This transcript has been edited for clarity.
Christopher J. Chiu, MD: Welcome back to The Cribsiders and our video recap summary of one of our most recent podcast episodes. Justin, what are we reviewing today?
Justin L. Berk, MD, MPH, MBA: We had a great episode on supraventricular tachycardia (SVT). Our guest was Dr Mike Fahey from the University of Massachusetts. He's the chief of pediatric cardiology and program director for the pediatric residency program. He's the recipient of multiple teaching awards across training levels, and during this episode, he taught us how to approach narrow-complex tachycardia and the different types of SVT. We discussed treatment for SVT and he gave us "his bundle" of information on how to approach cardiac arrhythmia in kids.
Chiu: What's the most common cause of SVT in kids?
Berk: It's something called atrial ventricular reentry tachycardia (AVRT). There's an extra pathway that connects the atria to the ventricles, and it basically goes around the AV node. One of the most common forms of AVRT is Wolf-Parkinson-White (WPW) syndrome.
Chiu: So if I have a child in tachycardia and I get an EKG, what am I looking for?
Berk: This is the big thing. Sinus tachycardia is something that most people feel comfortable diagnosing. These kids would have a relatively normal EKG, except with an increased rate. How do you identify this AVRT or another form of SVT? EKG is the diagnosis tool that the cardiologists love, and so the answer is in those squiggles.
What you're looking for is retrograde P waves — the atrium is not using the SA node when there's this reentry pathway. Usually you're going to see some retrograde P waves or P waves are absent. It is a narrow, complex tachycardia, so you're going to see a narrow and very regular QRS. It makes sense being a supraventricular tachycardia and the ventricles are beating normally.
Chiu: So I think I'm seeing SVT on the EKG. Should I be freaking out?
Berk: You definitely don't need to freak out immediately. There are other things to be on the lookout for. You want to make sure that you are checking to see if there is evidence of WPW — a classic shortened PR interval and a sloped delta wave. It's difficult to look at some of the other forms of SVT, like AVRT, without the help of a cardiologist. But let's say that you have a tachycardic child and you feel confident that it's SVT. How worried are you?
This was a question that we asked our expert, Dr Fahey, and he emphasized that there is no immediate urgency. This isn't a crisis, but the longer the child has tachycardia, the more damage that can occur to the heart, ultimately leading to tachycardia-induced cardiomyopathy. So over time, this can lead to essentially heart failure. Dr Fahey becomes worried about reduced cardiac output when a child has been in SVT for 10-20 hours or more.
In the immediate case, there's no need to worry. But if a child is in SVT for hours, we do get worried. The one exception is WPW, which in rare instances can lead to sudden cardiac death. That's an important reason to diagnose it early.
Chiu: Okay. We aren't freaking out, but we know there are probably things we can do. So how can we treat SVT?
Berk: We start with the easiest and least invasive intervention: vagal maneuvers. Different practitioners have different tricks of the trade. Dr Fahey shared some of his. One is just having the child blow as hard as possible through a partially occluded straw, which creates a Valsalva maneuver. You can make it into a game, and it's one way to help get the child out of SVT.
Another common maneuver is ice to the face. Dr Fahey recommends grabbing a bag of ice and pouring water into it to create a slurry, and then placing it on the upper portion of the child's face with gentle pressure. No splashing of cold water, no ice pack all around the body — just a slurry of ice water to the front of the head to try to stimulate the vagus nerve. You might ask, how do we do this to an infant? Do we cover them in water? His suggestions were to stimulate a gag reflex or even try rectal stimulation, which can both stimulate the vagal nerve in an infant.
Chiu: We talked about the REVERT trial, in which they used a syringe and an inverted leg drop as well.
Berk: Especially for older adolescents, that's probably one of the first-line treatments for vagal maneuver.
Chiu: Are we giving any medications?
Berk: This is the next step. If you're in the emergency department or maybe in a cardiology office, you might consider giving something like adenosine, as long as there is a rhythm strip running. It's an important part of the diagnostic proves. Adenosine blocks the AV node. It is the first-line drug treatment for SVT. The problem is you can't give it in WPW, so make sure you're not overlooking those delta waves and narrow PR intervals. This should be done with a cardiologist an arm's length away. Adenosine also needs to be delivered in a very specific way with a three-way stopcock attached to an IV line. We talk about this more in the podcast, along with other antiarrhythmics and when to use cardioversion or ablation. If you want to learn more, be sure to check out the full episode.
Chiu: So, what are the greatest hits from this episode?
Berk: The greatest hits that I took away are:
The most common form of SVT in children is AVRT.
WPW is one form of SVT.
Vagal maneuvers can be the first-line treatment for SVT. They often break SVT.
There are a few ways to do a vagal maneuver, depending on the age of the patient.
If it doesn't work, we can try adenosine and other antiarrhythmic medications.
Ablation procedures can also be indicated.
Chiu: Excellent. Thanks for joining us for another episode of our Medscape video recap series from The Cribsiders pediatric podcast. You can download the episode at any podcast player or check it out at our website. Thanks for tuning in.
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Cite this: How to Stop SVT in Kids - Medscape - Mar 10, 2022.
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