An Easy Way to Memorize STEMI Locations and Leads
For the CCRN one section of questions relies on your ability to recognize where an infarction's location is at solely by what leads show ST elevation. This has to be done through simple recognition and without the use of those badge cards you usually get from your unit educator. Throughout my study sessions for the CCRN, I came up with a simple way of learning which leads correlate with certain STEMI locations.
Learning > Memorizing
You might notice how I used the word "learning" instead of "memorizing". It is very important that the information you are studying is retained and you really understand why something is the way it is or why something works the way it does. The CCRN does not ask you to simply regurgitate information it requires you to use that information as a tool to critically think through a question. This sometimes requires you to extrapolate information from previous knowledge, something you can not do with memorization.
Which lead monitors which part of the heart?
You can imagine leads as individual people holding cameras pointed at the heart. Each lead monitors or "looks at" a certain part of the heart and shows it's own version of the hearts EKG rhythm. There are a lot of technicalities involved and expected variations between leads and their displayed rhythm but for this article, we will only focus on ST elevation via infarction and its location on the heart. If you look at the picture above you will notice 3 different colors demonstrated 3 different types of leads. You have your original planar leads demonstrated as green (I, II, III). These leads view the heart in a 2D frontal plane. The next leads visualized in red are known as the augmented leads (aVL, aVR, aVF). These leads are derived from the 3 standard leads to give slightly different areas of visualizations. Finally, you have your V leads in blue which incorporated leads V1-V6. These V leads look at the heart on a horizontal plane and give us somewhat of a 3D view of the heart. Using the picture above we can visualize which leads would show ST elevation with certain infarctions.
Lateral MI (aVL, I, V5, V6)
The lateral aspect of the heart when looking at the picture above will be the right side or the patients left side. Looking at the picture you can see that the most lateral leads in the picture include aVL ("left"), I, V5, and V6. Therefore, with a lateral MI, you will see ST elevation in these leads.
Anterior MI (V3, V4)
The anterior aspect of the heart is going to be the region of the heart closest to the sternum. When looking at the leads displayed in the picture above this position would correlate with leads V3, and V4.
Septal MI (V1, V2)
The septum of the heart is a little harder to visualize with the picture as the septum is somewhat skewed with the left side of the heart having more mass. Due to this, the leads monitoring the septal region of the heart will be more to your left or the patient's right. This gives us leads V1 and V2 to monitor for ST elevation in a septal MI.
Inferior MI (aVF, II, III)
The leads to monitor for an inferior MI are actually pretty easy to learn. This is where the picture's orientation somewhat alters the actual visualization of the leads positions. Normally the apex of the heart is more to the patients left (your right). The heart is not normally straight up and down as the picture shows but actually on its side. This would make the most inferior or "down" leads to be aVF ("foot"), II, and III. ST elevation in these leads could also demonstrate a right sided MI. More on that in another article. If you can learn this picture and visualize it with the location of the leads then MI location becomes a breeze.