EKG of the Week 2019 4-21

A 73 year old male with a history of a-fib S/P ablation 3 years ago. Presented to the ED complaining of weakness and near-syncopal episodes. He had no recent changes in medication. He had no chest pain.

His monitor strip is below. This occurred several times during his ED stay.

2019 4-21.jpg

1.      What does the monitor show?

2.      How would you manage this patient?

ANSWER:

The monitor strip shows a sinus rhythm with a prolonged sinus pause.

 The patient is symptomatic with prolonged pauses. He should have a transvenous pacemaker placed.

 

The patient presented with near syncopal episodes. He was noted to be in sinus rhythm. However, on the monitor he had multiple prolonged pauses.

Pauses on EKG can be caused by: 1) non-conducted PAC’s (most common cause); 2) sinus node disease (Sinus arrest or SA block); 3) AV block.

In a non-conducted PAC, you will see a P wave that comes earlier than expected with no QRS complex following it. This happens because the PAC occurs so early that when it hits the AV node, it is still refractory. The P wave may come so early that it is buried in the preceding T wave just before the pause. Look back at the last T wave before the pause and see if it looks different than the other T waves on the strip. If it looks different, it might be because there is a P wave buried in that T wave. These pauses are usually very brief.

In sinus node disease, you will see a pause with no P waves. In sinus arrest, the SA node takes a little vacation and doesn’t fire. So there will be a pause with no P waves and the length of the pause will be random. In SA block, the SA node continues to fire but can’t depolarize the atrium. So, again there are absent P waves, however the length of the pause will be a multiple of the normal P-P length. Meaning, if you make believe a P wave happened during the pause at it’s expected location, the next P wave will come on time.

Finally, if the pause is due to AV block (2nd or 3rd degree), there will be P waves coming on time with no QRS complex following.

In our case, the patient has a prolonged pause with no P waves and is consistent with sinus node disease.

The patient had a transvenous pacemaker placed and subsequently had a permanent pacemaker inserted.

The following algorithm is useful in diagnosing pauses:

Algorithm Pauses.jpg