Supraventricular Tachycardia - SVT -- It's Not All The Same! 

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Well, my son told me live streaming would be easier than creating a ChalkTalk, because I don't have to edit it. But I didn't want it to look cheap and unprofessional, so I spend like 2 hours getting everything set up (lighting and equipment... two cameras, sound, etc)... all by myself!! So, it actually takes more work to live stream, but I can really talk in detail about things... I'm glad you like them. Please spread the word!

@@ECGDoc Thanks Doc. I'm now learning, and from your way it's more interesting. Don't stop now. Love in the house.

By the way, no one with SVT should ever require a shock unless they are unconscious. Adenosine is very effective.

Thank you, Kim! :-)

Hi, Liz! SVTs are very complicated. Some sustained tachycardias are due to an accessory pathway, which is considered a congenital abnormality - you're born with an AP. However many other SVTs are less well defined. AVNRT is the most common cause of sustained PSVT but there are at least 3 different kinds and I consider them "opportunist" arrhythmias... the pathways are there but autonomic tone has to be just right and the premature beats have to be timed properly to get it started, and then it can sometimes just stop. Atrial tachycardias are less common but more unpredictable. I cannot say that dietary intake or topical meds have a proven relationship, but some patients swear by it. It's just hard to prove it one way or the other. But SVT is mostly benign... it's just annoying. Unless it becomes recurrent and sustained. Accessory pathways and AVNRT are usually ablated with a very high success rate and relatively low risk. However, non-sustained arrhythmias are not good targets for ablation since they often cannot be reproduced in the EP Lab and then it's impossible to map the region where they're coming from. BTW -- if you don't have a discreet pathway that's causing SVT, then yes indeed sometimes they just go away. Hope that helps! -- Dr. Nick

Sustained rapid tachycardia can cause a bump in the troponin, but 130 bpm is not terribly fast. Perhaps you might need a stress test?

@@ECGDoc Thanks for your reply. I’m having Myoview test to test cardiac function as my LAD is 50-70% stenosis and I asked for echo but this was suggested. In the first attack of tachycardia it was sudden and I felt something was terrible was going to happen ie impending doom... layered on sofa and raised legs which has been shown to reset SVTs.. sweating started with short of breath. Tachycardia stabilised to 100 when Help arrived. Have had this many times but only once wax troponin raised to 19.5 then 50 four hrs later, The tachycardia was never sustained for long maybe 10 mins but fell to 90-100. I’m now thinking it was probably a NStemi.. the strange thing is I have T wave inversion in lead 3 as nonspecific but when this happens .. when heart is struggling usually after I eat as I have IBS .. t wave inversion spreads to leads 2 and AVF as well suggesting inferior infarct. Thus ER admitted and troponin gets tested . Only 6 weeks ago was it positive .. in last 2 occasions was negative. I have been unable to record ECG to show SVT when it happens. The fact that ambulance showed a delta wave has me thinking it might be WPW syndrome but PR interval is ok.

Yes, definitely. Sometimes the electrical short circuits are only capable of causing tachycardia when adrenaline levels are high (such as during exercise).

I have t wave inversion on lead 3 at rest but when the tachycardia starts lead 2 and avf get t wave inversion too leading DRs to suspect inferior infarction but troponin has been negative twice...

Interesting, mine usually happen when I am sitting down. Only had it happen once during exercise and that was in 2004.

That sucks, mostly mine are when exercising or having panick attacks. Sometimes when I am exhusted from lack of sleep and stressed it can happen at rest, then it's always worse because I'm so tired! Last night heart was 239bpm. I was impressed I asked for a copy of the ecg lol.

It really depends on the kind of SVT you have, but the success rate is extremely high on the usual varieties. If it's happening frequently and meds aren't working, you should speak to an electrophysiologist and have them go over it with you.

Well, heart rates of 350 are very difficult to hit in normal individuals. The AV node will usually block such rapid rates unless there's a problem with the function of that structure as well. Who is analyzing the strip for you? Sometimes there can be artifact that won't be recognized as such on the "official" reading. Even cardiologists make mistakes sometimes. Plus, you say "the rhythm doesn't change" -- that's not expected if the heart rate is truly going up and down as you suggest.

@@ECGDoc I’m looking at the rate box that’s above the rhythm section on the ILR. It shows the time I recorded symptoms. Most of the time the rate was around 170 with very short spikes in rate. The highest was 350. It’s literally just one spike. There’s multiple sudden spikes in a row like this anywhere from 200 to 350 bpm. Both the rate section and rhythm section show the 7 minutes where I triggered the recorder. It looks like there are PACs happening when the rate is spiking up. I will be speaking with my EP. The report said I had 3 SVT episodes this past month that were above 170. I don’t think they count anything below 170 bpm. I have LOTS of episodes below that 130 - 150 bpm. I signed up on your website to get a better understanding of what’s going on which has helped me not worry about these episodes anymore. Unfortunately they still cause presyncope and other symptoms. Wish RU-vid would allow me to share a photo of the heart rate spikes. It clearly shows multiple spikes as high as 350. I don’t know if that’s an error or not 🤷‍♀️ Just wanted your thoughts on the interpolated PACs. It looks like I have those but they don’t interrupt the sinus rhythm. I can’t find much information on them. It looks like I have some sort of beat sandwiched in between beats that don’t change the main rhythm. That’s when the spikes occur 200-350 bpm

Hey, thanks for the feedback! The answer to your question is complex. One reason that PSVT can get worse with age is that in young people the AV node conducts so well that there's not enough slowing of the signal to allow the rest of the circuit to recover, so the signal kind of runs into it's own tail. With age the conduction takes longer (mostly down the slow AV nodal pathway) and that gives the circuit the ability to sustain itself.

