ABC of clinical electrocardiography: Atrial arrhythmias.

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.