November 20, 2008



Tetralogy of Fallot Glossary of Medical Terms

These are medical definitions of medical terms from the MedTerms.com medical dictionary that appear in the Tetralogy of Fallot article.

Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
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Anesthesia: Loss of feeling or awareness. A general anesthetic puts the person to sleep . A local anesthetic causes loss of feeling in a part of the body such as a tooth or an area of skin without affecting consciousness. Regional anesthesia numbs a larger part of the body such as a leg or arm, also without affecting consciousness. The term "conduction anesthesia" encompasses both local and regional anesthetic techniques. Many surgical procedures can be done with conduction anesthesia without significant pain . In many situations, such as a C-section , conduction anesthesia is safer and therefore preferable to general anesthesia. However, there are also many types of surgery in which general anesthesia is clearly appropriate.
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Aorta: The largest artery in the body, the aorta arises from the left ventricle of the heart, goes up (ascends) a little ways, bends over (arches), then goes down (descends) through the chest and through the abdomen to where ends by dividing into two arteries called the common iliac arteries that go to the legs.
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Aortic: Pertaining to the aorta , the largest artery in the body.
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Arrhythmia: An abnormal heart rhythm.
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Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red.
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Atria: The plural of atrium. The atria are the two smaller chambers of the heart. Each atrium consists of an open space with recessed walls.
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Atrium: One of the two smaller chambers of the heart. Each atrium consists of an open space with recessed walls. The plural of atrium is atria.
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Birth defect: Any defect present in a baby at birth, irrespective of whether the defect is caused by a genetic factor or by prenatal events that are not genetic.
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Blalock-Taussig operation: A pioneering heart operation named after the American surgeon Alfred Blalock (1899-1964) and the pediatric cardiologist Helen B. Taussig (1898-1986).
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Blood: The familiar red fluid in the body that contains white and red blood cells , platelets , proteins , and other elements. The blood is transported throughout the body by the circulatory system . Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.
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Breathing: The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction, and then exhaled due to muscle relaxation.
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Bypass: An operation in which a surgeon creates a new tubular pathway for the movement of fluids and/or other substances in the body.
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Cardiac: Having to do with the heart.
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Cardiologist: A doctor who specializes in treating heart disorders.
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Cardiovascular: The circulatory system comprising the heart and blood vessels which carries nutrients and oxygen to the tissues of the body and removes carbon dioxide and other wastes from them.
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Catheter: A thin, flexible tube . For example, a catheter placed in a vein provides a pathway for giving drugs, nutrients, fluids, or blood products. Samples of blood can also be withdrawn through the catheter.
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Cell: The basic structural and functional unit in people and all living things. Each cell is a small container of chemicals and water wrapped in a membrane .
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Chest: The area of the body located between the neck and the abdomen . The chest contains the lungs , the heart and part of the aorta . The walls of the chest are supported by the dorsal vertebrae , the ribs , and the sternum .
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Chest X-ray: Commonly used to detect abnormalities in the lungs, but can also detect abnormalities in the heart, aorta, and the bones of the thoracic area. Metallic objects, such as jewelry are removed from the chest and neck areas for a chest x-ray to avoid interference with x-ray penetration and improve accuracy of the interpretation.
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Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time.
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Circulation: The movement of fluid in a regular or circuitous course. Although the noun "circulation" does not necessarily refer to the circulation of the blood, for all practical purposes today it does. Heart failure is an example of a problem with the circulation.
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Circulatory: Having to do with the circulation, the movement of fluid in a regular or circuitous course. Although the adjective "circulatory" need not necessarily refer to the circulation of the blood, for all practical purposes today it does. A circulatory problem is taken usually to be a problem with the blood circulation, for example with heart failure.
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Circulatory system: The system that moves blood throughout the body. The circulatory system is composed of the heart, arteries, capillaries, and veins. This remarkable system transports oxygenated blood from the lungs and heart throughout the body via the arteries. The blood goes through the capillaries which are situated between the arteries and veins. And the blood that has been depleted of oxygen by the body is then returned to the lungs and heart via the veins.
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Condition: The term "condition" has a number of biomedical meanings including the following:

  1. An unhealthy state, such as in "this is a progressive condition."
  2. A state of fitness, such as "getting into condition."
  3. Something that is essential to the occurrence of something else; essentially a "precondition."
  4. As a verb: to cause a change in something so that a response that was previously associated with a certain stimulus becomes associated with another stimulus; to condition a person, as in behavioral conditioning.

