Which statement about Einthoven's triangle is true?

Which statement about Einthoven's triangle is true?

• A. It is formed by the chest leads V1-V6
• B. It is formed by the augmented limb leads aVR, aVL, aVF
• C. The bipolar limb leads I, II, III form the triangle
• D. It is formed by the precordial leads V1-V6 in conjunction with limb leads

Answer: (C)

Einthoven's triangle is defined by the three standard limb leads that are bipolar and placed on the arms and leg, forming a triangle around the heart in the frontal plane. These three leads measure the heart’s electrical dipole from three different angles: between the right and left arms (lead I), between the left leg and the right arm (lead II), and between the left leg and the left arm (lead III). This setup projects the heart’s electrical activity onto the frontal plane and is what the triangle represents. The augmented limb leads (aVR, aVL, aVF) are unipolar views derived from the same limb electrodes, but they do not define the triangle. The precordial leads (V1–V6) are placed on the chest to view the heart from an anterior perspective and likewise do not form Einthoven's triangle.

Einthoven's triangle is defined by the three standard limb leads that are bipolar and placed on the arms and leg, forming a triangle around the heart in the frontal plane. These three leads measure the heart’s electrical dipole from three different angles: between the right and left arms (lead I), between the left leg and the right arm (lead II), and between the left leg and the left arm (lead III). This setup projects the heart’s electrical activity onto the frontal plane and is what the triangle represents.

The augmented limb leads (aVR, aVL, aVF) are unipolar views derived from the same limb electrodes, but they do not define the triangle. The precordial leads (V1–V6) are placed on the chest to view the heart from an anterior perspective and likewise do not form Einthoven's triangle.