Glossary of Terms

Apolipoprotein B (APOB) is the primary apolipoprotein of low density lipoproteins (LDL or "bad cholesterol"), which is responsible for carrying cholesterol to tissues.

Through a mechanism that is not fully understood, high levels of APOB can lead to plaques that cause heart disease (atherosclerosis). There is considerable evidence that levels of APOB are a better indicator of heart disease risk than total cholesterol or LDL. However, primarily for practical reasons, cholesterol, and more specifically, LDL-cholesterol, remains the primary lipid target and risk factor for atherosclerosis.

Atherosclerosis (pronounced ath-uh-roh-skluh-roh-sis) is the progressive buildup of plaque — fatty deposits and other cells — in the walls of your arteries. Its name comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness).

One surprising fact about atherosclerosis, or athero as we call it, is how early the disease can begin inside us. For many, the process may start in early adulthood. As we get older, arterial plaque can build up and restrict blood flow. Over time this disease can eventually clog your arteries, making them stiff and inflexible.

Atrial fibrillation is a disorder found in about 2.2 million Americans. During atrial fibrillation, the heart's two small upper chambers (the atria) quiver instead of beating effectively. Blood isn't pumped completely out of them, so it may pool and clot. If a piece of a blood clot in the atria leaves the heart and becomes lodged in an artery in the brain, a stroke results. About 15 percent of strokes occur in people with atrial fibrillation.

The likelihood of developing atrial fibrillation increases with age. Three to five percent of people over 65 have atrial fibrillation.

The endothelium is the thin layer of cells that line the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. Endothelial cells line the entire circulatory system, from the heart to the smallest capillary. These cells reduce friction of the flow of blood allowing the fluid to be pumped further

High-density lipoproteins (HDL) form a class of lipoproteins, varying somewhat in their size (8–11 nm in diameter), that carry fatty acids and cholesterol from the body's tissues to the liver. About thirty percent of blood cholesterol is carried by HDL.

It is hypothesized that HDL can remove cholesterol from atheroma within arteries and transport it back to the liver for excretion or re-utilization—which is the main reason why HDL-bound cholesterol is sometimes called "good cholesterol", or HDL-C. A high level of HDL-C seems to protect against cardiovascular diseases, and low HDL cholesterol levels (less than 40 mg/dL) increase the risk for heart disease.[1] When measuring cholesterol, any contained in HDL particles is considered as protection to the body's cardiovascular health, in contrast to "bad" LDL cholesterol.

Blood pressure is the force in the arteries when the heart beats (systolic pressure) and when the heart is at rest (diastolic pressure). It's measured in millimeters of mercury (mm Hg). High blood pressure (or hypertension) is defined in an adult as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure.