12-Lead Home ECG Monitor?

12-lead ECG monitor is standard in medical facilities for getting the electrical activities generated by a heart. Each lead refers to a perspective of the cardiac electrical activity from a given angle. As the cardiac electrical signal is 3 dimensional and multiple leads are required to get an accurate picture for diagnostic purpose. The ECG waveform can reveal the heart's condition, including irregular heartbeats, damage to heart muscle, and heart enlargement. A 12-lead EKG machine uses 10 electrodes to capture 12 leads (signals).

Home ECG monitors have become affordable and available lately. For cost reasons, they only have 2-3 electrodes and can only capture one single lead at a time. However by placing the electrodes at appropriate locations on the body, home EKG machines can simulate a 12-lead EKG monitor by capturing data one lead at a time.

See What is ECG to get a more detailed description on the 12 ECG leads.

Different ECG monitor manufacturers may have different configurations. Here we use the Choice MD100A12 as a reference. MD100A12 uses a 3-electrode cable, labeled LA (positive), RA (negative), and LL (ground) respectively.

Electrodes placement

The following table lists the electrode placements for the 12 leads.

Body Positions

• RA² - right arm
• LA² - left arm
• RL² - right leg
• LL² - left leg
• v1 - v6 (see diagram below)

¹ Put two electrodes at the indicated locations and connect them together via a cable.

² Limb electrode (RA, LA, LL, RL) can be placed anywhere on the limb as long as it is at least 4 inches away from the heart.