pacemaker

(noun)

A structure that sets the rate at which the heart beats. Under normal conditions, the SA node serves this function for the heart.

Related Terms

Examples of pacemaker in the following topics:

  • Artificial Pacemakers

    • A pacemaker, or artificial pacemaker, so as not to be confused with the heart's natural pacemaker is an implantable medical device that uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart.
    • Single-chamber pacemaker.
    • Dual-chamber pacemaker.
    • Rate-responsive pacemaker.
    • This artificial pacemaker, manufactured by St.

  • Electric Activity in the Heart

    • Electric energy stimulating the heart occurs in the sinoatrial node, the heart's pacemaker, and is transmitted partially by Perkinje fibers.
    • Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary pacemaker.
    • If the AV node also fails, Purkinje fibers are capable of acting as the pacemaker.
    • In short, they generate action potentials, but at a slower rate than sinoatrial node and other atrial ectopic pacemakers.
    • Thus they serve as the last resort when other pacemakers fail.

  • Electrical Events

    • The SA and AV nodes act as a pacemaker for the heart, determining the rate at which it beats, even without signals from the larger nervous system of the human body.
    • Without autonomic nervous stimulation, the SA node will set the heart rate itself, acting as the primary pacemaker for the heart.

  • Arrhythmia

    • These palpitations have also been known to be caused by atrial/ventricular fibrillation, wire faults, and other technical or mechanical issues in cardiac pacemakers/defibrillators.
    • The sinoatrial node is a single specialized location in the atrium which has a higher automaticity (a faster pacemaker) than the rest of the heart and, therefore, is usually responsible for setting the heart rate and initiating each heart beat.
    • Arrhythmias with atrial origin include: Premature Atrial Contractions (PACs), Wandering Atrial Pacemaker, Atrial flutter , and Atrial fibrillation (Afib).

  • Muscularis

    • Activity is initiated by the pacemaker cells (interstitial cells of Cajal).

  • NMR and MRIs

    • The strong magnetic fields and radio pulses can, however, affect metal implants (including cochlear implants and cardiac pacemakers).

  • Biofilms and Disease

    • They produce dental plaque and colonize catheters, prostheses, transcutaneous and orthopedic devices, contact lenses, and internal devices such as pacemakers.

  • Agonists, Antagonists, and Drugs

    • Increases in vagal activity to the SA node decreases the firing rate of the pacemaker cells by decreasing the slope of the pacemaker potential decreasing heart rate.

  • Circadian Rhythms

    • The circadian pacemaker, located in the SCN, regulates the timing and consolidation of the sleep-wake cycle, while sleep-wake homeostasis governs the accumulation of sleep debt and sleep recovery.
    • Our internal circadian pacemakers regulate the timing and duration of sleepiness and wakefulness throughout the day.

  • The Cardiac Cycle

    • The autonomous beating of cardiac muscle cells is regulated by the heart's internal pacemaker that uses electrical signals to time the beating of the heart.
    • The internal pacemaker starts at the sinoatrial (SA) node, which is located near the wall of the right atrium.