True Unipolar ECG Machine for Wilson Central Terminal Measurements

Abstract

Since its invention (more than 80 years ago), modern electrocardiography has employed a supposedly stable voltage reference (with little variation during the cardiac cycle) for half of the signals. This reference, known by the name of “Wilson Central Terminal” in honor of its inventor, is obtained by averaging the three active limb electrode voltages measured with respect to the return ground electrode. However, concerns have been raised by researchers about problems (biasing and misdiagnosis) associated with the ambiguous value and behavior of this reference voltage, which requires perfect and balanced contact of at least four electrodes to work properly. The Wilson Central Terminal has received scant research attention in the last few decades even though consideration of recent widespread medical practice (limb electrodes are repositioned closer to the torso for resting electrocardiography) has also sparkled concerns about the validity and diagnostic fitness of leads not referred to the Wilson Central Terminal. Using a true unipolar electrocardiography device capable of precisely measuring the Wilson Central Terminal, we show its unpredictable variability during the cardiac cycle and confirm that the integrity of cardinal leads is compromised as well as the Wilson Central Terminal when limb electrodes are placed close to the torso.

On the “Zero of Potential of the Electric Field Produced by the Heart Beat”. A Machine Capable of Estimating this Underlying Persistent Error in Electrocardiography

“…In order to preserve the mentioned characteristics, the printed circuit board is designed to take advantage of the embedded active guard ring amplifier on a Teflon substrate. Although the guard ring amplifier's primary job is to reduce the noise pick-up at cable and board connections, because this offers a replica of the input signal, we also use it to measure the raw voltage of the WCT components [17][18][19][20].…”

“…As noted in Figure 2, the circuit includes a modified voltage bootstrap circuitry [18,20,[26][27][28]] that directly drives the reference voltage of the circuit with a damped version of the average of all the electrodes. This solution proved successful in all of our past circuit implementations [18,20,29], particularly when the right-leg connection is included in the average. However, for this implementation we introduced a driven-right-leg circuitry designed and dimensioned to contain current drive to 20 µA [8,30,31].…”

“…In addition, we assessed the point to point correlation between limb leads reconstructed using the limb components and limb leads that are recorded directly. To reconstruct the limbs, we simply operated a point by point subtraction between recorded signals and assessed the correlation between signals using the embedded MATLAB correlation function [19,20].…”

Capturing Electrocardiogram Signals from Chairs by Multiple Capacitively Coupled Unipolar Electrodes

“…Koichi Mizukami et al [ 23 ] recorded two-channel 24-h Holter ECG with unipolar leads (V1 and V2) and aimed to estimate the ST segment during the daily life. Gargiulo et al [ 22 , 24 , 25 , 26 ] introduced a nine-channel unipolar ECG system. The front-end circuits are designed based on the voltage supply bootstrap technology.…”

Chest‐lead ST‐J amplitudes using arm electrodes as reference instead of the Wilson central terminal in smartphone ECG applications: Influence on ST‐elevation myocardial infarction criteria fulfillment

“…When recording the conventional 12-lead ECG, the chest leads are created by subtracting the potential at the socalled Wilson central terminal (WCT) from the potential at each chest electrode (C1, …, C6). The WCT is the average potential of the three limb potentials, R, L, and F (Gargiulo, 2015;Kligfield et al, 2007). In the smartphone 12-lead ECG application, the right or the left arm is used as reference instead of the WCT (Baquero, Banchs, Ahmed, Naccarelli, & Luck, 2015;Muhlestein et al, 2015).…”