High-frequency ventricular ectopy can increase sympathetic neural activity in humans.
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.
Smith
Michael L
ML
Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas, USA. msmith@hsc.unt.edu
Hamdan
Mohamed H
MH
Wasmund
Stephen L
SL
Kneip
Christina F
CF
Joglar
Jose A
JA
Page
Richard L
RL
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
D002395:Catecholamines