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Guide To 12-Lead ECG Placement

By January 1, 2023January 2nd, 202342 Comments

Talk to my EMT partner about my biggest pet peeve, and aside from the lack of professionalism in the EMS industry, he’ll tell you I can’t stand people who do not know or practice proper 12-lead ECG placement. I’ve been in EMS for 5 years, and I’m sad to say I have never once seen someone apply a 12-lead properly. Don’t believe me? Just search “12-lead placement” in Google Images after reading this post and you’ll see that almost everyone is guilty.

What is an ECG?

An ECG stands for electrocardiogram. It is a tool used to detect a wide range of heart dysrhythmias using waveforms on a monitor. It is used by healthcare providers regularly both in the hospital and by EMS.

Why Is 12-Lead ECG Placement Important?

This is a big deal to me because I have on two occasions moved the someone else’s 12-lead ECG placement and identified a STEMI that was not visible with the original placement. On the flip side, recently I found a huge STEMI and when I got to the main heart hospital, the tech took my leads, moved them down, and couldn’t see the STEMI.

It’s terrible patient care! These patients sit in the ED for hours while they wait for their lab work to come back. Only then do they realize they’re having a heart attack. A lot of times this could be avoided if the 12-lead was performed properly and the STEMI was identified on the first go-around.

It takes literally less than 30 seconds to find the correct position for a 12-lead ECG placement! By the way, did you know that if your electrodes are off by 2 centimeters that it can completely skew your EKG morphology?

4-Lead Placement

Before we can get to placing our precordial leads, we need to know where our 4-lead goes. Ever heard 4-leads referred to as “limb leads”? There’s a reason for that. These leads are not suppose to go anywhere on the torso. It’s not as big of a deal if you’re only doing a 4-lead, but doing so when you’re going to put the precordial leads on will alter the morphology of your EKG.

Limb leads can be placed on any part of the patient’s respective limbs. Just make sure the leads are symmetrical. For example, don’t put one lead on the left shoulder and the other lead on the right forearm. I’ve heard of one local doctor that preferred all 4 leads to be placed relatively equal distances distally. For example, if you put leads on the wrists, then leads should also go on the ankles. I haven’t found anything to back that, but that’s at least one professional’s theory.

4 lead ecg placement

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.

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

12 lead ecg placement

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.

posterior 15-lead placement

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.

Righ Side 12-lead placement

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.

12 lead ecg vectors

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.


  • Peter Beshay says:

    Thanks for this outstanding quick review
    But I do have couple of questions, please:
    * How to reduce artifacts in a patient with Parkinsonism disease??
    * What is the best position to stand regarding the patient when placing the 12-lead EKG electrodes? Is it to the right or the left of the patient?

    • Andrew Randazzo says:

      Hey Peter, I appreciate the feedback.
      1) Parkinsons is a challenge for sure. There are two options. A) You can sedate the person to diminish the shaking. B) If the shaking is not severe, you can have a few people physically put their hands on the electrodes and hold down firmly which will help lessen the artifact.
      2) There’s no wrong or right place to stand when placing the 12-lead EKG electrodes. Since the leads generally go on the left side of the chest, I suppose it could be slightly easier to stand on the left side to prevent reaching across the patient.



  • Jack says:

    I really like your review and commentary. I have worked in an ekg department for 16 years and very often find leads for V1 and V2 near the clavicle, or any place in between.
    As of late, I find myself asking various physicians, if ekg’s really make a difference. Because, in our hospital, I find such variations in quality of placement, as well as quality of tracing, and there is no one taking charge.
    As you know, when a patient is in the middle of a code or stat situation, it is hard enough to get to a patient, let alone, follow normal procedure. So I have learned, if I need to, to do an ekg, by sight. Experience helps. But there are times, I am asked to do an ekg, while the patient is upright, or laying on either side, or shaking so hard, it is almost impossible to get a decent tracing.
    So what I usually do, is just get the best tracing I can and relate the change of position, to the reading doctor and make note on the ekg.
    It frustrates me to occasionally have a less than clear ekg.
    These are the times I find myself asking questions, but cannot really get any clear answers. So I will investigate your web site and see, if I can pass on what I learn to my supervisor.
    Thanks again, for a great intro.

    • Andrew Randazzo says:

      Jack, you draw out a good point. Medicine can often be related to working in less than ideal conditions. Experience does help with efficiency, though. That’s a great suggestion to make notes on the EKG about any interferences or less-than-desirable conditions. Thanks for the input.

  • Angela says:

    I was at my physicians office upset due to misdiagnosis and lack of empathy and ability to listen to me, I bacame very upset and I spoke to Manager for about an hour then as I was going to leave I didnt feel well my chest was ice cold my left arm tprwards the back shoukder hurt I explain this to them as I first arrived to office blood pressure was high after the discussion of dr not listening it was extremley higher they offered oxygen and I said I had horrible headache and that most likely call an ambulance doctor came in a few seconds and poped a pill in my mouth I dont know what it was all I remember is it me e my mouth very dry and I hurt and was stiff all over. Dr called ambulance and didnt tell them she had given me any pill then paramedics placed the leads incorrecly after correcting this only a few short minutes they were done. They said nothing to me and I was unable to drive I left my car at dr parking lot. I noticed the placing of the sticky pads were on odd places I’ve had ekg done before. So it os on my collar bone exacly and the lower ones are on my fold of fat seens I’m obese. Many hours later dr calls to tell me the hospital told her that it was inaccurate results because I was moving. What? I couldnt move and I was given oxygen while this test is being done. They were the ones who continued to laugh joke around and keep talking.
    I’m speaking to an Attorney about this because there is no way Im paying them ofcourse they already billed my insurance the highest imaginable cost for NO RESULTS! THEYRE MISDOAGNOSIS I FEEL VERY ILL BEEN IN BED ALL DAY AFTER MY FRIEND DROPED ME OFF!

  • Janet Nnabuife says:

    So sorry Angela

  • Cindy Manson says:

    Hi there. I am cardiac RN that works with nuclear stress testing. During the stress portion, the patient is connected to a 12 lead EKG monitoring system and an EKG is printed every minute of the 4 minute test. The result is dependent on the imaging from the Spect-CT camera read by the radiologists (in our hospital) and the cardiologists dictate the 4 minute injection portion (we use regadenoson). My question is, how critical is lead placement? I know where they go, but the EKG techs insist that the nurses arent placing EXACTLY 4th intercostal space etc.. our patches may be 1/4 inch off or I may place the leg limb lead on the abdomen, where the EKG tech may place it on the ribs. Again, the patient is discharged and or diagnosed dependent on the imaging portion, not the EKG tracings. For example, the cardiologist may not even dictate for weeks after the patient is discharged. Thank you for taking the time to read this and answer, Its a long one

    • Andrew Randazzo says:

      Hi Cindy. Good questions. Lead placement can be pretty critical even if you’re 1/4 inch off. If you happen to place a lead over a rib vs the intercostal space, that can affect what you see. Also, it’s important to put limb leads on the limbs especially when performing a 12-lead because having all the leads so close together can cause electro-interference. Hope that helps.

      • Dennis says:

        If we are to put lead 1 and 2 over the 4th intercostal space and 4 in the 5th, doesn’t lead 3 go directly over the rib?

        • Andrew Randazzo says:

          Hey Dennis, that’s a very insightful question. You don’t find any answers online about exact placement of V3. Most people do put it on the rib directly between V2 and V4. I would recommend putting V3 on the 5th intercostal centered between V2 and V4. That should more than sufficiently capture the anterior part of the heart.



  • Maria del Mar Sanchez Sanchez says:

    Good Morning,
    My name is Mar Sánchez, Intensive Care nurse. The other day I had to make an EKG to a patient in prone (severe respiratory distress). How would you place the leads from V1 to V6? Thank you

  • rashad bahnasy says:

    very useful informations.
    thank you

  • Dania Emad says:

    Hi, ı wanna thank you for these simple informations . ı want to ask how much the removing of dead skin cells is effcient in increase the ecg’s quality ?

    • Andrew Randazzo says:

      The answer is that it depends. On some patients it hasn’t made any difference for me, and in a few it makes a big difference.

  • Brian Aeschliman says:

    I have been a pre hospital provider for 26 years 18 of them as a paramedic. I have also been a nurse for nine years in the ED, flight, and now as an educator. 12 lead placement has been a never-ending topic of debate when it comes to the placement of V3-V6 on large breasted females. Nearly everyone says that leads should be placed under the breast of females. For years in the prehospital world as well as all of my time in the hospital, we have taught an exception to that rule.
    In the case of extremely large breasted females, if the 5th intercostal space can be clearly palpated above the breast then that is where the leads are to be placed. “It is bones not boobs” that determine lead placement. We know that breast tissue is not a superconductor of electricity however; we go back to the bones guiding us. If the 5th intercostal space can be clearly palpated above the breast then there should be no more tissue interfering with the electrical activity then there is on a male.
    As an argument say that I can clearly feel the 5th intercostal space and I still choose to place the leads under the breast. How far out of place, do you think the leads are now? A 12 lead serves as a diagnostic test. Results are based upon the machines interpretation and the machine has asked for specific placement. However, as an educator I want to teach what is best for the patient so I ask, is it bones or boobs?

