Pro- and antiarrhythmic effects of fast cardiac pacing in a canine model of acquired long QT syndrome

Increasing the heart rate is one option for suppressing bradycardia-dependent polymorphic ventricular tachycardias (PVTs). The mechanisms underlying preventive pacing in acquired forms of the long QT syndrome (LQTs) are still not fully understood. Using two needle electrodes, local effective refract...

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Bibliographic Details
Published in:Naunyn-Schmiedeberg's archives of pharmacology 2004-04, Vol.369 (4), p.447-454
Main Authors: Bauer, Alexander, Donahue, J Kevin, Voss, Frederik, Becker, Ruediger, Kraft, Patricia, Senges, Julia C, Kelemen, Kamilla, Katus, Hugo A, Schoels, Wolfgang
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Animals
Cardiac Pacing, Artificial - adverse effects
Chromans - administration & dosage
Chromans - pharmacology
Disease Models, Animal
Dogs
Electrocardiography
Female
Heart Block - physiopathology
Long QT Syndrome - physiopathology
Male
Phenethylamines - administration & dosage
Phenethylamines - pharmacology
Potassium Channel Blockers - pharmacology
Refractory Period, Electrophysiological - drug effects
Refractory Period, Electrophysiological - physiology
Sulfonamides - administration & dosage
Sulfonamides - pharmacology
Time Factors
Ventricular Function - drug effects
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Summary:Increasing the heart rate is one option for suppressing bradycardia-dependent polymorphic ventricular tachycardias (PVTs). The mechanisms underlying preventive pacing in acquired forms of the long QT syndrome (LQTs) are still not fully understood. Using two needle electrodes, local effective refractory periods (ERPs) were determined in the left (LV) and right ventricle (RV) in 20 dogs with acute AV node ablation before continuous pacing, during a 20-min period of continuous fast pacing (Cl 300 ms, fastpac) and during a 35-min recovery period with slow (Cl 500 ms) pacing. This protocol was applied to control dogs (5 dogs) and dogs with pretreatment of the IKs blocking agent chromanol 293b (5 dogs, LQTs1), the IKr-blocking agent dofetilide (5 dogs, LQTs2) or a combination thereof (5 dogs). Fastpac resulted in a significant abbreviation of ERPs in control dogs and dogs receiving dofetilide or chromanol 293b. During recovery, shortening of ERPs persisted in the control group, but diminished in dogs with acquired LQTs. In dogs with LQTs2 fastpac could not suppress inhomogeneity of refractoriness during recovery. With pretreatment of dofetilide and chromanol 293b in combination, MAP duration during fastpac significantly increased (first beat: 256+/-6 ms vs. sixth beat: 278+/-9 ms, p
ISSN:0028-1298
1432-1912
DOI:10.1007/s00210-004-0874-0