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Isolation of Atrial Myocytes from Adult Mice
08:34

Isolation of Atrial Myocytes from Adult Mice

Published on: July 25, 2019

Action potentials, afterpotentials, and arrhythmias

P F Cranefield

    Circulation Research
    |October 1, 1977
    PubMed

    Insights

    Triggered activity, driven by afterpotentials, explains extrasystoles and tachycardias. This mechanism, distinct from spontaneous or circus movement activity, is crucial for understanding cardiac arrhythmias.

    Area of Science:

    • Cardiology
    • Electrophysiology
    • Cardiac Pathophysiology

    Background:

    • Cardiac arrhythmias like extrasystoles and tachycardias arise from complex electrical activity.
    • Existing models attribute arrhythmias to spontaneous activity or circus movements.
    • A third mechanism, triggered activity, is increasingly recognized.

    Purpose of the Study:

    • To elucidate the mechanism of triggered activity in cardiac arrhythmias.
    • To differentiate triggered activity from spontaneous and circus movement-based arrhythmias.
    • To explore the clinical significance and potential triggers of triggered activity.

    Main Methods:

    • Review of electrophysiological principles governing cardiac rhythm.
    • Analysis of factors influencing triggerable foci, including catecholamines and acetylcholine.
    • Examination of specific examples like coronary sinus fibers and digitalis toxicity.

    Main Results:

    • Triggered activity originates from phase 4 depolarization due to afterpotentials.
    • Rhythmic activity of a triggerable focus depends on critical pacing rates or premature impulses.
    • Catecholamines enhance triggering, while acetylcholine can suppress it.

    Conclusions:

    • Triggered activity is a significant cause of atrial and ventricular arrhythmias.
    • Coronary sinus fibers serve as a key example of clinically relevant triggered activity.
    • Further research is warranted to identify additional triggered arrhythmias and their therapeutic targets.

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