Atherosclerosis can be defined as the build up of plaque in the inner part of the arterial walls. Plaque is made of a variety of substances that clog the lining of an artery. This includes deposits of fatty substances, cholesterol, cellular waste products and calcium. As arteries carry oxygenated blood to the heart, the narrowing of these vessels can lead to a decrease in blood to the heart, which can cause numerous problems and can be fatal.

Congenital Heart Diseases exist at birth, and can describe a wide variety and different abnormalities affecting the heart. "Congenital" refers to aspect of time, not to causation. It means "present at birth" or “born with”. Heart defects originate in the early part of pregnancy when the heart is forming and affect any of the parts or functions of the heart. Therefore Congenital Heart Disease is a type heart disease occurring in newborns, and includes structural defects which lead to irregular heart beats or arrhythmia and malfunctioning of heart muscles.