Pacing-induced chronic atrial fibrillation impairs sinus node function in dogs: Electrophysiological remodeling

Arif Elvan, Kevin Wylie, Douglas P. Zipes

Research output: Contribution to journalArticle

268 Scopus citations

Abstract

Background: We assessed the effects of pacing-induced chronic atrial fibrillation (AF) on sinus node function, intra-atrial conduction, and atrial refractoriness. Methods and Results: In 15 mongrel dogs (20 to 30 kg), AV nodal block was produced by radiofrequency catheter ablation, and a ventricular-inhibited (VVI) pacemaker (Minix 8330, Medtronic) was implanted and programmed to pace at 80 pulses per minute. In 11 of these dogs, right atrial endocardial pacing leads were connected to a pulse generator (Itrel 7432, Medtronic) and set at a rate of 20 Hz to induce AF. Corrected sinus node recovery time, P-wave duration, 24-hour Holter ECG to assess AF duration, maximal heart rate in response to isoproterenol (10 μg/min), intrinsic heart rate after administration of atropine (0.04 mg/kg) and propranolol (0.1 mg/kg), and atrial effective refractory periods (ERPs) were obtained at baseline (EPS-1) and after 2 to 6 weeks (EPS-2) of VVI pacing alone (n=4) or VVI pacing and rapid atrial pacing (n=11). At EPS-2, corrected sinus node recovery time and P-wave duration were prolonged, maximal heart rate and intrinsic heart rate were decreased, atrial ERPs were shortened, and the duration of AF was increased significantly compared with EPS-1. These changes partially reversed toward baseline 1 week after conversion to sinus rhythm. Sinus node function and AF inducibility observed in the control dogs that underwent ventricular pacing alone (n=4) did not change. Conclusions: Pacing-induced chronic AF induces sinus node dysfunction, prolongs intra- atrial conduction time, shortens atrial refractoriness, and perpetuates AF, changes that reverse gradually after termination of AF.

Original languageEnglish (US)
Pages (from-to)2953-2960
Number of pages8
JournalCirculation
Volume94
Issue number11
DOIs
StatePublished - 1996

Keywords

  • electrophysiology
  • fibrillation
  • pacing
  • remodeling

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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