Abdomen – The area of the body between the bottom of the ribs and the top of the thighs.

Abdominal aorta – The portion of the aorta in the abdomen.

Ablation – Elimination or removal.

ACE (angiotensin-converting enzyme) inhibitor – A medicine that lowers blood pressure by interfering with the breakdown of a protein-like substance involved in blood pressure regulation.

Acetylcholine – A type of chemical (called a neurotransmitter) that transmits messages among nerve cells and muscle cells.

Acquired heart disease – Heart disease that arises after birth, usually from infection or through the build-up of fatty deposits in the arteries that feed the heart muscle.

Alveoli – Air sacs in the lungs where oxygen and carbon dioxide are exchanged.

Amiodarone – A kind of medicine (called an antiarrhythmic) used to treat irregular heart rhythms such as atrial fibrillation and ventricular tachycardia. It works by regulating nerve impulses in your heart. Amiodarone is mainly given to patients who have not responded to other antiarrhythmic medicines.

Aneurysm – A sac-like protrusion from a blood vessel or the heart, resulting from a weakening of the vessel wall or heart muscle.

Angina or angina pectoris – Chest pain that occurs when diseased blood vessels restrict blood flow to the heart.

Angiography – An x-ray technique in which dye is injected into the chambers of your heart or the arteries that lead to your heart (the coronary arteries). The test lets doctors measure the blood flow and blood pressure in the heart chambers and see if the coronary arteries are blocked.

Angioplasty – A nonsurgical technique for treating diseased arteries by temporarily inflating a tiny balloon inside an artery.

Angiotensin II receptor blocker – A medicine that lowers blood pressure by blocking the action of angiotensin II, a chemical in the body that causes the blood vessels to tighten (constrict).

Annulus – The ring around a heart valve where the valve leaflet merges with the heart muscle.

Antiarrhythmics – Medicines used to treat patients who have irregular heart rhythms.

Anticoagulant – Any medicine that keeps blood from clotting; a blood thinner.

Antihypertensive – Any medicine or other therapy that lowers blood pressure.

Antiplatelet therapy – Medicines that stop blood cells (called platelets) from sticking together and forming a blood clot.

Aorta – The largest artery in the body and the main vessel to supply blood from the heart.

Aortic valve – The valve that regulates blood flow from the heart into the aorta.

Aphasia – The inability to speak, write, or understand spoken or written language because of brain injury or disease.

Arrhythmia (or dysrhythmia) – An abnormal heartbeat.

Arrhythmogenic right ventricular dysplasia (ARVD) – ARVD is a type of cardiomyopathy with no known cause. It appears to be a genetic condition (passed down through a family’s genes). ARVD causes ventricular arrhythmias.

Arteriography – A test that is combined with cardiac catheterization to visualize an artery or the arterial system after injection of a contrast dye.

Arterioles – Small, muscular branches of arteries. When they contract, they raise resistance to blood flow, and blood pressure in the arteries increases.

Artery – A vessel that carries oxygen-rich blood to the body.

Arteritis – Inflammation of the arteries.

Arteriosclerosis – A disease process, commonly called “hardening of the arteries”, which includes a variety of conditions that cause artery walls to thicken and lose elasticity.

Artificial heart – A manmade heart. Also called a total artificial heart (TAH).

Ascending aorta – The first portion of the aorta, emerging from the heart’s left ventricle.

Aspirin – Acetylsalicylic acid; a medicine used to relieve pain, reduce inflammation, and prevent blood clots.

Atherectomy – A nonsurgical technique for treating diseased arteries with a rotating device that cuts or shaves away material that is blocking or narrowing an artery.

Atherosclerosis – A disease process that leads to the buildup of a waxy substance, called plaque, inside blood vessels.

Atrium (right and left) – The two upper or holding chambers of the heart (together referred to as atria).

Atrial flutter – A type of arrhythmia in which the upper chambers of the heart (the atria) beat very fast, causing the walls of the lower chambers (the ventricles) to beat inefficiently as well.

Atrial septal defect – See septal defect.

Atrial tachycardia – A type of arrhythmia that begins in the heart’s upper chambers (the atria) and causes a very fast heart rate of 160 to 200 beats a minute. A resting heart rate is normally 60 to 100 beats a minute.

Atrioventricular block – An interruption or disturbance of the electrical signal between the heart’s upper two chambers (the atria) and lower two chambers (the ventricles).

Atrioventricular (AV) node – A group of cells in the heart located between the upper two chambers (the atria) and the lower two chambers (the ventricles) that regulates the electrical current that passes through it to the ventricles.

Atrium – Either one of the heart’s two upper chambers.

Autologous – Relating to self. For example, autologous stem cells are those taken from the patient’s own body.

Autoregulation – When blood flow to an organ stays the same although pressure in the artery that delivers blood to that organ may have changed.

Bacteria – Germs that can lead to disease.

Bacterial endocarditis – A bacterial infection of the lining of the heart’s chambers (called the endocardium) or of the heart’s valves.

Balloon catheter – A long tube-like device with a small balloon on the end that can be threaded through an artery. Used in angioplasty or valvuloplasty.

