Get certified in PALS Recertification for just $175.00.
To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video
Let's take a deeper dive into supraventricular tachycardia in the PALS patient. Narrow complex tachycardia called supraventricular tachycardia, or SVT for short, is caused by some sort of stimulus originating above the ventricles, as opposed to the normal stimulus generated by the SA node. Instead, with SVT, the stimulus comes from a rogue myocardial cell that stimulates an erratic atrial contraction, or a series of atrial contractions like those found in atrial fib or atrial flutter. SVT can persist until medical intervention is offered or it can be intermittent and self-limiting, and come and go without warning. By looking at an ECG alone, SVT can be difficult to differentiate from sinus tachycardia, atrial flutter, or atrial fibrillation. However, there are things that can be done to help us determine which rhythm is being displayed. First, determine if QRS duration is narrow or wide. A normal or narrow QRS would be about .09 seconds or less for a pediatric patient. It's unusual for SVT to present with a wide complex QRS. Is there a P-wave present for each QRS? P-waves are not present or may appear abnormal with SVT, possibly even after the QRS. Next, we should determine if the rhythm is regular or irregular, and determine the rate. SVT presents with a heart rate of 220 times per minute or greater in an infant, or 180 times per minute or greater in a child. In our example, the QRS is normal, no P-waves are present, and the rhythm is regular with a rate 270 beats per minute. From the ECG alone it would appear that our patient is in SVT. However, the signs and symptoms must be taken into account to properly identify the rhythm correctly and to determine whether or not treatment is necessary. Usually a patient with SVT has a history of vague or non-specific symptoms or palpitations along with sudden onset. In addition, their history is not compatible with sinus tachycardia. In other words, the patient has had no fever, no dehydration, or other identifiable cause. Unlike sinus tachycardia, the heart rate does not vary with activity, like when the child moves around or cries or becomes agitated. Now, keep in mind that if the patient is hemodynamically unstable, such as in hypotension, a rapid treatment must be given to correct the heart rhythm.
Narrow complex tachycardia, also called supraventricular tachycardia or SVT for short, is caused by some sort of stimulus originating above the patient's ventricles, as opposed to the normal stimulus that's generated by the SA node.
In this lesson, we'll take a deeper dive into supraventricular tachycardia for the PALS patient, including looking more closely at an example of what it looks like on an ECG and seeing what findings and measurements lead us to our conclusion.
With SVT, that stimulus comes from a rogue myocardial cell that stimulates an erratic atrial contraction or a series of erratic atrial contractions like those found in patient's with atrial fibrillation and atrial flutter.
Atrial fibrillation (also called AFib or AF) is a quivering or irregular heartbeat (arrhythmia) that can lead to blood clots, stroke, heart failure, and other heart-related complications.
Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate.
Pro Tip #1: While these appear to be the same, the difference is in the beat. Atrial flutter and atrial fibrillation are both abnormal heart rhythms. However, in atrial fibrillation, the atria beat irregularly, while in atrial flutter, the atria beat regularly, but faster than usual and more often than the ventricles, so you may have four atrial beats to every one ventricular beat.
The important thing to note with SVT is that it can persist until there is medical intervention, or it can be intermittent and self-limiting, and can come and go without warning.
By looking at an ECG readout alone, SVT can be difficult to differentiate from sinus tachycardia, AFib, or AFL. However, there are things that you can look at to help you determine which rhythm is being displayed.
Now let's take a look at an ECG for a patient in supraventricular tachycardia.
*Supraventricular Tachycardia
The first thing you'll want to look at is the heart rhythm. Does the heart rhythm look regular? Or does it look irregular? In the ECG above, the rhythm is regular.
Next, you'll want to look at the heart rate of the patient. What is the patient's heart rate? Is it normal? Or is it too slow or too fast? In this case, it's too fast. SVT usually presents with a heart rate of 220 beats per minute in infants or 180 in children.
After looking at the heart rate, check to see if the patient's P-waves look normal by asking yourself the following few questions.
Next, look at the PR interval on the patient's ECG readout and ask yourself the following questions:
The last thing you should look at to determine if the sinus rhythm is normal or not is the QRS complex and ask yourself these questions while you do:
Pro Tip #2: It's unusual for SVT to present with a wide complex QRS.
So, what is your cardiac interpretation? Based on these questions and on the findings from the ECG readout above, it would appear that this patient is in supraventricular tachycardia.
Pro Tip #3: SVT is always more symptomatic than sinus tachycardia. Sinus tachycardia has a rate of 160 – 220 (infants) and 120 – 160 (older children), while SVT has a rate of 220 – 320 (infants) and 160 – 280 (older children).
From the ECG alone, it would indicate that the patient is in SVT. However, patient signs and symptoms must be taken into account to properly identify the rhythm correctly and to determine whether or not treatment is necessary.
Pro Tip #4: Usually a patient with SVT will have a history of vague or non-specific symptoms or palpitations along with sudden onset. In addition, the patient's history is often not compatible with sinus tachycardia. In other words, the patient won't have a fever, won't be dehydrated, and won't be exhibiting any other identifying causes for the SVT.
Unlike with sinus tachycardia, the heart rate doesn't vary with activity, such as when a child is moving around, cries, or becomes agitated.
Keep in mind, though, that if the patient is hemodynamically unstable, such as in hypotension, quick and effective treatment must be provided to correct the abnormal heart rhythm.