Quiz #38: EKG Answer

Question: 5-month old with Down Syndrome. 2nd Postoperative day after surgical closure of large inlet VSD. What is the diagnosis?

Answer: Wenckebach phenomenon (2nd Degree, Mobitz type 1 AV block).

Discussion:

1) There are ventricular ectopies (escape beats) after the non-conducted P waves (Large, dark arrows). These beats have confused some responders.

2) "Grouping of beats" as seen here is a feature of Wenckebach phenomenon and is helpful in gestalt recognition.

3) Remember: Shortest PR interval should be seen in the beat that immediately follows the non-conducted beat. This will help to differentiate other rhythms (e.g. 3rd degree AV block with coincidental appearance to Wenckebach, for a short time). If you look at a longer strip of EKG, 3rd AV block with betray itself.

(Click on the image to enlarge)