Find definitions for thousands of medical terms, treatments, and tests -- even health-related abbreviations, prefixes, and suffixes.
An abdominal ultrasound uses reflected sound waves to produce a
picture of the organs and other structures in the upper abdomen. Sometimes a
special ultrasound is done for a closer look at a specific organ, such as a
An ultrasound does not use X-rays or other
types of radiation. During an abdominal ultrasound, a small handheld unit
called a transducer is gently moved over the belly. A computer converts the
reflected sound waves into a picture shown on a TV screen.
abdominal ultrasound may help find problems of the liver, gallbladder, spleen,
pancreas, abdominal aorta, and kidneys.
November 29, 2012
Kathleen Romito, MD - Family Medicine & Howard Schaff, MD - Diagnostic Radiology
An abnormal heartbeat (arrhythmia) is any variation in the normal
heartbeat. Abnormal heartbeats occur when the heart has an irregular heart
rhythm, beats too fast (tachycardia), or beats too slow (bradycardia).
The electrical system of the heart creates signals that trigger the
heart to pump. These electrical signals control the heart rate and rhythm.
Normally, the heart beats in a regular rhythm and at a rate that is appropriate
for the work the body is doing. An arrhythmia results from a problem in the
electrical system of the heart. Things that can cause the heart to beat
abnormally include heavy smoking, alcohol use, excess caffeine or other
stimulants, stress, thyroid disease, and fever.
Many arrhythmias are minor, causing only occasional abnormal
heartbeats and requiring no treatment. Others, such as atrial fibrillation, can
be life-threatening because they increase the risk of blood clots and strokes.
Arrhythmias are of special concern in people who also have heart disease or
heart failure. Some arrhythmias can be treated with medicine. Others may
require an electrical shock (cardioversion), surgery, or a pacemaker.
June 2, 2011
E. Gregory Thompson, MD - Internal Medicine & Rakesh K. Pai, MD, FACC
An abscess is a pocket of pus that forms at the site of infected
tissue. An abscess can form on the skin or on tissues within the body and cause
pain, swelling, and tenderness.
Bacteria are a common cause of the infections that form abscesses.
Depending on the size and location of the abscess, your doctor may treat the abscess by:
November 13, 2012
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
Acanthosis nigricans is a skin condition that results in
darkened skin and velvety growths that look like warts. These skin changes can
occur under the arm, on the back of the neck, over finger and toe joints, or in the groin and genital
In adults, acanthosis nigricans may be a sign of
disorders of the hormone system (endocrine system). It can occur in people who are very overweight
(obese). It may be a sign of lung cancer or of a cancer of the digestive system. It can
occur in people who have type 2 diabetes and in people who are resistant to insulin
but have not yet developed type 2 diabetes. Acanthosis nigricans can occur
in women who have polycystic ovary syndrome (PCOS).
June 20, 2012
E. Gregory Thompson, MD - Internal Medicine & David C.W. Lau, MD, PhD, FRCPC - Endocrinology
Acute coronary syndrome (ACS) occurs when a plaque inside a
coronary artery suddenly ruptures. A blood clot forms and blocks blood flow to the heart muscle,
depriving the heart of oxygen-rich blood and causing unstable angina or a heart attack. The amount of time blood flow is blocked and the
extent of heart damage determine which type of ACS occurs, but it is always
considered a life-threatening condition.
April 6, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Robert A. Kloner, MD, PhD - Cardiology
Acute renal failure is the sudden loss of kidney function. When
acute renal failure occurs, the kidneys are unable to remove waste products and
excess fluids, which then build up in the body and upset the body's normal
The most common causes of acute renal failure are dehydration,
blood loss from major surgery or injury, or medicines such as nonsteroidal
anti-inflammatory drugs (NSAIDs), antibiotics, or the dyes (contrast agents)
used in X-ray tests.
