12 lead ECG placement - a simple guide

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For researchers, it is vital to capture clear ECG/EKG signals in order to gain accurate insights and results.

Electrocardiography (ECG or EKG) studies the heart's electrical activity produced during myocardial contraction and relaxation, usually recorded by electrodes on the skin. ECG/EKG signals are recorded to examine heart rate, heart rate variability, analysis of the waveform morphology, arrhythmia, and other similar functions.

But it can be a real challenge to record clean signals, especially when performing a 12-lead ECG. There are numerous elements to get right: the data recording equipment needs to be set up correctly, the subject needs to be comfortable, and you need to position the surface electrodes on the subject's torso and limbs precisely in order to get results that you can interpret accurately. 

Related: The equipment you need to record and analyze ECG/EKG data for cardiovascular research in human subjects 

Simple steps for the correct placement of electrodes for a 12 lead ECG/EKG:

Prepare the skin

Before placing your electrodes, it is very important to prepare the subject's skin by wiping the chest area thoroughly with skin cleansing (alcohol) swabs. This removes any oil that may be on the skin and which can cause drift in your ECG/EKG signals.

Once the skin is clean, find and mark the placements for the electrodes...

Identify V1 and V2

First, find the correct placement for the chest leads, starting with V1 and V2. 

It is especially important to correctly place V1 and V2 because the remaining chest leads are placed in relation to these.

To determine the placement of V1 and V2, feel to identify the top of your subject's sternum. Approximately 4 centimeters below this, there is a ridge. This identifies the second intercostal space. Feeling down, you will come across the third and fourth intercostal spaces. Use a skin-safe marker to mark the fourth intercostal space as V2.

Mark V1 in the mirror position on the opposite side of the chest. 

Next, find and mark V3 - V6

First, identify V4 and V6, then fill in V3 and V5 as outlined below...

V4 can be found one intercostal space lower than V2, in line with the middle of the clavicle. Mark V4 with your skin safe marker.

Next, track along the torso to the subject's left to find V6 at mid auxiliary on the same level as V4. Mark V6.

V5 can be marked at midway between V4 and V6. 

Likewise, mark V3 midway between V2 and V4.

You should now have 6 marks for V1 to V6.

Apply electrodes to the chest at V1 - V6

Apply your electrodes to your 6 marks!

Connect wires from V1 to V6 to the recording device

The 6 electrode wires can now be connected to your recording device. In this case, we are using ADInstruments' Octal Bio Amp and connect the wires to channels 1 through to 6.

Apply limb leads 

Apply lead 1 to the left arm. We suggest the front of the left shoulder in a place where there is little muscle or muscle movement, to avoid any EMG signal disturbance.

Next, apply lead 2 to the right arm. Again, the front of the shoulder is suggested here, in a place with little or no muscle or movement.

Then connect the left leg. Place the electrode slightly above the ankle. This electrode is the reference for all of the augmented leads.

Finally, apply the "common" on the right-hand side ankle. This connects to the ground input on your recording device (Octal Bio Amp).

Connect the limb leads to your recording device and test you are receiving a signal.

To see a short video and guide on the end to end process of setting up equipment and recording signals for a 12-lead ECG using the Octal Bio Amp and Cardiac Axis calculator from ADInstruments, please click through here

Related: Equipment guide for ECG/EKG recording and analysis in human subjects

How can ADInstruments help with my ECG/EKG research? 

ADInstruments offer a range of Bio Amps for recording ECG/EKG signals that are tested and certified for use in human subjects. Our Bio Amps interface seamlessly with PowerLab and LabChart forming a streamlined ECG/EKG acquisition and analysis system.

For ECG/EKG recording, our single, dual, and octal Bio Amps are tested to meet the standards for certified patient isolation.

Record and analyze your ECG/EKG data within a single, streamlined system. Bio Amps interface seamlessly with PowerLab for high-quality signal acquisition, with data flowing directly into LabChart for analysis, with specialized features and modules including the ECG Analysis Add-On and Heart Rate Variability Add-On designed for the analysis of signals from humans. 

LabChart software is designed specifically for life science data and provides up to 32 channels for data display and analysis options that are powerful and easy to use. With auto-recognition of ADI and LabChart Compatible hardware, multi-window views, one-touch recording, simultaneous recording from multiple devices, specialized preconfigured settings, easy sharing options, and an interface that can be customized to show only the features you want to use.

All of our hardware recommended for human use is backed by the appropriate safety certification standards. More information on safety standards.