Balloon valvuloplasty – A procedure to repair a heart valve. A balloon-tipped catheter is threaded through an artery and into the heart. The balloon is inflated to open and separate any narrowed or stiffened flaps (called leaflets) of a valve.

Beta-blocker – An antihypertensive medicine that limits the activity of epinephrine, a hormone that increases blood pressure.

Biopsy – The process by which a small sample of tissue is taken for examination.

Blalock-Taussig procedure – A shunt between the subclavian and pulmonary arteries used to increase the supply of oxygen-rich blood in “blue babies” (see below).

Blood clot – A jelly-like mass of blood tissue formed by clotting factors in the blood. Clots stop the flow of blood from an injury. Clots can also form inside an artery when the artery’s walls are damaged by atherosclerotic buildup, possibly causing a heart attack or stroke.

Blood pressure – The force or pressure exerted by the heart in pumping blood; the pressure of blood in the arteries.

Blue babies – Babies who have a blue tinge to their skin (cyanosis) resulting from insufficient oxygen in the arterial blood. This condition often indicates a heart defect.

Body mass index (BMI) – A number that indicates an increased risk of cardiovascular disease from a person being overweight. BMI is calculated using a formula of weight in kilograms divided by height in meters squared (BMI =W [kg]/H [m2]). Click here for a BMI calculator.

Bradycardia – Abnormally slow heartbeat.

Bridge to transplant – Use of mechanical circulatory support to keep heart failure patients alive until a donor heart becomes available.

Bruit – A sound made in the blood vessels resulting from turbulence, perhaps because of a buildup of plaque or damage to the vessels.

Bundle branch block – A condition in which parts of the heart’s conduction system are defective and unable to conduct the electrical signal normally, causing an irregular heart rhythm (arrhythmia).

Bypass – Surgery that can improve blood flow to the heart (or other organs and tissues) by providing a new route, or “bypass” around a section of clogged or diseased artery.

Calcium channel blocker (or calcium blocker) – A medicine that lowers blood pressure by regulating calcium-related electrical activity in the heart.

Capillaries – Microscopically small blood vessels between arteries and veins that distribute oxygen-rich blood to the body’s tissues.

Cardiac – Pertaining to the heart.

Cardiac amyloidosis – A disorder caused by deposits of an abnormal protein (amyloid) in the heart tissue, which make it hard for the heart to work properly. Also called “stiff heart syndrome.”

Cardiac arrest – The stopping of the heartbeat, usually because of interference with the electrical signal (often associated with coronary heart disease).

Cardiac cachexia – A term for the muscle and weight loss caused by severe heart disease. It is often related to the depressed cardiac output associated with end-stage heart failure, but it can also occur with severe coronary artery disease.

Cardiac catheterization – A procedure that involves inserting a fine, hollow tube (catheter) into an artery, usually in the groin area, and passing the tube into the heart. Often used along with angiography and other procedures, cardiac catheterization has become a primary tool for visualizing the heart and blood vessels and diagnosing and treating heart disease.

Cardiac enzymes – Complex substances capable of speeding up certain biochemical processes in the heart muscle. Abnormal levels of these enzymes signal heart attack.

Cardiac output – The amount of blood the heart pumps through the circulatory system in one minute.

Cardiologist – A doctor who specializes in the study of the heart and its function in health and disease.

Cardiology – The study of the heart and its function in health and disease.

Cardiomegaly – An enlarged heart. It is usually a sign of an underlying problem, such as high blood pressure, heart valve problems, or cardiomyopathy.

Cardiomyopathy – A disease of the heart muscle that leads to generalized deterioration of the muscle and its pumping ability.

Cardiopulmonary bypass – The process by which a machine is used to do the work of the heart and lungs so the heart can be stopped during surgery.

Cardiopulmonary resuscitation (CPR) – An emergency measure that can maintain a person’s breathing and heartbeat. The person who performs CPR actually helps the patient’s circulatory system by breathing into the patient’s mouth to give them oxygen and by giving chest compressions to circulate the patient’s blood. Hands-only CPR involves only chest compressions.

Cardiovascular (CV) – Pertaining to the heart and blood vessels that make up the circulatory system.

Cardiovascular Disease (CVD) – A general term referring to conditions affecting the heart (cardio) and blood vessels (vascular system). May also simply be called heart disease. Examples include coronary artery disease, valve disease, arrhythmia, peripheral vascular disease, congenital heart defects, hypertension, and cardiomyopathy. Refer to specific conditions for detailed explanations.

Cardioversion – A technique of applying an electrical shock to the chest to convert an abnormal heartbeat to a normal rhythm.

Carotid artery – A major artery (right and left) in the neck supplying blood to the brain.

Cerebral embolism – A blood clot formed in one part of the body and then carried by the bloodstream to the brain, where it blocks an artery.

Cerebral hemorrhage – Bleeding within the brain resulting from a ruptured blood vessel, aneurysm, or head injury.

Cerebral thrombosis – Formation of a blood clot in an artery that supplies part of the brain.

Cerebrovascular – Pertaining to the blood vessels of the brain.