Symptoms depend on the cause of the problem and can include:
The treatment of acute renal failure includes correcting the
cause and supporting the kidneys with dialysis until proper
functioning is restored. Most people who develop acute renal failure are
already in the hospital.
May 7, 2012
E. Gregory Thompson, MD - Internal Medicine & Tushar J. Vachharajani, MD, FASN, FACP - Nephrology
Acyanotic heart defects are heart problems that develop before or
at birth but do not normally interfere with the amount of oxygen or blood that
reaches the body's tissues. Acyanotic heart defects include ventricular septal
defect (VSD), atrial septal defect (ASD), patent ductus arteriosus (PDA),
pulmonary valve stenosis, aortic valve stenosis, and coarctation of the aorta.
Acyanotic heart defects do not usually cause cyanosis—a bluish tint
to the skin, lips, and nail beds due to reduced oxygen flow. If cyanosis
develops in a person with acyanotic heart defects, it is typically a result of
increased activity (such as crying and feeding) during which more oxygen is
October 11, 2011
John Pope, MD - Pediatrics & Larry A. Latson, MD - Pediatric Cardiology
Addison's disease is a rare condition that develops when the
adrenal glands, located above the kidneys, are not able to produce enough of
the hormones cortisol and aldosterone.
The adrenal glands release cortisol to help the body cope with
stress from illness, injury, surgery, childbirth, or other reasons. Aldosterone
helps the body retain salt and maintain blood pressure. Adrenal gland failure
can be caused by a problem with the body's immune system (autoimmune disease)
or by infection, tumor, bleeding, or injury.
Symptoms of Addison's disease include weakness, weight loss,
nausea, vomiting, diarrhea, darkening of the skin (called hyperpigmentation),
emotional distress, and a decreased ability to tolerate cold.
People who have Addison's disease need to take medicine for the
rest of their lives to replace cortisol and aldosterone. Treatment relieves
symptoms and usually reverses any darkening of the skin. After proper treatment
is started, most people with Addison's disease can lead healthy lives. If
Addison's disease is not treated, an adrenal crisis may occur that can lead to
death because of a severe drop in blood pressure.
December 5, 2011
The adrenal glands are located above the kidneys. The hormones
produced by the adrenal glands affect nearly every organ in the body.
The inner layer of the adrenal gland releases substances (hormones)
such as adrenaline that:
The outer layer of the adrenal gland releases hormones such as
May 17, 2012
E. Gregory Thompson, MD - Internal Medicine & Alan C. Dalkin, MD - Endocrinology
An advance directive is a legal form you fill out to say what kinds of medical care you want if you aren't able to make decisions for yourself. It tells your family and your doctor what to do if you're badly hurt or have a serious illness that keeps you from saying what you want.
There are two main types of advance directives: a living will and a medical power of attorney.
October 9, 2012
Anne C. Poinier, MD - Internal Medicine & Shelly R. Garone, MD, FACP - Palliative Medicine
Some people continue to drink excessive amounts of alcohol even
though it causes problems in their lives. These people have an alcohol use problem.
Most people refer to people who drink too much alcohol as having a
drinking problem. Health professionals distinguish between people who have
problem drinking (alcohol abuse) and people who are
dependent on alcohol (alcohol dependence or alcoholism).
The causes of alcohol use problems and alcoholism are complex and involve
physical, social, and emotional aspects.
People with alcoholism may not drink alcohol every day, but they
usually drink heavily when they drink and have withdrawal symptoms if they stop
Alcoholism is a lifelong disease that often causes health,
emotional, behavioral, and social problems. If untreated, it can even lead to
death from the effects of alcohol on the heart, liver, and other parts of the
body. Alcoholism cannot be cured, but it can be successfully treated.
January 18, 2012
E. Gregory Thompson, MD - Internal Medicine & Peter Monti, PhD - Alcohol and Addiction
Beer, wine, and liquor (distilled spirits) are alcoholic beverages.
