BaroLoop: using a multichannel cuff electrode and selective stimulation to reduce blood pressure

The therapy of refractory hypertension is an increasing problem for health care systems and a frontend in research in both pharmacology and neuroelectronic engineering. Overriding the baroreceptive information of afferent nerve fibers, originating from pressure sensors in the aortic arch, can trigger the baroreflex, a systemic control system that lowers the blood pressure (BP) almost instantaneously. Using a multichannel cuff electrode, wrapped around a rat vagal nerve, we were able to regulate the BP using selective, tripolar stimulation. The tripolar stimulation was sufficiently selective to not trigger any unwanted side effects like bradycardia or bradypnea. The BP was reduced best with charge balanced stimulation amplitudes of 1 mA and pulse duration of 0.3 ms. The stimulation frequency had only a mild influence on the effectiveness of the stimulation and did work best at 40 Hz. We found that the BP took up to five times the stimulation period to recover to the value prior to stimulation.