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Toxicologic myocardial sensitization

Lewis S Nelson1

  • 1New York City Poison Center, 455 First Avenue, #123, New York, NY 10016, USA. lnelson@pol.net

Journal of Toxicology. Clinical Toxicology
|January 1, 2003
PubMed

Insights

Drug-induced torsades de pointes (TdP) can cause sudden cardiac death. This occurs through myocardial sensitization, involving altered repolarization from potassium channel blockade or calcium overload, leading to dangerous heart rhythms.

Area of Science:

  • Cardiology
  • Pharmacology
  • Electrophysiology

Background:

  • Drug-induced polymorphic ventricular tachycardia, or torsades de pointes (TdP), is a life-threatening arrhythmia.
  • This condition can lead to syncope and sudden cardiac death.
  • Myocardial sensitization is a key mechanism underlying drug-induced TdP.

Purpose of the Study:

  • To elucidate the mechanisms of myocardial sensitization that predispose to drug-induced torsades de pointes.
  • To explain the roles of altered cellular repolarization and afterdepolarizations in TdP development.

Main Methods:

  • Discussion of cellular electrophysiology mechanisms.
  • Analysis of ion channel function, specifically potassium and calcium channels.
  • Review of factors contributing to altered myocardial substrate and afterdepolarizations.

Main Results:

  • Drug-induced TdP arises from myocardial sensitization, involving altered cellular repolarization.
  • Potassium channel blockade disrupts repolarization, promoting early afterdepolarizations and reentry.
  • Calcium overload can cause delayed afterdepolarizations, contributing to ventricular ectopy and tachycardia.

Conclusions:

  • Altered potassium and calcium ion flow are critical in the pathogenesis of drug-induced TdP.
  • Understanding these mechanisms is vital for predicting and preventing TdP.
  • This knowledge aids in managing patients at risk for malignant cardiac dysrhythmias.

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