Atrial arrhythmias
BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7337.594 (Published 09 March 2002) Cite this as: BMJ 2002;324:594- Steve Goodacre,
- 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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