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Congenital: Present at birth. A condition that is congenital is one that is present at birth. There are numerous uses of "congenital" in medicine. There are, for example, congenital abnormalities. (For more examples, see below.)
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Congenital heart disease: A malformation of the heart or the large blood vessels near the heart. The term "congenital" speaks only to time, not to causation; it means "born with" or "present at birth."
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Cyanosis: A bluish color of the skin and the mucous membranes due to insufficient oxygen in the blood. For example, the lips may show cyanosis. Cyanosis can be evident at birth, as in a "blue baby" who has a heart malformation that permits blood that is not fully oxygenated to enter the arterial circulation. Cyanosis can also appear at any time later in life.
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Developmental delay: Behind schedule in reaching milestones of early childhood development.
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Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV.
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ECG: Abbreviation for electrocardiogram or EKG. The K is from "kardio" (in German).
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Echocardiography: Echocardiography is a diagnostic test which uses ultrasound waves to make images of the heart chambers, valves and surrounding structures. It can measure cardiac output and is a sensitive test for inflammation around the heart ( pericarditis ). It can also be used to detect abnormal anatomy or infections of the heart valves.
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Electrocardiogram : A recording of the electrical activity of the heart. An electrocardiogram is a simple, non-invasive procedure. Electrodes are placed on the skin of the chest and connected in a specific order to a machine that, when turned on, measures electrical activity all overaround the heart. Output is usually in the form of a long scroll of paper displaying a printed graph of activity. Newer models output the data directly to a computer and screen, although a print-out may still be made.
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Emergency department: The department of a hospital responsible for the provision of medical and surgical care to patients arriving at the hospital in need of immediate care. Emergency department personnel may also respond to certain situations within the hospital such cardiac arrests.
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Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness and tiredness. Fatigue can be acute and come on suddenly or chronic and persist.
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Fetus: The unborn offspring from the end of the 8th week after conception (when the major structures have formed) until birth. Up until the eighth week, the developing offspring is called an embryo.
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Groin: In anatomy, the area where the upper thigh meets the trunk. More precisely, the fold or depression marking the juncture of the lower abdomen and the inner part of the thigh.
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Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
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Heart block: A block in the conduction of the normal electrical impulses in the heart.
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Heart disease: Any disorder that affects the heart. Sometimes the term "heart disease" is used narrowly and incorrectly as a synonym for coronary artery disease . Heart disease is synonymous with cardiac disease but not with cardiovascular disease which is any disease of the heart or blood vessels. Among the many types of heart disease, see, for example: Angina ; Arrhythmia ; Congenital heart disease ; Coronary artery disease ( CAD ); Dilated cardiomyopathy ; Heart attack ( myocardial infarction ); Heart failure ; Hypertrophic cardiomyopathy ; Mitral regurgitation ; Mitral valve prolapse ; and Pulmonary stenosis .
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Hemoglobin: The oxygen-carrying pigment and predominant protein in the red blood cells . Hemoglobin forms an unstable, reversible bond with oxygen. In its oxygenated state it is called oxyhemoglobin and is bright red. In the reduced state it is called deoxyhemoglobin and is purple-blue.
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Hospital: It may seem unnecessary to define a "hospital" since everyone knows the nature of a hospital. A hospital began as a charitable institution for the needy, aged, infirm, or young.
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Hypertrophy: Enlargement or overgrowth of an organ or part of the body due to the increased size of the constituent cells. Hypertrophy occurs in the biceps and heart because of increased work. Cardiac hypertrophy is recognizable microscopically by the increased size of the cells. The term hypertrophy is applied to the enlargement of the uterus during pregnancy. The term benign prostatic hypertrophy is a misnomer because the increased size of the prostate is due to hyperplasia , an increase in the number of cells.
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Hypoxia: A subnormal concentration of oxygen . By contrast with normoxia (normal oxygen) and anoxia (the absence or near absence of oxygen). From hyp– (below) + -ox- (oxygen) + –ia.
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Inferior: In anatomy, below or toward the feet. As opposed to superior. The liver is inferior to the lungs.
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Inferior vena cava: A large vein that receives blood from the lower extremities, pelvis and abdomen and delivers it to the right atrium of the heart.


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Internal medicine: A medical specialty dedicated to the diagnosis and medical treatment of adults. A physician who specializes in internal medicine is referred to as an internist. A minimum of seven years of medical school and postgraduate training are focused on learning the prevention, diagnosis, and treatment of diseases of adults. Subspecialties of internal medicine include allergy and immunology, cardiology (heart), endocrinology (hormone disorders), hematology (blood disorders), infectious diseases, gastroenterology (diseases of the gut), nephrology (kidney diseases), oncology (cancer), pulmonology (lung disorders), and rheumatology ( arthritis and musculoskeletal disorders).
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Laboratory: A place for doing tests and research procedures and preparing chemicals, etc. Although "laboratory" looks very like the Latin "laboratorium" (a place to labor, a work place), the word "laboratory" came from the Latin "elaborare" (to work out, as a problem, and with great pains), as evidenced by the Old English spelling "elaboratory" designating "a place where learned effort was applied to the solution of scientific problems."
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Left atrium: The upper right chamber of the heart. The left atrium receives oxygenated blood from the lungs and pumps it down into the left ventricle which delivers it to the body.


