The heart is a muscle, and like any other muscle, it needs a constant supply of oxygen and nutrients to function. When they become partially blocked, chest pain or angina results. If these arteries become totally blocked, that part of the heart muscle receives no oxygen and dies. This is known as a myocardial infarction or heart attack. The primary cause underlying heart disease is atherosclerosis.
Atherosclerosis is the gradual buildup of fat and cholesterol deposits in the arteries.
These deposits slow the passing of blood through the vessels. Scar tissue and debris build up behind these fatty deposits, creating areas of plaque. The walls of the arteries grow thick and irregular and the opening narrows further. A blood clot can get caught in this narrowed channel and block it, or, over time, the deposits can completely block the passage. Atherosclerosis can occur in any artery in the body.