ECG Case 001

Inspired by Vince D. 

70 year old man with recent diagnosis of hyperthyroidism walks into the ED with palpitations. Has had them since the hyperthyroidism started but states something changed a few hours ago and now he feels a bit light headed with them.

Vitals are all stable, and the patient looks well.

His ECG looks like this:


[peekaboo_link name=”Click for answer”]Click for answer[/peekaboo_link][peekaboo_content name=”Click for answer”]

OK, so  first thoughts were this is sinus tachy. It’s a patient with uncontrolled hyperthyroidism. They certainly can get AF but this doesn’t look like AF.

But the rate is pretty much bang on 150 bpm which should always make you think Atrial Flutter. Especially if it’s regular and unchanging.

I did my favourite trick of doubling the paper speed to 150 bpm to see if I could see it more clearly (H/T Jerome Hoffman…)

Someone much smarter than me thought it was A. Flutter but I still wanted proof so I figured let’s pull out the adenosine and see what happens.


[peekaboo_link name=”What happened?”]What happened?[/peekaboo_link][peekaboo_content name=”What happened?”]

Initially nothing unexpected

  • AV block from adenosine stops ventricular response and flutter waves clearly seen

Now at this point we know it’s a flutter and what normally happens is that the AV block wears off and you end up back where you started with flutter with 2:1 block.


[peekaboo_link name=”What happened next?”]What happened next?[/peekaboo_link][peekaboo_content name=”What happened next?”]

  • resumption of ventricular activity followed by sinus rhythm

Unfortunately I don’t have the repeat 12 lead to show full sinus rhythm but trust me she went into sinus and stayed there.


[peekaboo_link name=”How often does adenosine convert Atrial Flutter?”]How often does adenosine convert Atrial Flutter?[/peekaboo_link][peekaboo_content name=”How often does adenosine convert Atrial Flutter?”]

*shrugs shoulders in ignorance*

I really don’t know. I’ve not seen it before – usually when you give the adenosine it just stays in flutter.

A quick pubmed and search of uptodate didn’t give me any obvious answers. Neither did the excellent post on ERCast on A Flutter.

So if you have any insight into this let me know


Adam Herbstritt from Christchurch ED sent me another case of A Flutter conversion with adenosine that he was happy to share. Makes me wonder how often this works and if anyone has studied it before. If anyone has any more cases or info let me know.

Initially A Flutter 2:1, then A Flutter with about 1:8 block, then atrial arrhythmia breaks and a junctional rhythm then sinus. [click on image twice for full size]

And the post adenosine 12 lead



About Andy Neill

EM Reg/Resident based near Dublin. Former anatomy lecturer, theology student and occasional musician @andyneill | + Andy Neill | Contact


  1. It looks like a PVC interrupts the flutter circuit, pretty neat.

  2. This is neat and I have thought of it at times and done it once or twice. But then I have started thinking I might be skyrocketing an (atrial) thrombus -- they say it’s the converting to sinus process that bears the most risk, not the electroconversion. Call me a wooze but I don’t think I can do this with a genuine smile until the statistics tell me it’s ok!

  3. It happened on a patient we were treating today! -- the first time in my experience and that of my colleagues (which probably adds up into the hundreds)


  1. […] ECG Case 001 -- Is it sinus tachy, AF or A-flutt -- you be the judge! […]

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