An Interesting ECG Case

A 62 year old female presents with presyncope.

Findings

•Sinus rhythm

•Second degree AV block (Mobitz I)

•AKA Wenckebach

•The PR interval prolongs before a QRS beat is dropped (non-conducted)

Tips

•Anytime there is grouped beating on the ECG, it’s important to see if there are p waves that are not conducted (aka QRS is dropped).

•Sometimes the p waves are easy to see in Lead II, other times, the biphasic waves in lead V1 may be easier to see.

•A quick trick is look at the PR interval right before and right after the dropped beat. If the PR interval right before the dropped beat is longer than the PR interval after the dropped beat, then it’s Mobitz Type 1.