Sinus Rhythm: ECG, AFib, Arrhythmias, and More

Medically Reviewed By Uzochukwu Ibe, MD, MPH
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Sinus rhythm is the rhythmic beating of your heart. Electrical activity controls your heart beating. Normal heart rhythm, or normal sinus rhythm, refers to the rhythm of a regular, healthy heart. In contrast, arrhythmia is when your heart beats out of rhythm. Some types of arrhythmias are not dangerous. However, others can prevent your blood from carrying oxygen to the body. Occasionally, arrhythmias can increase your risk of heart-related issues, such as stroke.

This article will describe how your heart beats, what rhythms it can have, and what tests can measure your sinus rhythm. It will also discuss some symptoms and treatment options for different arrhythmias.

What is sinus rhythm? 

A series of hearts
Juan Moyano/Stocksy United

A sinus rhythm refers to the rhythm of the heart beating, which starts in the sinus node. An internal pacemaker sends electric signals to power your beating heart. These electrical signals tell your heart to pump blood at a timed pace. Every time your heart beats, it sends blood through the body. In just 1 day, your heart will beat over 100,000 times.

Your heart will alter its rate and rhythm based on your activity level. For instance, exercise requires a faster rate and rhythm because your body needs more oxygen.

When your body is resting, your muscles need less oxygen. Therefore, your heart rate and rhythm will be slower.

The heart also pumps blood to carry nutrients to your organs and carry away waste products. If your heart cannot pump at a regular rate and rhythm, your organs may not be able to function.

Normal sinus rhythm

Normal sinus rhythm is a healthy heart’s standard rhythm or pattern of beats. In a normal sinus rhythm, your heart does not skip or add any beats.

Heart rhythm vs. heart rate

Your heart rhythm, or sinus rhythm, is the pattern at which it beats. In contrast, your heart rate is how many times your heart beats in 1 minute.

A full heartbeat is when your heart contracts and relaxes. At rest, a typical adult should expect their heart rate to be 60–100 beats per minute (bpm). Stress, caffeine, illness, and exercise can all cause temporary increases in your heart rate. 

Learn more about normal heart rate ranges and when to contact a doctor.

What is an ECG?

An ECG is a test to measure the rhythm and rate of your heartbeat. During this test, your healthcare team will place stickers on your torso. A machine will read the electrical current as it moves through your heart.

An ECG helps identify if your heart is in a normal sinus rhythm or if any arrhythmias are present. An arrhythmia is when your heart beats at an irregular rhythm. If an arrhythmia is present, an ECG will determine what part of the heart causes it.

If you have ever felt your heart skip a beat, you may have experienced a premature heart contraction. After a premature heart contraction, the next heartbeat may be more forceful. An ECG will help your doctor determine whether you have a premature contraction.

There are two types of premature contractions: premature atrial contraction and premature ventricular contraction.

Premature atrial contractions are extra heartbeats originating from the upper chambers of your heart. In contrast, premature ventricular contractions are extra heartbeats originating from the heart’s lower chambers.

These premature contractions can cause your sinus rhythm to become irregular.

An occasional extra heartbeat is typical and does not always indicate a serious condition. However, consistent premature atrial contractions can cause atrial fibrillation (AFib). If you regularly feel skipped or forceful heartbeats, contact your doctor.

Atrial fibrillation 

Atrial fibrillation (AFib) is a potentially serious heart condition. About 2.7 million people in the United States have AFib. During this arrhythmia, the upper chambers of your heart quiver instead of beat. This erratic quivering throws your sinus rhythm off track.

If your heart quivers instead of beating, it cannot pump blood out all the way. This leads to blood backing up and pooling. When blood pools for too long, it can form a clot. Then, your heart may send the clot to different parts of your body, potentially causing a stroke.

AFib can increase your chances of having a stroke by five times

If you have AFib, you may experience symptoms such as: 

Treatment for AFib focuses on slowing your heart rate and restoring your normal sinus rhythm. Your doctor may prescribe medications to manage your AFib. 

