What happens when a embolus enters an artery too small for it to fit through?

Embolus. When an embolus enters an artery too small for it to fit through it will prevent blood from flowing through the artery. The tissue that relies on the blood flow from the artery can die. This is what happens when people have heart attacks. An artery that supplies the heart - called a coronary artery - loses its blood flow and part of the heart dies.