Inherited long QT syndrome is not nearly as common as a prolonged QT interval caused by a medication or an imbalance of certain minerals in the blood stream. More than 50 medications are known to lengthen the QT interval and upset the heart rhythm.
https://www.drugs.com/health-guide/long-qt-syndrome.html
The two best understood inherited long QT syndromes are the Romano-Ward syndrome and the Jervell and Lange-Nielsen syndrome. Of the two, the Romano-Ward syndrome is more common. It is an autosomal dominant inherited condition — meaning you can have a long QT if you inherit one abnormal gene from either parent.
https://www.drugs.com/health-guide/long-qt-syndrome.html
Editor: Hugh Calkins, M.D. QT Interval: How to Measure It and What Is “Normal”. ILAN GOLDENBERG, M.D., ARTHUR J. MOSS, M.D., and WOJCIECH ZAREBA, M.D., PH.D. From the Cardiology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA. Abnormally long and short QT intervals have been shown.
http://iranep.org/Articles/QT%20How%20to%20measure%20JCE%202006.pdf
Heart Disease. Long QT Syndrome (LQTS) is an inherited disorder of the heart's electrical system. LQTS can lead to a sudden, unexpected, life-threatening type of ventricular tachycardia commonly called torsades de pointes. People who have LQTS are at risk for syncope (loss of consciousness) and sudden death, often at a young age.
https://www.verywell.com/long-qt-syndrome-1745221
Long QT syndrome is an uncommon inherited condition — meaning it's caused by genes passed on to you from your parents. The electrical activity of heart cells is controlled by a set of channels that pump minerals, such as sodium and potassium, in and out of cells.
https://www.drugs.com/health-guide/long-qt-syndrome.html
The condition is named for the appearance of the electrocardiogram (ECG/EKG) on which a prolongation of the QT interval occurs. Normally, the QT interval duration is between 350 and 440 milliseconds. In some individuals, the QT prolongation occurs after the administration of certain medications, which may be dangerous.
https://en.wikipedia.org/wiki/Long_QT_syndrome
Long QT syndrome. Long QT syndrome (LQTS) is a rare congenital and inherited or acquired heart condition in which delayed repolarization of the heart following a heartbeat increases the risk of episodes of torsades de pointes (TdP, a form of irregular heartbeat that originates from the ventricles).
https://en.wikipedia.org/wiki/Long_QT_syndrome
U wave. In such cases, it is best to record both the QT. interval (T-wave offset measured as the nadir between the. T and U wave) and the QTU interval (repolarization off-. set measured at the end of the second wave).
http://iranep.org/Articles/QT%20How%20to%20measure%20JCE%202006.pdf
QT Interval. 1  The QT interval is the time from the start of the Q wave to the end of the T wave. 2  It represents the time taken for ventricular depolarisation and repolarisation.
https://lifeinthefastlane.com/ecg-library/basics/qt_interval/
QT Interval. The QT interval is the time from the start of the Q wave to the end of the T wave. It represents the time taken for ventricular depolarisation and repolarisation. An abnormally prolonged QT is associated with an increased risk of ventricular arrhythmias, especially Torsades de Pointes.
https://lifeinthefastlane.com/ecg-library/basics/qt_interval/
what is the qt wave
The QT interval is the time from the start of the Q wave to the end of the T wave.