Long QT Syndrome
Description of Long QT Syndrome
Long QT syndrome (LQTS) is a disorder of the heart's electrical activity that may cause you to develop a sudden, uncontrollable, and dangerous heart rhythm (called an arrhythmia) in response to exercise or stress. Such abnormal heart rhythms also can develop for no known reason in people who have LQTS. Not everyone who has LQTS develops a dangerous heart rhythm, but if one does occur, it may be fatal.
The term "long QT" refers to an abnormality seen on an EKG (electrocardiogram). An EKG is a test that detects and records the electrical activity of the heart. The QT interval, recorded on the EKG, corresponds to the time during which the lower chambers of your heart (the ventricles) are triggered to contract and then build the potential to contract again.
The timing of the electrical activity of the heartbeat is complex and carefully controlled by the body. Normally the QT interval of the heartbeat lasts about a third of each heartbeat cycle on the EKG. But in people with LQTS, the QT interval usually lasts longer than normal, which can upset the careful timing of the heartbeat and trigger a dangerous, irregular rhythm.