known as baroreceptors, to regulate blood pressure back to normal without affecting other vital processes. As nearly one-third of the U.S. has high blood pressure, yet less than half of those people actively treat it, the cause for concern is imminent.
In their study, researchers from the University of Freiburg used a miniature prototype of the device on five male lab rats. In each rat, they wrapped an electrode-stuffed band around a nerve in the spinal cord, called the vagal nerve. The device then extended down toward the rats’ abdomens and ended on various organs, such as the heart and blood vessels. The entire device was two centimeters long and less than a millimeter in diameter.
After testing various stimulation sites along the vagal nerve, with different frequencies, amplitudes, and durations, the team eventually managed to reduce the rats’ blood pressure by 60 percent in a wide range of stimulation sites and frequencies. Importantly, there were no adverse side effects, which, as lead author Dr. Dennis Plachta points out, “is important for a wide variety of potential treatments that could utilize nerve stimulation without actually penetrating the nerve.”
Plachta cautions, however, that the device isn’t mean to be the first line of defense against high blood pressure — actually the opposite. It’s only after a person’s medication fails, he says, that people should consider invasive surgery to treat a condition. He and his colleagues also concede that this may be the case for around 30 percent of the population with high blood pressure, a group that, for whatever reasons, doesn’t “respond sufficiently to medical treatment.”
“Nevertheless,” Plachta said, “the long-term goal is to provide 'treatment-on-demand' for the patient, whereby the implantable device uses an intelligent circuit to record the activity of the patient.” Take exercise, for example. Not only would the device be capable of measuring the person’s blood pressure — such novelties have already been used in some fashion in popular fitness trackers. The device would also be interactive: automatically adjusting the person’s blood pressure so he or she can still function in the activity safely.
As for the device’s effectiveness and safety in humans, that research remains years down the line. Researchers will continue along the animal model route until all kinks, both knowable and unknowable, have been ironed out. "We will now look to develop the implantable device further,” Plachta said, “and investigate whether it interferes with existing medication, and ultimately test it on larger animals such as pigs and sheep.”
Source: Plachta D, Gierthmuehlen M, Cota Oscar, et al. Blood pressure control with selective vagal nerve stimulation and minimal side effects. Journal of Neural Engineering. 2014.