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Phasic left ventricular blood velocity alternans in man

K B Desser, A Benchimol

    The American Journal of Cardiology
    |September 1, 1975
    PubMed

    Insights

    Pacemaker-evoked pulsus alternans causes measurable left ventricular blood flow velocity alternations, particularly at higher pacing rates. These findings offer new insights into cardiac mechanics and potential underlying physiological factors.

    Area of Science:

    • Cardiology
    • Physiology
    • Biomedical Engineering

    Background:

    • Pulsus alternans, an alternating pattern of strong and weak heartbeats, can be induced by pacemakers.
    • Understanding the hemodynamic consequences of pacemaker-evoked pulsus alternans is crucial for patient management.

    Purpose of the Study:

    • To comprehensively describe left ventricular blood flow velocity alternans in humans during pacemaker-evoked pulsus alternans.
    • To investigate the relationship between pacing rate and the manifestation of blood velocity alternans.

    Main Methods:

    • Utilized Doppler ultrasonic flowmeter catheters and radiotelemetry to measure instantaneous left ventricular blood flow velocity.
    • Recorded data in 28 subjects experiencing pacemaker-evoked pulsus alternans.

    Main Results:

    • Blood velocity alternans were more pronounced at faster pacing rates.
    • Four patients exhibited diastolic blood velocity alternans at the mitral valve.
    • Discordant alternans between right heart pressure and left ventricular blood velocity were observed in three subjects.

    Conclusions:

    • This study presents the first detailed description of left ventricular blood velocity alternans in humans.
    • Observed alternans may be linked to changes in myocardial inotropy or beat-to-beat variations in end-diastolic fiber length.

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