Overnight tracings from Holter monitor recording. There is a pause. What do you think?

Fusion is another lesson in timing! Fusion beats are an amalgam of two competing rhythms. Both are responsible for partial depolarization of the respective chambers and depending on the contribution of each, result in progeny with similarities to one or both parents.

The ventricular ectopic compensatory pause is a lesson in timing!

Our last ECG topic was reversed arm leads and dextrocardia. This topic also looks at twisted leads, but this time involving all limbs. I have discussed this before, but I would like to take it further. Let us twist the arm and leg leads with “leg leads on arms” and “arm leads on legs”.

I thought I would discuss bundle branch block. Can I hear “Booorring”? Maybe it isn’t so boring. Look at this ECG.The rhythm strip shows sinus rhythm with two QRS configurations; one narrow (yellow highlight) and one wide with a right bundle branch block configuration (red highlight). This is a bidirectional rhythm (or tachycardia if greater than 100 bpm).

Last week, I showed this ECG which was interpreted as ventricular tachycardia with 3:2 Wenckebach block at the ectopic-myocardial junction. I immediately had a number of emails, requesting evidence that such a block exists. Non-sustained ventricular tachycardia with Wenckebach exit block. However, let us try and prove this for ourselves on the surface ECG!! Is this possible? The answer is yes yes yes!

The techs wanted to know whether to call this a run of ventricular tachycardia or idio-ventricular rhythm. My first impression was a bizarre run of ventricular couplets with no sinus complex between. I had no idea what that meant!There is, however, a pattern akin to Wenckebach sequences. Could this be so!