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Supraventricular Tachycardia


Supraventricular Tachycardia (SVT)

SVT is a broad term for a number of tachyarrhythmias that originate above the ventricular electrical conduction system (purkinje fibers).

Classic Paroxysmal SVT has a narrow QRS complex & has a very regular rhythm. Inverted P waves are sometimes seen after the QRS complex. These are called retrograde p waves

Supraventricular Tachycardia EKG Rhythm Strip

The heart fills during diastole, and diastole is normally 2/3 the cardiac cycle. A rapid heart rate will significantly reduce the time which the ventricles have to fill. The reduced filling time results in a smaller amount of blood ejected from the heart during systole. The end result is a drop in cardiac output & hypotension.

With the drop in cardiac output, a patient may experience the following symptoms. These symptoms occur more frequently with a heart rate >150 beats per minute:

  • Shortness of air (S)
  • Palpitation feeling in chest (S)
  • Ongoing chest pain (U)
  • Dizziness (S)
  • Rapid breathing (S)
  • Loss of consciousness (U)
  • Numbness of body parts (S)

The pathway of choice for SVT in the tachycardia algorithm is based on whether the patient is stable or unstable. The symptoms listed above that would indicate the patient is unstable are noted with the letter (U). Stable but serious symptoms are indicated with the letter (S).

Unstable patients with SVT and a pulse are always treated with cardioversion

Below is a short video which will help you quickly identify supraventricular tachycardia on a monitor.
Please allow several seconds for the video to load.

  84 Responses to “Supraventricular Tachycardia”

  1. Hi Jeff Great website!!! However, I have returned for my recertification, which is to take place at UCMC in Cincinnati, Ohio. The education department sent me a ACLS study guide. The study guide “ACLS Crucial Management Considerations & Teaching Points” for Superventricular Tachycardia is to try vagal maneuvers. In addition, Adenosine 6mg can be given, repeat 12mg and then another 12mg rapid IV push. I was under the impression that Adenosine can be given just 2 times (6mg, 12mg). Please advise. Thank you. Kim

    • Giving a second dose of 12mg of adenosine is fine. This is not clear in the manual and I do think that AHA will clear this up with their next series of guidelines in 2015. The AHA manual has 6 mg given and then 12 mg. For many years is always listed 6-12-12 and then in 2010 it changed to 6-12. Honestly, I have never gotten a clear answer from AHA. I have been told and have seen that at times a 3rd dose of 12 mg may be necessary. It can be given. Kind regards, Jeff

      • Hi Jeff Thank you. In addition, you always respond with Honest answers, the Literature/References for best practices, and thank you for the wonderful website. During my first time of becoming certified for ACLS, I was terrified. However, I came across this wonderful web site (Lucky me), and passed on my first attempt :). Now that recertification is to occur, I feel 100% confident. May God continue to shower blessings on you and your brother. Kim

  2. hi
    is supraventrical svt the same as paroxymal svt. if not the same please explain the difference
    thank you

    • Hi ,

      Thanks for the question. You asked:
      “is supraventrical svt the same as paroxymal svt. if not the same please explain the difference”

      SVT is a general term for a number of different arrhythmias that have their origin in the atria hence the name SUPRAventricular.

      Paroxysmal SVT is the most common SVT. A person experiencing this type of PSVT may feel the heart rate accelerate from 60 to 200 beats per minute or more. Typically, when it reverts to normal rhythm, this is also sudden. This type of SVT can come and go without any apparent cause.
      Kind regards,

  3. My Question
    How I can identify the SVT wide QRS related to antidromic re-entry and stable patient with monomorphic ventricle tachycardia in ECG

  4. My only complaint about this scenario is the rates of SINUS TACH , SVT are not shown… An experienced nurse can tell just by looking at the monitor … but a newer nurse or student may not especially if this is her/ his first exposure to the information / ACLS. I think rates would be helpful to be posted with changes in rthym.

  5. Having some difficulty distinguishing SVT, (unless it’s reentry), and sinus tachy. Any helpful suggestions? Thanks!

    • The easiest way to differentiate between SVT and Sinus Tachycardia is to simply look at the rate. The rate of sinus tachycardia for a person at rest, in most circumstances, will not exceed 150 bpm. If the rate is high and you do not suspect SVT then you should ask yourself why the rate is high. When a person has SR and an elevated rate, there is a specific reason that is causing the elevated heart rate. (fever, blood loss, dehydration, infection, etc.)
      Also the rate of SVT will usually be greater than 150 bpm.
      The vague area will be when a person has a rate that is 150-170 bpm.

      I hope this helps.

      Kind regards,

  6. Having trouble understanding if stable or unstable if pt. Is unstable do you go straight to cardioversion. And if so when do you give adenosine.

  7. Hi Jeff,
    Today I took the pre assessment on the AHA student site and the rhythm section had several reentry tachycardias—what is the difference from other tachycardias and what do I look for on the rhythm strip. I have minimal EKG knowledge and am struggling a bit.

  8. How can you tell the difference between rapid A-Fib and PSVT when the rate is so high? Both can be treated very differently.

    Thanks, Love this site!

