EKG of the Week

+ EKG Interpretation


The rhythm is fast (rate ~145) and regular. The computer called it “sinus tachycardia”, is it?

It is regular but what do you think of the rate in a 68 year old? What is the MAXIMUM sinus rate? It is 220 minus age, which for a 68 year old would be about 150 but lets look at the clinical context. This is not a person running on a treadmill, so right away sinus tachycardia is not very likely.

Next, are there P waves? Certainly not preceding the QRS, so again NOT sinus tachycardia.

So, what can give us a REGULAR rhythm rate nearly 150? The 2 options I would consider would be an SVT and atrial flutter with 2:1 block. Are there flutter waves? It is sometimes difficult to pick out flutter waves at this rate when every other one is on top of the QRS so sometimes need to look at multiple leads but I do not see flutter waves. What I do see is small negative deflections at the end of the QRS in the inferior leads→ retrograde P waves. This looks like an AV node reentry SVT.

Looking at the QRS, he has a leftward axis. The computer thinks the QRS is wide, but I think that is because of that retrograde P sitting on the end of the QRS.

This is an AV node reentry SVT at rate 145, he has a left axis deviation.

He was given adenosine and promptly converted to sinus rhythm at a rate of 80 with clear P waves (and without the retrograde P at the end of the QRS).

Further Reading:

Life in the Fast Lane: AVNRT

Follow up EKGs: