Long QT syndrome (LQTS)

Episodes of a rapid heartbeat or fainting can be unsettling. At Aurora, our team of heart specialists is nationally recognized as established leaders in diagnosing, managing and treating long QT syndrome. We’re here to help you pinpoint the cause and get you the care and confidence you need to enjoy life again.

What is long QT syndrome?

Long QT syndrome (LQTS) is an abnormality in the rhythm of your heartbeat. Your heart's electrical system controls the coordinated action of contracting and relaxing the heart muscle to pump blood. Normally after each heartbeat, it recharges itself to prepare for the next one. With long QT syndrome, it takes longer to recharge between beats. Doctors can often see this delay as a pattern, called prolonged QT interval, on an electrocardiogram (EKG).

Long QT syndrome causes fast, erratic and sometimes dangerous heartbeats, usually when you exercise or feel stressed. The most dangerous side effect of long QT syndrome is sudden cardiac arrest, which happens when your heart suddenly stops beating.

Long QT syndrome causes

Most often, long QT syndrome is inherited, meaning it’s passed down from your parents’ genes. Occasionally, long QT syndrome is acquired and develops during your lifetime.

Some medications like antibiotics, diuretics and antihistamines can cause acquired long QT syndrome. Certain health conditions can also cause it, such as severe diarrhea, vomiting, eating disorders like anorexia nervosa and bulimia, and some thyroid disorders. These conditions lower the sodium or potassium levels in your blood, which can trigger long QT symptoms.

Long QT syndrome symptoms

With inherited long QT syndrome, you may not have any symptoms. That’s why it’s important to be tested if you have family members who have the condition. If you do have long QT syndrome symptoms, they typically first appear in childhood.

Symptoms of long QT syndrome include:

• Fainting (syncope), which can occur when the heart isn’t pumping enough blood to the brain
• Irregular heart rhythm (arrhythmia) during sleep
• Heart palpitations, which feel like fluttering in the chest
• Seizures

Long QT syndrome diagnosis

To diagnose long QT syndrome, your doctor will start with a thorough physical exam and ask about your family history and any potential long QT syndrome symptoms you may be experiencing. They may refer you to a cardiologist or an electrophysiologist, a doctor who specializes in diagnosing and treating arrhythmia (irregular heartbeat).

We’ll likely order an electrocardiogram (EKG), to see if you have a prolonged QT interval or other issues with the electrical activity of your heart. Other tests we may use include:

• Laboratory testing: Blood work and other lab tests can detect abnormal electrolyte or thyroid hormone levels, which can be signs of arrhythmia.

Heart function tests: Several tests can help doctors check the function of your heart. These include:

• Echocardiogram, a heart ultrasound
• Coronary angiography
• Radiographic imaging, such as chest X-ray, CT scan or MRI

Portable monitoring, which includes two main types:

• Holter monitoring uses a small, battery-powered EKG that continuously monitors your heart rate and rhythm, usually for 24 to 48 hours.
• Event monitoring records heart rhythms when long QT syndrome symptoms occur, usually over about a month.

• Stress test: This test looks at how your heart functions when it’s working hard, like during exercise. If you’re unable to exercise, we’ll give you medication to simulate exercise during the test.
• Cardiac catheterization: In these minimally invasive procedures, we insert catheters, which are thin tubes with a tiny camera, through a blood vessel to examine the arteries and heart.
• Nuclear cardiology imaging: This type of imaging includes positron emission tomography or PET scan, which uses a safe dose of radioactive material to evaluate blood flow through the heart.

Find out more about our heart and vascular testing and diagnosis.

Long QT syndrome treatment

If you’re diagnosed with long QT syndrome, treatment may depend on your symptoms and underlying cause of the condition. We may suggest:

• Medications to regulate your heartbeat
• Implantable cardioverter defibrillator (ICD), pacemaker or other devices to restore your regular heart rhythm
• Surgery on the nerves that regulate your heartbeat

A care plan that includes:

• Seeing your doctor regularly
• Making sure your family, friends, roommates and co-workers know you have a condition that can trigger cardiac arrest and to call 911 if you faint
• Keeping an automated external defibrillator with you and making sure those with you know how to use it
• Talking with your doctor about counseling or support groups if you’re experiencing anxiety about long QT syndrome