it was found that best information about the work done by the heart could be obtained by placing the electrodes along the axis line of the heart dipole polarity , and this corresponded to the negative electrode ( a red one ) of apex cordis -- vth and vist interrib space at the height behind the elbow processus , and to the positive electrode ( a yellow one ) of the front angle of the right and the left spadebone .
C0018787
heart
C0225811
apex cordis