4 limb electrodes are used to view the frontal plane: RA, LA, LL, RL. These electrodes are used to produce the ___ ____ ___. I, II, III. All of these are bipolar leads.

4 limb electrodes are used to view the frontal plane: RA, LA, LL, RL. These electrodes are used to produce the ___ ____ ___. I, II, III. All of these are bipolar leads.

• A. Standard Limb Leads
• B. Precordial Leads
• C. Unipolar Leads
• D. Central Terminal Leads

Answer: (A)

The limb leads that view the frontal plane are formed from the four limb electrodes (right arm, left arm, left leg, and right leg as ground). Each lead is a voltage difference between two distinct electrodes, so these standard limb leads are bipolar. Specifically, Lead I compares the left arm to the right arm, Lead II compares the left leg to the right arm, and Lead III compares the left leg to the left arm. That frontal-plane view using these two-electrode differences matches what’s described. The chest (precordial) leads, by contrast, view the horizontal plane and are not part of this set. The augmented limb leads (aVR, aVL, aVF) are unipolar leads derived from the same limb electrodes using a central terminal reference, which is why they’re not considered part of the standard limb leads. Grounding with the RL electrode is not one of the measuring pairs, but it’s used for stabilization. So the correct designation for these measurements is Standard Limb Leads.