 Hi, welcome to Nursing School Explained. And today's video on myocardial infarction or MI, also known as heart attack. And of course, this is a very serious problem because it is a partial or a complete occlusion of one of the coronary arteries. And as we know, the coronary arteries supply the heart muscle with blood. And when there's no blood flow to a certain part of the heart muscle, then bad things start to happen. The underlying cause is mostly due to coronary artery disease, which then leads to acute coronary syndrome. And I have a separate video that goes into more of the specifics of how this plaque develops. But here for myocardial infarction, we have to distinguish between two terms. And that is STEMI or non-STEMI. And what STEMI stands for is ST elevation MI. So the ST segment of the EKG is elevated ST elevation myocardial infarction. And that basically means, do we see changes on the EKG or do we not? Even if we don't see changes on the EKG, that doesn't mean that the patient is not having a myocardial infarction and we'll get into more into this in a little bit here. So here to distinguish between STEMI and non-STEMI, we have to see if the ST segment on the EKG is elevated. And in this case for STEMI, it's clear ST elevation MI. And for non-STEMI, it's not elevated. Now the occlusion of the coronary artery in a STEMI is complete, which is why we have those EKG changes. And in a non-STEMI, it's an incomplete or a partial obstruction. The treatment for STEMI and the time that we should aim to have that treatment completed is, for STEMI is PCI, which stands for Percutaneous Coronary Intervention, otherwise known as an angiogram. And that is sometimes also called door to balloon time. So from when the time that the patient arrives through the doors of the hospital to balloon to when the balloon gets inflated and they can actually take a look inside the patient's heart should be no greater than 90 minutes to have the best outcomes. Now in cases where PCI is not available at this specific facility where maybe this is a rural area or it's not available or the hospital currently does not have the availability to perform this procedure, we can give the patient thrombolytics, which are clot busters that we sometimes also give to patients who experience a stroke, which is practically the same thing, an occluded artery, but this time not in the heart but in the brain. And the time to thrombolytics should be door to thrombolytics within 30 minutes. And the reason that there is more leeway that there is a one hour difference is that PCI takes some time to get set up. If it's after hours or the weekend, the team will be on call and they will have to arrive to the hospital in order to get this patient on the table and perform this angiogram. Now if we have a non-stemmy because it is an incomplete occlusion of the coronary artery, the patient will still have an angiogram but it can be done within 12 to 24 hours. Well in the meantime, the patient will be medically managed with medications to restore that blood flow to that part of the heart muscle and through that coronary artery that's partially obstructed. And when we talk about MI, we have to distinguish between three different terms, ischemia, injury and infarction, which are basically the three different levels. So ischemia meaning lack of blood flow, which is an inadequate supply of oxygen to the heart muscle or an inadequate, or there's an increase in demand. So there's this imbalance between oxygen supply and demand to a certain part of the heart muscle. But ischemia is reversible if it's treated early, which is why we need to encourage our patients if you have in these kinds of symptoms that we'll go over later, go to the hospital right away because you don't know and if we catch it early, the outcomes is gonna be very much better. On an EKG, we will see ST depression. So now we're not talking about elevation, but we're talking about depression because it's the precursor to the elevation. And the way this looks, this ST segment here, so in black you see the isoelectric line and the ST segment usually goes above with the T-wave above the isoelectric line and then comes back to it. But in this case, the ST segment is depressed. It's below this isoelectric line and all your alarm bells should be going off if you see a patient with ST depression. But ischemia can also be manifest itself with T-wave inversion. So now the T-wave is not positive above the isoelectric line, but it's negative or inverted, which again could be indication of ischemia, could also be other underlying causes, but all our red flags and bells should be going off. Now if ischemia is not treated right away or if the patient doesn't come in right away, this inadequate oxygen supply and blood flow to that part of the heart gets worse. Now there's no perfusion and as we know if there's no perfusion, no blood flow, the tissue suffers. And so now that there's injury, so from lack of blood flow, we go now that we have actually created injury, which is still potentially reversible if again the patient comes in right away and we can do this door to balloon time within the 90 minute period. And here we do see this ST elevation. So this is the first time that we actually see that. And it has to be one millimeter elevation at least in two continuous leads. And that is more for your 12 lead EKG interpretation. And please refer to my EKG interpretation playlist where I go into explaining all the different ins and outs of the EKG interpretation and how to actually read it. So here again, we have the isoelectric line, but this time here we have the ST segment below the isoelectric line in the ST depression, but here we actually have it above. And sometimes they also refer to this as the fireman's hat because if you see, if you kind of draw a face here, the eye and the nose and the mouth of that fireman, that could be their hat. And so that's sometimes referred to as that ST elevation. Now, if this is treated quickly, infarction can be avoided or limited. So again, time to balloon time or door to balloon time is super, super important here. However, with this injury, we typically won't see an elevation in those cardiac enzymes, in those cardiac markers because we have still caught it on time and there will typically not be enough time for those cardiac markers to be elevated. Now, if we don't get this patient in the ischemic and the injury phase, then we have actual infarction. And infarction means death of tissue. In this case, we will definitely have this ST elevation on the EKG. And then we also have to distinguish between the Q wave. You might have heard about this. And we have to distinguish between the physiological and the pathological Q wave. And if you think about, pathology is the study of disease. So that is more, always more severe than physiologic. So a physiologic Q wave, in both case scenarios, we have this ST elevation, but the Q wave here is the one that comes right between, right, the PQRST. So the Q wave here goes down and it's kind of short and narrow, almost normal like on the normal EKG. Where the pathologic Q wave is more deep, it goes down more and it's wider than the physiologic one. And the implication here is that this might stay on the EKG forever. So even if the patient had an IMI five years ago, they still