What is Junctional Ectopic Tachycardia?
Junctional ectopic tachycardia (JET) is an irregular heart rhythm that typically occurs in babies and children. It starts in a part of the heart known as the atrioventricular (AV) node or AV junction, which includes a pathway in your heart, known as the bundle of His (BH). There are two types of JET: congenital junctional ectopic tachycardia (CJET) and postoperative junctional ectopic tachycardia (POJET).
CJET is present without any prior heart surgery and it can even be present at birth. CJET has a high rate of sickness and death, as high as 35 percent, if it’s not diagnosed and treated properly because it usually doesn’t respond well to medicine.
POJET often happens in the first 72 hours after repairing birth defects in the heart. It is caused by issues with blood supply (ischemia), stretching, and direct injury to the AV part of the heart during these repairs. It can have a consistent or inconsistent rhythm. Unlike some other irregular heart rhythms, it doesn’t involve a looped pathway in the heart (the reentry circuit). It can involve backward flow of electrical signals in the heart in a 1:1 pattern, or varying heart rhythm due to the AV part not being in sync.
What Causes Junctional Ectopic Tachycardia?
Junctional ectopic tachycardia is a heart condition that can be present at birth. This condition often becomes apparent within the first six months after birth, even without any history of heart surgery. Still, there’s a form of this condition that happens after heart surgery, typically after the repair of heart defects present from birth.
Certain factors can increase the risk of getting this postoperative type, such as using certain post-surgery medications like dopamine and milrinone, having unusually high body temperature after the operation, experiencing imbalances in body salts, being under six months old, undergoing a long surgery, and the specific type of surgery.
Risk Factors and Frequency for Junctional Ectopic Tachycardia
Congenital junctional ectopic tachycardia, a heart condition, is incredibly rare in infants and children. It’s so uncommon that only 100 cases have been reported over 40 years at major heart health centers. However, a similar condition, postoperative junctional ectopic tachycardia, is a bit more common. This condition can occur in up to 5% of cases following heart surgery.
Signs and Symptoms of Junctional Ectopic Tachycardia
Congenital junctional ectopic tachycardia is a heart condition that often affects infants less than six months old. However, diagnosis can also happen after six months. This condition leads to rapid heart rates, clocking between 200 to 250 beats per minute. In some instances, this abnormal heartbeat can start before birth, which causes congestive heart failure or excessive fluid accumulation in the fetus.
Babies with this condition can show signs such as shortness of breath and enlarged heart at presentation. They may also experience ventricular fibrillation, which is a severe heart rhythm problem, and a complete blockage of the heart’s electrical system, potentially causing sudden death. In the past, the death rate for this condition was as high as 35%. However, recent reports suggest a decrease, with death rates ranging from 4 to 9%. It’s worth noting that younger infants often have more persistent rapid heart rates than older infants and thus a higher risk of death.
- Gradual start with a warming-up and cooling-down phase
- Variability in heart rate
- Signs of the condition usually show up within 72 hours after surgery
- During a physical check-up, the baby might have a rapid heart rate and signs of congestive heart failure
- ‘Cannon waves’ might be observed in the jugular vein’s pulse if there’s been a disconnection between the heart’s chambers
Testing for Junctional Ectopic Tachycardia
If you have certain symptoms, your doctor may conduct tests to check for an imbalance in the minerals that help your body function (electrolyte abnormalities) or for high levels of acid in your body (acidosis). A chest x-ray might be needed to check if your heart is larger than it should be (cardiomegaly) or if there’s fluid in your lungs (pulmonary edema).
An electrocardiogram (EKG), a test that measures the electrical activity of your heartbeat, can be used to check for a condition called narrow complex tachycardia. This condition happens when your heart beats very quickly making it hard for your heart to pump enough blood to the body. It typically presents as irregular heart rates. If the ventricular (lower chambers of the heart) and atrial (upper chambers of the heart) rates are the same, then it might be difficult to tell it apart from other heart abnormalities, such as AV nodal reentry tachycardia (a type of rapid heart rate) and AV reentry tachycardia (another form of rapid heart rate).
