Post-myocardial Infarction (Nursing)

by Prof. Lawes

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    00:00 Let's talk about what happens when someone survives a heart attack, things have gone fairly well and what happens after dead tissue.

    00:08 Because we know that we have dead tissue because blood supply was cut off to an area for about 20 minutes at least after four hours those cells or the cardiomyocytes die off.

    00:20 I know this is a little bit of the sad part.

    00:22 It's kind of like watching Bambi.

    00:23 We have to fast-forward through the mom's death to get to the good part at the end.

    00:28 So let's get this part out of the way.

    00:30 The tissue is dead after 4 hours.

    00:33 It cannot be revived.

    00:35 So the cells or the cardiomyocytes die.

    00:38 So in this example, it's been longer than four hours and those cells have died off.

    00:43 So the cardiomyocytes are dead.

    00:48 I just had a moment of silence for them.

    00:49 We want to recognize that and keep moving.

    00:51 All right, so the cardiac myocytes they fought a good fight, but after four hours, they are irreversibly dead.

    00:59 So let's talk about the wave of first responders.

    01:02 There's a first wave, a second wave and a third wave.

    01:06 Now the first wave is the first 12 to 24 hours.

    01:10 What happens in your body these myocytes are dead.

    01:13 Then the first 12 to 24 hours neutrophils will respond.

    01:17 They will rush into the dead heart muscle and they'll begin the first waves of breaking down the tissue that's part of the process of rebuilding the wall.

    01:25 You've got to get the rubble out of the way.

    01:28 So first wave neutrophils so circle the word neutrophils just as a quick reminder to you.

    01:34 The second way starts one to three days now and even larger team of neutrophils arrives in (tada).

    01:41 It's gonna help lice the dead cells.

    01:44 Remember those cardiomyocytes.

    01:46 First wave, neutorphil's are the first team that arrives over 1 to 3 days even more neutrophils will arrive to help do the work.

    01:54 In the third wave It's the macrophages that arrive they are the movers and the shakers.

    02:00 They're going to start removing all the debris including the neutrophils that are flat tuckered out from the first and second wave and there you do this through phagocytosis.

    02:10 So first wave 12 to 24 hours team and neutrophils arrives to the dead tissue and one two, three days even more and even larger team of neutrophils arrived so underline that again, but the third phase is the movers and the shakers, right? You've got the macrophages.

    02:27 They are going to start getting rid of the debris including those guys that are just flat out too tired to keep going and they're going to do this through phagocytosis, which is what macrophages do.

    02:39 Now this are signs of new life granulation tissue is kind of like springtime been through the winter and the dark and the dead.

    02:46 Now we're kind of getting ting to spring It's the sign of new life in that wall of your heart.

    02:51 After about 7 to 10 days, these really thin blood vessels will start to grow and they can provide some oxygen but it's going to take a week to 10 days for these guys to just start growing, now they're pretty fragile and they're really thin but that's what happens in the first week to 10 days.

    03:11 After that, We get some fibroblast and they start making some structural protein strands called type ll collagens so we've got these very thin blood vessels they're going to start to grow and they can give you some oxygen which that's really good for the wall.

    03:28 Then we get these fibroblasts and they're going to make these structural protein strands and we call them what? Right, type ll collagen.

    03:36 That's going to be a little stronger.

    03:38 Now these together these tiny blood vessels and these fibroblasts that made this type to collagen.

    03:44 They start making granulation tissue.

    03:47 That's a really positive sign.

    03:50 Now later on, the granulation tissue is going to be replaced with much stronger type l collagen that's called scar tissue.

    03:58 Scar tissueis going to be tough, but it's not going to be as flexible and as workable as the tissue was before and here's even more about the problem because scar tissue isn't as effective as the original cardiomyocytes.

    04:14 Okay, that's a really important point.

    04:15 So I want to make sure I don't just speak through that too quickly.

    04:19 Scar tissue is not as effective as original cardiomyocytes.

    04:24 It's better than dead tissue, but it's not like the original equipment because scar tissue isn't as quite as strong as the original muscle.

    04:32 It's also not contractile.

    04:35 So depending on how big the hit was and where it was the heart just isn't going to flat pump as efficiently.

    04:41 Remember that initial animation that we looked at how everything was smooth and work together and everything was equal.

    04:49 Well, once you've got scar tissue, it's not going to be quite as strong as the original muscle and it's not going to be as contractile.

    04:56 So it doesn't pump as efficiently because it's kind of stiff.

    04:59 It also could increase the risk of the patient developing heart failure later because if it's a big enough hit or as things progressed, remember the heart is not as efficient and it might not be able to handle the patient's fluid volume.

    About the Lecture

    The lecture Post-myocardial Infarction (Nursing) by Prof. Lawes is from the course Acute Coronary Syndrome (Nursing) .

    Included Quiz Questions

    1. 4 hours
    2. 20 minutes
    3. 12–24 hours
    4. 1–3 days
    1. Macrophages
    2. Neutrophils
    3. Cardiomyocytes
    4. Leukocytes
    1. Type II collagen and thin blood vessels
    2. Type I collagen and thin blood vessels
    3. Pulsatile vasculature and collagen
    4. Type I and type II collagen

    Author of lecture Post-myocardial Infarction (Nursing)

     Prof. Lawes

    Prof. Lawes

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