EKG of the Week 2017 1-22

This EKG comes courtesy of Dr. Adamakos.

An 85 year old female presents to the ED complaining of gradual onset SOB. No chest pain and no syncope.

V/S: P 40, R 18, BP 118/74.

She is awake and alert with a normal mental status.

Her EKG is below:

1.    What is the rhythm?

2.    How would you manage this patient?




The rhythm is 2:1 AV block.

Our patient is stable so no emergent intervention is necessary. Atropine can be given but may not work in high grade AV block. Check for causes of the bradycardia including potassium level and medications.


The EKG shows a bradycardia at a ventricular rate of ~38. P waves are present but there are also dropped P waves. The dropped P waves are indicated by arrows on the  EKG below:

Dropped P waves can be caused by 3 things:

1.    Non-conducted PAC’s

2.    2nd degree AV block

3.    3rd degree AV block

To differentiate these causes, first look to see if the dropped P wave comes on time or earlier than expected. If it comes early, it is a non-conducted PAC.

If the P wave comes on time, the cause can be 2nd degree AV block or 3rd degree AV block. Use the algorithm below to differentiate 2nd degree block from 3rd degree block:

Since on this EKG the RR interval are regular and the PR intervals are regular, we are dealing with a 2nd degree AV block. Now we must differentiate 2nd degree type I from type II:

However, on this EKG, we do not have any two consecutive PR intervals. This is because every second P wave is dropped. So, we can not say for certain whether this is type I or type II. This is called 2:1 AV block. For every two P waves there is one QRS complex.

Incidentally, on this EKG, the QT interval is also prolonged.

This patient was admitted to the hospital and had a permanent pacemaker placed.

Use the following algorithm to diagnose bradycardias on EKG: