What is this article about?
An electrocardiogram, or ECG, is a reading assessing the magnitude and direction of the electrical currents of the heart, and measuring the depolarisation and repolarisation of the cardiac muscle cells. It is important that an ECG is recorded accurately. ECG electrode placement is standardised, allowing for the recording of an accurate trace - but also ensuring comparability between records taken at different times. Poor electrode placement can result in mistaken interpretation, which may then lead to possible misdiagnosis, patient mismanagement or inappropriate procedures. Deviation of lead placement even by 20-25mm from the correct position can create clinically significant changes on the ECG, including changes to the ST-segment.
Learning you'll love
An Ausmed Subscription will unlock access to 1,000+ learning resources. High quality education helps you provide high quality care.
Contents
Document and reflect on your learning
- 4m of CPD
References
Clinical guidelines by consensus: recording a standard 12-lead electrocardiogram. An approved method by the Society for Cardiological Science and Technology (SCST). 2017. //tinyurl.com/y9l265eu (accessed 11 June 2019)
Davey P. ECG at a glance.Oxford: Wiley-Blackwell; 2008
Garcia TB. 12-lead ECG: the art of interpretation, 2nd edn. Burlington (MA): Jones & Bartlett Learning; 2015
Jevon P. ECGs for nurses, 2nd edn. Oxford: Wiley-Blackwell; 2009
National Institute for Health and Care Excellence. Remote ECG interpretation consultancy services for cardiovascular disease. NICE Medtech innovation briefing 152. 2018. //www.nice.org.uk/advice/mib152/ (accessed 11 June 2019)
Nursing and Midwifery Council. The code: professional standards of practice and behaviour for nurses, midwives and nursing associates. 2018. //tinyurl.com/gozgmtm (accessed 11 June 2019)
02 June 2019
The 12-lead ECG electrode placement is essential for paramedics and EMTs in both prehospital and hospital setting as incorrect placement can lead to false diagnosis of infarction or negatively change the EKG.
Proper 12-Lead ECG Placement
Now that we have our 4-leads straight, let’s talk about where your precordial leads will go. Everyone slaps them on below the breast and sometimes below the entire rib cage. That is completely unacceptable! Below is a bullet point list for each lead, a description of where they go, and the order they should be applied.
| ELECTRODE | PLACEMENT |
| V1 | 4th Intercostal space to the right of the sternum |
| V2 | 4th Intercostal space to the left of the sternum |
| V3 | Midway between V2 and V4 |
| V4 | 5th Intercostal space at the midclavicular line |
| V5 | Anterior axillary line at the same level as V4 |
| V6 | Midaxillary line at the same level as V4 and V5 |
| RL | Anywhere above the right ankle and below the torso |
| RA | Anywhere between the right shoulder and the wrist |
| LL | Anywhere above the left ankle and below the torso |
| LA | Anywhere between the left shoulder and the wrist |
Aside from a 12-lead ECG placement, there’s something known as a 15-lead placement which includes placing leads V4-V6 on the posterior side of the patient below their left scapula (see below). When viewing the EKG strip, V4-V6 on the strip will be referred to as V-13-15. To clarify, leads will equal: V4=V7, V5=V8, and V6=V9.
Lastly, a right sided 12-lead ECG placement allows you to detect a right sided infarct. At a minimum, lead V4 should be placed on the 5th intercostal, mid-clavicular (exact opposite of the regular left side placement) if an inferior infarct was originally seen in leads II, III, and AVF.
These give you more views of the heart and can help inform your treatment plans. For instance, you never want to give nitroglycerin if you see an inferior infarct until after performing a right-sided EKG. You can view these and other helpful diagrams.
Electrode Misplacement
- Up to 50 percent of cases have V1 and V2 in too high of a location which can mimic an anterior MI and cause T wave inversion. This article explains how to properly find the intercostal spaces and where to place the electrodes.
- Up to 33 percent of the cases have the precordial electrodes (V1-V6) lower or laterally misplaced which also leads to misdiagnosis.
12-Lead ECG Electrode Placement Explained
One of the most common questions related to 12-lead ECG electrode placement is why there are only 10 electrodes. It’s very important to understand what the term “lead” really means. A lead is a view of electrical activity of the heart from a specific angle across the body. So, even though you only have 10 leads, you are actually getting 12 views from different angles. Cables and Sensors does a great job explaining more of the morphology, vertical plane, and Einthoven’s Triangle.
Best Practices For 12-Lead ECG Electrode Placement
- Counting intercostals – When counting down to the 4th intercostal, it’s helpful to know that the 1st intercostal space is the space right below the clavicle.
- Clean surfaces – For our patients who seem adverse to hygiene, it’s important to clean the surface of dead tissue to get an accurate EKG reading. Taking a 4×4 of gauze and aggressively rubbing the area until it is pink will do the trick.
- The breast – Often times, the 5th intercostal space is about nipple line. On a guy, that’s ok, it doesn’t have have to be below the breast contrary to popular belief. Only for women with large breasts do we need to alter our placement and place the leads in the crest underneath the breast. This is because there is too much tissue to get a clear reading
- Look at trending – it’s recommended to get a baseline before giving oxygen or other medication and then performing multiple EKGs to see any how the patient is trending.
Reducing Artifact
The heart’s electrical signal has very little output, so it can easily be combined with other signals of identical frequency to create artifact. It is not uncommon to have some form of artifact for a 12-lead ECG placement but it’s important to attempt to lessen any interference in order to ensure an accurate EKG. The following are a few guidelines that are very helpful to reduce artifact while performing EKG’s.
- Place patient in a supine position if the patient will tolerate.
- Place the patient’s arms down by their side to relax their shoulders.
- Patient’s legs should be uncrossed.
- Electrical devices such as mobile phones should be away from the patient as these devices may interfere with the machine.
- Dry the skin if it is diaphoretic or moist.
- Shave any hair that can interfere with electrode placement.
- Electrode gel should be moist.
- Electrodes should not be placed over bones and over areas where there is a lot of muscle movement.
- Sometimes an abrasive material such as a wash cloth may need to be used to remove dead skin cells.
- Chris Kaiser makes a good point
I hope this was a helpful review and that all of you will take it to “heart”. These are things we regularly go over in our ACLS and PALS classes. If you have comments or additions to what we covered, please let us know in the comments section below. If you’re looking for other great guides, check out what we wrote for using waveform capnography in cardiac arrest.
Prime Medical Training provides life-saving training taught by real emergency responders. You can view our current locations where we have regularly scheduled classes, or request for us to do on-site training at your location.