Clinical Usefulness Of ECG Frequency Spectrum Analysis

The QRS portion of the electrocardiogram of the complexes of patients were sampled at the rate of 1024 samples per second. The power spectral densities were calculated using the fast Fourier transform on a quarter of a second portion of an FM recorded ECG, centered on the peak of the R wave. It was discovered that in a typical QRS complex of normal duration, virtually all of the power is contained in frequencies below 30 Hz with peak power occurring in the range of 4 to 12 Hz. It should be noted that the frequency corresponding to the location of the peak is the heart rate of the patient. Furthermore, most noticeably, premature ventricular contractions typically contain less high frequency power than normal beats, with virtually all the power contained in frequencies below 12 Hz with peak power located at about 4 Hz. FinalIy, notches in some QRS complexes was associated with a broadened distribution of power in the power spectral density even though the tail from 30-100 Hz contained relatively less power than that contained in the frequency band below 30 Hz.