@@ntullomd Aha That makes perfect sense, and hopefully explains it, as there is always some speculation involved in explaining complex phenomena but thats the best answer I've heard, Thankyou from Perth Australia!!!!!!!

Suhgavath

Hi! First, PAT is a type of SVT, so those terms are sometimes confused and may be used interchangeably, but some SVTs are not PAT, so keep that in mind. POTS, on the other hand, is an inappropriately rapid heart rate when someone stands up, so it's actually SINUS tachycardia. That's why it's different than SVT. Now, some (about 20%) of POTS patients do have excessive adrenaline (so-called "hyperadrenergic POTS") and it feels like "fight or flight" all the time. Then again, stress or increased sympathetic stimulation can, in people with the substrate for an arrhythmia, trigger SVT. So it can feel the same. SVT can be ablated. POTS cannot. Good luck to you!

@@ECGDoc I definitely have POTS. I take Corlanor for it. I also know I have atrial tachycardia. I wear a loop monitor which picks it up when it’s over 100 bpm lasting longer than 4 hours. My loop recorder has also labeled SVT episodes over 170 bpm. Haven’t seen my EP yet so I don’t know if those episodes are also atrial tachycardia (PAT), the report says SVT. I’ve tried coming off the Corlanor many times but all my POTS symptoms come back and the SVT episodes seem to increase. Thank you for always taking the time to respond. Your videos really helped me. I no longer worry about my episodes even though I feel like I’m going to pass out. Unfortunately they seem to happen at the worst times. Feeling like I’m going to pass out while driving is the worst. I just want it to go away!

Emotional stress it has gets worse.

Judy -- sounds like a complex problem. You need to see a good doctor! Vasovagal syncope is most often triggered by stress. Rapid heart rates can also be triggered by stress. However, you could have an arrhythmia. It seems that you've been living with symptoms for 20 years -- are you seeing a specialist at this point?

No. SVT is due to electrical problems in the heart. Excessive thyroid hormone can cause SINUS tachycardia, however.

Hi, Hassan!! So, adenosine will generally break PSVT on the antegrade limb (AV node, generally) and you will see the tachycardia terminate with a p-wave that fails to reach the ventricle. If you have a calcium-dependent atrial tachycardia, usually the tachycardia terminates with a conducted QRS (from the last beat of the AT). There are always exceptions to the rule, but seeing SVT terminate with a non-conducted p-wave is pretty good evidence that the AV node is part of the circuit. ALL THE BEST TO YOU!!

Not everyone with SVT has an accessory pathway. APs are congenital -- you are born with it, but they usually don't cause problems until adolescence or young adulthood, though rarely children get SVT from APs,

There are many factors to consider. First and foremost, are they long and uncomfortable enough to interfere with your lifestyle? Or are they just a minor annoyance? Are you willing to risk a 1-2% risk of serious complications to get rid of them? If they are very short, they may not even be inducible in the EP lab and an ablation may not be possible. Have you tried meds? This is a conversation to have with an electrophysiologist. Good luck!

@@ECGDoc do you have a video on Sinoatrial Nodal Reentrant Tachycardia

It generally won't. Corlanor affects the sinus node only. Some people have tried using it to slow the AV node to help control the rate of atrial fibrillation but it does not work very well for that.

Hi, Crystal -- thanks for your question. Reading complex recordings from an ILR (or any monitor) is an art. That's why I created ECGAcademy.com -- sometimes it's hard to tell the difference between sinus tachy and atrial tachycardia coming from the high right atrium... often you can only tell looking at the way the rhythm behaves.

@@ECGDoc do you have videos or papers on sinoatrial reentry tachycardia?

@@crystalkeara8868 I do in my Expert level membership.

@@ECGDoc I’m a premier member. Sinus nodal reentrant tachycardia didn’t come up when I searched for it.

Yes, MJ -- it's a common problem and it's a good idea to try to catch it on a monitor, though most cardiologists are not intimately familiar with the different kinds of SVT. You might plan on seeing an EP doc (cardiac electrophysiologist) if the problem persists. On the other hand, if the symptoms are mild, fleeting or infrequent then you could sometimes get away without any treatment or meds. Everybody is different. Hopefully your cardiologist will be able to give you good advice. Good luck!

@@ECGDoc thank you so much, sir! I've been doing the best I can to research what's going on, and it's put a lot of control back in my hands. I'm growing more confident in my ability to handle this, but the inconsistency and inability to know when the next attack will happen still has me tangled with anxiety. I'm working on it, though! I go in for an echo on the first, and I'll be back for my stress test on the 4th. If I'm able to procure my ekg, could I send you the information?