Cerebrovascular accident – Also called cerebral vascular accident, apoplexy, or stroke. Blood supply to some part of the brain is slowed or stopped, resulting in injury to brain tissue.

Cerebrovascular occlusion – The blocking or closing of a blood vessel in the brain.

Cholesterol – An oily substance that occurs naturally in the body, in animal fats and in dairy products, and that is transported in the blood. Limited amounts are essential for the normal development of cell membranes. Excess amounts can lead to coronary artery disease.

Cineangiography – The technique of using moving pictures to show how a special dye passes through blood vessels, allowing doctors to diagnose diseases of the heart and blood vessels.

Circulatory system – Pertaining to circulation of blood through the heart and blood vessels.

Claudication – A tiredness or pain in the arms and legs caused by an inadequate supply of oxygen to the muscles, usually due to narrowed arteries or peripheral arterial disease (PAD).

Collateral circulation – Blood flow through small, nearby vessels in response to blockage of a main blood vessel.

Commissurotomy -A procedure used to widen the opening of a heart valve that has been narrowed by scar tissue.

Computed tomography (CT or CAT scan) – An x-ray technique that uses a computer to create cross-sectional images of the body.

Conduction system – Special muscle fibers that conduct electrical impulses throughout the heart muscle.

Congenital – Refers to conditions existing at birth.

Congenital heart defects – Malformation of the heart or of its major blood vessels present at birth.

Congestive heart failure – A condition in which the heart cannot pump all the blood returning to it, leading to a backup of blood in the vessels and an accumulation of fluid in the body’s tissues, including the lungs.

Coronary arteries – Two arteries arising from the aorta that arch down over the top of the heart and divide into branches. They provide blood to the heart muscle.

Coronary artery anomaly (CAA) – A congenital defect in one or more of the coronary arteries of the heart.

Coronary artery bypass (CAB) – Surgical rerouting of blood around a diseased vessel that supplies blood to the heart. Done by grafting either a piece of vein from the leg or a piece of the artery from under the breastbone.

Coronary artery disease (CAD) – A narrowing of the arteries that supply blood to the heart. The condition results from a buildup of plaque and greatly increases the risk of a heart attack.

Coronary heart disease – Disease of the heart caused by a buildup of atherosclerotic plaque in the coronary arteries that can lead to angina pectoris or heart attack.

Coronary occlusion – An obstruction of one of the coronary arteries that hinders blood flow to the heart muscle.

Coronary thrombosis – Formation of a clot in one of the arteries carrying blood to the heart muscle. Also called coronary occlusion.

Cryoablation – The removal of tissue using an instrument called a cold probe.

Cyanosis – Blueness of the skin caused by a lack of oxygen in the blood.

Cyanotic heart disease – A birth defect of the heart that causes oxygen-poor (blue) blood to circulate to the body without first passing through the lungs.

Death rate (age-adjusted) – A death rate that has been standardized for age so different populations can be compared or the same population can be compared over time.

Deep vein thrombosis – A blood clot in a deep vein in the calf (DVT).

Defibrillator – A device that helps restore a normal heart rhythm by delivering an electric shock.

Diabetes (diabetes mellitus) – A disease in which the body doesn’t produce or properly use insulin. Insulin is needed to convert sugar and starch into the energy used in daily life.

Diastolic blood pressure – The lowest blood pressure measured in the arteries. It occurs when the heart muscle is relaxed between beats.

Digitalis – A medicine made from the leaves of the foxglove plant. Digitalis is used to treat congestive heart failure (CHF) and heart rhythm problems (arrhythmias).

Dissecting aneurysm – A condition in which the layers of an artery separate or are torn, causing blood to flow between the layers. Dissecting aneurysms usually happen in the aorta, the large vessel that carries blood from the heart to other parts of the body and can cause sudden death.

Diuretic – A drug that lowers blood pressure by causing fluid loss. Diuretics promote urine production.

Doppler ultrasound – A technology that uses sound waves to assess blood flow within the heart and blood vessels and to identify leaking valves.

Dysarthria – A speech disorder resulting from muscular problems caused by damage to the brain or nervous system.

Dyspnea – Shortness of breath.

Echocardiography – A method of studying the heart’s structure and function by analyzing sound waves bounced off the heart and recorded by an electronic sensor placed on the chest. A computer processes the information to produce a one-, two- or three-dimensional moving picture that shows how the heart and heart valves are functioning.

Edema – Swelling caused by fluid accumulation in body tissues.

Ejection fraction – A measurement of the rate at which blood is pumped out of a filled ventricle. The normal rate is 50% or more.

Electrocardiogram (ECG or EKG) – A test in which several electronic sensors are placed on the body to monitor electrical activity associated with the heartbeat.

Electroencephalogram (EEG) – A test that can detect and record the brain’s electrical activity. The test is done by pasting metal disks, called electrodes, to the scalp.

Electrophysiological study (EPS) – A test that uses cardiac catheterization to study patients who have arrhythmias (abnormal heartbeats). An electrical current stimulates the heart in an effort to provoke an arrhythmia, determine its origin, and test the effectiveness of medicines to treat the arrhythmias.

