Definition

Atrial flutter is a heart rhythm disorder in which the atria beat too quickly due to excessive electrical impulses. The normal heart rate is 60-100 beats per minute, but atrial flutter is a type of arrhythmia, an irregular heart rhythm, with a rapid heart rate (tachycardia), defined as more than 100 beats per minute.

Atrial flutter is rare in children without congenital heart disease. In children with normal hearts, atrial tachycardia is mostly observed in fetuses late in pregnancy or in newborns. In fetuses with atrial flutter, the atrial rate can reach 300-600 beats per minute, often accompanied by atrioventricular block, which slows the ventricular rate.

In older children, atrial flutter usually occurs due to congenital heart disease, myocarditis (inflammation of the heart muscle), or cardiomyopathy (heart muscle dysfunction).

In infants and newborns with normal heart structure, atrial flutter tends to be benign. After therapy to restore a normal heart rhythm, antiarrhythmic medications are generally not recommended, as recurrences are rare.

Causes

Atrial flutter accounts for about one-third of fetal tachyarrhythmia cases (excessively fast heartbeat). Most fetuses and newborns with atrial flutter have structurally normal hearts. However, in cases of atrial flutter in a fetus, structural heart abnormalities should be ruled out due to their high prevalence. Certain conditions or abnormalities in infants and young children may be associated with atrial flutter.

Atrial aneurysms, or enlargement of the atrial blood vessels, are linked to ongoing heart rhythm issues in newborns, though less commonly than in adults. Cardiomyopathy is also associated with recurrent atrial flutter. Costello syndrome is another condition often associated with prolonged atrial tachycardia and atrial flutter.

Atrial flutter may also occur after surgery for congenital heart defects, where inflammation of the heart's outer layer, scar formation, or inflammation of the operated area can trigger the condition.

Case studies have noted connections between atrial flutter and specific herbal medicines and foods. However, atrial flutter in these cases typically resolves when the triggers are avoided.

Risk Factor

Patients who have undergone surgery to repair congenital heart defects are at higher risk for atrial flutter due to surgical scarring in the atria and enlargement of the right atrium. Atrial flutter is also associated with obesity, alcohol use, and hyperthyroidism (overactive thyroid). Pediatric patients with heart muscle dysfunction may also experience atrial flutter and cardiomyopathy.

Symptoms

Atrial flutter may cause the following symptoms:

• Chest pain or pressure
• Fainting (syncope)
• Fatigue
• Lightheadedness or dizziness
• Palpitations, the sensation of a rapid or irregular heartbeat
• Shortness of breath

Symptoms vary based on the frequency, duration, and severity of the condition, and some children may be asymptomatic. Symptoms may be brief, resolve spontaneously, or persist until treated.

Frequent or prolonged symptoms can increase the risk of blood clot formation in the heart. If a clot dislodges and blocks a blood vessel in the brain, it can result in a stroke.

Atrial flutter is rare in infants with normal hearts. If it does occur, it usually resolves within the first year of life. Episodes that are infrequent and have minimal symptoms may require limited intervention. It's important to note that some children may struggle to describe or explain their symptoms.

Diagnosis

In addition to symptoms, medical history, and physical examination results, there are several tests that can help diagnose atrial flutter. 

A 12-lead to 15-lead electrocardiogram (ECG) is the primary test for diagnosing atrial flutter. Patients receiving antiarrhythmic therapy require monitoring of blood levels of certain medications as well as electrolytes, creatinine, and ECG monitoring. Electrophysiological studies can also be used to assess arrhythmias.

Consider transesophageal echocardiography (ultrasound of the heart through the esophagus) in patients with associated structural and functional cardiac abnormalities to rule out thrombus (blood clots) within the heart, impaired heart muscle function, or blood flow disorders that could trigger atrial flutter.

Management

Treatment for atrial flutter in children aims to:

• Ensure stable blood flow before, during, and after restoring a normal heart rhythm.
• Minimize conditions that trigger or support atrial rhythm disturbances (atrial arrhythmias), such as electrolyte imbalances, fluid buildup in the heart’s outer membrane, or catheter placement in the atria.
• Prevent and manage complications like ventricular dysfunction.

Treatment depends on the child’s age and heart structure. Fetal atrial flutter is usually treated with antiarrhythmic medication taken by the mother. Further action is often unnecessary if the fetus’s ventricular function is normal and the placenta shows no signs of swelling.

After birth, most infants respond well to oral antiarrhythmic medications, with many cases resolving fully. Children with structural heart abnormalities or surgical scars may experience recurrent atrial flutter.

Treatment options include:

Cardioversion

Synchronized cardioversion is the primary treatment for unstable patients or those unresponsive to other therapies. In stable patients with long-term atrial flutter, cardioversion is only done after confirming that the patient is free of blood clots or after two weeks of anticoagulation therapy.

Radiofrequency Catheter Ablation

This technique is effective in treating post-surgical atrial flutter in children.

Surgery

Surgery aims to address blood flow disorders that can cause a burden on the volume of the atria. Therefore, care must be taken when performing surgery on the atria.

Activity Restriction

For children, effective measures to restore and maintain a normal sinus rhythm should be prioritized. Persistent atrial flutter managed by heart rate control may require children to avoid competitive sports.

Complications

Atrial flutter can lead to low cardiac output, brain and organ injuries, or sudden death. Other possible complications include heart failure, thrombosis, and thromboembolism.

Prevention

Atrial stretching, scar formation from surgery, and sinus node dysfunction (natural pacemaker) are key factors in atrial flutter development in congenital heart disease patients.

New surgical techniques to prevent atrial stretching and scarring may reduce atrial flutter incidence in these patients.

Preserving the sinus node during surgery, along with pacemaker therapy for sinus node dysfunction, plays a crucial role in preventing atrial flutter.

When to See a Doctor?

Consult a doctor if your child has any symptoms of atrial flutter as described above.

If your child is diagnosed and receiving treatment for atrial flutter, visit the emergency room immediately if they experience:

• Severe chest pain
• Lightheadedness or dizziness
• Fainting