In certain cases, a medication called adenosine can be given through an IV. This can cause the lower and upper chambers of your heart to beat out of sync (ventriculoatrial dissociation). This will show that the upper chamber of the heart (atrium) is not participating in the irregular heart rhythm (arrhythmia). In rare cases, a patient might have both this irregular heartbeat and a condition called complete heart block, which is a type of abnormal heart rhythm.
An echocardiogram, a test that uses sound waves to produce images of the heart, can be used to see if the heart is enlarged or if its pumping power is less than normal (systolic dysfunction) due to a disease caused by the heart beating too fast too long (tachycardia-induced cardiomyopathy).
Treatment Options for Junctional Ectopic Tachycardia
If you have an imbalance in the levels of certain important substances in your body, referred to as electrolytes, your doctor will aim to correct this. Amiodarone is often the preferred medication for managing Junctional Ectopic Tachycardia (JET), a heart rhythm disorder. This medication is usually administered in a high initial dose, followed by a maintenance dose to keep the levels stable in your body. This can be used on its own, but it’s often combined with other medications like propranolol and flecainide. However, Intravenous adenosine, another medication, is not effective in treating this condition as it does not impact the specific area of the heart affected by JET.
Ivabradine is another drug that has proven effective in treating JET, especially when the condition is present from birth. It’s essential to note that using multiple medications together may increase the risk of sudden death due to the potential for causing irregular heart rhythms. For JET occurring after a surgery – known as postoperative JET, cooling the body (also known as inducing hypothermia) may help manage the condition. Additionally, using an infusion of a substance called magnesium sulfate before surgery can also reduce the risk of experiencing these heart rhythm irregularities.
Usually, postoperative JET gets better within 72 hours. Other medications like dexmedetomidine, propafenone, procainamide, and sotalol may also be used to treat this condition. For cases where the disease is resistant to these treatments, a procedure called catheter ablation may be used. This procedure uses heat or cold energy to create small scars in your heart that prevent the irregular heart rhythm.
What else can Junctional Ectopic Tachycardia be?
There are several medical conditions that can exhibit symptoms similar to Junctional Ectopic Tachycardia (JET), including:
- AV nodal reentry supraventricular tachycardia: This condition generally responds to treatment with a medication called intravenous adenosine, something that is not the case with JET due to its unique underlying causes.
- Pediatric atrial flutter
- Pediatric atrial ectopic tachycardia
- Accelerated junction rhythm
- Wolf Parkinson White syndrome
- Permanent junctional reciprocating tachycardia
What to expect with Junctional Ectopic Tachycardia
Congenital junctional ectopic tachycardia, a type of abnormal heart rhythm present at birth, is more challenging to treat and tends to have a higher risk of serious complications and death compared to postoperative junctional ectopic tachycardia, which usually occurs after heart surgery. The latter type usually responds better to treatment and often resolves by itself within 72 hours of appearing.
Earlier reports had indicated congenital junctional ectopic tachycardia to be fatal in up to 35% of cases. However, recent reports suggest this figure to be between 4% and 9%. It’s crucial to understand that each individual’s situation may be different and so the doctor might tailor treatment options based on each person’s specific needs and health condition.
Possible Complications When Diagnosed with Junctional Ectopic Tachycardia
Junctional Ectopic Tachycardia, when present since birth, can cause the heart to increase in size due to its constant fast pace, and it can lead to death from congestive heart failure, irregular heartbeats, or complete heart blockage. This condition following surgery typically leads to dangerously low blood pressure, but the success rate for treatment is generally better compared to when it is present from birth.
Possible Complications:
- Heart increase in size
- Congestive heart failure
- Irregular heartbeats
- Complete heart blockage
- Low blood pressure following surgery
Preventing Junctional Ectopic Tachycardia
The parents of the patient need to be informed about the symptoms and signs of this irregular heartbeat, so they can identify it quickly if it happens again after the patient is sent home. Any decisions regarding treatment should be communicated clearly to them, including any potential risks. This will help them understand what’s going on and give them peace of mind.
