EKG of the Week 2016 12-25

This EKG comes courtesy of Dr. Dersim Kaya.

 

A 74 y/o female S/P total left knee replacement with recent PE, presents to the ED complaining of a near syncopal episode. No chest pain or shortness of breath.

The EKG is below.

1.      What rhythm does the EKG demonstrate?

2.      What is the treatment for this rhythm?

 

ANSWER:

The EKG demonstrates Ventricular Bigeminy.

No specific treatment is necessary.

 

The EKG demonstrates a sinus rhythm. However every second QRS complex represents a PVC. When PVC’s occur with every second beat, that is called ventricular bigeminy.

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 looks the same as all the other QRS complexes in that lead. 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 a multiple of 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 MI (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 normal P waves, they will continue to arrive at the expected time after the PVC. The distance from the P wave preceding the PVC to the P wave following the PVC will be twice the distance between the normal P waves. 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. One P wave is missed because of the PVC. The next P wave should come on time. In this EKG, you do not see that it is a compensatory pause because there are never two sinus beats in a row without a PVC.

Bigeminy is usually a very stable rhythm. It is unlikely to degenerate into ventricular tachycardia.

PVC’s have many causes and usually require no specific treatment.