Ectopy in Groups

Group beating always provide interesting ECGsHere is an example. Try and work out what is going on.

Here is my interpretation.

• Sinus rhythm (red vertical arrows)
• Sequences of low atrial couplets (red highlight) in trigeminy.

I know of no name for these ectopy sequences, but my staff call them “atrial trigemilets”.We can also have ventricular trigemilets (red highlight)!

Remember aberration not excluded.When they occur as bigeminy (red highlight), I call them “ventricular bigemilets”.

The individual ectopics in a couplet (red highlight) may not be identical.

Obviously, the way the ectopic is conducted.Another example of possible aberration (red highlight)?

Now let us get silly!!What do you call couplets without an intervening sinus beat (red arrow)?

These are ventricular couplets in sequence (red highlight). Suggest Wenckebach block at the ventricular-ectopic junction, unless someone has a better explanation. (Mond, Vohra. Heart Lung and Circulation 2017; 26: 1252).Just when you thought that there were no more combinations!Ventricular triplets (red highlight) in bigeminy.

This is complicated. The triplets have a long cycle, short cycle sequence which  suggests it is Wenckebach at the ectopic-ventricular junction They are interrupted by narrow QRS complexes which are probably sinus with P waves in the previous ectopic T wave (red arrow). There may be other P waves (red stippled arrow)? The Wenckebach triplets have no dropped beats and are interpolated. Now I have a headache.

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Harry Mond