Login or Register to unlock everything MedSchool has to offer!
Fast heart rhythms on an ECG may be caused by supraventricular or ventricular rhythms, some of which are imminently life threatening and require rapid assessment.

Atrial Fibrillation



  • Atrial fibrillation is a common cardiac arrhythmia that originates from an ectopic atrial focus.
    • Look For

    • Ventricular rate 100-180bpm (may be <100 with block or medications)
    • Irregular rhythm
    • No P waves, with oscillating baseline waves
    • Classification

    • Paroxysmal AF - occurring for <7 days
    • Persistent AF - occurring for >7 days
    • Permanent AF - long-standing despite attempts at cardioversion
    • Mechanism

    • Atrial fibrillation occurs due rapid impulse generation by an ectopic atrial focus, most commonly adjacent to or within the pulmonary vein orifices. Once atrial fibrillation has commenced it is maintained by abnormalities within atrial tissue, such as atrial remodelling.
    • Causes of Atrial Fibrillation

    • Severe acute illness - especially in septic or postoperative patients
    • Cardiac - post cardiac surgery, myocardial infarction, valvular disease, cardiomyopathy, congestive cardiac failure, congenital heart disease, Wolff-Parkinson-White
    • Cardiovascular risk factors - hypertension, diabetes, obesity
    • Pulmonary embolism
    • Obstructive sleep apnoea
    • Thyrotoxicosis
    • Alcohol abuse
    • Diagnostic Tests

    • ECG - single ECG or continuous inpatient monitoring
    • Holter monitor (24-48 hours)
    • External loop recorder
    • Implanted loop recorder
Last updated on December 29th, 2018