What is a STEMI and how does it look like on a 12 Lead EKG / ECG

If you know what ST elevation is an can identify it on an EKG / ECG then you’re close to identifying a STEMI. What’s a STEMI? It stands for ST Segment Elevation Myocardial Infarction . STEMI’s are usually caused by blood clots that have blocked off one or more of the coronary arteries that feed oxygenated blood to the heart. Since all parts of your body need oxygen to stay alive, when tissue (like heart muscle for example) stops getting oxygen, that part of the heart starts to die. When this starts to happen, you can notice key changes on a patients EKG / ECG, like ST Segment Elevation. But just because you see ST Elevation in a lead doesn’t mean a patient is having a STEMI. By definition, a STEMI is ST Elevation in 2 or more contiguous leads. What’s a contiguous lead? It means 2 or more leads that look at the same part of the heart.

Looking at a 12 Lead EKG / ECG strip can be daunting. There are leads called: I, II, III, AVF, AVL, V1, V2, V3, V4, V5, & V6. So how do you know what lead looks at what part of the heart? With a simple acronym called I SEE ALL LEADS one can easily remember what lead looks at what part of the heart. Here’s how it works:

I – looks at the Inferior part of the heart and comprises of the following leads: II, III, and AVF

S (see) looks at the Septal part of the heart through leads: V1 & V2

A (all) looks at the Anterior part of the heart with: V3 & V4

L (leads) looks at the Lateral portion of the heart utilizing: V5, V6, I, & AVL

Take a look at the following EKG / ECG and see if you can see clearly that this patient is having a STEMI in the inferior portion of their heart:


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