Acidosis - A lowering of the pH in blood tissue due to excessive acid caused by circulation failure or severe lack of oxygen.

Aneurysm - A balloon-like sac in the wall of an artery, vein, or heart caused by a weakening of the wall by injury, disease, or abnormality present at birth.

Angiocardiography - An x-ray method using dye in the bloodstream to show the dimension of the heart.

Angioplasty - A procedure using a deflated balloon on the end of a catheter used to widen narrow arteries.

Antiarrhythmic drugs - Medicines used to treat heart rate rhythm disorders. Frequently used drugs include: lidocaine, procaine, amide, digitalis, propanolol, quinidine, alroprine, and isoproterenol.

Antibody - A substance produced by the immune system to fight infections and foreign substances. Antibodies are produced in response to specific antigens.

Anticoagulant - A drug that delays clotting but does not dissolve existing clots. Tends to prevent new clots from forming on artificial valves and existing clots from enlarging.

Antigen - Substances recognized by the immune system as infectious or foreign. The immune system produces antibodies to fight antigens.

Aorta - The main artery which receives blood from the left ventricle of the heart and flows to the body.

Aortic valve - The heart valve between the aorta and the left ventricle.

Arrhythmia - An abnormal rhythm of the heart.

Arteriography - An x-ray opaque dye injected into the blood stream to study arteries (usually coronary) for damage.

Artery - One of the series of vessels that carries blood from the heart.

Atresia - The failure of a bodily structure to develop and the tissue to fully close as it normally would. Usually present and open at birth.

Atria - (atrium-singular) The two upper holding chambers of the heart.

Atrial Septal defect - A congenital defect in the atrial septum.

Atrial Septum - The wall dividing the right and left atria.

Atrioventricular node - Conducting tissue at the bottom of the right atrium in which electrical impulses must pass to reach the ventricles.

Atrioventricular canal defect (A-V Canal defect) - Also atrioventricular septal defect or endocardial cushion defect. A congenital defect in which defects are present between the atria and ventricles and the tricuspid and mitral valves are abnormal.

B Cell - A certain kind of white blood cell that plays a central role in antibody production.

Bacterial endocarditis - A bacterial infection of the inner layer of the heart.

Balloon catheter - Used to dilate a narrow structure. (see angioplasty)

Biopsy - The removal and examination of tissue for diagnosis.

Blood pressure - The pressure exerted by the heart in pumping blood.

Blue babies - A result of insufficient oxygen in the arterial blood. Can be caused by a heart defect, premature birth, or poor respiration.

Bradycardia - An unusually slow heart rate.

Cardiac - Relating to the heart.

Cardiac arrest - The blood ceases to circulate and the heart stops beating.

Cardiac Catheterization - putting a catheter into an artery or vein to examine the heart sometimes using a fluoroscope to view the heart.

Cardiologist - A doctor specializing in the diagnosis and treatment of heart disorders.

Cardiopulmonary Resuscitation (CPR) - Used when the heart stops beating, a method of mouth-to-mouth breathing and external cardiac compression to keep oxygenated blood circulating.

Catheter - A fine, flexible tube which is inserted into an artery or vein. It is made of material to which blood will not adhere.

Catheterization - The process of inserting a catheter into a vein or artery and guiding it through the heart chambers and surrounding vessels for purposes of examination or treatment.

Cineangiocardiography - A similar procedure to angiocardiography except that this method uses motion pictures instead of x-ray slides.

Closed heart surgery - Performed on blood vessels in the chest but not in the heart. Does not require a heart-lung machine.

Coarctation - A narrowing of the aorta where the aorta and pulmonary arteries are joined by the ductus arteriosus.

Collateral Circulation - A network of small arteries normally closed. When the coronary artery is blocked, they may open to carry blood to the heart.

Congenital - Existing at birth.

Congestive heart failure - The inability for the heart to pump the blood out of the heart. The build up of fluid on lungs and tissue can be acute or gradual.

Corticosteroids - Hormones naturally produced by the body which can also be manufactured synthetically. High doses of corticosteroids will suppress the immune system. See Prednisone.

Crossmatching - The testing of blood samples to determine the compatibility of a potential donor's and a recipient's blood.

