Summary about Disease
Junctional ectopic tachycardia (JET) is a rare type of abnormal heart rhythm (arrhythmia) that originates in the atrioventricular (AV) junction. The AV junction is a region in the heart between the upper chambers (atria) and lower chambers (ventricles) where electrical signals pass through. In JET, the AV junction fires rapidly and independently, overriding the heart's normal pacemaker (the sinoatrial node). This rapid firing causes the ventricles to contract prematurely and often at a faster rate than normal, leading to an excessively fast heart rate (tachycardia). JET can occur in both children and adults but is more common in infants and children, often associated with cardiac surgery.
Symptoms
Symptoms of JET can vary depending on the heart rate and the age of the individual. Common symptoms include:
Rapid heart rate (often 150-250 beats per minute or higher in infants and children).
Poor feeding (in infants).
Lethargy.
Irritability.
Pale skin.
Sweating.
Shortness of breath.
Palpitations (awareness of a rapid or irregular heartbeat).
Dizziness or lightheadedness.
Syncope (fainting) in severe cases.
Heart failure (in prolonged, uncontrolled JET).
Causes
The causes of JET are not always fully understood. Some common factors associated with JET include:
Cardiac surgery: JET is a relatively common complication after heart surgery, particularly in children undergoing repair of congenital heart defects.
Congenital heart disease: Some individuals with pre-existing heart conditions are more prone to developing JET.
Myocarditis: Inflammation of the heart muscle can sometimes trigger JET.
Medications: Certain medications (e.g., digoxin toxicity) can rarely cause JET.
Idiopathic: In some cases, no specific underlying cause can be identified.
Medicine Used
Medications used to treat JET aim to slow down the heart rate and restore a normal rhythm. Common medications include:
Amiodarone: An antiarrhythmic drug used to control heart rhythm.
Propafenone: An antiarrhythmic agent.
Flecainide: An antiarrhythmic medication.
Esmolol: A beta-blocker used to slow down the heart rate, often in acute situations.
Procainamide: An antiarrhythmic agent, less commonly used now.
Digoxin: Although it can rarely cause JET, it can also be used to control the ventricular response in some cases, but use with extreme caution.
Magnesium sulfate: Can sometimes help to stabilize heart rhythm. In some cases, medication may not be sufficient, and other interventions like cardioversion (electrical shock to reset the heart rhythm) or catheter ablation (burning away the abnormal tissue causing the arrhythmia) may be necessary.
Is Communicable
No, junctional ectopic tachycardia is not a communicable disease. It is not caused by an infectious agent and cannot be spread from person to person.
Precautions
There are no specific precautions to prevent the development of JET, as it is often related to underlying heart conditions or cardiac surgery. However, the following steps can be taken to minimize risks:
Careful pre-operative assessment: In individuals undergoing cardiac surgery, a thorough evaluation of their heart condition and risk factors for arrhythmias is essential.
Monitoring after cardiac surgery: Closely monitor patients after cardiac surgery for any signs of JET or other arrhythmias.
Medication management: Proper monitoring and management of medications that could potentially trigger arrhythmias.
Prompt medical attention: Seek immediate medical attention if you experience symptoms of a rapid or irregular heartbeat.
How long does an outbreak last?
JET is not an outbreak, but an arrhythmia that can vary in duration.
Self-limiting: Some episodes of JET may be brief and resolve on their own without treatment.
Prolonged/Persistent: Other episodes can last for hours, days, or even weeks if not treated effectively.
Chronic/Recurrent: In some individuals, JET may be a chronic condition with recurring episodes. The duration depends on the underlying cause, the effectiveness of treatment, and individual factors.
How is it diagnosed?
JET is diagnosed through a combination of the following:
Electrocardiogram (ECG/EKG): This is the primary diagnostic tool. It records the electrical activity of the heart and can identify the characteristic features of JET, such as a rapid heart rate, narrow QRS complexes (usually), and absence of visible P waves or P waves occurring after the QRS complex.
Holter monitor: A portable ECG that records the heart's activity over 24-48 hours or longer to capture intermittent episodes of JET.
Event monitor: A device that records heart activity only when triggered by the patient or automatically when an abnormal rhythm is detected.
Electrophysiology (EP) study: An invasive procedure where catheters are inserted into the heart to map the electrical pathways and pinpoint the source of the arrhythmia. This is often used to guide catheter ablation.
Clinical evaluation: A thorough medical history and physical examination to assess symptoms and identify potential underlying causes.
Timeline of Symptoms
The onset of symptoms can vary, but a general timeline might look like this:
Sudden Onset: JET typically starts abruptly.
Initial Symptoms: The first sign is often a rapid heart rate. Other symptoms, such as palpitations, dizziness, or shortness of breath, may develop soon after. In infants, poor feeding, irritability, and lethargy may be the first signs.
Progression: If the rapid heart rate is sustained, symptoms can worsen over time. Prolonged JET can lead to heart failure, especially in young children.
Resolution (with treatment): With appropriate treatment, the heart rate usually returns to normal within minutes to hours. Symptoms typically subside quickly once the rhythm is controlled.
Recurrence (in some cases): JET can recur, and the timeline of subsequent episodes may be similar.
Important Considerations
Prompt treatment is crucial: Untreated JET can lead to significant complications, including heart failure and even death, especially in infants and young children.
Long-term management: Individuals with JET may require long-term monitoring and management to prevent or control recurrences. This may involve medication, lifestyle modifications, and regular follow-up with a cardiologist.
Catheter ablation: This can be a curative option for some individuals with JET, particularly those with medication-refractory or frequently recurring episodes.
Individualized care: Treatment plans should be tailored to the individual's specific needs, considering their age, underlying heart condition, and the severity of their arrhythmia.
Awareness and education: Patients and their families should be educated about the symptoms of JET and the importance of seeking prompt medical attention if they occur.