Sinus Rhythm Vs. First Degree AV Block on Your Watch ECG

Sinus Rhythm First Degree AV Block ECG
Qaly Heart
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

Got other questions on Sinus Rhythm or First Degree AV Block? See the Qaly guides on Sinus Rhythm and First Degree AV Block:

Introduction

In our increasingly connected world, wearable technology has revolutionized how we understand and monitor our health. ECG-enabled watches, for example, provide critical insights into our heart rhythms, enabling us to detect irregularities that may indicate heart health issues. Today, we will explore two different rhythms: sinus rhythm and first degree AV block, helping you understand their differences, implications, and how they might appear on your watch ECG. Let’s dive in!

What’s Sinus Rhythm?

Sinus rhythm, or normal sinus rhythm, is considered the standard rhythm of a healthy heart. In this pattern, electrical signals originate from the sinoatrial (SA) node located in the right atrium, initiating each heartbeat and ensuring they occur at a steady, regular rate.

Sinus Rhythm read on a Kardia ECG through the Qaly app, which provides unlimited ECG readings, while KardiaCare only provides 1 reading every 90 days.
Sinus Rhythm read on a Kardia ECG through the Qaly app, which provides unlimited ECG readings, while KardiaCare only provides 1 reading every 90 days.

On an ECG, sinus rhythm is characterized by a distinct P wave (indicating atrial contraction) followed by the QRS complex (signifying ventricular contraction), then the T wave (representing ventricular relaxation). This cycle repeats at a rate of 60-100 times per minute in adults at rest. Here’s more on what sinus rhythm looks like on your watch ECG.

Sinus Rhythm read on a Samsung Watch ECG through the Qaly ECG analyzer.
Sinus Rhythm read on a Samsung Watch ECG through the Qaly ECG analyzer. Notice this came back as Inconclusive on the Samsung ECG.

What’s First Degree AV Block?

First degree AV block, on the other hand, is a condition where there is a delay (but no blockage) in the conduction pathway between the atria and ventricles. On an ECG, this block is characterized by a prolonged PR interval (>200 milliseconds). Here’s more on what first degree AV block looks like on your watch ECG.

First Degree AV Block read on an Apple Watch ECG through the Qaly app.
First Degree AV Block read on a Samsung Watch ECG through the Qaly ECG checker. Notice how Samsung thought it was as an Atrial Fibrillation ECG.


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First Degree AV Block read on an Apple Watch ECG through the Qaly app.
First Degree AV Block read on an Apple Watch ECG through the Qaly app.

What’s the Difference Between Sinus Rhythm and First Degree AV Block?

When comparing sinus rhythm and first degree AV block, the key difference lies in the PR interval on an ECG. While a sinus rhythm has a PR interval of 120-200 ms, a first degree AV block is characterized by a PR interval that exceeds 200 ms.

While both rhythms have regular P waves followed by a QRS complex, the delay in electrical signals from the atria to the ventricles in first degree AV block can occasionally cause symptoms like dizziness or fainting, especially if it progresses to higher degrees of heart block.

Understanding these differences is critical, as it could influence management strategies and potential health outcomes. Remember, while your watch ECG can help identify irregular rhythms like a first degree AV block, it doesn't replace a comprehensive evaluation by a healthcare provider. If you detect any irregular rhythms on your watch ECG, always seek medical advice for a thorough evaluation. Stay informed, stay proactive, and stay heart healthy!

Still Not Sure if It’s Sinus Rhythm or First Degree AV Block on Your ECG?

Differentiating between sinus rhythm vs first degree AV block on your ECG can be tricky. If you’re still looking for help interpreting your ECG further, check out the Qaly app on App Store or Play Store. On Qaly, human experts will interpret your ECGs within minutes, day or night. Try out the Qaly app for free today!

Wondering if it's Sinus Rhythm or First Degree AV Block? On the Qaly app, human experts will interpret your ECGs for Sinus Rhythm and First Degree AV Block within minutes. Get started for free today.

Try free, cancel any time
Try Qaly for Free
App Store - Download Qaly | ECG Reader
Try Qaly for Free
Google Play - Download Qaly | ECG Reader
Try Qaly for Free
3 days free, cancel any time
QALY app - ecg reviews, ecg reader, ecg interpretations, review your ecg

Get 3 days of unlimited ECG reviews for free -->

Get 3 days of unlimited ECG reviews for free -->

Wondering if it's Sinus Rhythm or First Degree AV Block? On the Qaly app, human experts will interpret your ECGs for Sinus Rhythm and First Degree AV Block within minutes. Get started for free today.

Try Qaly for Free