Does cardiac pacing reproduce the mechanism of focal impulse initiation?

Emilio Macchi, Silvana Baruffi, Stefano Rossi, Michele Miragoli, Andrea Bertuzzi, Ezio Musso, Domenico Corradi, Franco Di Gregorio

Research output: Contribution to journalArticlepeer-review

Abstract

Stimulation of myocardium by either a native pacemaker or an artificial stimulus requires the initiation of a self-propagating wave of depolarization originating from the site of initial activation. In the present study we perform artificial stimulation at a site of focal discharge with the aim to compare the two mechanisms of impulse formation. High resolution epicardial mapping in senescent rat hearts provided examples of focal discharge during sinus rhythm at a single epicardial breakthrough (BKT) point emerging from an isolated Purkinje-ventricular muscle junction (PMJ) site. Stimulation was also performed at the same BKT point and potential distributions recorded during spontaneous and artificial stimulation were compared. During excitation latency, the negative potential pattern was elongated perpendicularly to fiber direction at both pacing and BKT point, in agreement with virtual cathode membrane polarization predicted by the bidomain model during point stimulation. During impulse initiation, activation wave fronts were initially circular around pacing site or BKT point and then elongated along local fiber direction. The similarity between impulse initiation during focal discharge and point stimulation in cardiac muscle suggests that high resolution pace mapping studies can help to elucidate the mechanism of abnormal impulse formation.

Original languageEnglish
Pages (from-to)135-143
Number of pages9
JournalJournal of Electrocardiology
Volume37
Issue numberSUPPL.
DOIs
Publication statusPublished - Oct 2004

Keywords

  • breakthrough point
  • cardiac electrophysiology
  • Cardiac pacing
  • epicardial mapping
  • focal activity

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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