A nurse hands you this EKG with a concerned look…


She say it’s a 35 y/o man who is coming in for shortness of breath and palpitations since last night. The next question you ask is vitals? Yes! BP 96/57, HR 201 ,RR25, pO2 99 on 4LNC and Afebrile. You put your thinking cap on and head over to see the patient.

He looks a little drowsy but is answering questions. He adds he has a history of “hole in his heart” repaired when he was 2 and 5 years old (two surgeries). He’s been well since, plays basketball with no issue. No clear chest pain. Denies drugs, caffeine, alcohol. Works nights in construction. He says nothing like this has ever happen to him.

Your superstar nurse comes by saying she’s found an old EKG, Hurray!


So, what current rhythm is this? What’s your next move?

The voice of Amal Mattu pops into your head: “Greetings everyone…what is the differential for a regular wide complex tachycardia?”

  • Ventricular tachycarida
  • Ventricular tachycardia
  • Ventricular tachycardia
  • SVT with aberrancy
  • Aflutter with constant block with aberrancy
  • Sinus tach with aberrancy

Most regular WCT should be Vtach until proven otherwise, specially in old, sick, CAD patients. The fact that this is a young patient with a previous hx of RBBB, with a WTC morphology similar to his baseline RBBB morphology, is reassuring for some kind of fast rhythm with aberrancy. However, VTach still cannot be completely ruled out, specially given this patient’s history of some unknown congenital problem.

Given that the patient was stable, the decision was made to try adenosine to identify the rhythm. The following strip was obtained during administration:

Img_3222betterLeads got disconnected (this is not asystole)

Multiple doses of adenosine were given, with no lasting effect on the rhythm. It did slow down for a second. Take a look and decide what you think the underlying rhythm is.






We can see P waves (circled below). The P waves are going about 200 bpm.


Thus, is seems that this rhythm is Aflutter (or some kind of atrial tachycardia) with no block (all P waves are being conducted) with an old RBBB. Aflutter is notoriously difficult to convert with AV nodal blocking agents.

What’s your next step? Given that Adenosine did not work, the patient was cardioverted (synchronized). 

This broke the rhythm and put the patient back into sinus. Post cardioversion EKG looked like this: 


Watching all those Mattu videos finally pays off and you think do yourself, as the cardiologist pulls up in his Porsche, maybe I should have gone into cardiology?

May 2024