What is a 12 lead Electrocardiogram and how does it work?

The most common EKG test is a 12-lead electrocardiogram.

It is performed by placing ten electrodes for EKGs on specific parts of the body.

These ten electrodes enable the measurement of the heart’s electrical potential along twelve different pathways – hence the name,12 lead EKG.

The term lead here refers to each pathway between a pair of electrodes
that are measured to generate the EKG reading.

It does not, as is commonly perceived,
refer to the wires that run from the electrodes to the EKG machine or the electrodes for EKG themselves.


Therefore, the placement of ten electrodes actually provide as with twelve different pictures of the activity of the heart.

What is a 12-lead Electrocardiogram







How are the twelve leads generated?


Six of the pathways or leads are generated from each of the precordial chest electrodes that are placed across the torso for a view of the heart from a horizontal plane.

  • V1 and V2 give a septal view of the heart
  • V3 and V4 provide an anterior view
  • V5 and V6 give us a lateral view of the heart.


The other six pathways involve the limb electrodes and give a view of the heart from a vertical plane.

  • Lead I between the Right Arm and Left Arm – Lateral view
  • Lead II between the Right Arm and Left Leg – Inferior view
  • Lead III between the Left Arm and Left Leg – Inferior view
  • aVR between the Left Arm/Left Leg and Right Arm – None
  • aVL between the Right Arm/Left Leg and Left Arm – Lateral view
  • aVF between the Right Arm/Left Arm and Left Leg – Inferior view


The Allbrand 12 Lead EKG Electrodes Belt has been purposefully designed to make sure that it is as easy and reliable as possible to ensure the correct placement of each of these electrodes for a 12-Lead EKG test.

The silicon belt itself is a simple way to place the six precordial electrodes in their correct position – both on the chest and in relation to each other.

By stretching the belt across the chest in accordance with the size of the patient’s torso,

each of the precordial electrodes will be positioned correctly.

There is no possibility of inverting the electrodes because they are built into the belt and they can be pre-connected to the wires from the EKG machine according to the standard color-coding.


The belt is also supplied with four color-coded limb clamps which are designed for the easy application of the electrodes for EKG to the ankles and wrists to form the 3 bipolar limb leads and 3 augmented unipolar limb leads.

Together with the belt, the correct placement of the ten electrodes for the 12-lead EKG test is simple,

straightforward and foolproof.