Embolus – Also called embolism; a blood clot that forms in a blood vessel in one part of the body and travels to another part.

Endarterectomy – Surgical removal of plaque deposits or blood clots in an artery.

Endocardium – The smooth membrane covering the inside of the heart. The innermost lining of the heart.

Endothelium – The smooth inner lining of many body structures, including the heart (endocardium) and blood vessels.

Endocarditis – A bacterial infection of the heart’s inner lining (endothelium).

Enlarged heart – A state in which the heart is larger than normal because of heredity, long-term heavy exercise, or diseases and disorders such as obesity, high blood pressure, and coronary artery disease.

Enzyme – A complex chemical capable of speeding up specific biochemical processes in the body.

Epicardium – The thin membrane covering the outside surface of the heart muscle.

Estrogen – A female hormone produced by the ovaries that may protect premenopausal women against heart disease. Estrogen production stops after menopause.

Estrogen (or hormone) replacement therapy (ERT or HRT) – Hormones that some women may take to offset the effects of menopause.

Exercise stress test – A common test to help doctors assess blood flow through coronary arteries in response to exercise, usually walking, at varied speeds and for various lengths of time on a treadmill. A stress test may include use of electrocardiography, echocardiography, and injected radioactive substances. Also called exercise test, stress test, nuclear stress test, or treadmill test.

Familial hypercholesterolemia – A genetic predisposition to dangerously high cholesterol levels.

Fatty acids (fats) – Substances that occur in several forms in foods; different fatty acids have different effects on lipid profiles.

Fibrillation – Rapid, uncoordinated contractions of individual heart muscle fibers. The heart chamber involved can’t contract all at once and pumps blood ineffectively, if at all.

First-degree heart block – Occurs when an electrical impulse from the heart’s upper chambers (the atria) is slowed as it moves through the atria and atrioventricular (AV) node.

Flutter – The rapid, ineffective contractions of any heart chamber. A flutter is considered to be more coordinated than fibrillation.

Fusiform aneurysm – A tube-shaped aneurysm that causes the artery to bulge outward. Involves the entire circumference (outside wall) of the artery.

Gated blood pool scan – An x-ray analysis of how blood pools in the heart during rest and exercise. The test uses a radioactive substance to tag red blood cells to allow doctors to estimate the heart’s overall ability to pump and its ability to compensate for one or more blocked arteries. Also called MUGA (multiple gated acquisition scan) or nuclear ventriculography.

Genetic testing – Blood tests that study a person’s genes to find out if he or she is at risk for certain diseases that are passed down through family members.

Guidewire – A small, bendable wire that is threaded through an artery; it helps doctors position a catheter so they can perform angioplasty or stent procedures.

Heart assist device – A mechanical device that is surgically implanted to ease the workload of the heart.

Heart attack – Death of, or damage to, part of the heart muscle caused by a lack of oxygen-rich blood flowing to the heart.

Heart block – General term for conditions in which the electrical impulse that activates the heart muscle cells is delayed or interrupted somewhere along its path.

Heart failure – See congestive heart failure.

Heart-lung machine – An apparatus that oxygenates and pumps blood to the body during open heart surgery; see cardiopulmonary bypass.

Heart murmur -An abnormal heart sound caused by turbulent blood flow. The sound may indicate that blood is flowing through a damaged or overworked heart valve, that there may be a hole in one of the heart’s walls, or that there is a narrowing in one of the heart’s vessels. Some heart murmurs are a harmless type called innocent heart murmurs.

Hematocrit – A measure of the percentage of red blood cells in a given amount (or volume) of whole blood.

Hemochromatosis – A disease in which too much iron builds up in your body (iron overload). Too much iron in the heart can cause irregular heartbeats (arrhythmias) and heart failure. Too much iron in the pancreas can lead to diabetes.

Heredity – The genetic transmission of a particular quality or trait from parent to child.

High blood pressure – A chronic increase in blood pressure above its normal range.

High density lipoprotein (HDL) – A component of cholesterol, HDL helps protect against heart disease by promoting cholesterol breakdown and removal from the blood; hence, its nickname “good cholesterol.”

Holter monitor – A portable device for recording heartbeats over a period of 24 hours or more.

Homocysteine – An amino acid (one of the building blocks that makes up a protein) normally found in small amounts in the blood. Too much homocysteine in the blood may promote the buildup of fatty plaque in the arteries. For some people, high homocysteine levels are genetic. For others, it is because they do not get enough of certain B vitamins in their diet. (Common misspelling: homocystine)

Hormones – Chemicals released into the bloodstream that control different functions in the body, including metabolism, growth, sexual development, and responses to stress or illness.

Hypertension – High blood pressure.

Hypertrophic obstructive cardiomyopathy (HOCM) – An overgrown heart muscle that creates a bulge into the ventricle and impedes blood flow.

Hypertrophy – Enlargement of tissues or organs because of increased workload.

Hyperventilation – Rapid breathing usually caused by anxiety. People feel like they can’t get enough air, so they breathe heavily and rapidly, which can lead to numb or tingly arms and legs, or fainting.

