Bipolar Leads utilize one positive and one negative electrode and produce sufficient voltage to be seen on the monitor.
Unipolar Leads utilize one positive electrode but instead of one negative electrode, a negative area, or field, is created from multiple negative electrodes.
The lower voltage produced with Unipolar Leads, needs to be amplified or augmented.
Voltage augmentation is noted in the Unipolar Lead prefix of "aV", such as aVR which means Augmented Voltage Right arm.