User:Gubon74/draft article on High Frequency ECG

High Frequency ECG refers to the high frequency spectral components of the electrocardiogram (ECG).

In order to limit artifacts in routine cardiac rhythm monitoring, most standard ECG systems operate within a constrained boundary of frequencies. The low frequency filter (also called the high-pass filter because signals above the threshold are allowed to pass) is set at either 0.5 Hz or 1 Hz and the high frequency filter (also called the low-pass filter because signals below the threshold are allowed to pass) is set at 40, 100, or 150 Hz. Therefore most standard ECG systems do not analyse the high frequency components of the ECG, beyond 150 Hz.

However there are technologies which utilize the high frequency components of the ECG for diagnostic purposes. For instance, signal-averaged electrocardiography (SAECG) measures small variations (in the micro volt range) in the final high frequency portion of the QRS complex (the so-called "late potentials, or more accurately, "late ventricular potentials") to diagnose dangerous ventricular tachyarrhythmias.

In addition, analysis of micro volt changes in the mid portion of the QRS complex (HFQRS), in the 150-250 Hz frequency band, is employed to diagnose myocardial ischemia. A device developed by NASA and CardioSoft using HFQRS analysis is currently available for research purposes only. A device with a clinical implementation of HFQRS has been developed by Biological Signal Processing.