Einthoven’s triangle

Figure 10.5 Einthoven s triangle. The triangle is in the frontal plane of the patient, m is the heart vector bound to the center of the heart u is the instantaneous scalar voltage measured in a respective lead a is the instantaneous angle of the electric axis of the heart.

The axes of the three bipolar limb leads (I, II, and III) form a shape known as Einthoven s triangle. Because the electrodes for these leads are about equidistant from the heart, the triangle is equilateral. 

The three limb leads I, II and III combine to form the bipolar leads. By bipolar we mean that the lead has both a positive and negative pole. Willem Einthoven established this standardised lead system, which was named after him, called Einthoven s Triangle (Fig. 2.4). Different electrode positions were also tested but produced little or no measurable results in comparison. 

Einthoven s electrode placement has been adopted and standardized into the ECG Lead system known as the Einthoven triangle and is shown in Fig. 17.38. Electric potential differences are measured between the three limb electrodes along the line between the electrode placements, and their potentials are called lead I, n, and III such that... 

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