Raena Morgan: What exactly is the heart attack Dr. Thompson? What is going on physically? Dr. Owen Thompson: Well, you know, our heart is a very interesting organ. In the normal human, if you take your fist and wrap your other hand around it, that's about the size of your heart. So, if you're seven feet tall and have big hands, you have a bigger heart, than if you're shorter. Raena Morgan: Okay. Dr. Owen Thompson: And that heart is basically a pump. And the average human has about 60,000 miles of blood vessels, and about five quarts of fluid blood, and that little gizmo, that little heart, circulates that five quarts through that 60,000 miles, about 1500 times a day. So, it's really an efficient little pump. Raena Morgan: That's genius. Dr. Owen Thompson: Yes, it is. It really is. And basically the heart has three main components. One is the actual structure of the heart. It's mostly muscle, and it has four chambers and four valves. But structurally it has this fibrous tissue that makes up the chambers and the valves, and then everything is encased in muscle. And obviously, the star of the show is the muscle to pump all that fluid through all those miles of blood vessels, everyday, 100 to 115,000 beats a day. Busy little operation there. So, the way it does that, is it has a rate switch, its own internal pacemaker and its own little wiring system to tell the muscle how to beat, and to beat rhythmically. And so it all runs real smooth. Now, the coronary arteries bring blood to the muscle. This muscle is obviously working very, very hard to pump this fluid and needs oxygen and other nutrients, glucose, amino acids from our body to use as fuel for all of this beating, the contracting that these muscle fibers do. And then there are waste products, carbon dioxide, urea, nitrogen and other things that those cells have to get rid of, so it dumps those into the coronary veins. But a heart attack involves the coronary arteries. These arteries that bring the blood to the heart muscle, the cardiac muscle, have a lining in them that is very, very smooth. It's called the entema, or the endothelium, and it's a very smooth lining. And the reason it's smooth is, blood tends to clot on a rough surface. Raena Morgan: Oh, like when you have a wound. Dr. Owen Thompson: Right. If you have a wound. If you cut yourself slicing an apple with a kitchen knife, you transect across the artery, then the artery is no longer a smooth surface because it's been cut. And that trips what we call the clotting mechanism, and the blood platelets stick together, and bingo, you form a clot that totally occludes the blood vessel, so you quit bleeding. And it's a wonderful thing. And unless we have hemophilia, that works like clock work, literally, probably millions of times in our lifetime that we get cuts and scrapes and we bleed a little bit and it stops. So clotting, in and of itself is a wonderful thing. Raena Morgan: A good thing. Dr. Owen Thompson: Good thing. Now, in the coronary arteries, if we have plaque build up, fatty deposits of cholesterol, this lipid plaque, it gets deposited underneath the lining of this very smooth chamber. And what happens then is you have a rough surface. And we already talked about, the blood is programmed to clot on a rough surface. So, the rougher the surface in the artery, the more likely a clot will form. And when a clot forms in the coronary vessel, just like in the tiny blood vessel of our finger, the clot grows quickly, totally occluding the blood vessel to stop the blood flow. And when we stop the blood flow in a little vessel in our finger, the bleeding stops, because the blood flow stops. But when we stop the blood flow in the coronary artery, the part of the heart muscle that received that blood, the oxygen and the other nutrients, now gets nothing. So, the heart muscle starts to deteriorate, decay and die. And that's what causes the pain. And some people don't have any pain, because our heart muscle, like I said, yo