Glossary of Terms

This glossary of terms has been compiled for your reference. Select the first letter of the word you’re searching for to begin.

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A group of therapeutic methods that physically destroy the cardiac tissue that causes or contributes to some types of tachycardia (fast heartbeat). May be done through surgery or using a transcatheter approach with an electrode catheter.


A substance produced in humans that helps protect against ischemia (lack of blood flow). It’s produced in blood vessels, heart and skeletal muscle, and other organs.


A ballooning-out of the wall of an artery, a vein or the heart due to weakening of the wall by disease, injury or an abnormality present at birth.


Medical term for chest pain or discomfort due to coronary heart disease. A condition in which the heart muscle doesn’t get enough blood, resulting in chest pain.


An X-ray examination of the blood vessels or chambers of the heart. A special fluid (contrast medium or dye) visible by X-ray is injected into the bloodstream. Tracing the course of this fluid produces X-ray pictures called angiograms.


The creation of blood vessels. The body creates small blood vessels called “collaterals” to help compensate for reduced blood flow.


An X-ray picture of blood vessels or chambers of the heart that shows the course of a special fluid (contrast medium or dye) injected into the bloodstream.


A procedure sometimes used to dilate (widen) narrowed arteries. A catheter with a deflated balloon on its tip is passed into the narrowed artery segment, the balloon inflated, and the narrowed segment widened. Then the balloon is deflated and the catheter is removed.

Angiotensin Converting Enzyme (ACE) Inhibitors

A class of drugs used to treat high blood pressure and heart failure. ACE inhibitors interfere with the body’s production of angiotensin.

Angiotensin II Receptor Blockers

A class of drugs used to treat high blood pressure and heart failure. They block the effects of angiotensin.


A blood-thinning drug used to reduce the risk of clots.


The large artery that receives blood from the heart’s left ventricle and distributes it to the body.

Aortic Stenosis (AS)

A congenital heart defect in which the aortic valve, between the left ventricle and the aorta, is narrowed.

Aortic Valve

The heart valve between the left ventricle and the aorta. It has three flaps (cusps).

Arrhythmia (or Dysrhythmia)

An abnormal rhythm of the heart.


A testing procedure in which a dye visible to X-rays is injected into the bloodstream, then X-ray pictures are taken and studied to see if the arteries are damaged.


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


Commonly called hardening of the arteries, this includes a variety of conditions that cause artery walls to thicken and lose elasticity. Some hardening of arteries often occurs when people grow older.


One of a series of vessels that carry blood from the heart to the various parts of the body. Arteries have thick, elastic walls that expand as blood flows through them.


A procedure to remove plaque from arteries. An ultra-thin wire is threaded through a special catheter into the blocked artery. Several devices then may be used. One is a high-speed rotating “burr” that grinds the plaque into very tiny pieces. Another is a small rotating cutter that “shaves off” pieces of the blockage. Another is a laser catheter that vaporizes the plaque. (See Laser Angioplasty.)


A form of arteriosclerosis in which the inner layers of artery walls become thick and irregular due to deposits of fat, cholesterol and other substances. This buildup is called “plaque.” As the interior walls of arteries become lined with these deposits, the arteries become narrowed, reducing the blood flow through them.


The heart’s two upper chambers.

Atrial Fibrillation

A disorder in which the heart’s two small, upper chambers quiver instead of beating effectively. Blood that isn’t pumped completely out of the atria when the heart beats may pool and clot. Then a blood clot may enter the bloodstream, become a cerebral embolus and cause an ischemic stroke.

Atrial Septal Defect (ASD)

A congenital heart defect in which an opening exists between the heart’s two upper chambers.

Atrioventricular (AV) Canal Defect (or Atrioventricular Septal Defect)

A congenital heart defect in which a large hole in the center of the heart exists where the wall between the upper chambers joins the wall between the lower chambers. Also, a single large valve crosses the defect.

Atrioventricular (AV) Node

A small mass of specialized conducting tissue at the bottom of the right atrium. The electrical impulse stimulating the heart to contract must pass through this node to reach the ventricles.


Either of the heart’s two upper chambers in which blood collects before being passed to the ventricles.