Some medications that can help manage AFib include:

  • anticoagulants to slow blood clotting and reduce your chance of developing a clot
  • beta-blockers to slow your heart rate
  • calcium channel blockers to reduce the force of your heart’s contraction
  • digoxin (Digox, Lanoxin) to slow the electrical current that causes arrhythmia 

Your doctor may recommend a pacemaker if you have AFib alongside an atrioventricular block. An atrioventricular block is a condition that impairs the electrical signal between the upper and lower heart chambers.

An artificial pacemaker will override your body’s natural pacemaker, sending electrical signals that tell your heart when to beat. This can help your heart maintain a regular heart rate and rhythm.

Heart arrhythmias 

An arrhythmia is a health condition where your sinus rhythm is irregular. There are many types of arrhythmias aside from AFib. These include:


Tachycardia is when your heart rate is over 100 bpm. During exercise, your heart rate may increase to meet the oxygen demands of your body. Temporary tachycardia, which can result from exercise or even a fever, is not dangerous.

However, regular tachycardia or tachycardia resulting from a medical condition can be dangerous. For instance, some arrhythmias can cause tachycardia. Atrial tachycardia occurs when your upper chambers initiate a faster heartbeat. 


Bradycardia is when your heart rate drops below 60 bpm. Medications, heart disease, and issues with your heart’s natural pacemaker can all cause bradycardia.

Some people, such as athletes, may have a naturally slow heart rate. However, bradycardia resulting from a medical condition or causing symptoms will require treatment.

Without treatment, bradycardia could cause heart failure, fainting, or irregular blood pressure.  

Sick sinus syndrome

Sick sinus syndrome is a disorder that occurs when the heart’s natural pacemaker in the sinus node fires irregularly. This causes the heart to beat faster or slower than it should. Sick sinus syndrome is most common in older adults.


Sinus rhythm is the repetitive pattern your heartbeat makes. In contrast, your heart rate is the number of times your heart beats in 1 minute. The optimal range for your heart rate is 60–100 bpm. Another term for normal sinus rhythm is normal heart rhythm.

Sometimes, you can develop arrhythmias that change your heart rhythm. Tachycardia is when your heart beats too fast. In contrast, bradycardia is when your heart beats too slowly. Some common arrhythmias include atrial fibrillation (AFib), sick sinus syndrome, premature ventricular tachycardia, and premature atrial tachycardia.

Occasional missed or skipped heartbeats are typical and may not indicate a heart condition. However, contact your doctor if you regularly experience missed or forceful beats. Additionally, discuss other symptoms with your doctor, such as racing heart rate, feeling dizzy or out of breath, or a fluttering feeling in your chest.

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Medical Reviewer: Uzochukwu Ibe, MD, MPH
Last Review Date: 2022 Aug 17
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. About arrhythmia. (2016).
  2. All about heart rate (pulse). (2015).
  3. Atrial fibrillation medications. (n.d.).
  4. Bradycardia: Slow heart rate. (n.d.).
  5. Dakkak, W., et al. (2022). Sick sinus syndrome.
  6. Electrocardiogram (ECG or EKG). (2015).
  7. Gunda, S., et al. (2019). Consequences of chronic frequent premature atrial contractions: Association with cardiac arrhythmias and cardiac structural changes.
  8. Other heart rhythm disorders. (2016).
  9. Pacemaker. (2016).
  10. Premature contractions - PACs and PVCs. (2016).
  11. Sauer, W. H. (2022). Normal sinus rhythm and sinus arrhythmia.
  12. Surgical procedures for atrial fibrillation (AFib or AF). (2016).
  13. Tachycardia: Fast heart rate. (2016).
  14. Target heart rates chart. (2021).
  15. Treatment and prevention of atrial fibrillation. (2016).
  16. What are the symptoms of atrial fibrillation (AFib or AF)? (2016).
  17. What is atrial fibrillation (AFib or AF)? (2016).
  18. Why atrial fibrillation (AF or AFib) matters. (2016).