title: Transvenous parasympathetic cardiac nerve stimulation: an approach for stable sinus rate control.
abstract: BACKGROUND
  Epicardial electrical stimulation of parasympathetic nerves innervating the sinus node has been shown to decrease sinus rate. We investigated whether intravascular parasympathetic cardiac nerve stimulation (IPS) can be achieved over a relatively long-term period to slow the supraventricular rate.
  
  
  RESULTS
  Fifteen dogs were investigated. IPS was performed with rectangular stimuli (0.05-msec duration, 20 Hz) using a catheter with an expandable electrode basket. The catheter was positioned in the superior vena cava (SVC; n = 9) or right pulmonary artery (RPA; n = 6). The basket then was expanded to hold the catheter in place. Nonfluoroscopic identification of effective IPS sites was achieved within 5 minutes in the SVC. Increasing IPS voltage resulted in a graded response of supraventricular rate slowing. A 50% prolongation of the baseline atrial cycle length was achieved with 28 V in the SVC (1,056 +/- 355 msec vs 489 +/- 154 msec; P < 0.001) and 25 V in the RPA (1,181 +/- 306 msec vs 518 +/- 138 msec; P < 0.01). The rate slowing started immediately after IPS onset, terminated abruptly after IPS cessation, and could be maintained over 10 hours. A rate slowing effect also was observed when the sinus rate was increased by isoproterenol (SVC: 304 +/- 8 msec/RPA: 341 +/- 9 msec with isoproterenol vs SVC: 635 +/- 12 msec with isoproterenol + IPS at 39 V/ RPA: 584 +/- 16 msec with isoproterenol + IPS at 38 V; n = 6).
  
  
  CONCLUSIONS
  IPS results in a significant supraventricular rate slowing that is stable over a relatively long period and may be applied to slow undesirable sinus tachycardia in acute ischemic syndromes or to counteract undesirable chronotropic effects of catecholamines during treatment of cardiogenic or septic shock and acute congestive heart failure.
authors.affiliation: Department of Internal Medicine, University of Oklahoma Health Sciences Center and Department of Veterans Affairs Medical Center, Oklahoma City 73104, USA.
authors.forename: P N
authors.initials: PN
authors.lastname: Schauerte
authors.forename: B J
authors.initials: BJ
authors.lastname: Scherlag
authors.forename: M A
authors.initials: MA
authors.lastname: Scherlag
authors.forename: S
authors.initials: S
authors.lastname: Goli
authors.forename: W
authors.initials: W
authors.lastname: Jackman
authors.forename: R
authors.initials: R
authors.lastname: Lazzara
mesh_terms: D000818:Animals; D002404:Catheterization; D004285:Dogs; D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D005471:Fluoroscopy; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D007601:Jugular Veins; D010275:Parasympathetic Nervous System / Q000502:physiology*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D013997:Time Factors; D014683:Vena Cava, Superior / Q000000981:diagnostic imaging / Q000502:physiology