The following common alcoholic beverages contain equal amounts of
Proof is the percentage of alcohol in an alcoholic drink. The
percentage of pure alcohol is usually one-half the proof (for example,
100-proof liquor is about 50% pure alcohol). The higher the proof, the more
pure alcohol the drink contains.
An allergic reaction is an overreaction of the immune system to
a substance called an allergen. Allergens include chemicals, foods, medicines,
mold, plants, and pollen.
Symptoms of an allergic reaction can
range from mild and annoying to severe and life-threatening.
Allergic reactions do not occur the first time a person is
exposed to an allergen. A person may become more sensitive to the allergen with
April 29, 2011
An allergic reaction to a medicine is an overreaction by the
body's immune system to a substance (allergen) in a medicine that a person has
taken. An allergic reaction to a medicine may cause symptoms that range from
a minor rash to severe anaphylactic shock, depending on the person and the type
and dose of the medicine.
A medicine allergy is different from an adverse medicine
reaction, such as a medicine side effect or a reaction when taking more than
one medicine. Because symptoms and treatments vary, a doctor
should determine whether a person has a medicine allergy or an adverse
reaction. A severe medicine allergy can be life-threatening. An adverse
reaction usually is not.
A person who has been diagnosed with a medicine allergy should
wear a medical alert bracelet or other identification and should not take that
June 30, 2011
Adam Husney, MD - Family Medicine & Rohit K Katial, MD - Allergy and Immunology
Allergic rhinitis means allergies or hay fever. When you are exposed to particles in the air that you're allergic to, like pollen, dust, or cat dander, your immune system attacks the particles and causes symptoms such as sneezing and a runny nose.
You may have symptoms often during the year, or just at certain times.
E. Gregory Thompson, MD - Internal Medicine & Rohit K Katial, MD - Allergy and Immunology
Alzheimer's disease damages the brain and causes a steady loss of memory and of how well you can speak, think, and do your daily activities. It gets worse over time, but how quickly this happens varies. There are medicines that may slow down the symptoms for a while and make the disease easier to live with.
October 29, 2012
Anne C. Poinier, MD - Internal Medicine & Myron F. Weiner, MD - Psychiatry, Neurology
Amino acids are the chemicals that make up proteins. The human body
needs 20 different amino acids to function properly.
Some amino acids are made by the body, while others, called
essential amino acids, can be obtained only from foods.
June 29, 2011
Adam Husney, MD - Family Medicine & Marc S. Micozzi, MD, PhD - Complementary and Alternative Medicine
Amniotic fluid is the liquid that surrounds a developing baby
(fetus) in the uterus throughout pregnancy. The amniotic fluid protects
the fetus from temperature extremes and from being bumped or hurt as the mother
Amniotic fluid allows the fetus to move before
birth and is important for lung development. It is produced by the fetus and
the placenta and contains cells and other substances that have been shed by the
Amniocentesis is a test done to
collect a sample of amniotic fluid.
April 4, 2012
Sarah Marshall, MD - Family Medicine & Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Amphetamines are drugs that stimulate the nervous system. They may
be used in the treatment of attention deficit hyperactivity disorder (ADHD),
narcolepsy (a sleeping disorder), and other conditions.
Amphetamines produce increased alertness and a feeling of euphoria.
Common amphetamine medicines include dextroamphetamine (Dexedrine) and
Amphetamines can be abused and are sometimes sold illegally with
names such as speed, ice, and lid poppers.
October 13, 2011
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Peter Monti, PhD - Alcohol and Addiction
Amyloidosis refers to a group of conditions in which proteins
(amyloids) accumulate in the body's organs and tissues in abnormal amounts,
disrupting normal functions. Amyloidosis may be caused by a bone marrow cell
disorder or an inherited protein variation. Or it may be associated with other
conditions, including multiple myeloma, tuberculosis, and familial
Organs most often affected by amyloidosis include the heart, liver,
kidney, skin, and certain nerves. But any organ system may be involved.
