Your sinus rhythm is the pattern of electrical pulses from your sinus node, your heart’s pacemaker. It’s not uncommon for sinus rhythm to be too slow or too fast, but symptoms that persist may warrant seeing a doctor.

Sinus rhythm refers to the rhythm of your heartbeat, determined by the sinus node of your heart. The sinus node creates an electrical pulse that travels through your heart muscle, causing it to contract, or beat. You can think of the sinus node as a natural pacemaker.

While similar, sinus rhythm is a little different from heart rate. Your heart rate is the number of times your heart beats in a minute.

For most people, a resting heart rate of 60 to 100 beats per minute (bpm) is considered normal. However, your heart rate can be either faster or slower than this, depending on the demands placed on your heart as well as other underlying health conditions.

Sinus rhythm, on the other hand, refers to the pattern of your heartbeat. It corresponds to the rate at which electrical pulses are sent out from the sinus node. When these pulses are sent out at a normal rate, it’s referred to as normal sinus rhythm.

As you can probably see, sinus rhythm and heart rate are linked. Electrical pulses must first be generated by the sinus node (sinus rhythm). As these pulses travel through the heart muscle, they cause it to beat (heart rate). Because of this, sinus rhythm often aligns with your heart rate.

Learn what your ideal heart rate is.

Normal sinus rhythm is defined as the rhythm of a healthy heart. It means the electrical pulse from your sinus node is being properly transmitted throughout the heart muscle.

In adults, normal sinus rhythm usually accompanies a heart rate of 60 to 100 bpm. However, it’s possible for sinus rhythm to be faster or slower than this and still be considered normal.

Sinus tachycardia

Sinus tachycardia occurs when your sinus node sends more rapid electrical pulses, leading to a heart rate that’s higher than 100 bpm. It’s normal to temporarily have sinus tachycardia in some situations, such as when you:

However, when you’re having sinus tachycardia at rest, it can put you at risk of potentially serious health complications.

Sinus bradycardia

Sinus bradycardia is the opposite of sinus tachycardia and happens when your sinus node sends slower pulses, resulting in a heart rate of fewer than 60 bpm.

A heart rate below 60 bpm can be normal for some people, particularly younger adults and athletes. It can also happen when you’re in a deep sleep or are taking certain types of medications.

For some people, however, it can be a sign that your heart isn’t distributing enough oxygenated blood to your body.

When your heart rhythm or heart rate is abnormal, it’s called arrhythmia. There are different types of arrhythmia. Below, we’ll give an overview of sinus arrhythmias.

Sinus tachycardia

Earlier, we discussed how sinus tachycardia may happen normally. There are also some situations where sinus tachycardia can happen at rest. When this happens, it can increase your risk of serious complications, including:

It’s possible to have sinus tachycardia and have no symptoms. When symptoms are present, they can include things like:

There are many possible causes of sinus tachycardia, including:

Sinus bradycardia

Like sinus tachycardia, sinus bradycardia can be dangerous in some cases. This is because a heart that’s beating too slowly can mean that blood isn’t flowing effectively to the organs and tissues of the body. When this happens, some potential complications can include:

Similar to sinus tachycardia, many people with sinus bradycardia have no symptoms. Some signs that you may have sinus bradycardia include:

  • being lightheaded or dizzy
  • feeling fatigued or weak
  • having trouble exercising
  • chest pain
  • shortness of breath
  • fainting

Sinus bradycardia can be caused by a number of things, with some examples including:

Sick sinus syndrome is an umbrella term for a group of symptoms that indicate a problem with the sinus node. In addition to the sinus arrhythmias mentioned above, other types of sick sinus syndrome include:

  • Sinus arrest. This causes your sinus node to briefly stop transmitting electric pulses.
  • Sinoatrial block. Electrical pulses move too slowly through your sinus node, leading to a slower-than-normal heart rate.
  • Bradycardia-tachycardia (tachy-brady) syndrome. Your heartbeat alternates between fast and slow rhythms.
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Normal sinus rhythm vs. atrial fibrillation Illustration by Bailey Mariner.

Atrial fibrillation (AFib) is the most common type of arrhythmia. In AFib, your heart often beats faster than normal. Additionally, the upper and lower chambers of the heart aren’t coordinated. AFib happens for reasons similar to the other types of arrhythmia we’ve discussed, such as:

  • damage due to heart disease or a previous surgery
  • age-related changes to heart tissue
  • the presence of other underlying health conditions

AFib is characterized by uncoordinated electrical activity in the upper chambers of your heart. This can be due to the sinus node not generating electrical pulses as it should. In fact, AFib frequently, but not always happens along with sick sinus syndrome.

AFib can have potentially serious health effects. For example, the lower chambers of your heart often don’t properly fill, meaning that your heart isn’t pumping enough blood to your body. Additionally, blood may pool in your heart, which can increase your risk of experiencing a serious blood clot.

The treatment of AFib typically involves medications to lower heart rate, such as beta-blockers or calcium channel blockers. Steps may also be taken to normalize heart rhythm through the use of medications or procedures like electrical cardioversion, although AFib may sometimes recur after these interventions.

Sinus rhythm refers to the pace of your heartbeat that’s set by the sinus node, your body’s natural pacemaker. A normal sinus rhythm means your heart rate is within a normal range.

Sometimes, the sinus node sends electric pulses too fast or too slowly. This is referred to as sinus tachycardia or sinus bradycardia, respectively. In some cases, this is normal, such as sinus tachycardia during exercise or sinus bradycardia in athletes.

For some, sinus arrhythmia isn’t anything to worry about. However, for others it can be potentially serious. If you’re experiencing symptoms consistent with an arrhythmia, be sure to visit your doctor to discuss them.