Strip 37

sinus tach with SVT


First Glance:

From across the room it looks like a fast sinus with a run of some kind of SVT.

Discussion:

This is fun. We start with a string of seven narrow complex sinus beats with a normal P, normal PR interval, and some ST and T changes.

Then beat 8 comes early, and it’s P wave is negative instead of positive. This is a PAC. Beat 9 and on is the run of SVT, and the P wave appears to be a sharp negative deflection as in the beat 8 PAC, but it is superimposed on top of the prior T wave so it is harder to pick out. The run continues for 11 beats (with a rate of 190 bpm) then spontaneously converts to sinus rhythm, with one more PAC two beats from the right.

This is a burst of ectopic atrial tachycardia.

Here’s another strip from the same patient:

Here we see the same sinus tachycardia, now with one fusion beat at beat 7 which looks like a cross between the native QRS and the PVC seen later.

The last few beats show some squirrely activity of unclear significance. The beat six beats from the right comes a tad early and has an apparent P’, so it could be a PAC, followed by a PVC. However, the P waves march out nicely before that possible PAC, so it is also possible that the normal appearing QRS before the PVC is pre-excited, or is an unusual fusion beat, or for whatever reason the conduction pathways were running faster. Then what looks most like a noncompensatory pause follows and sinus kicks back in now with a slightly extended PR interval and some small morphology changes. Let’s leave all that for another day, shall we?

Final Impression?

Sinus tachycardia @ 100 bpm with paroxysmal ectopic atrial tachycardia @ 190 and monomorphic PVCs, with some suspicion for ischemia.

Management implications:

A 12L will evaluate for ischemia, and will show you the ectopic P wave axis, which could show you where the ectopic focus is in the heart. Otherwise, treat per SVT and know that if sustained symptomatic AT occurs this is generally responsive to ablation therapy in the cath lab.

 The Take-home Point:

Ectopic atrial tachycardias are SVTs paced by an ectopic intra-atrial pacemaker. They generally run no faster than 250 bpm, which might help differentiate them from typical flutter which runs faster.

Atrial tachycardia looks different from reentry tachycardias because the P wave of the latter will generally be buried in the QRS or directly after it, whereas the ectopic atrial tachycardia has a P wave right out in front where it is supposed to be. It is usually hard to pick this up at fast rates, but here we have the benefit of some PACs to show us the P morphology to support our diagnosis.

 

 

2purple_starTwo star strip. The meat and potatoes.

—> see the next strip

Leave a Reply