Hypoglycemia – Low levels of glucose (sugar) in the blood.

Hypokinesia – Decreased muscle movement. In relation to the heart, hypokinesia refers to decreased heart wall motion during each heartbeat. It is associated with cardiomyopathy, heart failure, or heart attack. Also called hypokinesis.

Hypotension – Abnormally low blood pressure.

Hypoxia – Less than normal content of oxygen in the organs and tissues of the body.

Idiopathic – No known cause.

Immunosuppressants – Any medicine that suppresses the body’s immune system. These medicines are used to minimize the chances that the body will reject a newly transplanted organ, such as a heart.

Impedance plethysmography – A noninvasive diagnostic test used to evaluate blood flow through the leg.

Incompetent valve – Also called insufficiency; a valve that is not working properly, causing it to leak blood back in the wrong direction.

Infarct – The area of heart tissue permanently damaged by an inadequate supply of oxygen.

Infective endocarditis – An infection of the heart valves and the innermost lining of the heart (the endocardium), caused by bacteria in the bloodstream.

Inferior vena cava – The large vein returning blood from the legs and abdomen to the heart.

Inotropes – Positive inotropes: Any medicine that increases the strength of the heart’s contraction. Negative inotropes: Any medicine that decreases the strength of the heart’s contraction and the blood pressure in the vessels.

Internal mammary artery – A durable artery in the chest wall often used as a bypass graft in coronary artery bypass surgery.

Intravascular echocardiography – A combination of echocardiography and cardiac catheterization. A miniature echo device on the tip of a catheter is used to generate images inside the heart and blood vessels.

Introducer sheath – A catheter-like tube that is placed inside a patient’s vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter.

Ischemia – Decreased blood flow to an organ, usually due to constriction or obstruction of an artery.

Ischemic heart disease – Also called coronary artery disease and coronary heart disease, this term is applied to heart problems caused by narrowing of the coronary arteries, thereby causing a decreased blood supply to the heart.

Ischemic stroke – A type of stroke that is caused by blockage in a blood vessel.

Jugular veins – The veins that carry blood back from the head to the heart.

Left ventricular assist device (LVAD) – A mechanical device that can be placed outside the body or implanted inside the body. An LVAD does not replace the heart—it “assists” or “helps” it pump oxygen-rich blood from the left ventricle to the rest of the body.

Lesion – An injury or wound. An atherosclerotic lesion is an injury to an artery due to hardening of the arteries.

Lipid – A fatty substance that is insoluble (cannot be dissolved) in the blood.

Lipoprotein – A lipid surrounded by a protein; the protein makes the lipid soluble (can be dissolved) in the blood.

Low density lipoprotein (LDL) – The body’s primary cholesterol-carrying molecule. High blood levels of LDL increase a person’s risk of heart disease by promoting cholesterol attachment and accumulation in blood vessels; hence, the popular nickname “bad cholesterol.”

Lumen – The hollow area within a tube, such as a blood vessel.

Magnetic resonance imaging (MRI) – A technique that produces images of the heart and other body structures by measuring the response of certain elements (such as hydrogen) in the body to a magnetic field. MRI can produce detailed pictures of the heart and its various structures without the need to inject a dye.

Maze surgery – A type of heart surgery that is used to treat chronic atrial fibrillation by creating a surgical “maze” of new electrical pathways to let electrical impulses travel easily through the heart. Also called the Maze procedure.

Mitral stenosis – A narrowing of the mitral valve, which controls blood flow from the heart’s upper left chamber to its lower left chamber. May result from an inherited (congenital) problem or from rheumatic fever.

Mitral valve – The structure that controls blood flow between the heart’s left atrium (upper chamber) and left ventricle (lower chamber).

Mitral valve prolapse – A condition that occurs when the leaflets of the mitral valve between the left atrium and left ventricle bulge into the atrium and permit backflow of blood. The condition can be associated with progressive mitral regurgitation.

Mitral valve regurgitation – Failure of the mitral valve to close properly, causing blood to flow back into the heart’s upper left chamber (the left atrium) instead of moving forward into the lower left chamber (the left ventricle).

mm Hg – An abbreviation for millimeters of mercury. Blood pressure is measured in units of mm Hg—how high the pressure inside the arteries would be able to raise a column of mercury.

Monounsaturated fats – A type of fat found in many foods but mainly in avocados and in canola, olive, and peanut oils. Monounsaturated fat tends to lower LDL cholesterol levels, and some studies suggest that it may do so without also lowering HDL cholesterol levels.

Mortality – The total number of deaths from a given disease in a population during an interval of time, usually a year.

Murmur – Noises superimposed on normal heart sounds. They are caused by congenital defects or damaged heart valves that do not close properly and allow blood to leak back into the chamber from which it has come.

Myocardial infarction – A heart attack. The damage or death of an area of the heart muscle (myocardium) resulting from a blocked blood supply to the area. The affected tissue dies, injuring the heart. Symptoms include prolonged, intensive chest pain and a decrease in blood pressure that often causes shock.

Myocardial ischemia – Occurs when a part of the heart muscle does not receive enough oxygen.

