title: High-frequency ventricular ectopy can increase sympathetic neural activity in humans.
abstract: BACKGROUND
  Sudden cardiac death is usually caused by ventricular arrhythmias and in many cases, is preceded by frequent ventricular ectopy. It is known that ectopic beats cause transient increases in sympathetic nerve activity (SNA).
  
  
  OBJECTIVE
  Because high SNA is known to be arrhythmogenic, we hypothesized that high rates of ectopy increase SNA, thereby creating a milieu that favors development of ventricular tachycardia and/or fibrillation.
  
  
  METHODS
  This study measured muscle SNA, coronary sinus catecholamine, and arterial pressure during graded rates of ventricular ectopy (from 4:1 to 1:1, sinus to ectopic beat ratio) in a total of 21 patients referred for electrophysiologic testing.
  
  
  RESULTS
  Both muscle SNA and coronary sinus norepinephrine increased significantly with increased ectopy frequency (P < .05). Moreover, the change in muscle SNA correlated significantly with the change in coronary sinus norepinephrine levels (r = .72, P < .001).
  
  
  CONCLUSIONS
  These data demonstrate that sympathoexcitation evoked by high rates of ventricular ectopy can contribute to a state of elevated SNA both in peripheral tissues and within the heart. This altered autonomic state may contribute to an increased susceptibility to life-threatening tachyarrhythmias in patients with high rates of ectopy.
authors.affiliation: Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas, USA. msmith@hsc.unt.edu
authors.forename: Michael L
authors.initials: ML
authors.lastname: Smith
authors.forename: Mohamed H
authors.initials: MH
authors.lastname: Hamdan
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Wasmund
authors.forename: Christina F
authors.initials: CF
authors.lastname: Kneip
authors.forename: Jose A
authors.initials: JA
authors.lastname: Joglar
authors.forename: Richard L
authors.initials: RL
authors.lastname: Page
mesh_terms: D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000097:blood / Q000209:etiology*; D002395:Catecholamines / Q000097:blood; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D018879:Ventricular Premature Complexes / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D002395:Catecholamines