(lēd)
[Old English laedan, to guide]

1. Insulated wires connecting a monitoring or pacemaking device to a patient.
2. A conductor attached to an electrocardiograph. The three limb leads are lead I, right arm to left arm; lead II, right arm to left leg; lead III, left arm to left leg. These are also known as standard leads, bipolar limb leads, or indirect leads.
SEE: electrocardiogram for illus

abandoned lead

A lead that has been left inside the body after the device that controls it has been removed.

bipolar lead

In electrocardiography, any lead that consists of one electrode at one body site and another at a different site. A standard limb lead, I, II, or III, is a bipolar lead.

esophageal lead

An ECG lead that is placed in the esophagus.

limb lead

Any lead, unipolar or bipolar, in which a limb is the location of one of the electrodes.

precordial lead

A lead having one electrode placed over the precordium, the other over an indifferent region.

unipolar lead

An electrocardiographic lead in which one electrode is placed over the precordium, and the other over a different region of the body, e.g., a leg or the lower abdomen.