Cyanosis - Caused by insufficient oxygen. Causes a blueness to the skin, lips, and nail beds.

Defibrillator - A machine to stabilize normal contraction rhythms.

Dextrocardia - Abnormal position of the heart within the chest. The heart is usually on the left, and in this condition it is on the right.

Diastolic - The bottom of the two blood pressure numbers. Measures the heart at rest.

Digitalis (Digoxin)- A medicine that slows heart rate, strengthens contractions, and helps move fluid away from the body tissues.

Diuretic - A drug that increases the excretion of urine.

Echocardiography - A procedure in which pulses of sound are transmitted into the body and the echoes from the heart are recorded and charted. The Doppler color flow gives a picture to show the direction of blood flow.

Edema - Swelling due to excessive fluid in the body.

Electrocardiogram (EKG) - A print-out of the electrical impulses produced by the heart.

Endocardium - The inner lining of the wall of the heart.

Fibrillation - When the heart muscle fibers contract individually and quickly disabling the heart from pumping effectively.

Fluoroscope - A tool for looking at internal organs.

Gingival Hypertrophy - Swelling and thickening of the gums. A common side effect of the immunosuppressive drug cyclosporine.

Heart block - The electrical impulses causing the heart to beat are slowed or blocked along the pathway between the upper and lower chambers, and usually requires a pacemaker.

Heart-lung machine (cardiopulmonary bypass) - An instrument that oxygenates and pumps the blood during open-heart surgery.

Helper T Cell - A specialized white blood cell that calls upon other parts of the immune system to fight an infection or foreign material.

Heparin - A medicine used to slow the clotting of the blood.

Heterotaxy - Abnormal structure of the heart and other abdominal organs. Usually with multiple defects in the heart and the absence of or multiple spleens.

Holter monitoring - An instrument worn 24 to 72 hours at a time that records EKG information which is later analyzed for arrhythmias and other abnormalities.

Homograft - Also know as Allograft; a heart valve replacement using a human donor valve.

Hypertension - Blood pressure above the normal range.

Hypertrophy - When cells increase in size and cause enlarged tissues and organs.

Hypoplastic - An underdeveloped tissue or organ.

Hypotension - Low blood pressure.

Immune Response - A defensive action by the immune system to an infection or foreign material.

Interrupted aortic arch - A severe form of coarctation of the aorta.

Invasive - Introduced into the body.

Mitral valve - The valve between the left ventricle and left atrium having two flaps or cusps that prevent backflow.

Murmur - The noise between normal heart sounds caused by blood flow.

Open-heart surgery - An operation inside the heart while the patient is on a heart lung machine.

Pacemaker - An electrical device used to cause heart contractions and control heartbeats.

Palpitations - Irregular heartbeats felt as a skip or momentary cessation of the heart,

Patent Ductus - A blood vessel present prior to birth that bypasses the lungs of the fetus. The Patent Ductus closes shortly after birth.

Patent Ductus Arteriosus - Failure of the Patent Ductus to close shortly after birth as it should.

Pericarditis - Inflammation of the membrane sac.

Pericardium - A membrane sac surrounding the heart and the vessels close to the heart.

Prednisone - A manufactured steroid commonly used as an immunosuppressive drug.

Pulmonary artery - The artery that carries blood to the lungs from the heart.

Pulmonary artresia - Failure of the pulmonary valve or pulmonary artery to develop in utero.

Pulmonary Hypertension - High blood pressure in the blood vessels of the lungs.

Rejection - An immune system response to a transplanted organ.

Septum - The wall dividing the heart chambers.

Stenosis - An obstruction or narrowing of an opening or valve.

T Cell - Specialized white blood cells that destroy cells infected by viruses.

Tachycardia - Very quick heart rate.

Tetralogy of Fallot - A malformation where the right ventricle connects to the pulmonary artery causing pulmonary stenosis with a large ventricular septal defect.

Tissue Typing - A blood test used to evaluate the compatability of an organ donor's tissue with the tissue of a potential recipient.

Transplantation (heart) - The placement of a healthy heart from a donor to a patient when the patient's heart can no longer function adequately.

Tricuspid atresia - The failure of the development of the tricuspid valve.

Valve conduit - Tubing used with artificial valves.

Ventricle - One of the lower pumping chambers of the heart.