High-resolution ECG on a standard ECG cart.

High-resolution (HI-RES) ECG analysis software and a new front end have been designed for a standard 12-lead ECG cart, MAC-12. The front end acquires orthogonal ECG at 1,000 samples/sec and 1.2 microV/bit and transmits to the cart. The HI-RES software delineates QRS complexes and correlates them with a template in frequency domain to compute an average cardiac complex (P, QRS, and T). This complex is used for analysis of late potentials, bundle of His activity, and detection of coronary artery disease using its high-frequency content. Both time- and frequency-domain methods are implemented for analysis of ventricular late potentials. In the time-domain method, the average beat is bandpass filtered using three lower cutoff frequencies--25, 40, and 80 Hz--with the higher cutoff at 250 Hz. For each of these frequencies, the following features are extracted: RMS voltages in terminal 40 and 50 msec; ventricular activation time; and duration of high-frequency, low-amplitude signals. The frequency-domain analysis examines the spectral contents of the windowed segment of terminal QRS; ST-segment; and a combined segment of QRS and ST. The spectral features include ratios of magnitudes of Fourier coefficients and areas above 20 Hz, dB drop at 40 Hz, and areas after 60 dB offset. Initial testing of this system is complete, and it is due for clinical trials soon.