Anemia
A medical condition in which the body lacks sufficient hemoglobin, resulting in reduced oxygen to body tissues.

Angina (or Angina Pectoris)
Chest pain usually caused by a lowered blood supply to the heart.

Angiogram
An X-ray of blood vessels which can be seen because the patient receives an injection of dye to outline the vessels on the X-ray.

Anticoagulants 
Drugs that prevent the formation of blood clots that can block blood flow to the heart and brain. See "Antiplatelets."

Antiplatelets
Drugs that stop blood platelets (substances in blood that promote clotting) from clumping together to form clots.  See "Anticoagulants."

Arteriole
Small diameter blood vessel that extends and branches out from an artery and leads to capillaries.

Arteriosclerosis 
A chronic disease in which thickening, hardening, and loss of elasticity of the arterial walls result in impaired blood circulation. Also called hardening of the arteries. It develops with aging, hypertension, diabetes and other conditions, and occurs when cholesterol and other lipids are deposited in the artery wall, and inflammation and other degenerative processes cause the vessel to become obstructed.

Artery
Any of the muscular elastic tubes that form a branching system and that carry oxygenated blood to the cells, tissues, and organs of the body.

Beta-blockers
Drugs that reduce the heart's tendency to beat faster, and therefore help reduce blood pressure.

Blood Pressure
The force exerted by blood on the walls of the arteries. This pressure is greatest during the contraction of the ventricles of the heart (systolic pressure), which forces blood into the arterial system. Pressure falls to its lowest level when the heart is filling with blood (diastolic pressure).

Blood Vessels
The flexible tubular canals through which blood circulates in the body. Arteries, veins, and capillaries are all kinds of blood vessels.

Body Mass Index (BMI)
The standard measure of body fat. BMI is calculated based on an individual's weight relative to their height, and measured by multiplying the individual's weight in pounds by 703 and then dividing that number by the individual's height in inches squared.

Cardiac Catheterization
A diagnostic procedure during which a small tube, or catheter, is threaded into the arteries around the heart.

Cardiologist 
A physician who specializes in heart problems.

Cardiovascular Disease (CVD)
Any of several diseases involving the heart and blood vessels, including high blood pressure, coronary heart disease, stroke, rheumatic heart disease and other heart and blood vessel problems.

Cholesterol
A soft, waxy substance manufactured by the body and used in the production of hormones, bile acid, and vitamin D. It is present in all parts of the body, including the nervous system, muscle, skin, liver, intestines and heart. Cholesterol regulates membrane fluidity, functions as a precursor molecule in various metabolic pathways and as a constituent of low-density lipoproteins, and may cause arteriosclerosis.

Circulatory System 
The system in the body by which blood and lymph are circulated. The circulatory system includes the heart, arteries, veins, and capillaries. The organs of the lymphatic system are also considered to be part of the circulatory system.

Coronary Angiography
A special X-ray exam of the heart and blood vessels. It shows plaque buildup in the large coronary arteries. This test is often done during a heart attack to help locate blockages.

Coronary Arteries 
The vessels that supply the heart muscle with blood rich in oxygen. They are called the coronary arteries because they encircle the heart in the manner of a crown. The word "coronary" comes from the Latin "corona" and Greek "koron" meaning crown. Like other arteries, the coronaries may be subject to arteriosclerosis (hardening of the arteries). There are a number of coronary arteries.

Coronary Artery Disease (CAD)
A disease in which there is a narrowing or blockage of the coronary arteries (blood vessels that carry blood and oxygen to the heart). Coronary artery disease is usually caused by arteriosclerosis (a build up of fatty material and plaque inside the coronary arteries). The disease may cause chest pain, shortness of breath during exercise, and heart attacks.

Coronary Artery Flow Reserve (or Coronary Reactivity)
The capacity of the coronary circulatory system to dilate following an increase in myocardial metabolic demands.

Coronary Artery Spasm 
An abnormal or involuntary constriction of the muscle in an artery of the heart. This spasm makes the diameter of the artery smaller, restricting the supply of blood and oxygen to the heart, causing chest pain. In rare cases if the spasm is not stopped it can lead to a heart attack.

CT Scan 
Computed tomography (CT), which is sometimes called a CAT scan, combines X-ray and computer technology to produce cross-sectional images of the body. Unlike an X-ray, which images bones, computed tomography can produce an image that shows everything in that area of the body, such as organs, bones, and blood vessels.

Echocardiography 
Ultrasound examination of the heart.

Electrocardiogram (ECG, EKG)    
A test that produces tracings of the heart's electrical activity. The process of performing an ECG is called electrocardiography, which means "electric heart writing."

