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I think most of us know what the heart does in our body.

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It pumps the blood and in particular it takes in the blood from the rest of the body.

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That is blue over here in this diagram, because that blood does not have carried oxygen

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And it pumps that blood to the lungs where the blood gets oxygenated.

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And then it comes back from the lungs, depicted as red blood, now that it has oxygen in it.

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And then that oxygenated blood is pumped to the rest of the body.

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And I think also, most of us have the general idea that when people talk about heart disease or heart attacks,

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which we learn, are two different things, related but different things, that has something to do with the clogging of arteries.

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so when I was a kid and I first learnt about the clogging of arteries.

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and I knew enough that the heart is all about pumping blood to the body.

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I assumed the artery that people were talking about these big arteries that were coming away from the heart

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to the rest of the body that somehow these things got clogged up.

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so let me draw that, different colour you can see

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so this was my ....this is what I thought

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people were talking about when they were saying clogging of the arteries

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and maybe when they got clogged enough, the stopped blood flow to the rest of the body somehow

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and that would actually kill the person. I want to make it very clear right now.

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Those are not the arteries that people are talking about getting clogged,

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when people talk about heart disease or heart attacks.

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The arteries that they are talking about are the arteries that actually provide blood to the heart.

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Remember the heart itself is a muscle. It itself needs oxygen.

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So you have these arteries right over here, the red tubes. Those are arteries.

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and then the blue ones are veins.

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They're taking the de-oxygenated blood away from the tissue of the heart.

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And these are called coronary arteries.

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And this one over here at least from the point of view of me or you looks like it's on the right.

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Or from the point of view of the person whose heart it is, it's on the left.

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This right over here is called the left coronary artery or LCA.

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And this right over here in red is called the right coronary arteries or the RCA.

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And so when people talk about arteries getting blocked or getting clogged,

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they're talking about the coronary arteries.

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They're talking about the things that supply blood to the heart.

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So let's zoom in on one of them....Maybe we can zoom in right over here, that part of the artery.

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That's the tube....clear where I am zooming in. I am zooming in right over here.

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So over time, I am not going into the details how this happened. It is subject for another video.

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You can have these plaques build up along the walls of the artery.

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So over time if a person doesn't have the right diet, or maybe they just have a predisposition to it,

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you can have these things called plaques form on the walls of the arteries.

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And the plaques, the material inside of them are lipids, so things like

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fat, cholesterol and also dead white blood cells,

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which is this kind of messy substance right over here. This is what we call a plaque.

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And the formation of these plaques that obstruct the actual blood vessel, that actually obstruct the artery.

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We call it.....make it clear you see that. This is kind of tube over here. Let me draw the blood

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So this formation of these plaques we call atherosclerosis.

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So you can imagine if you have these things build up,

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it's narrowing the actual vessel that's supplying blood downstream from that obstruction.

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So it would be destructing the blood flow downstream right over there.

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In that general process we talk about the restriction of blood flow, that is ischemia that's happening.

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So ischemia is deprivation of blood flow and oxygen downstream from this right over there.

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That's what we call coronary artery disease, or heart disease.

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So this causes coronary artery disease, which is sometimes called heart disease.

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Coronary heart disease would be redundant, because coronary is already referring to the heart.

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This is also sometimes called heart disease. And so you can imagine if downstream the muscle tissue is

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not getting all the oxygen it needs, especially maybe when this person, whoever's heart this is,

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when they are exerting themselves, they need more oxygen. The heart needs to pump a little harder.

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If downstream the cells are not getting all of the oxygen they need,

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you can imagine that the heart maybe not able to provide all of the functions,

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whoever's heart this is, that they needed to do.

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And when that happens that's called heart failure.

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So heart disease is one of the causes of heart failure.

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Now I want to be clear, heart failure does not mean that the heart is stopping.

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That the heart is stopped and the person is dead, it literally just means

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that the heart is failing to do what it should be doing. It's failing to provide the needs of that person.

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So it's not pumping hard enough or well enough to provide adequate function for that person.

