Lectures

Myocardial Infarction

by Carlo Raj, MD
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    00:00 transmural. What kind of coronary artery or arteriole? It will be a coronary artery, transmural.

    00:01 What kind of changes that you are going to find on your EKG. Well, we will get into that here. Let us talk about transmural first. If it is transmural, what kind of artery or arteriole? It is going to be your artery and it is undergoing permanent type of obstruction.

    00:16 What are you going to find on your EKG? You are going to find a type of change, which is known as a STEMI, an ST-elevation myocardial infarction, left anterior descending branch.

    00:28 Take a look at where the occlusion is taking place. What part of the heart is that? You see that right there? That is the anteroseptal right. So you have your interventricular septum and then towards your apical. What leads would these be? Actually the second time, but I am walking you through all leads here, then keep repeating myself. So we have the following.

    00:52 We are supplying the, who is? The left anterior descending is supplying the interventricular septum, is it not? And so, therefore, it would be V1, V2 and for exam purposes also understand that you are going to supply the anteroapical. What leads would those be? V3, V4 good. Welcome to left anterior descending. Transmural, what kind of infarction? ST elevation in which leads? V1 through V4. I am hoping that you have done your precordial leads and you know how to place them. Next, permanent occlusion of left circumflex branch. Take a look at where you are here. Once again, it is an artery. What kind of myocardial infarction? STEMI. Next, what kind of leads that you are looking at? What is over here on your left lateral side? How about V5, V6? What else might you find? Lead 1, which augment the lead. Please do not say aVR. That is aVL, isn't it? Okay. So those are places that you do expect to find an ST elevation if it is left circumflex. And then if it is right coronary artery, where might you be here? Well, this is your II, III, aVF? That will be the inferior portion of the heart. Let us move on. Let us take a look at nontransmural.

    02:13 If it is nontransmural, then these are the different types of issues that you are looking at. We have transient/partial obstruction, point number one, subendocardial infarction.

    02:22 Global hypotension, what does that mean? It means overall the blood pressure is decreasing in your patient. Thus, you will find circumferential. Look for that description. Why is it happening? Overall the body. Let us say that there is massive type of hypovolemia due to massive hemorrhage. Is that global hypotension? Of course, it is. What part of the heart is most susceptible to hypoxia? It is the subendocardium, but now it is circumferential. Small intramural, these are microinfarcts. Now the two that you want to pay attention to, for sure would be the first and second one with subendocardial, either you have a partial obstruction or you have global with circumferential. All, however, would be nontransmural.


    About the Lecture

    The lecture Myocardial Infarction by Carlo Raj, MD is from the course Ischemic Heart Disease.


    Included Quiz Questions

    1. The endocardium is closest to the lumen, then the myocardium, these are both supplied by arterioles and the arteries supply the pericardium at the surface of the heart
    2. The pericardium is closest to the lumen, then the myocardium in the middle, these are both supplied by arterioles and arteries supply the endocardium at the surface of the heart
    3. The endocardium is closest to the lumen and supplied by the arteries, the arterioles supply the myocardium in the middle and the pericardium which is the surface of the heart
    4. The myocardium is closest to the lumen and supplied by the arterioles, the arteries supply the endocardium in the middle and the pericardium which is the surface of the heart
    5. The pericardium is closest to the lumen and supplied by arteries, the arterioles supply the myocardium in the middle and the endocardium which is the surface of the heart
    1. A non-STEMI involves a subendocardial infarction due to occlusion of coronary arterioles
    2. A non-STEMI involves transmural infarction and represents occlusion of the coronary arterioles
    3. A non-STEMI involves subendocardial infarction due to occlusion of the coronary arteries
    4. A STEMI involves a subendocardial infarction due to occlusion of the coronary arteries
    5. A STEMI involves a transmural infarction due to occlusion of the coronary arterioles
    1. Vasodilation in vessels near the occlusion causes further ischemia of occluded areas
    2. Vasodilation of coronary vessels increases blood flow to coronary vasculature causing reperfusion injury
    3. Chemically induced vasoconstriction of blood vessels induces chest pain and EKG changes
    4. Exercise induced vasoconstriction of blood vessels causes EKG changes
    5. Vasoconstriction of vessels near the occlusion causes blood to pool near the occlusion
    1. II, III, aVF
    2. V1-V4
    3. V5, V6, I, aVL
    4. II, III, aVL
    5. V2, V3
    1. Subendocardial
    2. Apex
    3. Septum
    4. Pericardium
    5. Base

    Author of lecture Myocardial Infarction

     Carlo Raj, MD

    Carlo Raj, MD


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