Phenylephrine-induced ventricular arrhythmias in dogs with inherited sudden death

N. Sydney Moïse, Paula F. Moon, William J. Flahive, Darcy Brittain, H. Paul Pride, Beth A. Lewis, Douglas P. Zipes, Randall J. Lee, Robert F. Gilmour

Research output: Contribution to journalArticle

17 Scopus citations


Dogs with Inherited Sudden Death. Introduction: Dogs with an inherited predisposition to sudden death display ventricular arrhythmias having certain characteristics, such as pause dependence, that are suggestive of early after depolarization-induced triggered activity. We hypothesized that α-adrenergic stimulation may facilitate the development of these arrhythmias by inducing a reflex bradycardia and by exerting a direct myocardial effect. Methods and Results: Twenty affected dogs and 7 unaffected dogs were studied. The incidence and severity of ventricular arrhythmias were determined after administration of phenylephrine (0.01 mg/kg IV), with or without pretreatment with propranolol (0.1 to 0.3 mg/kg IV), atropine (0.04 mg/kg IV), or prazosin (0.5 mg/kg IV). Third-degree heart block was induced by AV nodal ablation in 4 affected dogs. Phenylephrine increased ventricular arrhythmias in affected dogs, with or without pretreatment with propranolol, but did not induce ventricular arrhythmias in unaffected dogs. In dogs with intact AV nodal conduction, atropine increased sinus rate, which suppressed baseline and phenylephrine-induced arrhythmias. In dogs with heart block, arrhythmias were increased during baseline and after phenylephrine, with or without pretreatment with atropine. Prazosin and overdrive ventricular pacing suppressed phenylephrine-induced arrhythmias. Conclusion: Phenylephrine increases ventricular arrhythmias in dogs with inherited sudden death via both an induction of reflex bradycardia and a direct myocardial effect. Superimposition of heightened α-adrenergic and vagal tone may facilitate the development of sudden death in these animals.

Original languageEnglish (US)
Pages (from-to)217-230
Number of pages14
JournalJournal of Cardiovascular Electrophysiology
Issue number3
StatePublished - Jan 1 1996


  • alpha- adrenergic stimulation
  • dog
  • hereditary
  • phenylephrine
  • sudden death
  • ventricular tachycardia

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology

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