This is the conclusion to 57 year old male: Chest Discomfort. We suggest you read the backstory first!
We're now in the back of the ambulance with our stubborn 57 year old male with a rapid heart rate. He looks unwell, but is otherwise hemodynamically stable. Our partner is working on a line.
Let's review the initial rhythm and 12-Lead ECG:
The rhythm strip shows a narrow complex tachycardia at approximately 150 bpm. Atrial activity is not visible and may be buried in the T-waves. Our differentials include: sinus tachycardia, supraventricular tachycardia (e.g. AV Nodal Reentry Tachycardia and orthodromic AV Reciprocating Tachycardia), 2:1 atrial flutter, and junctional tachycardia.
The 12-Lead also shows a narrow complex tachycardia at approximately 150 bpm. Atrial activity is vaguely appreciable in the T-waves of V1 and III. The list of differentials remains unchanged, however, given the continued regularity sinus tachycardia seems less likely.
The paramedic who sent this case in elected to treat the patient with adenosine to convert or unmask the underlying rhythm.
The post-adenosine rhythm strip shows clear flutter activity in leads II and aVF, however, the paramedic admits they did not initially notice the F-waves. The rhythm then devolved into an irregularly irregular rhythm and a strip was printed.
While there is some baseline wander present, given the previous ECG, it seems very likely that this is atrial flutter with a variable response. However, the rhythm quickly accelerated to its original rate of 150 bpm.
As the treating paramedic did not appreciate atrial flutter, they administered a second dose of adenosine.
Atrial flutter is readily appreciable in Leads II and aVF, and as before the rhythm accelerated to its original rate.
The treating paramedic recognized atrial flutter and contacted medical control asking for orders for Cardizem.
Orders were received for 10 mg Cardizem slow IV push, which resulted in some reduction in rate but without conversion to a sinus rhythm.
The patient was transported to a local hospital where he was placed on a Cardizem drip, resulting in conversion to a sinus rhythm after a few hours. A follow-up with a cardiologist was scheduled and the patient was discharged home without sequelae.
Any time you are faced with a regular rhythm at around 150 bpm, remember that the most common atrial rate in atrial flutter is 300 bpm and the most common conduction is 2:1.
- For more tips to becoming an Atrial Flutter Rock Star, check out our friend Vince DiGiulio's blog post "Diagnosing Hidden Atrial Flutter".