Abstract
Objective : QT interval prolongation and torsade de pointes (TdP) are associated with congenital long QT syndrome. It is known that automated analysis and the tangent method produce different QT interval results, but the degree of difference is not well known. We investigated the difference between automatic measurement and the tangent method. Method : We compared the results of QT interval measurement by automatic measurement with an electrocardiograph (ECG-1450, Nihon Kohden) and the tangent method by cardiologists on leads II and V5. The number of cases was 200 males and females of ages 7, 13 and 16 years old.
Results : The difference between automatic measurement and tangent method was 25.4 msec ±19.7 msec in II and 31.9 msec ±18.0 msec in V5 (mean ± standard deviation). Automatic measurement gave a longer QT interval in each lead. Discussion : There is a difference between the tangent measurement method and automatic measurement method when screening QT interval.
