Direction-dependent conduction abnormalities in a canine model of atrial fibrillation due to chronic atrial dilatation

Sander Verheule, Emily Wilson, Smriti Banthia, Thomas H. Everett IV, Sujata Shanbhag, Haris J. Sih, Jeffrey E. Olgin

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Chronic rapid atrial pacing (RAP) leads to changes that perpetuate atrial fibrillation (AF). Chronic atrial dilatation due to mitral regurgitation (MR) also increases AF inducibility, but it is not clear whether the underlying mechanism is similar. Therefore, we have investigated atrial electrophysiology in a canine MR model (mitral valve avulsion, 1 mo) using high-resolution optical mapping and compared it with control dogs and with the canine RAP model (6-8 wk of atrial pacing at 600 beats/min, atrioventricular block, and ventricular pacing at 100 beats/min). At followup, optical action potentials were recorded using a 16 × 16 photodiode array from 2 × 2-cm left atrial (LA) and right atrial (RA) areas in perfused preparations, with pacing electrodes around the field of view to study direction dependency of conduction. Action potential duration at 80% repolarization (APD80) was not different between control and MR but was reduced in RAP atria. Conduction velocities during normal pacing were not different between groups. However, the MR LA showed increased conduction heterogeneity during pacing at short cycle lengths and during premature extrastimuli, which frequently caused pronounced regional conduction slowing. Conduction in the MR LA during extrastimulation also displayed a marked dependence on propagation direction. These phenomena were not observed in the MR RA and in control and RAP atria. Thus both models form distinctly different AF substrates; in RAP dogs, the decrease in APD80 may stabilize reentry. In MR dogs, regional LA conduction slowing and increased directional dependency, allowing unidirectional conduction block and preferential paths of conduction, may account for increased AF inducibility.

Original languageEnglish (US)
Pages (from-to)H634-H644
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume287
Issue number2 56-2
DOIs
StatePublished - Aug 1 2004

Keywords

  • Atrial conduction
  • Optical mapping

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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