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

Heart Attack 
Heart attack means the supply of blood and oxygen to the heart has been so drastically reduced that cells in the heart die.  The more severe the heart attack, the more heart muscle that dies.  The heart is essentially a muscle whose main job is to pump blood to all parts of the body, bringing needed nutrients and oxygen and removing waste products. The technical name for the heart muscle is the myocardium, and the most widely used technical term for a heart attack is myocardial infarction.  You may also hear the terms "coronary thrombosis" or "coronary occlusion."

Hemoglobin 
A substance contained in red blood cells that binds with oxygen molecules.

High-density Lipoprotein (HDL) Cholesterol
Also referred to as "good" cholesterol. These are specific particles that are important in carrying cholesterol from peripheral sites, like the blood vessels, to the liver for processing or breakdown. High levels of HDL particles promote removal of lipid from blood vessels and decrease the risk for ASCVD. Low levels of HDL are a risk factor for heart disease.

Hypertension 
Abnormally elevated blood pressure.

Ischemia 
A general term that means the flow of blood (and therefore oxygen) to a part of the body has been reduced; "cardiac ischemia" means not enough blood and oxygen are flowing into the heart. 

Lipids
Biologic fats. A general term for water insoluble compounds like cholesterol and triglyceride.

Low-density Lipoprotein (LDL) Cholesterol
Also referred to as "bad" cholesterol.  A lipoprotein of blood plasma that is composed of a moderate proportion of protein with little triglyceride and a high proportion of cholesterol and that is associated with increased probability of developing arteriosclerosis.

Macrovascular Disease 
Disease of the large blood vessels, including the coronary arteries, the aorta, and the sizable arteries in the brain and in the limbs. Macrovascular disease is by contrast to microvascular disease.

Magnetic Resonance Imaging (MRI) 
Magnetic resonance imaging (MRI) is a non-invasive way to take pictures of the body.  Unlike X-rays and computed tomographic (CT) scans, which use radiation, MRI uses powerful magnets and radio waves.

Microvascular Disease 
Disease of the smaller blood vessels in the body, such as the arterioles. In contrast to macrovascular disease.

Myocardial Ischemia 
Ischemia means that a part of the body is receiving a less than adequate supply of blood and oxygen; myocardial ischemia means not enough blood and oxygen are flowing into the heart.

Nitric Oxide 
A compound that is toxic but which, paradoxically, plays a number of important roles in the body, including the following:
• It acts as a vasodilator (blood vessel relaxant). It therefore controls blood flow to tissues.
• It regulates the binding and release of oxygen to hemoglobin. It thereby controls the supply of oxygen to mitochondria (cell powerhouses that generate energy).

Nuclear scan    
A variety of X-ray studies incorporating radioisotopes that are injected into the bloodstream, to reveal the functioning of the heart. These tests can accurately measure the efficiency of the heart pump and show areas where the muscle has been injured. While nuclear scans often fit into a thorough diagnosticc workup, they cannot take the place of cardiac catheterization because only catheterization can reveal blockages in the coronary arteries.

Obesity 
An excessive amount of body fat in relation to lean body mass or a body weight that is 30 percent over the ideal weight for a specified height

Plaque 
A deposit of fat or cholesterol that builds up inside a blood vessel which, left untreated, can eventually block the flow of blood through that vessel.

Platelets 
An irregular, disc-shaped element in the blood that assists in blood clotting. During normal blood clotting, the platelets clump together (aggregate). Although platelets are often classed as blood cells, they are actually fragments of large bone marrow cells called megakaryocytes.

Positron Emission Tomography (PET)  
A scanning technique used in conjunction with small amounts of radioactive compounds injected into your bloodstream. This radioactive substance goes to areas inside your body, where tissue either is damaged or not working properly. These areas usually have what doctors call increased or decreased "metabolic" activity. The PET scan machine then has hundreds of radiation detectors that can find this radioactive substance in your body. The PET scanner measures this radioactivity throughout your body and uses computers to create pictures of your heart or other body tissues.

Statins 
A class of drugs that help lower cholesterol levels in the blood.

Stress test
A test to provide information about blood flow through the coronary arteries to the heart muscle during physical stress.

Triglycerides 
A type of fat found in your blood and in foods you eat. They are the most common type of fat in your body and are a major source of energy. Triglycerides commonly circulate in the blood in the form of lipoproteins (also referred to as neutral fat).

Vasodilators 
Vasodilators are drugs that open ("dilate") the arteries, lowering blood pressure; ACE inhibitors are a class of vasodilators.