Exotic atrial ectopy part two

Previously, we covered some of the ECG patterns seen with atrial ectopy.

Let us continue.

An atrial couplet is defined as two consecutive atrial ectopics:

Both ectopics are premature and from a low atrial site.

However, only one may be “obviously premature”:

Or neither:

An atrial couplet may not always be a couplet:

In this example, there may only be a single interpolated atrial ectopic, but the timing is against this. The R-R interval with the embedded ectopic should be the same or longer (due to partial refractoriness in the atrio-ventricular conducting system) than the sinus cycle length. It is significantly shorter and therefore most likely an atrial couplet.

Atrial couplets may demonstrate Wenckebach atrio-ventricular block:

Non-conducted atrial ectopics (blue dots) may also occur:

But not all non-conducted atrial couplets are actually “couplets”:

The first non-conducted beat is part of a 2:1 atrio-ventricular block sequence (red dot) and the second is an atrial ectopic (blue dot), which not surprisingly is non-conducted.

Three consecutive atrial ectopics an atrial triplet:

They too can present as a Wenckebach atrio-ventricular sequence:

Can non-conducted atrial triplets occur?

Here is an example:

Although, there are three consecutive non-conducted atrial ectopics, the cycle length is very short and mimics the appearance of atrial flutter.

More correctly, this is a short run of focal atrial tachycardia with Wenckebach block at the ectopic-myocardial junction.

Here is a sequence of nine consecutive conducted atrial ectopics. We can’t call this supraventricular or atrial tachycardia, because the rate is <100 bpm.

My technicians call this an atrial run and it is a very common finding on Holter monitoring.

Not surprisingly atrial runs (red highlight) can occur together with supraventricular tachycardia (yellow highlight).

Remember, it’s all in the timing

Harry Mond