angina the discomfort and pain felt when a blockage in a coronary artery prevents enough oxygen-rich blood from reaching part of the heart.

angioplasty a procedure for treating blockages and blood clots. The procedure involves the use of thin balloons and other devices that are threaded up through a blood vessel in the groin and into a coronary artery.

antiarrhythmic agents drugs that slow or eliminate rapid contraction of the ventricle.

anti-inflammatory agents drugs that reduce inflammation and its effects.

aortic valve the one-way valve that allows blood to flow only out of the left ventricle and into the aorta.

arrhythmia irregular heartbeat that can be (1) very rapid ventricular contractions (tachycardia); (2) an excessively slow heartbeat (bradychardia); or (3) most common, extra or "premature" beats.

atherosclerosis condition in which cholesterol collects under the inner lining of damaged artery walls. The deposits (cholesterol plaques) eventually may narrow or block the artery and obstruct blood flow. Commonly called hardening of the arteries.

atria the right and left upper chambers of the heart (singular = atrium).

atrial fibrillation See fibrillation.

AV node atrioventricular node; a patch of electrical-wire-like specialized heart tissue located between the atria and the ventricles that conducts contractile impulses from the atria down into the ventricles.

beta-blockers drugs that relieve stress on the heart by "blocking" the stimulating effect of the hormone adrenaline.

blood clot an insoluble mass of blood.

blood culture laboratory examination of a blood sample to detect the presence of disease-causing microorganisms.

blood pressure measurement a measure of the force of blood flow against artery walls taken with an inflatable cuff, inflating bulb, and a pressure gauge.

blood thinners See heparin and warfarin.

calcium-channel blockers drugs that limit calcium entry into the cells, where it stimulates contraction.

cardiac catheterization diagnostic procedure using a flexible tube or catheter that is passed into the heart through a vein or an artery to withdraw samples of blood, measure pressures within the heart chambers or vessels, and inject X-ray contrast materials to view the heart.

cardiac transplantation replacement of a damaged or diseased heart with a healthy heart from a donor who has died of other causes.

chest pain See angina.

cholesterol a soft, waxy type of fatty particle (lipid) that circulates in the blood. Cholesterol is a building block for all cell membranes and many sex hormones, and is in the digestive substances released by the gall bladder.

congestive heart failure (CHF) a potentially lethal condition produced by a heart attack, poorly controlled or uncontrolled hypertension, or disease processes that weaken the heart. When the left chambers of the heart fail, blood backs up and congestion develops in the lungs. When the right chambers of the heart fail, blood backs up and congestion and edema (swelling) develops in the legs and the liver. Both sides often fail.

cor pulmonale enlargement and eventual failure of the right ventricle of the heart caused by lung disease.

coronary angiography an x-ray imaging of the coronary arteries. A catheter is inserted into an artery at the groin or elbow and guided through the aorta and into a coronary artery, where the x-ray contrast agent is injected to make visible the artery any any obstructions or abnormalities.

diastolic pressure arterial pressure measured while the heart rests between beats.

digoxin, or digitalis drug used to treat congestive heart failure by increasing the force of contraction and to treat atrial fibrillation by slowing transmission of atrial electrical impulses (i.e., slowing the heart rate) and restoring normal heart rate.

diuretics drugs that increase the elimination of salt and water by the kidneys, resulting in increased urine volume.

echocardiography a noninvasive cardiac imaging procedure used to diagnose heart disease, valve disorders (valvular heart disease), weakened heart muscle, fluid around the heart (pericarditis), and other abnormalities or defects. An ultrasound machine bounces sound waves at tissues of the heart and records an image using the patterns made when the sound waves bounce back ("echo") from the heart tissue.

ejection fraction the percentage of blood that is ejected out of the left ventricle into the aorta with each heart beat.

electrocardiography/electrocardiogram (ECG, EKG) a graphical recording of the electrical currents that pass through the heart muscle during each heartbeat. In this procedure, electrodes are attached to the arms and legs, and the electrical pulses are recorded. This test is commonly called an EKG because the procedure was developed in the Netherlands, where it was spelled "electrokardiogram."

endocarditis infection of a heart valve.

endothelium layer of epithelial cells that line the cavities of the heart and the blood vessels.

