Junctional rhythm is a type of irregular heart rhythm that originates from a pacemaker in the heart known as the atrioventricular junction.

The heart has several built-in pacemakers that help control its rhythm. Typically, the sinoatrial (SA) node controls the heart’s rhythm. However, if it is unable to function correctly, another part of the heart, known as the atrioventricular (AV) junction, may be able to control the pace of the heart.

When this area controls the pace of the heart, it is known as junctional rhythm. It can occur for a variety of reasons, and junctional rhythm itself is not typically a problem. However, the underlying cause of the junctional rhythm may require treatment.

In this article, we will discuss what a junctional rhythm is, including its different types, symptoms, causes, and more.

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The heart is a complex structure containing many different parts that work together to produce a heartbeat. Included in the structure are natural pacemakers that help regulate how often the heart beats.

The default pacemaker area is the SA node. It initiates an electrical impulse that travels through the heart’s electrical conduction system to cause the heart to contract, or beat.

Click here to learn more about the SA node.

However, if the SA node paces too slowly, or not at all, the AV junction may be able to pace the heart. The AV junction includes the AV node, bundle of His, and surrounding tissues that only act as pacemaker of the heart when the SA node is not firing normally.

As such, the AV junction acts as a secondary pacemaker. Rhythms originating from the AV junction are called junctional dysrhythmias or junctional rhythms.

There are several potential causes, including medical issues, medication side effects, and genetics, among others.

It occurs equally between males and females. It often occurs in people with sinus node dysfunction (SND), which is also known as sick sinus syndrome (SSS). This condition refers to the inability of the SA node to produce an adequate heart rate. Junctional rhythm can also occur in young athletes and children, particularly during sleep.

There are several types of junctional rhythm. A healthcare professional typically classifies them based on the number of beats per minute. The types and associated heart rates include:

Symptoms can vary and may not be present in people with a junctional rhythm. In some cases, a person may not discover it until they have an electrocardiogram (ECG) or other testing.

When symptoms do occur, they typically reflect the underlying condition causing the junctional rhythm. For example, an individual with rheumatic fever may present with a heart murmur, fever, joint pain, or a rash.

Other general symptoms can include:

  • intermittent palpitations
  • fatigue
  • dizziness
  • fainting or feeling like a person may pass out

There are several potential causes of junctional rhythm. Some possible causes include the following conditions and health factors:

Certain medications and therapies may also cause junctional rhythm. These include:

Diagnosis will likely start with a review of the person’s personal and family medical history. A doctor will also likely conduct a physical examination. In addition to taking a person’s vital signs, the doctor will likely order an ECG and review a person’s medication list to help rule out medication as a possible cause.

A doctor may also perform additional testing to check for underlying conditions. This can include testing for thyroid conditions or heart failure or performing:

  • routine blood work
  • lung function test
  • echocardiography

Treatment will vary greatly depending on the underlying cause. A medical professional will select the most suitable treatment routine.

In some cases, a doctor may need to switch a person’s medications or discontinue certain medications that may be responsible. Other people may need treatment for an underlying condition, such as Lyme disease or heart failure.

Some people with junctional rhythm may not need treatment if they have no underlying conditions or issues. Other individuals may require a pacemaker.

Complications can occur if a person does not notice symptoms and receive treatment for the underlying condition. Common complications of junctional rhythm can include:

  • passing out
  • dizziness
  • fatigue

The following section provides answers to commonly asked questions about junctional rhythm.

How serious is the condition?

Junctional rhythm itself is not typically very dangerous, and people who experience it generally have a good outlook. However, an underlying condition causing it could present a problem if not treated. A person should talk with a doctor if they notice any symptoms that could indicate an issue with their heart rate or rhythm.

How does it differ from idioventricular rhythm?

An idioventricular rhythm also occurs if the SA node becomes blocked. There are several potential, often differing, causes compared with junctional rhythm. It often occurs due to advanced or complete heart block. It regularly causes a heart rate of less than 50, though other types can cause increased heart rate, as with different types of junctional rhythm.

What are the common characteristics?

Some common symptoms of junctional rhythm may include fatigue, dizziness, fainting, feelings of fainting, and intermittent palpitations.

A person’s outlook is generally positive when a healthcare professional identifies and treats the condition causing the junctional rhythm. Treatments and outcomes can vary based on the underlying cause. A person should discuss their treatment options and outlook with a doctor. They can better predict a person’s success rate and overall outlook.