    • This can be a difficult thing. I have see adenosine as a diagnostic tool to differentiate between the two and it works well.
      When you give adenosine, it slows the heart and allows you to see the underlying rhythm. When adenosine is given and the rate temporarily slows, you will see the difference. If atrial fibrillation is present, you will see an irregular rhythm with no p-waves. If the rhythm is SVT, you should see a regular rhythm when the rate is slowed.

      Kind regards,

  9. If you were performing cardioversion on an SVT rhythm at 200J and then the monitor showed V-tach with no pulse—would you immediately defib at 300 J or into CPR for 2 minutes? If another shock is given that would be two in a row—is that OK to do according to AHA?

    • Since the patient had a pulse when in SVT and the change to pulseless VT was witnessed, you would move straight to a shock with 300 J.
      Shocking would not be considered two in a row since you had a change in the rhythm. When there is a change in the rhythm, you should start at the top of the algorithm. Also you would be changing form synchronized cardioversion to unsynchronized defibrillation.
      Kind regards, Jeff

      • 300 J Is it monophasic or biphasic ?
        Big THANKS to JEFF for answering all our questions with such a patience.

      • For this website you can assume that any dose that I recommend with by default be biphasic unless otherwise stated. Monophasic is being phased off of the market and biphasic is becoming the standard of care.

        Kind regards,

  10. Great site, Just needed information to meet the objectives of ACLS.
    I am enjoying it greatly. Thanks a ton for preparing this educational material. It shows great commitment too.

  11. In stable SVT we start with vagal maneuvers,right. My question is what should be the duration of time to perform vagal maneuvers.

    • Vagal maneuvers should be attempted for 5 to 10 seconds.
      This should be enough time to stimulate the vagus nerve.
      Kind regards, Jeff

      • There are several different vagal maneuvers, and not all of them work in the same patient. I have had SVTs for many years that respond well to bearing down on holding breath for a bit, but the other day I ended up in ER for the first time and the MD tried carotid massage with no effect at all, and it was extremely unpleasant to boot. So I would suggest that in cases when you have the time and the patient is lucid and cooperative, and one vagal maneuver fails, try a different one…

      • Yes, this is correct. You can use another method if one fails to work.
        Kind regards,

  12. This is site is so helpful!!! Thank you!!!

  13. Hi I have enjoyed your site we will see how I do tomorrow on the exam . In the mean time if you can fix the SVT video . I cannot get it to download and or play :(
    Thank you

    • Thanks for leaving a comment. I checked the video and it seems to be functioning properly. You may need to restart your computer. On rare occasions, the videos can hang up when downloading and a the best cure is to restart your computer. Please let me know of you need any further help.

      Kind regards,

  14. How to distinguish between SVT and sinus tach?

    • The rate for SVT will usually be greater than 150. With sinus tachycardia, the rate will usually be less than 150. Sinus tachycardia is usually related to some underlying cause like hypovolemia, fever, or sepsis and the rate will not exceed 150.
      This is the easiest way to determine the difference.
      For SVT, the symptoms can arise suddenly and may resolve without treatment. The rate for SVT will typically be 150-270/min and will often be accompanied by the following sympotms: pounding heart, shortness of breath, chest pain, rapid breathing, dizziness, or loss of consciousness.
      Kind regards,

  15. adenosine IVP
    how many ccs of normal saline DO WE USE SINCE IT HAS A SHORT HALF LIFE?

    • You would follow the dosage of adenosine with 10 ml of NS. You should have the 10 ml on a double port IV or put a 2nd port on with a stop-cock. This way you can push the adenosine in rapidly and then with as short a time as possible you can forcefully push the 10ml bolus of NS in. You must push both extremely fast. The faster the better.

      Kind regards,

  16. Great site! FYI, some of the EM residents I work with showed me a good resources for learning reviewing 12-lead ecgs. For example, the supraventricular tachycardia ecg page is here: http://www.emedu.org/ecg/svt.htm

    It has a bunch of SVT variants as well, and you can look at a strip and then hover your mouse to see the markup. Pretty cool.

  17. Jeff,

    How can you tell the difference in coarse VT/VF as to monomorphic and polymorphic?

  18. Hi Jeff,
    What is the easiest way of recognising reentry supraventricular tachycardia on a rhythm strip? also couldn’t find much detail on vagal maneuvers in the provider manual?

    great site btw!!:)

    • The 4 most common types of SVT are A-V Nodal Reentry Tachycardia, A-V
      Reentry Tachycardia, atrial tachycardia and atrial flutter. These rhythms
      are regular in nature and have a rate > 150.
      To distinguish the difference
      between the re-entry tachycardias and the other types really requires a 12
      lead ECG. The diagnostic criteria to determine that it is a reentrant
      tachycardia is actually quite complex. I attached a pic from my 12 lead ecg
      pocket reference that will help. Reentry tachycardias are very easy to
      convert and often vagal maneuvers will suffice to terminate the tachycardia.
      Kind regards,

  19. When is putting pressure on the jugular used, in this type of scenario?

    • Applying pressure or lightly massaging carotid artery would be considered a vagal maneuver. This or any type of vagal maneuver would be performed for symptomatic SVT if the patient is stable and the QRS complex is less than 0.12 second.

      Kind regards,

  20. Let me get this straight. Svt is a heart rate greater than 150 with conduction at or above the av node?

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