There is a reason to check the initiation of a tachycardia




A 70 yo c/o SOB.


Image 1

What is the rhythm?

This is a regular wide QRs tachycardia (WQRST) with a right bundle branch block (RBBB) morphology at aboout 150 bpm. The differential diagnosis could be ventricular tachycardia (VT) vs. supraventricular tachycardia (SVT) with aberrancy or SVT with fixed RBBB. V1 and V6 had a typical RBBB pattern. So, this is most likely a SVT. But which SVT?

According to the 2015 AHA SVT guideline: SVT is...

"An umbrella term used to describe tachycardias (atrial and/or ventricular rates in excess of100 bpm at rest), the mechanism of which involves tissue from the His bundle or above.These SVTs include inappropriate sinus tachycardia, AT (including focal and multifocalAT), macroreentrant AT (including typical atrial flutter), junctional tachycardia, AVNRT,and various forms of accessory pathway-mediated reentrant tachycardias"

Check the initiation strip

A way to look at SVT's is capture the initation of the arrhythmia.


Image 2 (20 sec telemetry strip)

The initiation strip showed sudden onset of the tachyarrhythmia. Distinct positive P waves can be seen on the latter part of the T waves. A positive P wave will rule-out reetrny tachyardia like AVNRT (typical/short RP or atypica/long RPl) because AVNRT will generate a negative P wave.


Image 3 (negative P waves in AVNRT)

As the tachycardia peaks, it will look like atrial flutter (AFL) as we can see in Image 4.


Image 4 (telemetry strip)

Because it looked AFL, diltiazem was given which revealed the separation of the P waves from the T waves.


Image 5 (telemetry strip when diltiazem was given)

The take home message here is in tachycardias, initiation strip can give you insight what is the tachycardia.

Final interpretration: Atrial tachycardia

#620




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