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Free radical scavenger specifically prevents ischemic focal ventricular tachycardia

Dezhi Xing1, Ashok K Chaudhary, Francis J Miller

  • 1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.

Heart Rhythm
|March 28, 2009
PubMed
Abstract

Insights

Reactive oxygen species (ROS) scavenger TEMPO blocked focal ventricular tachycardia (VT) by preventing triggered activity in myocardial ischemia. Antioxidant therapy shows promise for treating focal VT during ischemia.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Biochemistry

Background:

  • Focal ventricular tachycardia (VT) during acute myocardial ischemia is linked to triggered activity (TA).
  • Reactive oxygen species (ROS) may play a role in the development of TA and subsequent VT.
  • Scavenging ROS presents a potential therapeutic strategy for blocking VT.

Purpose of the Study:

  • To investigate the effects of the ROS scavenger 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) on focal VT in vivo.
  • To assess the impact of TEMPO on triggered activity (TA) in vitro.
  • To determine if TEMPO can attenuate ROS in ischemic cardiac tissue.

Main Methods:

  • Studied 43 anesthetized dogs with induced coronary artery occlusion and VT.
  • Utilized 3D activation mapping to pinpoint VT origins (focal or reentrant).
  • Administered TEMPO intravenously and analyzed endocardial tissue for ROS and TA.

Main Results:

  • TEMPO successfully blocked focal VT in 6 of 11 dogs, while reentrant VT remained unaffected.
  • In vitro studies showed TEMPO significantly reduced TA from 5.3 to 0.4 complexes.
  • TEMPO administration markedly decreased ROS levels in ischemic endocardial sites without altering hemodynamic parameters or refractory periods.

Conclusions:

  • TEMPO, as a ROS scavenger, effectively prevented TA-associated focal VT in myocardial ischemia.
  • These findings suggest that antioxidant therapy, specifically targeting ROS, could be a valuable approach for blocking focal VT in ischemic conditions.

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