EKG of the Week 2017 6-18

This EKG comes courtesy of Dr. Kong.

A 64 year old female presents to the ED complaining of fluttering in her chest. She has no past medical history and is on no medications.

Her vital signs are: Pulse 40, Respirations 16, BP 130/80.

Her EKG is below.

1.       What is the rhythm?

2.       How would you manage this patient?

 

ANSWER:

The rhythm is 2nd degree AV block type I (AKA Wenckebach block).

2nd degree AV block type I usually requires no specific emergency treatment.

 

The EKG shows some dropped P Waves (P waves with no QRS complexes following them). This can be caused by 2nd degree or 3rd degree AV block. 2nd degree AV block has 2 types: type I and type II. In type I 2nd degree AV block, there is progressive lengthening of the PR interval followed by a dropped P wave. Then the cycle begins again. In type II 2nd degree AV block, the PR interval is constant and there are dropped P waves.

A quick way to differentiate type I from type II 2nd degree AV block is to compare the PR intervals before and after the dropped P waves.  In type I, the PR interval before the drop will be longer than the PR interval after the drop. In type II, the PR interval before the drop and after the drop should be the same. (Note: This method is inaccurate in 2:1 AV block.)

On the EKG below, the red arrows are pointing at the dropped P waves. The PR intervals before and after the drop are circled in blue. Note that the PR interval before the drop (0.40 seconds) is longer than the PR interval after the drop (0.20 seconds). This is consistent with 2nd degree type I AV block.

An approach to interpreting a bradycardic EKG is below.

2nd degree AV block type I usually requires no specific emergency treatment. It can occur in the setting of an inferior wall MI. In that case the treatment is to treat the ischemia. If it occurs as an adverse effect of a medication, the medication should be withdrawn.