    • Andrew Randazzo says:

      Great comment, Brian. It’s hands down bone every time. Especially on older female patient’s who’s breasts are sagging. You can easily palpate the 5th intercostal. All too often, providers do not think about the “why” of what they’re doing and default to doing the same thing (placing electrodes under the breast) every time.

  • Angela says:

    Your guide says the first intercostal space is directly below the clavicle. I was taught this is the subclavicular space and should not be confused with and mistakenly counted as the first intercostal space. Now, I’m confused.

    • Andrew Randazzo says:

      Great question. Honestly, I can’t answer that. Where does the subclavicular space end and the 1st intercostal space begin? Maybe we’re just splitting hairs?

  • Will says:

    Thanks for the article! Just a note on limb lead placement – it can vary depending on your equipment, so it’s important to know what you’re using. The Phillips MRx manual, for example, recommends placement of RL and LL on the inferior/lateral abdomen, and RA/LA laterally and inferior to the clavicle.

  • Tasneem says:

    is it ok if the nurse holds down one of the leads on a 12 lead, because the gel glue came off? she held down the one on the left rib closest to my heart, would this give more deviations?

    thank you

    • Andrew Randazzo says:

      Holding electrodes down with your hand will not directly interfere with the ECG. The only kind of interference that could be caused is if they weren’t holding still which would cause artifact.

  • catherine heckman says:

    Why is it that the first ECG states “sinus sinus rhythm possible infarct abnormal ECG” and the second ECG taken immediately after the first with no change in electrode positions states “sinus rhythm normal ECG” ?

    • Andrew Randazzo says:

      There’s lots of variables. It could be artifact or the person has some occasional abnormalities in their ryhthm.

  • B Vanhoy says:

    Dear Sir I have been on this crusade for years. I am an Emergency nurse at major Level one trauma center , I have created training and it is so difficult to get others on board on this simple problme that means so much to patient care. would love to share your thoughts

  • Emma says:


    I am a 4th year engineering student trying to create a simple system to measure a infants heart rate. A 12 lead electrode would be excessive for my project as it needs to be integrated into a wearable sensor. Do you have any placement recommendations for a single electrode? It does not need to be extremely accurate as it’s not used for diagnosis, simply the parents peace of mind.

    Any suggestions would be appreciated. Thanks,

  • Sophonie Alphonse-Kouadio says:


    My name is Sophonie A-Kouadio i am in the CMA Program. I am currently working on my internship

  • jaidynn says:

    where would the 12 lead tracings be placed when working with a 3 channel ecg machine?

  • Harriet Akyeampong says:

    My name is Harriet Akyeampong, at the moment I am doing my Internship and my program is CMA. I have enjoyed the explanation of the 12-Lead EKG Replacement. It was very useful and insightful.

  • Allison says:

    My question is regarding the LE leads, are the patches supposed to point up or down? Should the lead clasp point down or circle around and point up? Or does it matter?

  • peter says:

    Congratulations on this website, this is really excellent information.
    I have a question regarding the 15-lead placement. There seems to be some conflicting information on the V4: most websources place V4 on the right thorax (V4R).
    You seem to place it on V7.
    Why is this? Who is right?

  • Ariana says:

    Question. When using the 12 lead ecg on a female. Can an bra with a underwire cause misreading due to electrode being in close proximity? Or is this a myth?

  • Brett Arron, MD says:

    Thank you for putting up this information. I concur correct EKG lead placement is an endemic problem, often haphazard. Placement does make a difference both for rate determination and ischemia detection. The EKG lead placement overlays specific cardiac regions. The heart position does not change with pendulous breasts, male or female. The EKG lead position should follow the bony rib landmarks and not determined by the location of the inframammary fold.

  • Dr T Al Musawi says:

    Thank you very much for these interesting ideas about ECG
    Have you please any image to show the full connection of the 12 leads of ECG in the body?
    Wish you all the best

  • Rosetta says:

    I have read some just right stuff here. Definiteloy price bookmarkinng for revisiting.

    I wonnder how much attempt yoou sset tto make thuis sort of maqgnificent informatige web

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