calcium channel blockers A group of drugs used in the treatment of angina, hypertension, and cardiac arrhythmias. They work by inhibiting the effect of calcium on the muscles of arteries, thereby reducing the degree of contraction. This results in a decrease in the workload of the heart, a decrease in blood pressure, and improved circulation of blood.
capillaries Tiny, thin-walled blood vessels through which the exchange of oxygen, nutrients, and wastes takes place.
carbon dioxide An odorless, colorless gas present in the air; also a by-product of metabolism. In the body, it is carried by the blood to the lungs and is then expelled from the body through exhaling.
cardiac arrest Incident during which the heart stops beating and loss of consciousness occurs because of cutoff of blood flow to the brain. It is usually the result of ventricular fibrillation, in which the heart’s ventricles twitch randomly and ineffectively rather than beating in a rhythmic fashion to pump blood from the heart. A complete cessation of all heartbeats can also cause a cardiac arrest.
cardiac catheterization Insertion of a catheter through the blood vessels into the chambers of the heart to measure pressure or to inject a dye to visualize the coronary arteries.
cardiac cycle The cycle of activities associated with one heartbeat.
cardiologist A physician specializing in the diagnosis and treatment of disorders of the heart.
cardiology The branch of medicine dealing with the functions of the heart and blood vessels.
cardiomyopathy A term denoting any disease of the heart muscle.
cardiopulmonary bypass machine (heart-lung machine) The machine that takes over the body’s heart and lung functions during open heart surgery.
cardiopulmonary resuscitation (CPR) Administration of lifesaving procedures such as compression of the heart muscle and mouth-to-mouth breathing for a person suffering cardiac arrest. This is done in order to restore blood circulation to the brain as quickly as possible to prevent possible brain damage.
cardiovascular Of or pertaining to the heart and blood vessels.
cardioversion Use of an electrical shock to restore normal heart rhythm. (See also defibrillation below.)
carotid arteries The principal arteries of the head and neck, each of which has two main branches, the external carotid artery and the internal carotid artery.
carotid sinus A small nerve center located at the point where the internal carotid artery branches off from the main or common carotid artery.
catheter A flexible tube that is inserted into a blood vessel or cavity for the purpose of examination, drainage of fluid, or other procedures.
cerebellum The region of the brain that coordinates movement and maintains posture and balance.
cerebrovascular accident The sudden blockage of a blood vessel in the brain caused by an embolus, or thrombosis, and resulting in decreased blood circulation in the brain. Also may result from a ruptured blood vessel that causes a cerebral hemorrhage.
cerebrum The largest portion of the brain. It consists of two hemispheres and an outer covering (the cortex); it controls mental functions and sensory activities.
cholesterol A fatty substance necessary for hormone production, cell metabolism, and other vital processes. It is also a component of cell membranes in all animals. Cholesterol is manufactured in the body and is also consumed in the diet. Dietary cholesterol
is found only in animal products. High levels of blood cholesterol are a contributing factor to coronary heart disease.
circulatory system The system that is made up of the heart and blood vessels and is responsible for circulating blood throughout the body, providing the tissues with oxygen and nutrients, and removing waste products.
circumflex Name of one of the three major coronary arteries.
coarctation of the aorta Also referred to as aortic coarctation; a congenital defect characterized by narrowing of the main artery (aorta) of the upper body, resulting in a reduced blood supply to the lower body and legs. As a result, blood pressure is increased in
the upper portion of the body and decreased in the lower portion.
collateral circulation Blood vessels that sometimes gradually take over the blood circulation when a main vessel is partially or completely blocked. They go around the narrowed area.
computerized tomography (CT) scan A diagnostic technique involving the use of computers and multiple X-ray images to produce cross-sectional images of body tissue. This technique provides more clearly detailed images than traditional X-rays.
congenital heart defects Abnormalities of the heart existing at birth.
congestive heart failure Inability of the heart to pump sufficient blood, resulting in an accumulation of fluids in the lungs, abdomen, and legs. This condition usually develops over a period of years, but may also result from a heart attack that damages a large portion of heart muscle.
contrast venography A diagnostic procedure in which a contrasting medium is injected into the veins to make them visible on X-ray film.
coronary artery disease Diseases of the arteries that supply blood to the heart muscle.
coronary bypass surgery Surgery to improve blood flow to the heart muscle in the presence of severe coronary artery disease. The procedure involves creating bypass routes for blood flow from the aorta to various areas of the heart muscle. The bypass grafts are usually portions of veins taken from the legs or a repositioned artery on the chest wall, which lies near the heart (the internal mammary artery).
coronary care unit (CCU) An intensive care unit for patients who have had a heart attack or other acute emergent cardiac problem.
coronary heart disease Diseases of the heart caused by narrowing of the coronary arteries, resulting in reduced blood flow to the heart. Also known as coronary artery disease and ischemic heart disease.
cyanosis A bluish discoloration of the skin caused by an abnormally high level of deoxygenated hemoglobin in the blood. It is noted in heart failure, some types of congestive heart disease, etc.