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Clinical Review ABC of clinical electrocardiography

Atrial arrhythmias

BMJ 2002; 324 doi: (Published 09 March 2002) Cite this as: BMJ 2002;324:594

This article has a correction. Please see:

  1. Steve Goodacre,
  2. Richard Irons

    In adults a tachycardia is any heart rate greater than 100 beats per minute. Supraventricular tachycardias may be divided into two distinct groups depending on whether they arise from the atria or the atrioventricular junction. This article will consider those arising from the atria: sinus tachycardia, atrial fibrillation, atrial flutter, and atrial tachycardia. Tachycardias arising from re-entry circuits in the atrioventricular junction will be considered in the next article in the series.

    Supraventricular tachycardias

    From the atria or sinoatrial node
    • Sinus tachycardia

    • Atrial fibrillation

    • Atrial flutter

    • Atrial tachycardia

    From the atrioventricular node
    • Atrioventricular re-entrant tachycardia

    • Atrioventricular nodal re-entrant tachycardia

    Clinical relevance

    The clinical importance of a tachycardia in an individual patient is related to the ventricular rate, the presence of any underlying heart disease, and the integrity of cardiovascular reflexes. Coronary blood flow occurs during diastole, and as the heart rate increases diastole shortens. In the presence of coronary atherosclerosis, blood flow may become critical and anginal-type chest pain may result. Similar chest pain, which is not related to myocardial ischaemia, may also occur. Reduced cardiac performance produces symptoms of faintness or syncope and leads to increased sympathetic stimulation, which may increase the heart rate further.

    Electrocardiographic characteristics of atrial arrhythmias

    Sinus tachycardia
    • P waves have normal morphology

    • Atrial rate 100-200 beats/min

    • Regular ventricular rhythm

    • Ventricular rate 100-200 beats/min

    • One P wave precedes every QRS complex

    Atrial tachycardia
    • Abnormal P wave morphology

    • Atrial rate 100-250 beats/min

    • Ventricular rhythm usually regular

    • Variable ventricular rate

    Atrial flutter
    • Undulating saw-toothed baseline F (flutter) waves

    • Atrial rate 250-350 beats/min

    • Regular ventricular rhythm

    • Ventricular rate typically 150 beats/min (with 2:1 atrioventricular block)

    • 4:1 is also common (3:1 and 1:1 block uncommon)

    Atrial fibrillation
    • P waves absent; oscillating baseline f (fibrillation) waves

    • Atrial rate 350-600 beats/min

    • Irregular ventricular rhythm

    • Ventricular rate 100-180 beats/min

    As a general rule the faster the ventricular rate, the more likely the presence of symptoms—for example, chest pain, faintness, and breathlessness. Urgent treatment is needed for severely symptomatic patients …

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