Myocarditis – A rare condition in which the heart muscle becomes inflamed as a result of infection, toxic drug poisoning, or diseases like rheumatic fever, diphtheria, or tuberculosis.

Myocardium – The muscular wall of the heart. It contracts to pump blood out of the heart and then relaxes as the heart refills with returning blood.

Myxomatous degeneration – A connective tissue disorder that causes the heart valve tissue to weaken and lose elasticity.

Nitroglycerin – A medicine that helps relax and dilate arteries; often used to treat cardiac chest pain (angina).

Necrosis – Refers to the death of tissue within a certain area.

Noninvasive procedures – Any diagnostic or treatment procedure in which no instrument enters the body.

NSTEMI – Non-ST-segment-elevation myocardial infarction. The milder form of the 2 types of heart attack, an NSTEMI does not produce an ST-segment elevation on an electrocardiogram. See also STEMI.

Obesity – The condition of being significantly overweight. It usually applies when a person is 30% or more over ideal body weight. Obesity puts a strain on the heart and can increase the risk of developing high blood pressure and diabetes.

Occluded artery – An artery in which the blood flow has been impaired by a blockage.

Open heart surgery – An operation in which the chest and heart are opened surgically while the bloodstream is diverted through a heart-lung (cardiopulmonary bypass) machine.

Pacemaker – A surgically implanted electronic device that helps regulate the heartbeat.

Palpitation – An uncomfortable feeling within the chest caused by an irregular heartbeat.

Pancreas – The organ behind the stomach that helps control blood sugar levels.

Pancreatitis – Swelling (inflammation) of the pancreas.

Paralysis -Loss of the ability to move muscles and feel in part of the body or the whole body. Paralysis may be temporary or permanent.

Paroxysmal supraventricular tachycardia (PSVT) – An occasional rapid heart rate (150-250 beats per minute) that is caused by events triggered in areas above the heart’s lower chambers (the ventricles). See also supraventricular tachycardia (SVT).

Patent ductus arteriosus – A congenital defect in which the opening between the aorta and the pulmonary artery does not close after birth.

Patent foramen ovale – An opening between the left and right atria (the upper chambers) of the heart. Everyone has a PFO before birth, but in 1 out of every 3 or 4 people, the opening does not close naturally, as it should, after birth.

Percutaneous coronary intervention (PCI)– Any of the noninvasive procedures usually performed in the cardiac catheterization laboratory. Angioplasty is an example of a percutaneous coronary intervention. Also called a transcatheter intervention.

Percutaneous transluminal coronary angioplasty (PTCA) – See angioplasty.

Pericarditis – Inflammation of the outer membrane surrounding the heart. When pericarditis occurs, the amount of fluid between the two layers of the pericardium increases. This increased fluid presses on the heart and restricts its pumping action.

Pericardiocentesis – A diagnostic procedure that uses a needle to withdraw fluid from the sac or membrane surrounding the heart (pericardium).

Pericardium – The outer fibrous sac that surrounds the heart.

Plaque – A deposit of fatty (and other) substances in the inner lining of the artery wall characteristic of atherosclerosis.

Platelets – One of the three types of cells found in blood; they aid in the clotting of blood.

Polyunsaturated fat – The major fat in most vegetable oils, including corn, safflower, sunflower, and soybean oils. These oils are liquid at room temperature. Polyunsaturated fat actually tends to lower LDL cholesterol levels but may reduce HDL cholesterol levels as well.

Positron emission tomography (PET) – A test that uses information about the energy of certain elements in your body to show whether parts of the heart muscle are alive and working. A PET scan can also show if your heart is getting enough blood to keep the muscle healthy.

Postural orthostatic tachycardia syndrome (POTS) – A disorder that causes an increased heart rate when a person stands upright.

Premature ventricular contraction (PVC) – An early or extra heartbeat that happens when the heart’s lower chambers (the ventricles) contract too soon, out of sequence with the normal heartbeat.

Prevalence – The total number of cases of a given disease that exist in a population at a specific time.

Pulmonary – Refers to the lungs and respiratory system.

Pulmonary embolism – A condition in which a blood clot that has formed elsewhere in the body travels to the lungs.

Pulmonary valve – The heart valve between the right ventricle and the pulmonary artery that controls blood flow from the heart into the lungs.

Pulmonary vein – The blood vessel that carries newly oxygenated blood from the lungs back to the left atrium of the heart.

Radial artery access – Using the radial artery in the wrist as the entry point for the catheter in an angioplasty or stent procedure. Also called transradial access, the transradial approach, or transradial angioplasty.

Radionuclide imaging – A test in which a harmless radioactive substance is injected into the bloodstream to show information about blood flow through the arteries. Damaged or dead heart muscle can often be identified, as can serious narrowing in an artery.

Radionuclide studies – Any of the diagnostic tests in which a small amount of radioactive material is injected into the bloodstream. The material makes it possible for a special camera to take pictures of the heart.

Radionuclide ventriculography – A diagnostic test used to determine the size and shape of the heart’s pumping chambers (the ventricles).

Regurgitation – Backward flow of blood through a defective heart valve.

