Superventricular Tachycardia - Has anyone ever figured out why?
August 4, 2022 4:30 AM   Subscribe

What do these signals look like? Why do they appear out of the blue as SVT? What happens exactly to trigger this re-entry? Where is the signal coming from exactly? The electric system is pretty vast. I need to know where - has anyone ever done any type of mapping as it's happening and can someone please post a link to this mapping? Thanks.
posted by watercarrier to Health & Fitness (7 answers total) 1 user marked this as a favorite
What do these signals look like?

I am not a doctor.

This American Family Physician article on Diagnosis and Management of Common Types of Supraventricular Tachycardia has a figure with ECGs of 4 common types of SVT along with descriptions. Helpfully there are also diagrams of the heart and the involved pathways.

This Canadian Medical Association Journal article on Diagnosis and management of supraventricular tachycardias has a detailed discussion of the mechanisms of different kinds of SVT.

This Circulation: Arrhythmia and Electrophysiology article on New Criteria During Right Ventricular Pacing to Determine the Mechanism of Supraventricular Tachycardia goes into substantial detail.

This is a very complicated subject, though, and if you're not used to looking at ECGs then I don't know how useful they will be.
posted by jedicus at 5:28 AM on August 4 [1 favorite]

Response by poster: @jedicus - it's obscure af - but I have been delving into sonography recently just to understand more than the common layperson/sufferer. I think beyond generalities what I'm looking for is someone saying *THERE!!* *See THAT?!* - THAT's the impulse and it's being generated from.....the brain - right here!. Anything like that? :)
posted by watercarrier at 5:35 AM on August 4

Forgive me if I'm being too obvious or basic, but the starting point for understanding the origins of SVT is that this type of arrhythmia (by definition) originates in the upper chambers of the heart, in the atria or the AV node, as opposed to ventricular tachycardia, which originates in the lower chambers of the heart. While the brain plays a role in heart pacing (when you're nervous, your heart may speed up, etc.), the heart is pretty autonomous. I would recommend the Wikipedia article on SVT and reading the pathophysiology sections of the articles associated with each of the linked types of SVT (atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia , and Wolf Parkinson White) to familiarize yourself with the causes of these diseases. Also, if you would like to learn more about the detection of SVT, I would recommend reading up on electrocardiograms (ECGs/EKGs), as they (not echocardiograms/sonograms) are the chief way that arrhythmias are diagnosed. Hope that helps!
posted by reren at 10:35 AM on August 4 [2 favorites]

For readers unfamiliar with SVTs, the 'beat/contract now' signal from point a to point b on the heart gets split, basically there's a short. Now there are 2 weak signals, so there are 2 weak beats/contractions. It is exacerbated by stress, caffeine and other stimulant drugs, and dehydration, which affects electrolytes, as well as other things.

I get episodes of SVTs. It's usually resolved with a very cold, very wet washcloth on the face, or the Valsalva maneuver(talk to your doctor before doing this), both of which affect the Vagus nerve. I've been instructed to go to the ER if I cna't resolve it and it lasts more than an hour. It's manageable for me so I have chosen not to have an ablation. If you experience it, you should see a doctor promptly.
posted by theora55 at 10:37 AM on August 4 [1 favorite]

It's not quite the same, but I suffered from PVCs until I had an ablation a couple of months ago. For the first part of the procedure, they run a sensor up into your heart (usually from the groin), to try to determine exactly where the stray impulses are coming from. (They also cover your chest and back with sensors as well.) I didn't really pay attention because there was no telling how long it would take, and I didn't have my glasses on, so the big monitors they were using were just a blur.
Then once they find the problem spot they cauterize it, and do some tests, including I think, a shot of adrenaline. That got my attention, and I started paying attention again, but it was pretty much over at that point.
Does that help? (I didn't hear someone say "There!" but I'm sure someone on the team said something like it.)
posted by Spike Glee at 10:37 AM on August 4 [1 favorite]

My friend had SVT, and it was caused by a (really minor) birth defect. Her heart had a miniscule piece of extra tissue that would occasionally make its electrical signals go haywire and beat too fast. She had first noticed it as a teenager, and was told it was anxiety 🙃 She had an ablation to get rid of it because she didn't want it to keep happening and didn't want to take meds.
posted by Violet Hour at 11:25 PM on August 5

I should add that they trigger the SVT during the procedure and then try to do it again to make sure it worked.
posted by Violet Hour at 11:32 PM on August 5

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