When setting up stand ard limb leads, you’ll place electrodes in positions commonly referred to as Einthoven’s triangle, shown here. The electrodes for leads I, II, and III are about equidistant from the heart and form an equilateral triangle. Axes The axis of lead I extends from shoulder to shoulder, with the right-arm electrode being the negative electrode and the left-arm electrode the positive electrode. The axis of lead II runs from the negative right-arm electrode to the positive left-leg electrode. The axis of lead III extends from the negative left-arm electrode to the positive left-leg electrode. |