Atrial fibrillation begets atrial fibrillation. A study in awake chronically instrumented goats

Circulation. 1995 Oct 1;92(7):1954-68. doi: 10.1161/01.cir.92.7.1954.


Background: In this study we tested the hypothesis that atrial fibrillation (AF) causes electrophysiological changes of the atrial myocardium which might explain the progressive nature of the arrhythmia.

Methods and results: Twelve goats were chronically instrumented with multiple electrodes sutured to the epicardium of both atria. Two to 3 Weeks after implantation, the animals were connected to a fibrillation pacemaker which artificially maintained AF. Whereas during control episodes of AF were short lasting (6 +/- 3 seconds), artificial maintenance of AF resulted in a progressive increase in the duration of AF to become sustained (> 24 hours) after 7.1 +/- 4.8 days (10 of 11 goats). During the first 24 hours of AF the median fibrillation interval shortened from 145 +/- 18 to 108 +/- 8 ms and the inducibility of AF by a single premature stimulus increased from 24% to 76%. The atrial effective refractory period (AERP) shortened from 146 +/- 19 to 95 +/- 20 ms (-35%) (S1S1, 400 ms). At high pacing rates the shortening was less (-12%), pointing to a reversion of the normal adaptation of the AERP to heart rate. In 5 goats, after 2 to 4 weeks of AF, sinus rhythm was restored and all electrophysiological changes were found to be reversible within 1 week.

Conclusions: Artificial maintenance of AF leads to a marked shortening of AERP, a reversion of its physiological rate adaptation, and an increase in rate, inducibility and stability of AF. All these changes were completely reversible within 1 week of sinus rhythm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atrial Fibrillation / etiology
  • Atrial Fibrillation / physiopathology*
  • Atrial Function / physiology*
  • Cardiac Pacing, Artificial
  • Consciousness
  • Electrocardiography
  • Electrophysiology
  • Goats / physiology*
  • Heart Conduction System / physiopathology*
  • Pacemaker, Artificial
  • Refractory Period, Electrophysiological / physiology
  • Time Factors