Glossary
AzCERT: Arizona Center for Education and Research on Therapeutics. One of 14 federally designated CERT centers across the nation, AzCERT focuses on drug-induced arrhythmias (torsade de pointes) and QT prolongation, drug interactions and warfarin.
Cardiac arrhythmias: Any deviation from the normal (sinus) heart rhythm. Some are more serious than others and may have very different treatment strategies.
Congenital Long QT Syndrome: "Congenital" refers to a characteristic you are born with. Some people are born with an abnormally long QT interval on their electrocardiogram. Different genetic causes have been identified, but all are included by the term "Congenital Long QT Syndrome" or CLQTS.
Drug-induced QT prolongation: Over 132 currently marketed medicines have been associated with a prolongation of the QT interval. Prolongation above the normal value of 440ms for men and 450ms for women is considered to potentially increase the risk for serious cardiac arrhythmias.
ECG: Stands for electrocardiogram. It is a non-invasive diagnostic tool that records the heart's electrical activity. Also referred to as EKG.
EKG: From the German Elektrokardiogramm; it's another abbreviation for ECG.
FDA: U.S. Food and Drug Administration. Federal regulatory agency for
pharmaceuticals, cosmetics, food and veterinary products and medical devices.
QT: Refers to the QT interval, a period of time that corresponds to a waves in the ECG that represent the contraction and relaxation of the heart muscle that forms the two largest chambers of the heart. The QT interval is measured in milliseconds (ms). See the image below.
QTc: Because the QT interval is influenced by heart rate, it is often "corrected" or normalized to a standard heart rate of 60 bpm. QTc is the QT interval corrected for differences in the specific heart rate at the time of measurement. In order to have a more accurate estimate of QT duration, several correction formulas have been proposed. The Bazett Formula is most often used but has limitations at high or low heart rates.
Sudden cardiac death: Some cardiac arrhythmias cause the heart to suddenly loose the ability to pump blood to the body. The loss of blood flow causes severe cell damage. The possibility of dying is very high if the underlying cardiac arrhythmia is not immediately treated.
Torsades de pointes (Pronounced: tor-SAHD duh PWAHN): A potentially life-threatening heart rhythm disturbance that occurs in the setting of prolongation of the QT interval and which causes the heart to stop pumping blood. Patients with a prolonged QT interval, whether drug-associated or congenital are at increased risk of torsades de pointes.