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Left ventricle: The left lower chamber of the heart that receives blood from the left atrium and pumps it out under high pressure through the aorta to the body.
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Lips: Aside from the lips of the mouth, there are two pairs of lips at the entrance to the vagina . They are the labia majora (the larger outside pair) and the labia minora (the smaller inside pair). Together they form part of the vulva (the female external genitalia ).
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Lungs: The lungs are a pair of breathing organs located with the chest which remove carbon dioxide from and bring oxygen to the blood. There is a right and left lung.
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Medical school: A school with a curriculum leading to a medical degree. The mission of every medical school includes medical teaching, research, and patient care. All medical schools share the goal of preparing students in the art and science of medicine, and providing them with the background necessary to enter the period of graduate medical education. The years of medical school preceding graduate medical education are typically divided into a preclinical phase and a clinical phase.
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Medication: 1. A drug or medicine. 2. The administration of a drug or medicine. (Note that "medication" does not have the dangerous double meaning of "drug.")
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Mitral valve: A valve in the heart situated between the left atrium and the left ventricle that permits blood to flow from the left atrium into the left ventricle but not in the reverse direction.
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Morphine: A powerful narcotic agent with strong analgesic (painkilling) action and other significant effects on the central nervous system . It is dangerously addicting. Morphine is a naturally occurring member of a large chemical class of compounds called alkaloids.
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Mortality: A fatal outcome or, in one word, death. The word "mortality" is derived from "mortal" which came from the Latin "mors" (death). The opposite of mortality is, of course, immortality. Mortality is also quite distinct from morbidity (illness).
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Mouth: 1. The upper opening of the digestive tract, beginning with the lips and containing the teeth, gums, and tongue. Foodstuffs are broken down mechanically in the mouth by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch. 2. Any opening or aperture in the body. The mouth in both senses of the word is also called the os, the Latin word for an opening, or mouth. The o in os is pronounced as in hope. The genitive form of os is oris from which comes the word oral.
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Mucous: Pertaining to mucus, a thick fluid produced by the lining of some tissues of the body.
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Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."
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Nose: The external midline projection from the face.
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Obstruction: Blockage of a passageway. See, for example: Airway obstruction ; Intestinal obstruction .
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Operation: Although there are many meanings to the word "operation", in medicine it refers to a surgical procedure.
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Oxygen: A colorless, odorless and tasteless gas that makes up about 20% of the air we breathe (and at least half the weight of the entire solid crust of the earth) and which combines with most of the other elements to form oxides. Oxygen is essential to human, animal and plant life.
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Oxygenation: The addition of oxygen to any system, including the human body. Oxygenation may also refer to the process of treating a patient with oxygen, or of combining a medication or other substance with oxygen.
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Pacemaker: A system that sends electrical impulses to the heart in order to set the heart rhythm. The pacemaker can be the normal "natural" pacemaker of the heart or it can be an electronic device.
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Pharmacy: A location where prescription drugs are sold. A pharmacy is, by law, constantly supervised by a licensed pharmacist.
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Postoperative: After surgery. As opposed to preoperative, before surgery.
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Primary: First or foremost in time or development. The primary teeth (the baby teeth) are those that come first. Primary may also refer to symptoms or a disease to which others are secondary.
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Puberty: A complex biologic and psychologic process involving sexual development, accelerated growth, and adrenal maturation heralded by the secretion of gonadotropin releasing hormone (GnRH) from a part of the brain called the hypothalamus . This event is the first known step in the reproductive cascade. It initiates the pulsatile release of gonadotropins , gonadal secretion of sex steroids, pubertal development, and gametogenesis (the production of sperm and ova ).
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Pulmonary: Having to do with the lungs. (The word comes from the Latin pulmo for lung).
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Pulmonary artery: One of the two vessels which are formed as terminal branches of the pulmonary trunk and convey unaerated blood to the lungs. The two pulmonary arteries differ in length and anatomy.
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Pulmonary stenosis: The pulmonary valve is too tight so that the flow of blood from the right ventricle of the heart into the pulmonary artery is impeded. This means the right ventricle must pump harder than normal to overcome the obstruction. If the stenosis is severe, babies may become blue (cyanotic). Older children often have no symptoms. Treatment is needed if the pressure in the right ventricle is higher than normal. The obstruction can usually be relieved by a procedure called balloon valvuloplasty or by open heart surgery during which the stenotic valve is opened. The outlook after either procedure is favorable.
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Pulmonary valve: One of the four valves in the heart, the pulmonary valve stands at the opening from the right ventricle in the pulmonary artery trunk. It lets blood head in the right direction (toward the lungs) and keeps it from sloshing back from the pulmonary artery into the heart.
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Red blood cell: The blood cell that carries oxygen. Red cells contain hemoglobin and it is the hemoglobin which permits them to transport oxygen (and carbon dioxide). Hemoglobin, aside from being a transport molecule, is a pigment. It gives the cell its red color (and name).
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Regurgitation: A backward flowing. For example, of food. Or the sloshing of blood back into the heart (or between chambers of the heart) when a heart valve is incompetent and does not close effectively.
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Residual: Something left behind. With residual disease, the disease has not been eradicated.
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Resistance: Opposition to something, or the ability to withstand it. For example, some forms of staphylococcus are resistant to treatment with antibiotics.
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Rest: 1. Repose. Relaxation.
2. A fragment of embryonic tissue that has been retained after the period of embryonic development. Also called an embryonic rest.
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Right atrium: The right upper chamber of the heart. The right atrium receives deoxygenated blood from the body through the vena cava and pumps it into the right ventricle which then sends it to the lungs to be oxygenated.