Renal – Pertains to the kidneys.

Restenosis– The re-closing or re-narrowing of an artery after an interventional procedure such as angioplasty or stent placement.

Revascularization – A procedure to restore blood flow to the tissues. Coronary artery bypass surgery is an example of a revascularization procedure.

Rheumatic fever – A disease, usually occurring in childhood, that may follow a streptococcal infection. Symptoms may include fever, sore or swollen joints, skin rash, involuntary muscle twitching, and development of nodules under the skin. If the infection involves the heart, scars may form on heart valves, and the heart’s outer lining may be damaged.

Rheumatic heart disease – A disease of the heart (mainly affecting the heart valves) caused by rheumatic fever.

Right ventricular assist device (RVAD) – A mechanical device that can be placed outside the body or implanted inside the body. An RVAD does not replace the heart—it “assists” or “helps” it pump oxygen-poor blood from the right ventricle to the lungs.

Risk factor – An element or condition involving a certain hazard or danger. When referring to heart and blood vessels, a risk factor is associated with an increased chance of developing cardiovascular disease, including stroke.

Rubella – Commonly known as German measles.

Saccular aneurysm – A round aneurysm that bulges out from an artery; involves only part of the circumference (outside wall) of the artery.

Sarcoidosis – An inflammatory disease that starts as tiny, grain-like lumps called granulomas, which most often appear in your lungs or lymph nodes. The granulomas can clump together and form larger lumps that attack other organs. Sarcoidosis often affects your skin, eyes, or liver, but it can lead to heart problems, such as irregular heartbeats (arrhythmias) or restrictive cardiomyopathy.

Saturated fat – Type of fat found in foods of animal origin and a few of vegetable origin; they are usually solid at room temperature. Abundant in meat and dairy products, saturated fat tends to increase LDL cholesterol levels, and it may raise the risk of certain types of cancer.

Second-degree heart block – Impulses traveling through the heart’s upper chambers (the atria) are delayed in the area between the upper and lower chambers (the AV node) and fail to make the ventricles beat at the right moment.

Septal defect – A hole in the wall of the heart separating the atria or in the wall of the heart separating the ventricles.

Septum – The muscular wall dividing a chamber on the left side of the heart from the chamber on the right.

Sheath – A catheter-like tube that is placed inside a patient’s vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter. Also called an introducer sheath.

Shock – A condition in which body function is impaired because the volume of fluid circulating through the body is insufficient to maintain normal metabolism. This may be caused by blood loss or by a disturbance in the function of the circulatory system.

Shunt – A connector that allows blood to flow between two locations.

Sick sinus syndrome – The failure of the sinus node to regulate the heart’s rhythm.

Silent ischemia – Episodes of cardiac ischemia that are not accompanied by chest pain.

Sinus (SA) node – The “natural” pacemaker of the heart. The node is a group of specialized cells in the top of the right atrium which produces the electrical impulses that travel down to eventually reach the ventricular muscle, causing the heart to contract.

Sodium – A mineral essential to life found in nearly all plant and animal tissue. Table salt (sodium chloride) is nearly half sodium.

Sphygmomanometer – An instrument used to measure blood pressure.

Stem cells – Special cells in the body that are able to transform into other cells. It is possible for stem cells to transform into heart cells, nerve cells, or other cells of the body, possibly helping to improve the function of failing organs, including the heart.

STEMI – ST-segment-elevation myocardial infarction. The more severe form of the 2 types of heart attack. See also NSTEMI. A STEMI produces a characteristic elevation in the ST segment on an electrocardiogram.

Stent – A device made of expandable, metal mesh that is placed (by using a balloon catheter) at the site of a narrowing artery. The stent is then expanded and left in place to keep the artery open.

Stenosis – The narrowing or constriction of an opening, such as a blood vessel or heart valve.

Stethoscope – An instrument for listening to sounds within the body.

Stokes-Adams disease – Also called third-degree heart block; a condition that happens when the impulses that pace your heartbeat do not reach the lower chambers of your heart (the ventricles). To make up for this, the ventricles use their own “backup” pacemaker with its slower rate. This rhythm can cause severe dizziness or fainting and can lead to heart failure or death.

Streptococcal infection (“strep” infection) – An infection, usually in the throat, resulting from the presence of streptococcus bacteria.

Streptokinase – A clot-dissolving medicine used to treat heart attack patients.

Sternum – The breastbone.

Stress – Bodily or mental tension resulting from physical, chemical, or emotional factors. Stress can refer to physical exertion as well as mental anxiety.

Stroke – A sudden disruption of blood flow to the brain, either by a clot or a leak in a blood vessel.

Subarachnoid hemorrhage – Bleeding from a blood vessel on the surface of the brain into the space between the brain and the skull.

Subclavian arteries – Two major arteries (right and left) that receive blood from the aortic arch and supply it to the arms.

Sudden death – Death that occurs unexpectedly and instantaneously or shortly after the onset of symptoms. The most common underlying reason for patients dying suddenly is cardiovascular disease, in particular coronary heart disease.

Superior vena cava – The large vein that returns blood from the head and arms to the heart.

