EKG of the Week 2017 4-30

This EKG comes courtesy of Dr. Hahn.

An 82 year old female presents to the ED complaining of palpitations. She has no chest pain and denies syncope.  Her vital signs are normal.

Her EKG is below.

1.       What is the rhythm?

2.       How would you manage this patient?



The rhythm is sinus with PAC’s. Every third beat is a PAC. This is called atrial trigeminy.

PAC’s usually require no specific management. Patients can be advised to avoid potential triggers such as sympathomimetics, caffeine, Red Bull, etc.


The EKG demonstrates an irregular rhythm, but there is a pattern to the irregularity (i.e. it is not irregularly irregular like a-fib). Beat #3 and beat #4 are preceded by P waves and appear to be sinus beats. Beat #5 comes earlier than expected, has a narrow QRS, and probably has a P wave buried in the T wave from beat #4. Thus, it is a PAC. Beats 6 and 7 are sinus, beat 8 is a PAC. Beats 9 and 10 are sinus and beat 11 is a PAC. This pattern continues. When every third beat is a PAC, that is known as atrial trigeminy.  (Every second beat would be bigeminy. Every fourth beat would be quadrigeminy.)

Premature beats can originate from the atria (PAC’s), the junction (i.e. the AV node – called PJC’s) or from the ventricles (PVC’s). PAC’s appear as a P wave which comes earlier than expected followed by a QRS complex that is narrow. Following the PAC, there is a non-compensatory pause. This means that the length from the P wave preceding the PAC to the P wave of the next normal beat is random. It is not related at all to the distance between the normal P waves in the normal beats. This happens because the PAC “re-sets” the SA node. This means, the PAC depolarizes the SA node, so it has to recover before it can generate the next normal beat.

++++PJCs may have a P wave before or after the QRS complex. The P wave will look different than the sinus P waves and it will often be retrograde (i.e. inverted). PJC’s are uncommon in healthy hearts. They occur in CHF, digoxin toxicity, ischemic heart disease, and AMI (especially of the inferior wall).++

PVC’s have no preceding P wave and the QRS complex is wide and bizarre. It looks distinctly different than the other QRS complexes in that lead. Following the PVC, there is a compensatory pause. This means, if you “march out” the P waves, the P waves will continue to arrive at the expected time after the PVC. This occurs because the PVC does NOT reset the SA node. As far as the SA node is concerned, the PVC never happened. So, the SA node continues to fire at its normal pattern.

PAC’s usually require no specific treatment. Patients should be advised to avoid known triggers. These include cocaine, amphetamines, caffeine, Red Bull, pseudoephedrine, etc. Stress is also a common cause of PAC’s.