Long QT syndrome (LQTS) is a rare, usually inherited and sometimes fatal disorder of the heart’s electrical system. LQTS patients often do not notice any symptoms until they are under some kind of physical or emotional stress. At that point, they could experience fainting (syncope) or more dangerous heart conditions such as ventricular tachycardia (a very fast heartbeat originating in the heart's lower chambers). In the most severe cases, LQTS patients may suffer sudden cardiac death. Women are more prone to sudden cardiac death as a result of LQTS.

Patients may or may not have symptoms, but many physicians will choose to treat all patients with confirmed LQTS because of the risk of sudden cardiac death. The most common treatment is medication (e.g., beta blockers), and patients are often recommended to limit their physical activity. If symptoms persist, surgery to implant an artificial pacemaker or an implantable cardioverter defibrillator (ICD) may also be recommended.

Long QT syndrome (LQTS) is a rare, usually inherited and sometimes fatal disorder of the heart’s electrical system. It is estimated to occur in about 1 in 10,000 people, and most often is diagnosed in children.

LQTS affects the way the heart responds to the electrical signals that stimulate the heartbeat. In a healthy heart, electrical impulses are generated from a specialized area in the upper right atrium known as the sinoatrial node. The signal first stimulates the upper chambers of the heart, the atria, to contract. Then it travels along a specific conduction pathway to another specialized area called the atrioventricular (AV) node, which lies between the upper and lower portions of the heart. From there, the impulse moves down into the lower half of the heart, where it stimulates the ventricles to contract.

These signals are generated in a regular pattern that changes in response to the body’s demand for oxygen-rich blood. When more oxygen is demanded, during exercise or stress for example, the heart rate is increased. However, when this steady stream of impulses is interrupted, or the regular conduction pathway is compromised, the result is an irregular heartbeat. The heart may beat too slowly, too quickly or in a disorganized fashion. An abnormal heartbeat is known as an arrhythmia.

The electrocardiogram (EKG) is a painless test that measures these electrical impulses as they travel through the heart. The EKG detects five distinct waves in each complete cycle. These five waves are labeled P, Q, R, S and T. The P wave is associated with activity in the heart’s upper atria. The other waves reflect activity in the heart’s lower chambers (ventricles).

Long QT syndrome (LQTS) is a disease in which the Q-T interval is longer than normal (all of these times are measured in fractions of a second). The interval between Q and T corresponds to the time it takes for the ventricles to contract and then rest before beginning the contraction cycle again. A patient with LQTS is at risk for arrhythmias as a result of the lengthened interval. Arrhythmias may be triggered by stress or other external factors such as thunder, alarm clocks, waking up suddenly or swimming. Additionally, exercise may trigger arrhythmias because the Q-T interval does not shorten as it should when the heartbeat increases.

There are several types of arrhythmias that may be caused by LQTS. They include:

Many patients with LQTS do not experience symptoms, making it difficult to determine exactly how common the condition is. People who do experience symptoms may faint (syncope), experience a galloping heartbeat (palpitations) or cardiac arrest. In many cases, these symptoms are the first indication that a person has LQTS, and some researchers have speculated that some cases of sudden infant death syndrome are caused by LQTS.

About one-third of long QT syndrome (LQTS) patients do not have any symptoms. Coupled with the fact that many cases of LQTS are diagnosed in children or young adults, there is often no reason to perform an electrocardiogram (EKG), so a diagnosis is often not made until a serious fainting (syncope) incident has occurred or the LQTS-related death of a family member.

A red flag for physicians is raised when there is a family history of any of the following:

The diagnosis for LQTS is usually made through an EKG evaluation. An EKG is noninvasive, quick, safe and painless. As a stand-alone test, it takes about 5 to 10 minutes.

However, the EKG is not always able to detect the condition. In some cases, the physician will request multiple EKG tests. If LQTS is still not found, but suspected, the physician may order an exercise stress test. This is an EKG that is performed in conjunction with exercise and is often abnormal among patients with LQTS. A new testing protocol, using short bursts of exercise (maximum exertion for one minute) has further improved the accuracy of traditional exercise stress testing. If exercise is not possible, a pharmacological stress test may be performed. During this test, the heartbeat is elevated through the use of medications, including epinephrine. In some cases, patients may also be required to wear a Holter monitor, which allows the physician to monitor the heart rate over a fixed period of time (e.g., 24 hours).

