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".
Interesting Case and Outcome.
I am wondering about the dose of Cardizem administered. Is it just me or does it seem small?
I know my protocols (standing orders) are for an initial dose 0.25 mg/kg which would make this patient weigh 88 pounds (40 kgs).
Is there a reason such a low dose was given?
Good case. I am concerned that the flutter waves were missed the first time around, and that a second dose of adenosine was administered after the first a) clearly achieved AV blockade and b) was ineffective. Opportunity for provider education, to be sure.
Dev, my own philosophy on diltiazem in relatively stable patients is to start low. It's easy to give more, and problematic to resuscitate an iatrogenic CCB overdose. There is no imperative to "fix" a stable patient in the back of the truck.
DevKrev,
Perhaps it was a medical control physician who isn't as comfortable with calcium channel blockers.
My personal preference is to draw up 20-25mg and add it 2.5mg at a time to a well-flowing line and to take a long time doing it. Slow reduction in rate, usually no hypotension, and a patient who feels much better!
Brian,
I agree that the flutter waves should have been caught, and so did the medic who sent it in. In fact, they sent the case in to make sure other folks could learn from it as well!
As for CCB administration, I concur with starting small and working your way up.
DevKrev
Some systems only allow 10mg of Cardizem and not the 0.25mg/kg with 0.35 mg/kg. My protocols only authorize 10mg regardless of weight on protocol, but the standard 0.25mg/kg followed by 0.35mg/kg can be requested by online direction.
I like to think I'm comfortable with CCBs, but I still think that 10mg is generally a good starting place. Frankly, using Chris's method of slow titration sounds even better, especially with those patients with a low-ish BP that will probably get better when you slow down the ventricles…
As the medic who sent this in, I'd like to make two comments. First, the reason the a-flutter wasn't caught the first time was because his wife handed me the phone to talk to his cardiologist just before it broke. I looked away from the screen and when I looked back it was right were it started. The printout was buried under new paper and I didn't review the break on printout either (that won't happen again
My practice when administering Cardizem is to put the dose in a 50cc bag of NS and run it wide which will basically administer the whole dose evenly over about two minutes. This allows you to recheck the BP and shut it down if the patient becomes hypotensive or if the rhythm breaks before the whole dose runs. I have seen a patient put into transient asystole with cardizem pushed too fast. (I do this with Morphine, Benedryl and SoluMedrol as well and have seen a much lower incidence of side effects and discomfort by doing this)
Mordy,
It shows good self-awareness to acknowledge a mistake, and even better to make sure that others learn from it. Well done, sir (or ma'am – not sure what the gender breakdown is on Mordy
All good paramedics should be able to identify classic 2:1 atrial flutter. Most of the time, the inferior leads have a very classic look. The most common form, called counter clockwise-isthmus dependant right atrial flutter (about 80 percent of atrial flutter) has this look. The adenosine of course will not "convert" it but will usually unmask it by changing the conduction ratio as it did in the example. The second dose of adenosine was inappropriate as the rhythms should have been obvious at that point.
I also must point out that the paramedic that shared this shows great integrity and every one who learns from this has him to credit. Good job.!!!
Very interesting case. I might not have considered Adenosine, but it definitely fits the AHA protocol. As far as the dose of Cardizem. During my ED time for medic school we administered it at 5mg per dose, each one given very slowly (over about 10 minutes).
@Mordy – Great case, and thanks for the open discussion as to how his care could have been improved. We all make errors, but if we don't discuss them, they'll just be repeated by someone else, and that would be the real mistake. If even one person learns to always check the monitor after adenosine administration who might not have otherwise – and I'm sure there several out there – then sharing this was a success.
This is definitely one of the more subtle 2:1 flutter cases I've come across, and adenosine was a perfectly reasonable first move. Thanks again!
Yeah… But the dose is .25 mg/kg, rebolus with .35 mg/kg. I do not understand why some med con docs will not accept a standard dose that is accepted all throughout the world as being the dose that will actually help
@Danny – Because they've seen the huge incidence of hypotension associated with the drug countless times. Dosing recommendations are just that, and there are plenty of times when the suggested bolus in print doesn't match real-world practice (i.e. nitro dosing in acute pulmonary edema).
To quote Brian H: "my own philosophy on diltiazem in relatively stable patients is to start low. It's easy to give more, and problematic to resuscitate an iatrogenic CCB overdose. There is no imperative to "fix" a stable patient in the back of the truck."
I would change "relatively stable patients" to "every single one," since there a very few patients in rapid a-fib who absolutely need immediate control of their rate, and if they do, you're going to do that through cardioversion first. Then, when shocking fails, it's even more imperative to be judicious in your dosing since their BP is in the tank to start. I love CCB's, but there's a certain amount of finesse in using them correctly.
If I were to opine about dosing in diltiazem, it would be how everyone loves to bolus the med up front and then wait until it has started to wear-off to start a drip. Now that's a good way to administer this med incorrectly.