Unmasking of Retrograde Conduction by Isoproterenol in a Concealed Accessory Pathway

DAVID W. FRAZIER, DOUGLAS L. PACKER, MARSHALL S. STANTON

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

A 52‐year‐old female with no structural heart disease presented with a right bundle branch block (RBBB)/right axis deviation tachycardia with a cycle length of 300 msec. P waves were not discernible on the surface ECG. Baseline electrophysiology study in the drug‐free state revealed no evidence for anterograde or retrograde conducting accessory pathways (APs) or for dual AV node physiology. Retrograde VA block with AV dissociation was present at a ventricular paced cycle length of 600 msec (sinus cycle length of 635–700 msec). AV nodal Wenckebach occurred during decremental atrial pacing at a cycle length of 300 msec. During isoproterenol administration, a left lateral AP with retrograde only conduction became manifest with 1:1 VA conduction to 380 msec. No anterograde AP conduction was present. Orthodromic reciprocating tachycardia with a cycle length of 285–315 msec was easily induced. We conclude that total functional conduction block can exist in APs, and unmasking of total conduction block can be accomplished with isoproterenol. All patients with undiagnosed tachycardias should have full repeat stimulation studies during adrenergic stimulation if the initial baseline evaluation is nondiagnostic.

Original languageEnglish (US)
Pages (from-to)492-497
Number of pages6
JournalPacing and Clinical Electrophysiology
Volume18
Issue number3
DOIs
StatePublished - Mar 1995

Keywords

  • accessory pathways
  • anterograde conduction block
  • isoproterenol
  • retrograde conduction

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Fingerprint Dive into the research topics of 'Unmasking of Retrograde Conduction by Isoproterenol in a Concealed Accessory Pathway'. Together they form a unique fingerprint.

  • Cite this