Vignette: A 50 yo with h/o of HTN and is a smoker came in due to shortness of breath and palpitations. Patient is awake with VS 160/90 RR 20 and 99% at 3LPM via NC. What is the rhythm?
Figure 1 - ECG case
This is a regular, narrow complex tachycardia at rate of about 214 bpm with no discernible P wave. This is a supraventricular tachycardia (SVT) but which SVT? SVT is a general term to describe any tachycardia with impulse coming above the ventricle. Thus, SVT can be sinus tachycardia, atrial fibrillation ,junctional tachycardia, AV nodal reentry tachycardia (AVNRT) , etc.
In this case, adenosine was given which converted it to sinus rhythm. Sorry, I do not have the transition rhythm strip. Anyway an electrophysiologic study was done which showed AVNRT and ablation was done.
Figure 2- Ladder diagram for the case
AVNRT especially the typical type is a short RP tachycardia. It is possible that the P wave will be hidden in the QRS as seen in the ladder diagram. The P wave cannot be seen because the time of atrial activation was simultaneous with the ventricular activation.