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Published on: September 13, 2011
Polymorphic reentrant ventricular tachycardia in the isolated rabbit heart studied by high-density mapping
Lucas Boersma1, Zoltan Zetelaki, Josep Brugada
1Physiology Department, Maastricht University, Maastricht, The Netherlands.
Circulation
|June 26, 2002
Summary
Polymorphic ventricular tachycardia (VT) arises from a shifting reentrant circuit within areas of prolonged refractoriness. This study demonstrates how spatial heterogeneity in refractory periods can trigger and sustain polymorphic VT.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
- Arrhythmogenesis
Background:
- Polymorphic ventricular tachycardia (VT) mechanisms are increasingly linked to refractoriness dispersion and reentry.
- Investigating polymorphic arrhythmias in a controlled 2D model with localized prolonged refractoriness.
Purpose of the Study:
- To elucidate the mechanisms of polymorphic arrhythmias.
- To examine the role of spatial heterogeneity in refractory periods for VT genesis.
Main Methods:
- Created regional prolonged refractoriness in rabbit ventricular epicardium using cryoprocedure.
- Induce polymorphic VT via programmed stimulation in cooled and control hearts.
- High-resolution epicardial mapping to analyze reentrant circuit dynamics.
Main Results:
- Polymorphic VT was inducible in all hearts with regional cooling, unlike controls.
- High-resolution mapping identified functional reentrant circuits within prolonged refractoriness zones.
- Reentrant wavefronts shifted dynamically, causing beat-to-beat excitation pattern changes.
Conclusions:
- Shifting functional reentrant circuits are the primary mechanism for polymorphic VT.
- Enhanced spatial heterogeneity of refractoriness serves as a substrate for these arrhythmias.
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