Understanding and treating long QT syndrome

January 4, 2018 by From Mayo Clinic News Network, Mayo Clinic News Network

DEAR MAYO CLINIC: I recently read that long QT syndrome is quite common. What is it, and how is it diagnosed? I have read that fainting may be one sign of the disorder. Can long QT syndrome be treated?

ANSWER: Long QT is a that is diagnosed due to symptoms, an abnormal 12-lead electrocardiogram (ECG), or as a result of a family history of the disease. Once it's diagnosed, long QT syndrome often can be treated effectively.

Your heart circulates blood throughout your body each time it beats. The chambers of your heart contract and relax to pump the blood. These actions are controlled by electrical impulses that travel through your heart. After each heartbeat, your heart's electrical system recharges itself in preparation for the next heartbeat.

In long QT syndrome, the heart muscle takes longer than normal to electrically recharge after it contracts. A test called an electrocardiogram (also called an ECG or EKG) can detect this problem. Most people don't have routine ECGs, though, so catching it with this test if you haven't had any symptoms, or if you don't have a of the disorder, is less common.

Congenital or inherited long QT syndrome affects about 1 in 2,000 people. That statistic, however, is likely an underestimate, because people can have the disorder for years and not know it. In addition, some unexplained deaths, such as those by drowning or unexplained vehicle accidents, may be the result of triggered by long QT syndrome.

As you note, one of the most frequent symptoms of long QT syndrome is fainting. The disorder triggers fainting when the heartbeat becomes irregular—usually during exercise or other physical exertion, or when you become scared, excited or angry. If the heartbeat continues to be dangerously fast and erratic for a prolonged period of time, long QT syndrome also can lead to seizures due to lack of oxygen to the brain. If the heartbeat doesn't return to normal, can occur.

At this time, universal screening does not include long QT syndrome. In most cases, it's diagnosed with an ECG after someone experiences a warning symptom—usually fainting without warning. Because long QT syndrome often has a genetic component, some people may be diagnosed if a family member has the disorder. Or, in some cases, first-degree family members (parents, siblings and children) may be tested for long QT syndrome when there is an unexplained, sudden death in a family. Genetic testing should be recommended as part of evaluation for long QT syndrome.

Once long QT syndrome is diagnosed, treatment usually starts with a medication called a beta-blocker. Other medications to counteract irregular heart rhythm may be used in conjunction with beta-blockers.

If medication isn't enough to control long QT, a surgery called left cardiac sympathetic denervation may be recommended. During this minimally invasive procedure, nerves that release a chemical called noradrenalin onto the heart's muscle are removed from along the left side of the spine. The surgery significantly reduces the risk of a long QT-triggered faint, seizure or sudden death.

Sometimes, despite medications and/or the denervation surgery, a person with long QT syndrome may be at unacceptably high risk for sudden death. In those situations, a defibrillator may be implanted under the skin of the chest. The device can stop a potentially fatal by delivering an electric shock to reset the rhythm back to normal.

Treatment for long QT syndrome is tailored to the individual after a comprehensive risk assessment. In most cases, once it's identified, long QT syndrome can be treated successfully so the patient should be able to live and thrive despite the diagnosis.

"Given the complexity of this disease and the importance of getting the diagnosis and treatment plan right, people suspected of having long QT syndrome should be referred to a center of excellence dedicated to families with this potentially lethal, yet highly treatable, genetic disease". - Dr. Michael J. Ackerman, Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.

Explore further: How a bite of a hot dog threatened and saved a boy's life


Related Stories

How a bite of a hot dog threatened and saved a boy's life

September 6, 2017
(HealthDay)—A 9-year-old boy in Turkey opened wide for a big bite of a tasty hot dog, but had no idea the simple act might almost kill him.

Sudden cardiac death of teen reminds physicians of precision medicine

October 31, 2016
The sudden death of a 13-year-old boy resulted in more than 20 relatives to be incorrectly diagnosed as having a potentially lethal heart rhythm condition. This erroneous diagnosis occurred as a result of inappropriate use ...

Device may help doctors diagnose lethal heart rhythm in womb

November 11, 2013
A promising technology may enable doctors to diagnose and possibly treat in utero a common cause of stillbirth and sudden death in infants, according to research published in the American Heart Association journal Circulation.

Study re-examines sports restrictions for children with heart rhythm disorder

April 20, 2015
Sports participation may be safer than previously thought for children with the heart rhythm disorder long QT syndrome, and authors of a new study in JACC: Clinical Electrophysiology say restrictions should be eased to allow ...

Team discovers patient-specific cure for dangerous heart rhythm disorder

September 17, 2013
The National Heart Centre Singapore (NHCS) research team has successfully and completely reversed the effects of the hERG (human ether-a-go-go-related gene) mutation in long QT syndrome 2 (LQTS 2) in patient-specific heart ...

Recommended for you

'Good cholesterol' may not always be good

July 19, 2018
Postmenopausal factors may have an impact on the heart-protective qualities of high-density lipoproteins (HDL) - also known as 'good cholesterol' - according to a study led by researchers in the University of Pittsburgh Graduate ...

Using adrenaline in cardiac arrests results in less than 1 percent more people leaving hospital alive

July 18, 2018
A clinical trial of the use of adrenaline in cardiac arrests has found that its use results in less than 1% more people leaving hospital alive—but almost doubles the risk of severe brain damage for survivors of cardiac ...

Omega 3 supplements have little or no heart or vascular health benefit: review

July 17, 2018
New evidence published today shows there is little or no effect of omega 3 supplements on our risk of experiencing heart disease, stroke or death.

Researchers discover new genes associated with heart function

July 17, 2018
A new study from an international research team, led by Dr. Yalda Jamshidi at St George's, University of London, has identified new genes associated with heart function and development.

Southern diet could be deadly for people with heart disease

July 12, 2018
People with a history of heart disease who eat a traditional Southern diet are more likely to die than those who follow a Mediterranean dietary pattern, according to new research.

Late-life high blood pressure may harm the brain, study says

July 11, 2018
Decades ago, hundreds of nuns and priests made an extraordinary decision: They agreed to donate their brains upon death to science, hoping to help solve mysteries about Alzheimer's and other diseases. Now, a study that used ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.