Germans are well-known for their development of high-tech products. As an alternative to medications to control blood pressure, German scientists have developed an implantable device that reduces blood pressure by sending electrical impulses to the brain. The research was published on May 8 in the Journal of Neural Engineering by researchers at the University of Freiburg.
The authors note that hypertension is the largest threat to patient health and a burden to healthcare systems throughout the planet. Although a large number of pharmaceuticals are available to treat the condition, 30% of patients do not respond adequately to medical treatment. Receptors are present in the aortic arch, which is the portion of the artery that emerges from the heart. These receptors relay blood pressure levels via the vagal nerve to the brainstem and trigger the baroreﬂex, which lowers blood pressure. Extending from the brain to chest and the abdomen, the vagal nerve supplies and stimulates major organs, such as the heart, as well as the blood vessels.
The investigators explain that selective electrical stimulation of nerve ﬁbers in the vagal nerve was found to lower blood pressure in rats; however, there is no technique available that can localize and stimulate these ﬁbers inside the vagal nerve without inadvertently stimulating non-baroreceptive ﬁbers; this situation results in untoward side-effects such as bradycardia (abnormally slow heart beat) and bradypnea (abnormally slow breathing rate). Therefore, they developed a novel method for selective vagal nerve stimulation to reduce blood pressure without these side-effects.
The scientists developed a “multichannel cuff electrode” (MCE), which is a cuff composed of 24 electrodes that wraps around the vagal nerve. The MCE device is able to identify and specifically stimulate the baroreceptor fibers; thus, regulating blood pressure, while avoiding the fibers that affect other major bodily functions. The investigators tested the device on five male rats; the MCI sent 40 electrical pulses per second to the baroreceptor fibers in the rats’ vagal nerves. Via this technique, they were able to reduce the rats’ blood pressure by 40%.
Because implanting the MCE device requires surgery, the investigators note that the device would not be suitable for all patients with high blood pressure, rather for those who do not otherwise respond to blood pressure lowering medications.