A heart

Cardiac Arrhythmias

A cardiac arrhythmia is when your heartbeat is too fast (tachycardia), too slow (bradycardia), or beats in an irregular rhythm due to a disruption of your heart’s normal electrical system

The severity of arrhythmias can vary tremendously. Many arrhythmias are benign and inconsequential, such as premature atrial complexes (PACs) that can cause an extra beat and brief palpitations. Others are extremely dangerous and life-threatening, such as ventricular tachycardia (a sudden, rapid, potentially very dangerous cardiac arrhythmia ) that can cause sudden cardiac arrest

A diagnosis of an arrhythmia generally requires capturing it on an electrocardiogram (ECG) (where electrodes record heart activity) or echocardiogram (an ultrasound of the heart), and a physical exam, and complete medical history.

Frequently Asked Questions

Key Terms

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Page Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Heart, Lung, and Blood Institute. Arrhythmia. Updated September 1, 2011.

  2. Pollack Ross A., Brown Siobhan P., Rea Thomas, et al. Impact of bystander automated external defibrillator use on survival and functional outcomes in shockable observed public cardiac arrests. Circulation. 2018;137(20):2104-2113. doi:10.1161/CIRCULATIONAHA.117.030700

  3. Cleveland Clinic. Pulse and heart rate. Updated November 18, 2018.

Additional Reading
  • National Heart, Lung, and Blood Institute. Arrhythmia.