QTc Calculator

The QTc calculator is aimed at determining the corrected QT interval. This is based on the use of the QT interval, as extracted from an ECG test and the pulse rate of the patient, measured in beats per minute.

The QT interval is one of the most important pieces of information provided by the ECG and represents the electrical depolarization and repolarization of the ventricles.

Normal values are considered to be below maximum 0.46s. Abnormally long intervals may indicate ventricular tachyarrhythmias.

The corrected QT interval is estimated through 4 different formulas:

■ Bazett’s formula: QTc = QT/√(RR in seconds)

■ Fridericia’s formula: QTc = QT/(RR0.33)

■ Framingham’s formula: QTc = QT + 0.154(1-RR)

■ Hodges’s formula: QTc = QT + 1.75(HR - 60)

According to the ACC/HRS, normal values are lower than 450 milliseconds for men and below 460 milliseconds for women.