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”:
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
In 49+ years as a practicing cardiologist, Assoc Prof Harry Mond has published 260+ published manuscripts & books. A co-founder of Cardiac Monitoring Service, he remains Medical Director and oversees 500K+ heart studies each year.
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