fibrillation uncontrolled rapid contraction of the fibers in the heart. When this occurs in the two atrial (upper) chambers of the heart, the condition is called atrial fibrillation. When it occurs in the ventricular (lower) chambers, the condition is called ventricular fibrillation.

fibrosis the formation of scar tissue as a reaction to injury or during a healing process.

heart attack also called myocardial infarction. A medical emergency that occurs when a blood clot forms suddenly in a coronary artery and blocks blood flow to an area of the heart. This usually occurs after the surface of cholesterol plaque in the artery breaks.

heart failure See congestive heart failure.

heart murmur whooshing sound caused by the turbulent flow of blood from the left ventricle across the mitral valve and back into the left atrium.

heart transplant See cardiac transplantation.

heparin a drug that inhibits blood clotting.

homograft valve an aortic valve that has been taken from a human organ donor that is used to replace a diseased heart valve.

hypercholesterolemia, or high cholesterol excessively large amounts of lipids (fats) in the circulating blood. Lipids that are significant in determining the condition include: high-density cholesterol (HDL), known as "good" cholesterol; low-density cholesterol (LDL), known as "bad" cholesterol; and triglycerides (TG).

hypertension, or high blood pressure a condition that occurs when increased resistance to blood flow through small blood vessels (arterioles) forces the heart to work harder.

idiopathic pericarditis inflammation of the tissues of the pericardium with no known or detectable cause.

invasive procedure a medical examination that invades the body either by incision or by insertion of an instrument through the skin.

isolated systolic hypertension condition usually found in the elderly in which only the systolic blood pressure is elevated.

left ventricular assist device (LVAD) a complex pump that is implanted in the body to assist the left ventricle in pumping blood.

mitral valve the one-way valve that allows blood to pass from the left atrium into the left ventricle.

myocardial infarction See heart attack.

noninvasive procedure a medical examination that does not penetrate the skin or invade the body, except needle sticks.

nonsteroidal anti-inflammatory drugs a class of drugs that act against inflammation, reduce feer, relieve muscle pain, and prevent blood clots.

pacemaker battery-powered implantable device that electrically stimulates the heart to contract and thus to pump blood throughout the body. Usually consists of a pager-sized device that houses a battery and the electronic circuitry that runs the device, and one or two long thin wires (leads) that travel through a vein in the chest to the heart. Usually implanted in patients whose hearts' electrical systems no longer function normally.

pericardiocentesis surgical puncuture of the pericardial space to drain fluid.

pericardial effusion accumulation of fluid between the pericardium and the heart.

pericarditis inflammation of the tissues of the pericardium (thin membranous covering of the outer surfaces of the heart.

porcine valve valve made of tissue from a pig that is used to replace a diseased heart valve.

pulmonary embolus a blockage in the lung; often refers to a blood clot located in the lung.

statins drugs that inhibit the manufacture of cholesterol by the liver that are used to treat high blood cholesterol levels.

stenosis a condition that develops when any of the four major valves that regulate blood flow through the heart and to the lungs is damaged or diseased. Valve leaflets thicken and become calcified and the volume of blood from ejected from the heart is reduced.

stress test monitoring the heart during exercise to identify the presence of heart disease or the risk of developing cardiac problems during strenuous activity. During a stress test, the patient typically walks on a treadmill or peddles a stationary bicycle while connected to an electrocardiograph (ECG) machine. A stress test is often accompanied by an imaging technique (nuclear myocardial imaging or echocardiography). Drugs can be used to simulate heart activity during exercise.

stroke a medical event that results from a blood clot causing blockage of the blood supply to the brain.

SA node sinoatrial node; small area of specialized heart tissue located in the right atrium that conducts impulses through the right and left atria, signaling these chambers to contract and pump blood into the ventricles.

systolic pressure arterial pressure measured while the heart contracts, pumping blood into the arteries of the body.

thyroid stimulating hormone (TSH) also thyrotropin; a hormone that stimulates hormonal secretion of the thyroid gland. transesophageal echo (TEE) a diagnostic procedure in which a transducer is passed down into the esophagus to a location behind the heart. Sound waves are transmitted through the esophagus to the heart and received by the transducer. The sound waves are then translated into images of the heart and surrounding tissue.

ventricles the right and left lower chambers of the heart.

warfarin drug used to prevent formation of blood clots.