What Supraventricular Tachycardia (SVT) Looks Like on Your Watch ECG

SVT ECG
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Qaly is built by Stanford engineers and cardiologists, including Dr. Marco Perez, a Stanford Associate Professor of Medicine, Stanford Cardiac Electrophysiologist, and Co-PI of the Apple Heart Study.

Key Takeaways

  • SVT is a rapid heart rhythm originating from the heart's upper chambers (atria) with a heart rate greater than 100 bpm, often between 150 bpm and 220 bpm. Identify an SVT ECG by its regular R-R interval, hidden P waves, and usually narrow QRS complex.
  • It's easy to confuse SVT with Sinus Tachycardia, but their distinctive features on the ECG can help differentiate between the two. This article provides visual examples of SVT.
  • If you're experiencing SVT or any rapid heart rhythm with symptoms like chest pain or shortness of breath, seeking immediate medical attention is essential. A healthcare provider can evaluate the underlying cause of SVT, provide appropriate treatment, and help manage the condition effectively.

Got other questions on SVT? See the Qaly guides on SVT:

Introduction

Hello, heart hero. In your quest to identify that irregular heart rhythm you just felt, you may have come across the terms Supraventricular Tachycardia or SVT. With your trusty watch ECG now in hand, you may be wondering, "What does Supraventricular Tachycardia look like on my watch ECG?" In this guide, we'll help you see Supraventricular Tachycardia on your watch ECG. Let's dive in.

What's Supraventricular Tachycardia?

Before trying to identify SVT on your ECG, it's helpful to remind yourself what SVT actually is. (If you're confident in your SVT knowledge, though, skip on ahead to the next section for some visual examples of a SVT ECG).

To start, remember how your heart beats? It produces an electrical signal, which squeezes and unsqueezes your heart, which in turn pumps your blood to your lungs for oxygen and then out to the rest of your body.

Normally, your heart produces that electrical signal from your "sinus node" to generate a Normal Sinus Rhythm. Sometimes, however, that electrical signal starts from somewhere else in your heart, where it isn't supposed to. In the case of SVT, it starts in your heart's upper chambers, or atria. That's the "Supraventricular" part in Supraventricular Tachycardia, where "supra" means above and "ventricular" refers to your heart's lower chambers, or ventricles. The "Tachycardia" part means that your heart rate is higher than normal. A fast heart rhythm is called "Tachycardia." So, put these two terms together and we get "Supraventricular Tachycardia": a fast heart rhythm originating in your heart's upper chambers, or atria.

So What Does Supraventricular Tachycardia Look Like on My Watch ECG?

To identify an SVT ECG, look for these tell-tale signs:

  • A heart rate greater than 100 bpm that's usually between 150 bpm and 220 bpm, though it can occasionally be slower or faster.
  • A regular R-R Interval.
  • P Waves that are often hidden. They are partially or completely buried within or at the end of the preceding T Wave.
  • QRS Complex that's usually narrow, but occasionally wide if there's a co-exinsting bundle branch block.
  • Non-Sustained SVT lasts less than 30 seconds, while Sustained SVT lasts at least 30 seconds, sometimes up to several hours.
  • Because SVT is a faster-than-normal heartbeat, it's often confused with Sinus Tachycardia. Here's an explainer guide on SVT vs Sinus Tach.

For visual examples, take a look at SVT seen on Qaly members' watch ECGs.

The ultimate SVT ECG guide, created with love by the team at Qaly ❤️ Find us on App Store or Play Store.
The ultimate SVT ECG guide, created with love by the team at Qaly ❤️ Find us on App Store or Play Store.

Here's Sustained SVT ECG caught on a Qaly member's Apple Watch. Notice the regular R-R Interval, a heart rate greater than 150 bpm, P Waves that aren't visible, and the narrow QRS Interval (< 120 milliseconds).
Here's Sustained SVT ECG caught on a Qaly member's Apple Watch. Notice the regular R-R Interval, a heart rate greater than 150 bpm, P Waves that aren't visible, and the narrow QRS Interval (< 120 milliseconds).

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Here's Non-Sustained SVT ECG caught on a Qaly member's Apple Watch. Notice how fast the heart rate is for the first 9 seconds, with only partially visible P Waves, indicating SVT. The SVT then transitions to Sinus Tachycardia. Since the SVT lasts for less than 30 seconds, it's considered a Non-Sustained SVT ECG.
Here's Non-Sustained SVT ECG caught on a Qaly member's Apple Watch. Notice how fast the heart rate is for the first 9 seconds, with only partially visible P Waves, indicating SVT. The SVT then transitions to Sinus Tachycardia. Since the SVT lasts for less than 30 seconds, it's considered a Non-Sustained SVT ECG.

What Are Different Types of SVT?

Supraventricular Tachycardia can also refer to several other types of fast heartbeats.

Atrial Tachycardia: These are short runs of SVT, typically caused by one or more areas in the atria that have started to beat automatically and faster than normal. You sometimes see this when the atria stretches or scars with age or due to other conditions.

Re-Entry Tachycardia: These are caused by the presence of an extra electrical connection that can then result in an electrical loop. This extra electrical connection is something that a small percentage of people are born with; however, it may not cause fast heartbeats until later in life.

Is Supraventricular Tachycardia a Cause for Concern?

SVTs are rapid heart rates that can cause people to feel unwell. If you have chest pain or sudden shortness of breath, along with an SVT, call 911.

Get checked out immediately when you develop a rapid heart rate like SVT. First, the strain on the heart caused by the additional pressure and rapid heartbeat can lead to collapse or heart damage. Second, those with many episodes of Non-Sustained SVT may be at risk of having atrial fibrillation in the future. Finally, if SVT is left untreated, it can lead to a stroke. This happens due to the ineffective blood pumping in the circulatory system, causing the blood to thicken and form clots.

The underlying cause of SVT needs to be investigated and the arrhythmia treated. For example, some SVTs are caused by thyroid disease, overuse of some medications, and underlying heart problems. Excess caffeine and recreational drug use also lead to SVT. In addition, some people have re-entry tachycardia that must be examined to ensure the correct treatment is given. Finally, SVT can sometimes be confused with VTach. See Qaly's explainer guide on the difference of SVT vs Vtach.

As always, if you show signs of SVT, contact your healthcare provider immediately to rule out the presence of harmful underlying conditions.

Conclusion

Well, that just about wraps up our guide on what SVT looks like on your watch ECG. We hope this could be of some help to you.

If you still need help interpreting your ECGs, don't worry, we understand how scary and confusing it can be to experience irregular heartbeats. That's why we created the Qaly app for you and for the hundreds of millions of people around the world who live with heart palpitations and abnormal heart rhythms. On the Qaly app, human experts will interpret your ECGs within minutes for clarity and peace of mind.

To get started with the Qaly app for free, grab the Qaly app from the App Store or Play Store today. If you have any more questions, or if you need our help in any other way, don't hesitate to reach out to us at support@qaly.co.

As always from the team at Qaly, stay heart healthy ❤️

Wondering if it's SVT? On the Qaly app, human experts will interpret your ECG for SVT within minutes. Get started for free today.

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Wondering if it's SVT? On the Qaly app, human experts will interpret your ECG for SVT within minutes. Get started for free today.

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