Atrial Fibrillation (AFib)

  • Medical Author:
    Daniel Lee Kulick, MD, FACC, FSCAI

    Dr. Kulick received his undergraduate and medical degrees from the University of Southern California, School of Medicine. He performed his residency in internal medicine at the Harbor-University of California Los Angeles Medical Center and a fellowship in the section of cardiology at the Los Angeles County-University of Southern California Medical Center. He is board certified in Internal Medicine and Cardiology.

  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Quick GuideAtrial Fibrillation: Heart Symptoms, Diagnosis & Treatment for AFib

Atrial Fibrillation: Heart Symptoms, Diagnosis & Treatment for AFib

Heart rate during AFib

In a heart that is beating normally, the rate of ventricular contraction is the same as the rate of atrial contraction. In atrial fibrillation, however, the rate of ventricular contraction is less than the rate of atrial contraction. The rate of ventricular contraction in atrial fibrillation is determined by the speed of transmission of the atrial electrical discharges through the AV node. In people with a normal AV node, the rate of ventricular contraction in untreated AFib usually ranges from 80 to 180 beats/minute; the higher the transmission, the higher the heart rate.

Some older people have slow transmission through the AV node due to disease within the AV node. When these people develop AFib, their heart rates remain normal or slower than normal. As disease in the AV node advances, these people can even develop an excessively slow heart rate and require a permanent pacemaker to increase the rate of ventricular contractions. Continue Reading

Reviewed on 7/13/2016
References
Medically reviewed by: Robert J. Bryg, MD; Board Certified Internal Medicine with subspecialty in Cardiovascular Disease.

REFERENCES:

UpToDate. Patient information: Atrial fibrillation (Beyond the Basics).

Wann, Samuel L., et al. "2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (Updating the 2006 Guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines." Journal of the American College of Cardiology 57.2 (2011): 223-242.

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