Reflected reentry in depolarized foci with variable conduction impairment in 1 day old infarcted canine cardiac tissue

James E. Rosenthal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

A recent study in 1 day old infarcted canine cardiac tissue demonstrated that variations in entrance and exit characteristics of depolarized spontaneous foci could profoundly affect their expression, resulting in behaviors such as modulated parasystole and entrainment, second and third degree exit block "autoentrainment" and annihilation (abrupt termination) of spontaneous activity. Foci with exit and entrance delay should also allow the occurrence of reflected reentry. To test this, the left circumflex coronary artery was ligated and, after 1 day, simultaneous microelectrode impalements were made in infarcted and uninfarcted portions of isolated ventricular preparations. Preparations were stimulated from the uninfarcted portions. Reflected reentry was demonstrated in 5 of 11 preparations. It occurred when exit conduction delay resulted in reexcitation of the focus or, alternatively, when entrance conduction delay resulted in reexcitation of extrafocal tissue. Reflection occurred in which the action potentials were reexcited during phase 2 or 3, resulting in prolongation of action potential duration (type I), and in which reexcitation occurred after full or nearly full repolarization, resulting in a closely coupled extrasystole (type II). Electrotonic modulation and reflection could coexist, the type of behavior depending on the phase relation between focal and extrafocal action potentials. An example is illustrated in which type I reflection occurred only when preceding driven activity induced overdrive suppression of exit conduction from the focus. The results suggest that, in infarcted tissue, entrance and exit conduction delays to depolarized foci may form the basis for the occurrence of reflected reentry.

Original languageEnglish (US)
Pages (from-to)404-411
Number of pages8
JournalJournal of the American College of Cardiology
Volume12
Issue number2
DOIs
StatePublished - Aug 1988

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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