title: Blood pressure control with selective vagal nerve stimulation and minimal side effects.
abstract: OBJECTIVE
  Hypertension is the largest threat to patient health and a burden to health care systems. Despite various options, 30% of patients do not respond sufficiently to medical treatment. Mechanoreceptors in the aortic arch relay blood pressure (BP) levels through vagal nerve (VN) fibers to the brainstem and trigger the baroreflex, lowering the BP. Selective electrical stimulation of these nerve fibers reduced BP in rats. However, there is no technique described to localize and stimulate these fibers inside the VN without inadvertent stimulation of non-baroreceptive fibers causing side effects like bradycardia and bradypnea.
  
  
  METHODS
  We present a novel method for selective VN stimulation to reduce BP without the aforementioned side effects. Baroreceptor compound activity of rat VN (n = 5) was localized using a multichannel cuff electrode, true tripolar recording and a coherent averaging algorithm triggered by BP or electrocardiogram.
  
  
  RESULTS
  Tripolar stimulation over electrodes near the barofibers reduced the BP without triggering significant bradycardia and bradypnea. The BP drop was adjusted to 60% of the initial value by varying the stimulation pulse width and duration, and lasted up to five times longer than the stimulation.
  
  
  CONCLUSIONS
  The presented method is robust to impedance changes, independent of the electrode's relative position, does not compromise the nerve and can run on implantable, ultra-low power signal processors.
authors.affiliation: Department of Microsystems Engineering (IMTEK), Laboratory for Biomedical Microtechnology, University of Freiburg, Georges-Koehler-Allee 102, D-79110 Freiburg, Germany.
authors.forename: Dennis T T
authors.initials: DT
authors.lastname: Plachta
authors.forename: Mortimer
authors.initials: M
authors.lastname: Gierthmuehlen
authors.forename: Oscar
authors.initials: O
authors.lastname: Cota
authors.forename: Nayeli
authors.initials: N
authors.lastname: Espinosa
authors.forename: Fabian
authors.initials: F
authors.lastname: Boeser
authors.forename: Taliana C
authors.initials: TC
authors.lastname: Herrera
authors.forename: Thomas
authors.initials: T
authors.lastname: Stieglitz
authors.forename: Joseph
authors.initials: J
authors.lastname: Zentner
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D025461:Feedback, Physiological / Q000502:physiology*; D008297:Male; D008904:Miniaturization; D011311:Pressoreceptors / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014630:Vagus Nerve / Q000502:physiology*; D055536:Vagus Nerve Stimulation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*