Coronary artery disease

The coronary arteries are the ones that carry blood to the heart itself. Coronary artery disease is atherosclerosis of those arteries: the buildup of plaques inside them that narrow the lumen, the hollow space the blood runs through. With the lumen narrowed, less blood and less oxygen reach the heart muscle. The plaque grows inside the artery and steadily takes away room for blood.

The plaque starts with a crack. The intima, the innermost layer of the artery, breaks, and white blood cells called monocytes get in through the opening. Inside the wall they become macrophages, cells whose job is to swallow whatever does not belong, and what they swallow here are particles of oxidized low-density lipoprotein, damaged cholesterol. As it fills with fat, the macrophage turns into a foam cell, and a pile of foam cells is the beginning of the plaque.

The disease causes trouble in two ways. If the plaque grows until it blocks at least seventy percent of the passage, exertion can bring on angina, the chest pain that comes from not getting enough oxygen. And if the plaque ruptures, a thrombus forms, a clot that can block the artery.