What question did this study set out to answer?

To elucidate the electrophysiological mechanisms responsible for post-pause action potential duration prolongation induced by antiarrhythmic agents.

September 1, 1996Clinical and Experimental Pharmacology and Physiology

Differential Effects of Antiarrhythmic Agents on Post‐pause Repolarization in Cardiac Purkinje Fibres

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Population

Canine Purkinje fibres

Design

Preclinical

Authors

KWKenneth R. WyseVictor Chang Cardiac Research Institute JBJane A. BursillVictor Chang Cardiac Research Institute TCTerence J. CampbellWilliam Harvey Hospital

Discussion

Member takes

Implication

May increase pause-dependent proarrhythmia risk with mixed Na/K blockade; hypothesis-generating in animals and leaves open clinical relevance versus pure class III agents.

Key Points

To elucidate the electrophysiological mechanisms responsible for post-pause action potential duration prolongation induced by antiarrhythmic agents.
Recorded action potentials from canine Purkinje fibres using standard microelectrode techniques at a baseline interstimulus interval of 1000 ms.
Evaluated action potential repolarization following pauses of 2 to 10 seconds under exposure to amitriptyline, quinidine, disopyramide, and class III agents (D-sotalol, clofilium, and dofetilide).
Amitriptyline, which blocks both sodium and potassium channels with rapid recovery kinetics (recovery time constant 2.3 ± 0.6 s), successfully reproduced the post-pause action potential duration prolongation observed with quinidine.
Pure class III potassium channel blockers (D-sotalol, clofilium, and dofetilide) failed to produce post-pause prolongation of repolarization.
Disopyramide exhibited substantially slower sodium channel unblocking kinetics (recovery time constant 12 to 50 s), preventing unopposed potassium channel blockade from extending repolarization after pauses.

Structured PICO

Population

Canine Purkinje fibres

Intervention

Antiarrhythmic agents (amitriptyline, D-sotalol, clofilium, dofetilide, quinidine, disopyramide)

Outcome

Post-pause prolongation of action potential duration (APD)surrogate

Agents with combined sodium and potassium channel blocking effects and rapid recovery kinetics (like quinidine and amitriptyline) cause post-pause APD prolongation, a precursor to torsade de pointes, unlike pure class III agents.

Cite This Study

Wyse et al. (1996) studied this question.

synapsesocial.com/papers/6a7d279ca3b6fd5035d5a678 https://doi.org/10.1111/j.1440-1681.1996.tb01187.x

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Implication

May increase pause-dependent proarrhythmia risk with mixed Na/K blockade; hypothesis-generating in animals and leaves open clinical relevance versus pure class III agents.

Differential Effects of Antiarrhythmic Agents on Post‐pause Repolarization in Cardiac Purkinje Fibres

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Differential Effects of Antiarrhythmic Agents on Post‐pause Repolarization in Cardiac Purkinje Fibres

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

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