This is due to a pathological process, the most prevalent being athero-sclerosis.
Atherosclerosis is a chronic accumulation of fat deposits within the wall of an artery.
Even with advanced medical technology, there are only theories to explain why fatty deposits in the blood stream are transformed into plaque within an artery. Many risk factors contribute to this process, including high cholesterol levels, smoking, obesity and diabetes. CAD is the leading cause of death in both men and women since The Center for Disease Control began keeping statistics. Approximately 7 million Americans have significant coronary artery disease. It kills more people than HIV and cancer.