Ventricular Tachycardia with Alternating Cycle Lengths: Self‐Entrainment of Parasystolic Rhythm?

AGUSTIN CASTELLANOS, IVAN J. MENDOZA, NADIR SAOUDI, JOSE JALIFE

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

A patient had ventricular tachycardia with cycle lengths consistently varying between 400 and 490 ms. Arrhythmias with a similar electrocardiographic pattern had been thought to result from the regular activity of an automatic pacemaker with either 3:2 exit block of the Wenckebach type or alternation in exit conduction times. However, the findings in our patient could also be explained by postulating the existence of modulated ventricular parasystole having 3:2 exit block or with alternating (short‐long) exit conduction times. In either case, the action potentials elicited by the parasystole must have reached (with variable delays) the ventricular tissue beyond the zone of protection to produce electrotonic depolarizations which, in turn, were reflected back to the ectopic focus itself. This resulted in runs of 2:3 or 2:2 “self‐entrainment” of the parasystolic pacemaker. Similar phenomena have been produced in biologic and mathematical models of modulated parasystole.

Original languageEnglish (US)
Pages (from-to)1291-1295
Number of pages5
JournalPacing and Clinical Electrophysiology
Volume11
Issue number9
DOIs
StatePublished - Sep 1988

Keywords

  • arrhythmias
  • exit block
  • modulated parasystole
  • self‐entrainment

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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