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
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.
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,
Jeff
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.
Thanks for sharing your comments and the link to the 12-Lead ECG examples site. Kind regards, Jeff
Jeff,
How can you tell the difference in coarse VT/VF as to monomorphic and polymorphic?
There is no such thing as coarse VT.
Kind regards, Jeff
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,
Chris
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,
Jeff
Let me get this straight. Svt is a heart rate greater than 150 with conduction at or above the av node?
That is correct.
Kind regards,
Jeff