The Form of the Electrocardiogram. III. Opposed Potential Differences

Abstract

At the onset of ventricular systole the excitation process is spreading within the ventricular muscle in many different directions simultaneously. Many of the electrical forces, or potential differences, produced are opposed by forces opposite in direction, and their effects are consequently neutralized. Other potential differences are not opposed; it is these potential differences and these alone which have an effect upon the electrocardiogram.Consider the simple strip of muscle AB (Fig. 1) immersed in a large body of physiological saline solution or other similar conducting material. Place one electrode at R, and a second electrode at S and connect these electrodes to a string galvanometer in such a way that relative negativity at R will cause an upward deflection when the electro gram of the muscle is recorded. Given that RX equals SX (Fig. 1). Stimulate this muscle at X; given that XA equals XY. It is obvious that the excitation process will spread toward A and toward Y simultaneously; that the potent...