Applying 12 Lead ECG

Hi there. I need some help with 12 Leads. Specifically, how to know where to apply them. A few Medics have told me that you start in the 4th intercostal space to the right and left of the sternum for V1/V2. They said you then go for V4 which is located in the 5th intercostal space, in the mid clavicular line (which happens to be right under the nipple line). Then V3 is placed between V2/V4 effectively making it located on the 5th Intercostal. Then you place V6 which is Mid Axillary, 5th intercostal space. V5 is then placed between V4 and V6.

My question is - memorizing the placements are pretty easy, but I'm finding it hard to make sure I'm located in the right spots. Palpating someone's thoracic cavity is often time consuming when I'm looking for the right spots - and I always see other Medics just slapping the leads on so quickly, how?

What is the best way to ensure you're placing the leads in the correct position? How do they locate the correct intercostal spaces so quickly? I want to be proficient when it comes to starting a 12 lead but am not sure how to quickly palpate and locate the lead placements.

They're guesstimating. There's nothing scientific about it.

STXmedic said:

They're guesstimating. There's nothing scientific about it.

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And that's okay? As long as you're close it doesn't matter?

Ideally, for a true diagnostic 12 lead, you want to be in the correct spot, and you don't want the leads placed over bone. With that said, I'd be lying if I said I palpated every time. For patients that I'm actually suspicious of a STEMI, I'm more cognizant of positioning. I've never noticed a significant difference in quality though. Maybe @Aprz can chime in with how much effect minor changes in positioning (as in leads not directly over the intercostal space) has on the tracing.

I'm not sure why it would be hard to feel the intercostal space unless the patient was very obese. You can even see it in some people that are thin. In the end, I don't think they need to be perfectly placed. Minor positional change will result in minor ECG changes. The most common issue I am aware of with the precordial leads being misplaced is lead V1 and V2 being placed an intercostal space too high. This is usually recognizeable on the ECG as a pseudo right bundle branch block pattern, an rSr' wave in lead V1. I am usually unfazed by this change when I see it (other than might consider the possibility of right ventricular (RV) strain pattern, but I consider "the company it keeps" with the rest of the ECG and the patient's symptoms). I've never read anything about misplacement of V3, but some people (eg Amal Mattu) do use that as a key lead for anterior wall MIs and poor R-wave progression (using the rule RV3 <3 mm in ECG for Emergency Physicans 1 & 2). It is mostly a useless lead by itself.

Check out this simulator you can use to see what a normal ECG looks like and how it compares when you misplace the leads. You'll see how minor/insignificant the changes are when you only slightly move the leads. Even the whole limb leads need to be on the limb is a bit overrated in my opinion. When placed on the torso, it causes very slight rightward axis with very slight change of amplitudes in the precordial leads. Most people don't even consider axis or struggle with it.

http://scm.ulster.ac.uk/~scmresearch/bond/marriott/

Aprz said:

Check out this simulator you can use to see what a normal ECG looks like and how it compares when you misplace the leads. You'll see how minor/insignificant the changes are when you only slightly move the leads. Even the whole limb leads need to be on the limb is a bit overrated in my opinion. When placed on the torso, it causes very slight rightward axis with very slight change of amplitudes in the precordial leads. Most people don't even consider axis or struggle with it.

http://scm.ulster.ac.uk/~scmresearch/bond/marriott/

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Wow, that's worth a bookmark!

STXmedic said:

Ideally, for a true diagnostic 12 lead, you want to be in the correct spot, and you don't want the leads placed over bone. With that said, I'd be lying if I said I palpated every time. For patients that I'm actually suspicious of a STEMI, I'm more cognizant of positioning. I've never noticed a significant difference in quality though. Maybe @Aprz can chime in with how much effect minor changes in positioning (as in leads not directly over the intercostal space) has on the tracing.

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Exactly.

Just don't go changing the lead placements and then compare the two EKGs for changes.

Dylan1105 said:

And that's okay? As long as you're close it doesn't matter?

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You'll get artifacts on the chart, and then either correct it or adjust interpretation. Once you've done it a few dozen times, you won't think about it anymore.

Good question. I guess I'll add my 2 cents. I've worked ambulance and ER. When doing an EKG in triage or the ER I liked placing the limb leads on the meaty part of the deltoids and the upper thigh. I did this mainly to eliminate artifact because the patient won't stop talking with their hands and sit still. The range of motion of the deltoid and upper thigh is a lot less than the range of motion of the wrists and ankles. I honestly don't know how much of a difference this will make on an EKG, I'll do some research on what Aprz said about the right axis shift.
Now I know the ER is a much more controlled environment than out in the field or ambulance work. Lots of other factors come into play. A patient who's shivering, a patient who's seizing, a patient who overdosed, a patient who's wet, a patient who's neurotic and mental and will not stop fidgeting. I've had much more luck using the deltoids and upper thighs getting an EKG in any of the situations mentioned above than I had placing the leads on the wrists and ankles.

PS. If you work ER and you get that tiny, 90lb grandma from the nursing home in the middle of the night and she's freezing cold, because that's just a biological law once you reach old age, strip her naked, put on her gown, put on all your EKG leads, then cover her with those warm blankets from the blanket warmer. Now wait 30 seconds. You should have no artifact, no movement, no shivering, a beautiful EKG and you just became her best friend.

I uploaded a video of correct lead placement here:


Tom