View source for 31. Active heterotopic abnormalities (premature beats)

A heterotopic disorder of the heart means that something other than the sinoatrial node works as the pacemaker.

Active heterotopy means that the heterotopic focus produces stimuli at a higher frequency than the sinus node. The opposite would be passive heterotopy.

The following conditions are active heterotopic abnormalities:

* Extrasystoles/premature beats
* Atrial fibrillation
* Atrial flutter
* Paroxysmal atrial or ventricular tachycardia

The latter three have their own topics, so only extrasystoles will be examined in this topic.

An extrasystole is a beat that comes earlier than expected according to the heart rate. We distinguish two types, one of which has two subtypes:

* Supraventricular extrasystole
** Atrial extrasystole
** Junctional extrasystole
* Ventricular extrasystole

Extrasystoles may occur randomly, or they can occur in patterns. The following patterns are the most frequent:

* Couplet – two extrasystoles in a row
* Triplet – three extrasystoles in a row
* Bigeminy – one extrasystole occurs after every sinus beat
* Trigeminy – one extrasystole occurs after every two sinus beats