1. Digitized Cardiac Potentials Recorded with CR Leads
Raul N. De Gasperi, M.D., David H. McCulloh, Ph.D. 
CHEST 
Volume 100, Issue 5, Pages (November 1991)
DOI: /chest
Copyright © 1991 The American College of Chest Physicians Terms and Conditions

2. FIGURE 1
Digitized cardiac potentials recorded in a normal adult with lead CR5. A smooth line connects the separate potential points sampled every ms. A 1-mV calibration is represented by the height of a thick bar on the left ordinate. Measured values of the Q wave included its voltage (QV), duration (QD), and rate of change of the voltage (QR). Measured values of the R wave included its peak voltage (RV), foot-to-peak duration (RD), and fastest rate of change of the voltage (RR). The rate of change of the intrinsicoid deflection (IR) was measured where it was fastest. Measured values of the S wave included its peak voltage (SV), duration (SD), and fastest rate of change of the voltage (SR). Ventricular activation time (not labeled) was measured from the onset of the Q wave to the last portion of the peak of the R wave. The QRS duration (not labeled) was measured from the onset of the Q wave to the end of the ascending portion of the S wave. The digitized potential points could be displayed highly condensed, to represent an ECG recorded at slow speed, or separated (as in this figure), to represent an ECG recorded at high speed. This display is equivalent to a tracing recorded at 400 mm/s.
CHEST  , DOI: ( /chest )
Copyright © 1991 The American College of Chest Physicians Terms and Conditions

3. FIGURE 2
The ECG tracings obtained in patient S. Left, Tracings obtained with leads V2 and V3 at a recording speed of 25 mm/s. Center, Cardiac potentials were recorded with bipolar leads CR2 and CR3 and displayed as if recorded at a speed of 100 mm/s (a fourfold expansion relative to the 25-mm/s recording speed). Right, The same cardiac potentials are displayed as if recorded at 400 mm/s (a 16-fold expansion relative to the 25-mm/s recording speed). Identification of the beginning and the end of the various waveforms and visual estimation of the duration of time intervals is facilitated by the latter form of display. Calculation of the slopes yields reproducible results when the onset/offset of the waveforms is accurately identified.
CHEST  , DOI: ( /chest )
Copyright © 1991 The American College of Chest Physicians Terms and Conditions

4. FIGURE 3
Comparison of data obtained in patient S with data obtained in a group of normal subjects. Each variable is plotted along the ordinate; the nine chest and two abdominal leads are plotted along the abscissa. Ranges of normal values for each variable in each lead are shown as vertical bars; values measured in patient S are shown as filled circles.
CHEST  , DOI: ( /chest )
Copyright © 1991 The American College of Chest Physicians Terms and Conditions