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The other symptom that actually might occur when someone has coronary heart disease,

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where they have obstruction or this ischemia

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or this deprivation of oxygen downstream from this obstruction, is that they might experience this kind of strangling chest pain

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That's called angina pectoris or sometimes angina.

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Very few people say the pectoris part. Sometimes you hear people say oh angina.

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Angina pectoris, which is really chest pain, angina literally comes from meaning this kind of strangling feeling,

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and pectoris is in the chest. This is strangling feeling in the chest.

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This is a symptom of heart disease. Now this is already not a situation you want to get into

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because already your body is not able to function as well as it maybe could be, as maybe it could.

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Sometimes as I might describe here is a plaque.

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Some plaques are actually unstable. These plaques just grow and grow and grow.

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It makes probably heart disease worse and worse, heart failure worse, and angina pectoris worse.

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These plaques are unstable. It can actually rupture.

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You can imagine all these blood flows, as plaque grows, the blood flows become a little turbulent around these plaques.

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It has to go really fast through this narrow section. It comes out turbulent on the inside and

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creates these friction and all the rest. At some point, you can imagine this plaque is unstable.

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It could actually rupture. Let me draw ruptured plaque over here....let me draw the same one....I am gonna draw the ruptured.

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Now this plaque has rupture. It got so big. Maybe the turbulent blood flow helped stimulate this and whatever else.

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For whatever reason, it ruptures.

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When it ruptures, now it sudden i am doing a simplification of the process right over here.

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Now the content of this plaque: the lipid, the cholesterol, the fat, the dead white blood cell.

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Now it sudden is exposed to the blood flow. in particular to the clotting factor in the blood.

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This is highly thrombogenic material. Thrombogenic, very fancy word.

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That just means, that tends to cause blood clot. Thrombosis is a blood clot.

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What happened is, as soon as this type of things happened, it can literally happen in seconds or in minutes.

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All the sudden you could have these clotting factors form a clot right over here right at the actual plaque.

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As this happens, it starts to really really really obstruct the blood vessel.

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Sometimes it can even completely obstruct the blood vessel.

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When it happens, you are significantly depleting the blood flow going downstream from there.

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You might even be shutting it off. When you do that, the cells downstream will no longer get oxygen.

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They will die. This right over here, is called an infarction. an infarct is actually a dead heart tissue.

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You can imagine when heart tissue begins to die, this is even worse than what we were describing with coronary heart disease.

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Not only coronary heart disease just is not getting enough oxygen, now they are actually dead.

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They are turning into dead tissue. This process of completely or almost completely depriving cells of oxygen so that they die, this is a heart attack.

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Let me completely obstruct this artery to make the point clear. this right over here is a heart attack.

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This is the primary cause of heart attack.

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It's less likely but sometimes a plaque could also go downstream, kind of form a thromboembolism.

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It would be this thrombogenic material, the clots around it.

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It would actually go and block the artery further downstream and be embolism.

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That can also block the artery and cause tissue to die. But the main cause is this intense clotting that can

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occur pretty quickly and completely obstruct the artery. There is one last word i want to touch

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sometimes mixed in with all the other words, that is cardiac arrest. That's because sometimes we use them in the same context.

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one thing can lead to another. Heart attack is not cardiac arrest. Cardiac arrest is the actual dying of the heart.

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What I just described in a heart attack, people can have a heart attack. They will have some part of their muscle tissue die.

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Some part infarct, that's what they called myocardial infarction. Myocardial means the tissue of heart or the muscle of the heart that's dying.

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Sometimes it is called myocardial infarction. That is not cardiac arrest.

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Cause you can have some of your heart tissue die and you can survive. Your heart would be impaired.

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But you will continue to live. Cardiac arrest is literally your heart stopping.

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This would obviously cause someone to die. If you have a bad enough heart attack,

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if you have enough of the tissue get starved of oxygen so that it dies, infarction occurs.

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Then it could lead to cardiac arrest. It always won't lead to cardiac arrest.

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Frankly, heart attack is not the only thing that can cause cardiac arrest.

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I also want to once again differentiate cardiac arrest from heart failure, because they sound the same, sound like heart is failing.

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Cardiac arrest is heart stopping. Heart failure is essentially just saying that heart can not provide all of the needs for the body.