It’s been a while since I’ve done a true “tips and tricks” post, and with new students these days not completely clear on the proper application of electrodes for a 12 lead, it seemed like a good place to pick up.
Now, some people think that the application of electrodes for 12 lead montoring isn’t important (you have probably seen what I call the “squared symbol” electrode placement of the precordial leads, or maybe the infamous “stomach leads” placement. Both of these are WRONG and will lead to a terrible 12 lead and an even worse interpretation. When your diagnosis determines transport speed, you may want a clear picture on which to base it from, especially if you transmit to the hospital en route.
So, the first step is to bare the chest. That’s right, take whatever is covering the chest and get it off. This will ensure you don’t have cables snag on clothing or clothing rubs off one of your leads during acquisition.
The next step is to prepare the chest area. In men, this may mean shaving and drying, in women, this may mean removal of the bar and placement of a hospital gown. I always try to grab a few gowns at the hospital for just this purpose. Remember, we may be having to work quickly, but we can always try and preserve modesty.
Most services will place a razor, either the cheap plastic ones or the electric ones, in the monitor for the purpose of shaving hair. In a pinch, you can get away with using a lead to tear the hair out, but it’s not too comfortable on the patient. My service also carries disposable wipes, I like to use them for drying a patient, but a towel or other dry cloth or paper towel will work fine.
Now you are ready for lead placement. Assuming the limb leads are attached appropriately (right arm on the arm, left leg on the leg, etc.) you can begin placing the precordial leads. If the patient can tolerate it, you should lay them supine. This will place the heart in it’s natural, neutral position without gravity pulling it out of position.
Lead V1 will go in the 4th intercostal space (the space between the 4th and 5th ribs) on the anterior chest to your left or the patient’s right. Similarly, lead V2 will go in the same place, just on your right or the patient’s left. You can locate the 4th intercostal space by palpating down the sternum starting from just under the collarbone. It is typically one or two spaces below the Angle of Luis.
This is where most new medics and students get confused. You place V4 BEFORE V3. Here’s why: V3 is supposed to go DIRECTLY between V4 and V2. With that said, where do we place V4?
It goes on the patient’s left midclavicular line in the 5th intercostal space. I remember this location by visualizing the intermammary line and palpate directly below it. This should be about the location of the 5th intercostal space. Now place V3 between V2 and V4.
Make sure that your leads are secured and that your limb leads are in the correct locations, and you are ready to acquire a 12 lead ECG.