Electrode placement

Grab your little packet of your ECG electrodes. There’s always 12 on a sheet, unless someone’s stolen some, as you can see. Someone’s already stolen some from that sheet there. That usually tells me they’ve had problems with adhesions so they’ve had to take another strip.

So picking up your electrodes, we’re going to go to the inner aspect of each ankle. And you want the free end of the tab facing towards the patient. That’s just purely on a practical basis. When you’re applying your actual leads themselves, it stops the electrode peeling back. And you do the reverse on the wrist. You actually want them facing down the little electric tab when you go to connect your cable.

I always just give them a nice little gentle press to make sure you have good contact because you’re reliant on the quality of the application to give you a good, reliable reading. Now, at this point I will need to actually place the chest electrodes, otherwise called the precordial leads. To do that, you need to identify clearly some specific anatomical landmarks. These are most important in terms of getting a good quality ECG, which is actually translatable into clinical assessment and management of your patient.

So you just need to make sure your patient’s chest is nice and clear and that they’re comfortably back at 45 degrees, and that you can actually feel the little V notch at the top of the sternum here. What you’re looking for is an anatomical position called the Angle of Louis, and that corresponds to intercostal space number two on the chest wall. For V1 placement, which is your first chest electrode, you’re looking to place V1 at the fourth intercostal space to the right of the sternal border. So in order to do that, most easiest way is to gently feel for that notch, which is very easy, whether the patient’s male or female. Slide your finger down.

You’ll come to a little raised ridge called the manubrium. And below that, where the ridge dips away and you move straight across on the horizontal plane, which automatically bring you over to intercostal space number two. And then you’re going to gently slide over the chest wall to feel for intercostal space number three. And then further down– and again, you’re going to feel for intercostal space number four. And note that position, and apply your electrode.

OK. We’ll need to do the same procedure to locate V2. V2 is described as being the fourth intercostal space to the left of sternal border. And in order to do that, you’ll perform the same process. You’ll feel for the notch of the sternum, slip down over the manubrium when you come off the ridge and into the indentation, and move horizontally straight across. You’re going to be, again, at intercostal space number two. And you want to feel for intercostal space number three and intercostal space number four. Note that position, and apply your electrode.

Generally, in most patients, it’s going to be a mirror image of V1, but there are certain clinical conditions– such as scoliosis, kyphoscoliosis, other chest wall deformities– which may mean that the patient’s chest is actually asymmetrical as opposed to symmetrical in most people. The next electrode you’re going to apply is slightly out of sequence. We’re going to apply electrode V4. To identify this, it is described as mid-clavicular line, fifth intercostal space. To do that, the tip of the clavicle articulates the center of the chest here with the notches and the tip of the clavicle comes all right out to the top of the arm here.

So what you have to imagine is that clavicle, and you want to imagine yourself halfway along it. And then you’re going to drop an imaginary plumb line straight down and you’re going to feel for one intercostal space lower. And that will be position V4.

So just to reiterate, it’s described as mid-clavicular line, fifth intercostal space. Then you’ll apply electrode V3, which is described as equidistant between V2 and V4.

And then you’re going to move along to apply electrode V5 and V6. In female patients with a significant amount of breast tissue or gentleman who happen to have enlarged breast tissue because of conditions such as gynecomastia, you’ll need to make sure that the breast tissue is moved away to apply electrodes V4, V5, and V6. You don’t want to apply on top of the breast tissue. So in order to assist you and to maintain the patient’s dignity, what I’ve found useful is to get the patient to pop their hand on top of their breast and just to lift and cover it so you could find the anatomical landmarks. And once your electrodes are placed, the patient can release the breast again.

So we’re going to apply precordial lead V5, which is described as the fifth horizontal plane, but this time anterior axillary line. To locate the axillary line, you’re looking at the crease here at the top of the arm where it joins the chest wall. Again, you’re coming down with an imaginary plumb line, parallel to V4, and that will be your V5 placement.

And the last electrode will be V6. Now, this one is described as fifth horizontal plane, mid axillary line. To locate the mid axillary line, we want to raise your patient’s arm gently up and look into the axilla. And, again, imagining about 50% along that axillary line here, which is represented by this crease. You want to, again, draw another imaginary plumb line coming down and meeting the fifth intercostal plane. That’s where V6 would sit. It’s often a little further around than you think. And the most important thing is you keep to the fifth horizontal plane as opposed to the fifth intercostal space because the heart is apex, is sitting here.

And if you were to follow just the intercostal space and follow the ribs, you’d actually move away from the apex, which is what you don’t want to do. You want to pick up the big muscle mass of the left ventricle on that side. So this represents the positioning for your precordial leads, V1 through to V6. The only thing I would suggest you do if you are new to performing 12 lead ECGs on a regular basis, or you may not be from a cardiac area, is once you have the electrodes positions at this point, call for someone senior to come and inspect the position to make sure it’s accurate before you apply your electrodes.

And you can cover your patient comfortably while someone’s coming along to do so.