Supraventricular tachycardia (SVT) – A regular rapid heart rate (150-250 beats per minute) that is caused by events triggered in areas above the heart’s lower chambers (the ventricles); see also paroxysmal supraventricular tachycardia (PSVT).

Syncope – A temporary, insufficient blood supply to the brain which causes a loss of consciousness. Usually caused by a serious arrhythmia.

Systolic blood pressure – The highest blood pressure measured in the arteries. It occurs when the heart contracts with each heartbeat.

Tachycardia – Accelerated beating of the heart. Paroxysmal tachycardia is a particular form of rapid heart action, occurring in seizures that may last from a few seconds to several days.

Tachypnea – Rapid breathing.

Tamponade – Also called cardiac tamponade. A condition in which the heart is compressed or constricted because of a large amount of fluid or blood in the space between the heart muscle and the sac that surrounds the heart (the pericardium).

Thallium-201 stress test – An x-ray study that follows the path of radioactive potassium carried by the blood into heart muscle. Damaged or dead muscle can be defined, as can the extent of narrowing in an artery.

Third-degree heart block – A serious condition also called Stokes-Adams disease; impulses from the heart’s upper chambers (the atria) are completely blocked from reaching the heart’s lower chambers (the ventricles). To make up for this, the ventricles use their own “backup” pacemaker with its slower rate.

Thrombolysis – The breaking up of a blood clot.

Thrombosis – A blood clot that forms inside the blood vessel or cavity of the heart.

Thrombolytic therapy – Intravenous or intra-arterial medicines that are used to dissolve blood clots in an artery.

Thrombus – A blood clot.

Thyroid – A gland located in the front of the neck, just below the voice box.

Tissue plasminogen activator (tPA) – A clot-dissolving medicine that is used to treat heart attack and stroke patients.

Trans fat – Created when hydrogen is forced through an ordinary vegetable oil (hydrogenation), converting some polyunsaturates to monounsaturates, and some monounsaturates to saturates. Trans fat, like saturated fat, tends to raise LDL cholesterol levels, and, unlike saturated fat, trans fat also lowers HDL cholesterol levels.

Transcatheter aortic valve implantation (TAVI) – A minimally invasive procedure to repair a damaged or diseased aortic valve. A catheter is inserted into an artery in the groin and threaded to the heart. A balloon at the end of the catheter, with a replacement valve folded around it, delivers the new valve to take the place of the old. Also called TAVR (Transcatheter aortic valve replacement).

Transcatheter intervention – Any of the noninvasive procedures usually performed in the cardiac catheterization laboratory. Angioplasty is an example of a transcatheter intervention. Also called a percutaneous coronary intervention (PCI).

Transesophageal echocardiography – A diagnostic test that analyzes sound waves bounced off the heart. The sound waves are sent through a tube-like device inserted in the mouth and passed down the esophagus (food pipe), which ends near the heart. This technique is useful in studying patients whose heart and vessels, for various reasons, are difficult to assess with standard echocardiography.

Transient ischemic attack (TIA) – A stroke-like event that lasts only for a short time and is caused by a temporarily blocked blood vessel.

Transplantation – Replacing a failing organ with a healthy one from a donor.

Tricuspid valve – The structure that controls blood flow from the heart’s upper right chamber (the right atrium) into the lower right chamber (the right ventricle).

Triglyceride – The most common fatty substance found in the blood; normally stored as an energy source in fat tissue. High triglyceride levels may thicken the blood and make a person more susceptible to clot formation. High triglyceride levels tend to accompany high cholesterol levels and other risk factors for heart disease, such as obesity.

Ultrasound – High-frequency sound vibrations, which cannot be heard by the human ear, used in medical diagnosis.

Valve replacement – An operation to replace a heart valve that is either blocking normal blood flow or causing blood to leak backward into the heart (regurgitation).

Valvuloplasty – Reshaping of a heart valve with surgical or catheter techniques.

Varicose vein – Any vein that is abnormally dilated (widened).

Vascular – Pertains to the blood vessels.

Vasodilators – Any medicine that dilates (widens) the arteries.

Vasopressors – Any medicine that elevates blood pressure.

Vein – Any one of a series of blood vessels of the vascular system that carries blood from various parts of the body back to the heart, returning oxygen-poor blood to the heart.

Ventricle (right and left) – One of the two lower chambers of the heart.

Ventricular Assist Device (VAD) – A mechanical pump that helps the ventricles pump blood, easing the workload of the heart in patients with heart failure.

Ventricular fibrillation – A condition in which the ventricles contract in a rapid, unsynchronized fashion. When fibrillation occurs, the ventricles cannot pump blood throughout the body.

Ventricular tachycardia – An arrhythmia (abnormal heartbeat) in the ventricle characterized by a very fast heartbeat.

Vertigo – A feeling of dizziness or spinning.

Wolff-Parkinson-White syndrome – A condition in which an extra electrical pathway connects the atria (two upper chambers) and the ventricles (two lower chambers). It may cause a rapid heartbeat.

X-ray – Form of radiation used to create a picture of internal body structures on film