What Is Junctional Tachycardia?

Overview

Junctional tachycardia is a type of arrhythmia, a condition where the heartbeat has an abnormal rhythm and initiates in a different part of the heart than normal. People living with this condition experience the highest number of beats per minute among the four types of junctional rhythms. It is typically seen in infants who are 6 months or younger and following heart surgery. 

We must first understand how the heart works to better understand this condition. The heart is one of the main organs in our body that relies on “electricity” for its function. Our heart creates small electrical signals that make our heart contract and relax to pump blood throughout the body. In the heart's right upper chamber, the right atrium, we have the sinoatrial node that acts as the primary natural pacemaker and generates a heartbeat. It sends electrical impulses to the upper heart chambers (the atria) to start a contraction. From here, the signals pass to a structure called the atrioventricular (AV) node and then through the bundle of His. Eventually, the signal propagates to the lower chambers of the heart, called the ventricles, to cause them to contract. 

Sometimes, the heartbeat starts from the wrong location. When the heartbeat originates from the AV node instead of the sinoatrial node, a dysregulated and improper heartbeat is generated. This dysregulation is referred to as a junctional rhythm and depending on the heart rate or heart beats per minute (bpm), there are four different subtypes.

The four types of junctional rhythm are:¹

Junctional tachycardia is defined as an abnormally high heart rhythm that originates from either the AV node or the bundle of His.

Types of junctional tachycardia

Junctional tachycardia can be either congenital (present at birth) or can develop later in life (acquired) due to heart surgery or injury. 

Congenital junctional tachycardia

This is categorised as occurring in infants who are 6 months of age or younger. Although rare, congenital junctional tachycardia has a high mortality rate of as high as 35%, if not diagnosed and properly treated.²  

Junctional tachycardia that occurs within 72 hours of surgical repair of a congenital heart defect is referred to as postoperative junctional ectopic tachycardia (POJET).^2,3 Some medications and conditions of surgery can increase the risk of POJET in certain patients. These factors include:

• Core body temperature 
• Length and duration of surgery 
• Type of surgery 
• Use of certain medications
• Abnormalities in electrolyte levels

Acquired junctional tachycardia

Some acquired causes of junctional tachycardia can be attributed to conditions that damage the heart, weaken the muscle and therefore affect the electric signalling of the heart. Some examples of these include:³

• Myocarditis (inflamed heart muscle)
• Myocardial infarction (heart attack)
• Lyme disease
• Toxicity from certain medications, such as digoxin

Signs and symptoms of junctional tachycardia

Some patients with junctional tachycardia do not present with any symptoms. However, some of the most common symptoms of symptomatic junctional tachycardia include:¹

• Irregular heartbeat
• Fast heart beat 
• Shortness of breath
• Fatigue
• Lightheadedness

Management and treatment for junctional tachycardia

Treatment for junctional tachycardia is dependent on two things: the cause and the symptoms. If the cause is due to previously taken medication, your doctor may recommend an alternative medication. In the case of previous heart disease, your doctor may prescribe medication to help regulate your heart rhythm or a pacemaker to return the normal rhythm of the heart. Medication may include:

• Calcium channel blockers
• Magnesium sulphate
• Antiarrhythmic drugs

In some cases of postoperative junctional tachycardia, the condition will resolve within 8 days following surgery if the cause is reversible, such as a disbalance in electrolyte levels.⁴

If you do not respond well to medication and other treatments, your cardiologist may recommend radiofrequency ablation. In this procedure, surgeons will guide a small tube into your heart to use radiofrequency to damage a section of the heart. While this may seem counterintuitive, this is a regular procedure done to fix arrhythmias and irregular heartbeats when treatment with medication is not successful.⁵ In the case of junctional tachycardia, it can slow the increased heart rate.

Diagnosis

Your doctor will first ask questions about your health and family history to determine if you have risk factors that could increase the likelihood of you having a junctional rhythm condition. If you have had heart surgery recently, your cardiologist will monitor your heartbeat while you recover.

Your cardiologist will be able to identify the irregularity of your heartbeat from an electrocardiogram (ECG). Your doctor may also order certain blood tests or an echocardiogram to look at the structure of your heart in real time.   

FAQs

How can I prevent junctional tachycardia?

Congenital junctional tachycardia cannot be prevented as you are born with it. Yet, the risk of junctional tachycardia during or after surgeries can be reduced with the use of appropriate medication. Hence, regular follow-ups with your doctors to help manage this condition and keep it in control is necessary. 

How common is junctional tachycardia?

Congenital junctional tachycardia is incredibly rare, with only 100 cases reported in the last 40 years. In contrast, postoperative junctional tachycardia is reported to occur in of 5% patients after heart surgery.²

Who is at risk of junctional tachycardia?

Those with a previous history of heart disease are at a higher risk of developing junctional tachycardia. It is also a potential complication following heart surgery so, people who undergo heart surgeries are more likely to acquire this condition than those who do not.²

What can I expect if I have junctional tachycardia?

Junctional tachycardia can present without symptoms and can only be diagnosed through an electrocardiogram, which looks at the electrical signals in the heart, or an echocardiogram, which looks at the structure of your heart. In other cases, you may feel symptoms, such as a fast and irregular heartbeat and fatigue.

When should I see a doctor?

Consult a doctor as soon as possible in cases when you experience any of the symptoms mentioned in this article. It is important to identify and treat this condition at an early stage to prevent any further complications.

Summary

Junctional tachycardia is a subtype of arrhythmias. Under normal conditions, the sinoatrial node is the first structure to send an electric signal in the heart to initiate a heartbeat. In junctional rhythms, the heartbeat originates from the atrioventricular node instead. People with junctional tachycardia experience a fast heart rate (over 100 beats per minute). This condition can be categorised as congenital or postoperative following heart surgery. Congenital junctional tachycardia is incredibly rare but is associated with a high mortality rate. Postoperative junctional tachycardia is relatively common, affecting up to 5% of all individuals who have had heart surgeries. Patients can present without symptoms and can be diagnosed through regular checkups. Some individuals present with a racing heart rate, fatigue, and lightheadedness. Treatments include cessation of medication that may be causing an irregular heart rhythm, regulation of electrolyte levels, or administration of new medication that can help regulate the heart. In cases where medication is not effective, ablation surgery may be recommended.