First, there are the AV junctional re-entrant tachycardias. These involve an additional electrical connection between atria and ventricles so an impulse can repeatedly and rapidly circulate between atria and ventricles along a circuit consisting of the AV junction and the additional AV connection. They are usually not associated with any other cardiac pathology.
Secondly, there are the atrial tachyarrhythmias caused by rapid, abnormal activity within the atria, i.e. atrial fibrillation, atrial flutter and atrial tachycardia: the AV node is not an integral part of the tachycardia mechanism but merely transmits some or all of the atrial impulses to the ventricles. They are often associated with other forms of cardiac disease.
Main types
Several tachycardias originate from the atria or atrioventricular (AV) junction and are therefore, by definition, supraventricular in origin. They have one thing in common: because they arise from above the level of the bundle branches, ventricular activation is via the rapidly conducting specialised intraventricular system and thus normal, and therefore narrow, ventricular complexes will usually result. However, it is very important to appreciate that there are significant differences in mechanism, ECG characteristics and treatment. It is necessary to identify the type of tachycardia and not merely treat all tachycardias with narrow QRS complexes as ‘supraventricular tachycardia’.
Atrial origin versus atrioventricular re-entry
Supraventricular tachycardias are of two main types: AV junctional re-entrant tachycardias and atrial tachyarrhythmias.
Atrioventricular junctional re-entrant tachycardias
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
