03.07 Supraventricular Tachycardia (SVT)

Hey guys, in this lesson we are going to talk about Supraventricular Tachycardia - also known as SVT. We are going to identify the characteristics on an EKG and nursing interventions and treatments for SVT. So let’s get started!

So in supraventricular tachycardia something is happening above the ventricles, it is a rapid heartbeat due to an increased electrical stimulation in the atria or AV node. This causes an additional electrical impulse that reaches the ventricles and causes them to contract a rate of 150-250 beats per minute. Since the heart is contracting so fast there is less blood going into the ventricles so cardiac output is decreased tremendously which is why people are symptomatic. Let’s look at the characteristics of SVT on the next slide and break it down on an EKG.

Using the 6- step method- step 1 we need look at the rhythm, do we have a regular or irregular rhythm so let’s count the boxes so from here to here we have 6, here to here 6 and here to here. So our rhythm is a regular rhythm. In step 2 let’s count the heart rate, so 28 times 10 since we have a 6 second strip is 280. But let’s do the 1500 method since it is a lot more accurate so 1500 divided by 6 and we get 250 beats per minute. So our heart rate is 250 beats per minute. Think of the normal heart rate of 60-100 beats per minute, its 3-4 times faster. Ok so let’s move on to step 3 and look at the P:QRS ratio. Do we have 1 P wave followed by 1 QRS. Look at the P waves in this strip, it’s very hard to determine where the T wave ends and where the P wave begins, that is very common in SVT. But here you can argue that these are P waves so we will count them, so there is a P wave followed by a QRS so we have a 1:1 ratio. In step 4 we will look at the PR interval and if we measure from here to here we get about 2 boxes so that is 0.08 seconds which is faster than normal but it’s expected when it’s such a rapid heartbeat. In step 5 we need to do the QRS complex so from here to here we have about 1 box or 0.04 seconds and again, it is expected because the heart is contracting so fast the QRS complex is shorter. So in step 6 we identify our rhythm and we have SVT. Let’s recap the characteristics, the rhythm is regular, the rate is between 150-250 beats per minute, if there are identifiable P waves the P to QRS ratio is 1:1, PR interval is less than 0.12 seconds and QRS complex is less than 0.06 seconds. Because there is a decreased cardiac output we have to do something about SVT asap so let’s talk about that!

When patients come in with SVT they usually complain of a fluttery feeling in the chest, palpitations, shortness of breath and chest pain because of how fast their heart is going. Because of decreased cardiac output. So the main nursing interventions are to determine if they are stable or unstable. Always get a 12 lead EKG as soon as possible to confirm the rhythm because it could be confused with A-fib with RVR. You need to confirm the rhythm to know how to treat the patient. So let’s talk about treatment measures.

So the therapeutic management for SVT is to determine the cause so you can treat the cause. Some of the common causes could be as simple as increased caffeine intake or stress and anxiety or it can be from heart and lung problems. Next we need to control the heart rate by doing a vagal maneuver and have them bear down to slow down the heart rate. We can also give them some beta blockers and calcium channel blockers. We must also follow the ACLS guidelines and if they are stable or unstable, if they are stable we can give them 6mg of Adenosine and repeat with 12mg to slow or stop the heart so it restarts at a normal rhythm. If they are unstable we can do a synchronized cardioversion. If they have a run of SVT just monitor them if they have sustained SVT we need to follow ACLS guidelines

So the key points to remember regarding SVT are to remember the abnormalities, the heart rate is between 150-250 beats per minute, there may be visible and pointed P waves or they may be hidden in the T waves. Nursing interventions are to determine if stable or unstable and identify the cause if possible. Follow the ACLS guidelines if they are stable we give them Adenosine if unstable we do a cardioversion.

I hope that you guys have enjoyed this lesson and feel more comfortable with identifying SVT and what to do if you see this rhythm. Make sure that you check out our other resources attached to this lesson. Now, go out and be your best self today! And, as always, happy nursing!