might have this pathologic Q wave because the injury to the heart muscle has occurred and is non-reversible. Now, we can certainly restore the blood flow and we talk about treatments here in a little bit, but this Q wave will stay no matter what, the pathologic Q wave. Signs and symptoms of MI can be varied, but mostly we think about chest pain that is not be relieved by rest or nitroglycerin. Otherwise, it would just be unstable angina or an angina. Typically, it's a substernal pain where the patient says, oh, I heard it's right here in the center of my chest or epigastric. So substernal, this really crushing tightness, excruciated and elephant sits on my chest, kind of a chest pain is experienced by male patients where many times female patients have one more vague symptoms. They might complain of a little bit of epigastric pain or some nausea, some queasiness, not feeling right, but they also, again, the alarm bells should be going off if we have a female with these vague symptoms because females are known not to have these typical heavy symptoms and then if we don't take it seriously, they might suffer a bad outcome because we haven't acted fast enough to detect that they actually have an MI. And this pain many times radiates to the jaw, neck, back or arm. So these are some questions that we need to ask with our PQRSD questionnaires. Many times the patient will also feel weak and fatigued, nausea and vomiting, like I mentioned, and they might be short of breath because now if we have low perfusion to the heart muscle, there's not enough blood being pumped because the cardiac muscle function is impaired and now the body is gonna try to compensate by increasing the respiratory rate, pulling in more oxygen to supply that coronary artery with that important oxygen. And then the sympathetic nervous system will kick in. So when the sympathetic nervous system kicks in, it's fight or flight. So it detects, hello, something is going on. The heart itself, one of the major organs of the body is not being supplied with enough oxygen. So I'm gonna shunt all the blood from the non-important things, such as the skin, to the core, the central circulation and therefore the patient's skin will be diaphoretic, pale and cool many times. They will show an increase in heart rate and blood pressure initially because of that sympathetic nervous system tries to fight or flight and speed everything up to perfuse that heart muscle. And then with the diaphoresis and the blood shunting away from the periphery, the peripheral pulses will be diminished. So they might have weak radiopulses and pedopulses. Now later on, when that sympathetic nervous system response kind of is dampened or kind of runs out or the infarction kind of continues and that heart muscle keeps dying, the blood pressure will go down. There might be crackles in the lungs, such as we see in patients, we see in Jeff because the heart muscle is just not strong enough to pump that fluid. And we might see other signs and symptoms of heart failure, such as JVD, hepatomegaly, and then peripheral edema, that swelling that we look for in the lower extremities. So for diagnostic tests, anybody with complain of chest pain should have an EKG performed within 10 minutes of the patient telling you that is such. And most hospitals have a standing protocol if chest pain perform an EKG right away. And this is really one of those core measures because we know the sooner we detect EKG changes, whether it's a STEMI or non-STEMI, the sooner we can treat the patient, call the cath lab, get the patient there, and get that blood flow restored. But the most important thing is the EKG. Certainly we will need to check cardiac enzymes. Troponin here is the most important one. We will also check CKMB many times and myoglobin, but those enzymes are not cardiac specific. Troponin is the one that we need to watch out for. That's the one that's gonna tell us the most about what's going on with that heart muscle. And then certainly we also wanna check a complete blood count to check the patient's platelets and CBC, their CMP to check for renal function, liver function as well as their electrolytes, and their PTI and R4 bleeding times because if we know the patient has to go to the cardiac cath lab, then we will need to make sure that all these are in order. We also many times check a chest X-ray to check for any kind of enlargement or underlying pulmonary physiology that could be the cause for the patient's chest pain. And then later, many times an echocardiogram is done. That is not typically done until the patient is kind of out of the cath lab to determine what the heart muscle function and the valves all look like. Now complications, as you can imagine, myocardial infarction and heart attack can be very serious. It can lead to dysrhythmias, heart failure if the heart muscle just dies and can't pump efficiently. It can lead to cardiogenic shock. It can lead to papillary muscle dysfunction which mostly affects the mitral valve. It can lead to an aneurysm in that left ventricle because that coronary artery is just so dilated or narrowed that it becomes very turbulent. The blood flow there and that can actually burst which then results in ventricular wall rupture and it can lead to cardiac arrest and the patient might die from an MI. Which is why again, this EKG within 10 minutes of anybody complaining of chest pain is super important because the sooner we know what's going on the sooner we can intervene and prevent the patient from having cardiac arrest. Now treatment for this, number one treatment, PCI, percutaneous coronary intervention also known as an angiogram and I will go more into the details about this especially the nursing care in detail in a separate video. And again with a STEMI we wanna have the patient in the cath lab within 90 minutes, door to balloon time. And many times with an angiogram depending on what they find most likely is a partially or completely obstructed coronary artery they might place some stents to open up and restore the blood flow. Treatment number two thrombolytics which are those clot busters and again those should be administered within 30 minutes from the patient's arrival if PCI is not available or not indicated for some reason in this particular patient. And even if they do the PCI but they usually find if they find three or more vessels that are diseased or if it's a complete obstruction that's in a very complicated location to go to and maybe to insert that stent, they will, the recommendation will be a cabbage which is a coronary artery bypass graft. And again I'll have a separate video on the details, the ins and outs of the cabbage procedure. Now these patients can be very, very sick and so I have a separate video on the nursing care about how to care for patients with NMI that also goes into the important medications where we use the acronym MONA and I'll talk more about priorities about how and when to administer these medications and in what order because that tends to come up on test questions. So thank you so much for watching this video on MI, myocardial infarction. Also check out all the other videos that are linked below here that pertain to this very important topic. Thanks for watching. Please give me a thumbs up and I'll see you right here on Nursing School Explained next time.