EKG of the Week 2018 7-29

An 82 year old female presents for light-headedness. She states she feels weak and feels like she will pass out. No chest pain, no SOB.

Vital signs: Pulse – 45, BP 100/70, Respirations – 16.

Her EKG is below.

2018 7-29.jpg

1.       What does the EKG demonstrate?

2.       How would you manage this patient?

 

ANSWER:

The EKG shows 3rd degree AV block.

Pacing pads should be placed on the patient’s chest. Causes of the AV block should be sought and corrected.

 

The EKG shows a bradycardia, with the presence of P waves and some dropped P waves (i.e. P waves without a QRS following it).

2018 7-29 dropped P waves.jpg

This can be caused by 2nd degree or 3rd degree AV block. Differentiating these can sometimes be difficult. First, measure the R-R intervals. If they are irregular, you are likely dealing with a 2nd degree AV block (likely type I). If the R-R intervals are regular, you should then measure the P-R intervals. If the R-R intervals are regular and the P-R intervals are also regular, you are again dealing with a 2nd degree AV block (likely type II). If the R-R intervals are regular and the P-R intervals are irregular, that is consistent with 3rd degree AV block.

On this EKG, the R-R intervals are regular…

2018 7-29 R-R intervals are regular.jpg

…and the P-R intervals are irregular:

2018 7-29 P-R interals are different.jpg

This is consistent with 3rd degree AV block.

The algorithm below may be helpful:

Algorithm 2nd degree vs 3rd degree AV block.jpg

The management of 3rd degree AV block depends on the patient’s stability and symptoms.

First look for correctable causes such as medication toxicity (beta blockers, calcium channel blockers, digoxin), or electrolyte abnormalities (hyperkalemia). If none of these exist and the patient is unstable they should have an emergent pacemaker placed. If the patient is stable, pacing pads should be placed on the chest in case the patient deteriorates and you need to start pacing them quickly. Otherwise they can then be observed until a permanent pacemaker can be placed.