However, individuals with LQTS can also have a normal EKG. This contradiction has led to a search for another way of diagnosing the condition. One method being explored involves the use of a pharmacological stress test, in which increasing doses of epinephrine are given to speed up the heart. Epinephrine is the hormone released by the body in response to emotional and physical stress. It can provoke the serious effects of LQTS.

Researchers are also working on ways to identify LQTS using a genetic test. Currently, seven specific genetic abnormalities have been identified among patients with LQTS. Tests are being designed to detect these abnormalities. They are still experimental, however, and not commercially available.

Many people with long QT syndrome (LQTS) do not have any symptoms related to their condition. However, because of the risk of sudden cardiac death, physicians may choose to treat all patients.

The first line of treatment for LQTS is beta blockers, which lessen the number of nerve impulses that occur within the heart and blood vessels. This reduction in heart rate lessens the blood force within the vessels and lowers the overall rate of work the heart performs. Slowing the heart rate can help mitigate the dangerously fast beat that can come about in times of stress, fear or exertion. This type of treatment is effective in preventing fainting (syncope) in about 75 to 90 percent of LQTS patients. Beta blockers are also effective in pregnant patients.

For patients not helped by medication, an artificial pacemaker or implantable cardioverter defibrillator (ICD) may be implanted under the skin in the chest. These devices can monitor and, if necessary, correct a potentially fatal abnormal heart rhythm (arrhythmia). In extremely difficult to treat cases, the patient may be recommended for a special surgery known as left cardiac sympathetic denervation. During this surgery, the physician removes very specific parts of the cardiac nerve structure, which reduces frequency of arrhythmias. This surgery is performed more frequently outside the United States.

Lifestyle changes related to physical activity are also important for someone diagnosed with LQTS. Although exercise does not need to be given up entirely, hard or strenuous exercise can be dangerous. It is also suggested that people with LQTS not be alone when engaging in those physical activities recommended by their physician. Teachers, friends, neighbors and anyone else in contact with the individual, especially if he or she is a child or young adult, should be aware of the situation, and plans should be in place in case of an emergency medical event. Time is of the essence in cases of oxygen deprivation to avoid sudden cardiac death. All LQTS patients should also be fully aware of the symptoms that could warn of decreased blood flow to the brain, so they can rest or seek help as needed.

LQTS patients need to be careful about which prescription and over–the–counter medications they take. Some medications are known to prolong the Q–T interval. They include certain antihistamines and antibiotics, and some drugs to treat heart disease, cancer, depression or gastrointestinal disorders.

The vast majority (about 85 percent) of LQTS cases cannot be prevented because the condition is inherited. If one parent has LQTS, then each of his or her children has a 50 percent chance of inheriting the condition. If both parents have LQTS, then each of their children has a 75 percent chance of inheriting the condition. Boys and girls are at equal risk. People should be tested for LQTS if it runs in their family, or if any family members have had unexplained fainting spells.

Although uncommon, LQTS can also be acquired, usually from medication therapy. Medications that have been associated with LQTS include antiarrhythmics. In this case, the first line of treatment also involves discontinuing the offending drug.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to long QT syndrome:

1. How dangerous is my condition?
   
   
2. How urgently do I need to begin treatment?
   
   
3. Is it possible for me to have long QT syndrome if I do not feel any symptoms?
   
   
4. What type of treatment do you recommend for my specific condition? Will I need to have a surgical procedure?
   
   
5. Could I need an artificial pacemaker or an implantable cardioverter defibrillator (ICD) implanted?
   
   
6. Am I currently taking any medications that might have caused this condition? Will any of the medications I am taking interfere with your recommended treatment?
   
   
7. Are there any lifestyle changes I can make to improve my condition?
   
   
8. Will long QT syndrome affect my ability to get pregnant? Could the condition harm my unborn child?
   
   
9. Is it possible for me to pass this condition on to my children?