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Representative vectorcardiogram. (A) Colour-coded (from red to purple) propagation of cardiac activation (red-yellow QRS loop) and repolarization (green-blue T loop). Peak QRS (red), T (green), and spatial ventricular gradient (blue) vectors. (B) Vector magnitude signal of a normal sinus median beat. Gray area indicates QT integral (scalar spatial ventricular gradient measure). (C) Corresponding orthogonal X, Y, Z ECG signal.