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Right ventricle: The lower right chamber of the heart that receives deoxygenated blood from the right atrium and pumps it under low pressure into the lungs via the pulmonary artery.
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Septum: A word borrowed from the Latin "saeptum" meaning a "dividing wall or enclosure."
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Skin: The skin is the body's outer covering. It protects us against heat and light, injury, and infection. It regulates body temperature and stores water, fat, and vitamin D. Weighing about 6 pounds, the skin is the body's largest organ. It is made up of two main layers; the outer epidermis and the inner dermis.


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Stenosis: A narrowing, as in:

  • aortic stenosis (narrowing of the aortic valve of the heart),
  • pulmonary stenosis (narrowing of the pulmonary valve of the heart),
  • pyloric stenosis (narrowing of the outlet of the stomach), and
  • spinal stenosis (narrowing of the vertebral canal).

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Subclavian: Under the clavicle (the collar bone), as the subclavian artery or the subclavian vein .
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Superior vena cava: A large vein that receives blood from the head, neck, upper extremities, and thorax and delivers it to the right atrium of the heart.


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Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
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Tachycardia: A rapid heart rate, usually defined as greater than 100 beats per minute. The tachycardias include sinus tachycardia, paroxysmal atrial tachycardia (PAT), and ventricular tachycardia.
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Tetralogy of Fallot: A combination of four heart defects that are present together at birth, accounting for about 10% of all congenital heart disease.
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Tricuspid: Having three flaps or cusps. The valve that is called the tricuspid valve is situated between the right atrium and right ventricle and permits blood to flow only from the atrium into the ventricle. The aortic valve in the heart also has three cusps.
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Tricuspid valve:One of the four heart valves, the tricuspid valve is the first one that blood encounters as it enters the heart. The tricuspid valve stands between the right atrium and right ventricle and allows blood to flow only from the atrium into the ventricle.
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Vena cava: The superior vena cava is the large vein which returns blood to the heart from the head, neck and both upper limbs. The inferior vena cava returns blood to the heart from the lower part of the body.
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Ventricle: A chamber of an organ. For example, the four connected cavities (hollow spaces) in the central portion of the brain and the lower two chambers of the heart are called ventricles.
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Ventricles: 1, The right ventricle and the left ventricle , the lower two chambers of the heart. 2. Two or more of the four connected spaces within the central portion of the brain.
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Ventricular: Pertaining to the ventricles, the lower chambers of the heart , as in ventricular fibrillation and ventricular septal defect .
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Ventricular septum: The wall between the two lower chambers (the right and left ventricles) of the heart.
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Ventricular tachycardia: An abnormally rapid heart rhythm that originates from a ventricle , one of the lower chambers of the heart. Although the beat is regular, ventricular tachycardia is life-threatening because it can lead to a dreaded condition, ventricular fibrillation .
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Vessel: A tube in the body that carries fluids: blood vessels or lymph vessels.
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VSD: A Ventricular Septal Defect , a hole in the septum (the wall) between the lower chambers of the heart (the ventricles).
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X-ray: 1. High-energy radiation with waves shorter than those of visible light. X-rays possess the properties of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting radiography), and of causing a fluorescent screen to give off light (permitting fluoroscopy). In low doses X-rays are used for making images that help to diagnose disease, and in high doses to treat cancer . Formerly called a Roentgen ray. 2. An image obtained by means of X-rays.
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