Figure 1.

ECGs A and B were recorded using Philips Page Writer touch electrocardiographs, at a speed of 25 mm/sec, calibration of 10.0 mm = 1.0 mV, and frequency response of 0.05 - 150 Hz. cutoffs. Measurements of peak-to-peak amplitudes of the QRS complexes were obtained from the commercially available for routine use automated morphology algorithm of the Philips Trace MasterVue Management System; sums of the 6 limb leads (ΣLimbLds), 6 precordial leads (ΣPrecLds), and all 12 ECG leads (Σ12Lds), were manually calculated.