Look at the picture below. What you are seeing is what an artery on the left that looks like that is clear. By clear we mean there are no plaque deposits on the walls of the artery. The blood is free to flow through the artery without interruption. This is not true of the artery on the right. In this artery there is a plaque deposit on both sides of the walls of the artery. You can imagine that if blood were flowing through the artery on the right, the blood flow would be constricted or limited by plaque that is adhering to the sides of the artery.

Do you see where the plaque deposits extend deep into near the center of the artery? At one point they are almost touching together. It really would not take much more in the way of a plaque buildup before this artery channel would be completely closed up and blood would not be able to get from one side of the artery to the other because there would literally be now room left through which the blood could flow.

When a heart attack happens what we just said is exactly what happens. The artery has a blockage that completely stops, interrupts, or impedes the flow of blood. The blood literally cannot continue through the artery to the other side of the blockage.

Look at the picture below. In this picture you can see in the smaller picture to the left, that a plaque has completely blocked the artery channel and therefore is stopping the flow of blood to the other side of the artery.