Prolonged QT Interval ECG Review

A prolonged QT interval has a variety of causes and can be a very serious ECG finding, as it may lead to the potentially fatal arrhythmia polymorphic ventricular tachycardia (Torsades de Pointes).

See the ECG Tutorial section on QT interval to learn how this is measured.

Enlarge 

Multiple medications, electrolyte abnormalities (hypocalcemia, hypomagnesemia and hypokalemia) and certain disease states (ie, intracranial hemorrhage) can prolong the QT interval. Prolonged QT genetic syndromes exist and include Romano-Ward syndrome, Jervell-Lange-Nielsen syndrome and long-QT 1-13 syndrome.

ECG Examples:

• Prolonged QT Interval ECG Example 1
• Prolonged QT Interval ECG Example 2
• Prolonged QT Interval ECG Example 3
• Prolonged QT Interval ECG Example 4

References:

1. Chou's Electrocardiography in Clinical Practice: Adult and Pediatric, Sixth Edition, Saunders, Philadelphia, 2008.
2. Surawicz B et al. ACC/AHA recommendations for the standardization and interpretation of the electrocardiogram. Circulation. 2009;119:e235-240.