Long QT Syndrome (LQTS) | MedStar Health

A disruption in the electrical activity between heartbeats

The QT interval is the period between heartbeats when the heart’s electrical system recharges. Long QT syndrome (LQTS) disrupts the heart’s electrical activity, causing the heart muscle to take longer than normal to recover after contracting. This irregular heart rhythm can lead to fainting, seizures, and, in severe cases, sudden death.

The specialists in our Cardiac Electrophysiology program are highly trained, advanced subspecialists who manage even the most complex arrhythmias. We will work with you to develop an individualized treatment plan to help you live a full, active life.

Long QT syndrome can be acquired due to a medical condition or as a side effect to a medication. However, it’s more commonly caused by a genetic mutation present at birth, known as a congenital condition.

Inherited LQTS occurs in about one out of every 2,000 people, and 15 genes have been identified as causes for the conditions to date. Our Cardiogenetics program focuses on conditions such as LQTS and offers state-of-the-art research and genetic testing. If you or a family member has been diagnosed with LQTS, talk to your doctor about whether you should consider genetic testing.

What are the symptoms for LQTS?

Long QT syndrome symptoms often are triggered by exercise, heightened emotions, or a slow heart rate while sleeping. The most common symptoms include:

Genetic counseling and testing for heart conditions

Our cardiogenetics experts work to improve early detection and treatment for patients at risk for certain genetic heart conditions.


Diagnosing a potential heart or vascular condition is the first step to developing a treatment plan. Our specialists may recommend one or more diagnostic and imaging procedures.

Angiogram (Angiography)

An angiogram is a special X-ray taken as a special dye is injected through a thin, flexible tube called a catheter to detect blockages or aneurysms in blood vessels.

Chest X-ray

Chest X-rays use a small dose of radiation to create pictures of the structures inside the chest, including the lungs, heart, and chest wall.

Computerized Tomography (CT) Scan

The cardiac computed tomography scan, or cardiac CT, uses X-rays to create three-dimensional images of your heart and blood vessels.


An echocardiogram uses high-frequency sound waves to create images of your heart.

Electrocardiogram (ECG)

An electrocardiogram, also known as an ECG, measures the heart’s electrical activity.

Event Monitors

An event monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but where an electrocardiogram takes place over a few minutes, an event monitor measures heart rhythms over a much longer time.

Holter Monitors

A Holter monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but whereas an electrocardiogram records over a few minutes, a Holter monitor records over the course of a day or two.


Your personal long QT syndrome treatment may include lifestyle modifications, such as avoiding strenuous activity or certain medications, medication to manage heart arrhythmia, or more advanced treatments, such as implanting a defibrillator.

Implantable Cardioverter Defibrillator (ICD)
An implantable cardioverter defibrillator (ICD) is a device implanted below your collarbone that monitors your heart’s rhythm. When it detects an abnormal rhythm, it delivers an electrical impulse or shock to the heart to correct it.

Ask MedStar Heart & Vascular Institute

Have general questions for our heart and vascular program? Email us at AskMHVI@medstar.net. If you have clinically-specific questions, please contact your physician’s office.