Group-Beating: The Footprints of Wenckebach

Vignette:

A 70 yo with history of diabetes mellitus (DM), hypertension (HTN), chronic kidney disease (CKD), heart failure with preserved ejection fraction. What is your interpretation? 

Image 1 - ECG case

Image 2 - Ladder Diagram

If you move backwards and look at the strip you will notice “group-beating”. R2R3, R7R8 and R9R10  is a group and there is progressive shortening of the RR interval in R4 to R6.  If you are an avid reader of ECG books, you will encounter the wisdom of the late Dr. Henry Marriott. According to Dr. Marriott, “”group-beating is a footprint of a Wenckebach”.

The P waves are best seen in the V lead and do not rely on lead II because you might interpret it as atrial fibrillation. Distinct P waves can be identified (P1,P2,P4,P5,P8P9,P11,P12 and 14). P3 can be identified by comparing the R3 to the rest of the QRS complexes. The terminal QRS is pointed and it means a P wave is there. P6 is seen distorting the descent of the T wave after R5. P7 and P10 and P13 are P waves that are “buried” in the QRS. If there were more leads, then most likely these P waves can be seen on the other leads.

Having established and marched the P waves in the A tier, we can then connect the R waves in the V tier. So, we can see the 3:2 and 4:3 AV Wenckebach pattern.

Interpretation: Sinus rhythm, first degree AVB, 3:2 and 4:3 AV Wenckebach

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