Torsades de Pointes: A Characteristic Spectral Pattern in Sudden Cardiac Death

Torsades de pointes type of ventricular tachycardia is represented by a power spectrum with multiple discrete frequency bands. The lowest apparent peak (at 1 Hz) corresponds to the envelope frequency of the oscillating QRS vector. Additional peaks corresponding, respectively, to the heart rate (~4 Hz) and its higher harmonics show a characteristic power scaling which was remarkably similar in three subjects with torsades. The consistency of this spectral pattern may be of diagnostic utility and also suggests, contrary to prevailing theory, that torsades is due to a single process, rather than to multiple ectopic foci.