Symptoms of amyloidosis depend upon the organ system affected and may not help
determine what condition is causing the protein accumulation. Amyloidosis can
be disabling and even life-threatening.
Treatment of amyloidosis depends upon the condition that is causing
the protein accumulation. In some cases chemotherapy, corticosteroid therapy, or stem cell transplant may be used.
July 24, 2012
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's
disease, is a progressive wasting away of the nerve cells in the brain and
spinal column that control the muscles that allow movement. Over a period of
months or years, ALS causes increasing muscle weakness, inability to control
movement, and problems with speaking, swallowing, and breathing.
The cause of ALS is unknown, and there is no cure. Treatment
focuses on helping you keep your strength and
independence for as long as possible. Treatment includes medicines to slow the disease and help with symptoms, physical therapy, occupational therapy, speech therapy, and supportive devices to help with daily tasks.
August 1, 2012
Anne C. Poinier, MD - Internal Medicine & Barrie J. Hurwitz, MD - Neurology
Anaphylaxis is a severe allergic reaction that affects the entire
body (systemic). It can occur within a few seconds or minutes after a person is
exposed to a substance (allergen or antigen).
Symptoms and signs of a severe allergic reaction may
The sooner symptoms occur after exposure to the substance, the more
severe the anaphylactic reaction is likely to be. An anaphylactic reaction may
occur with the first exposure to an allergen, with every exposure, or after
several exposures. An anaphylactic reaction can be life-threatening and is a
medical emergency. Emergency care is always needed for an anaphylactic
Androgens, such as testosterone, are male sex hormones that
produce male sexual characteristics; androgens are also present at low levels
in women. These hormones are important to the healthy functioning of many parts
of the body.
Androgens are used to treat men whose
hormone levels have decreased.
Anemia is a decrease in the amount of oxygen-carrying substance
(hemoglobin) found in red blood cells. Anemia causes weakness, pale skin, and
general tiredness (fatigue).
Anemia can be caused by blood loss or bleeding, an increase in the
destruction of red blood cells, or a decrease in the production of red blood
cells. Types of anemia include iron deficiency anemia, folic acid deficiency
anemia, and vitamin B12 deficiency anemia, among others. Each type of anemia is
November 27, 2012
E. Gregory Thompson, MD - Internal Medicine & Brian Leber, MDCM, FRCPC - Hematology
Anesthesiologists are medical doctors who specialize in
anesthesiology, which is the use of pain-blocking techniques or medicines
(anesthetics) during surgery and other medical procedures.
An anesthesiologist may administer medicine that numbs the area
of the body where a procedure is being performed (local or regional
anesthesia), inject medicine into the spinal canal to numb an area of the body
(spinal or epidural anesthesia), or make sure a person is unconscious and
pain-free during a procedure (general anesthesia) while also monitoring heart
rate, breathing, and blood pressure. An anesthesiologist may also supervise a
nurse anesthetist. Anesthesiologists can further specialize in critical care
medicine, pain management, pediatrics, or obstetrics.
Anesthesiologists can be board-certified through the Board of
Anesthesiology, which is recognized by the American Board of Medical
August 17, 2012
Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine
An aneurysm is a bulging section in the wall of a blood vessel that
has become stretched out and thin. As the wall of the blood vessel bulges out,
it becomes weaker and may burst or rupture, causing bleeding.
If an aneurysm in the brain bursts, it may cause a stroke. An
aneurysm in a vessel that carries a lot of blood, such as the aorta, is often
fatal if it bursts.
February 22, 2012
E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery
Angina is a symptom of heart disease. Angina happens when there is not enough
blood flow to the heart muscle. This is often a result of narrowed blood
vessels, usually caused by hardening of the arteries (atherosclerosis).
The most common symptom of angina is chest pain or pressure, or a strange feeling in the chest. Some people feel pain, pressure, or a strange feeling in the back, neck, jaw, or upper belly, or in one or both shoulders or arms.
Other symptoms of angina include shortness of breath, nausea or vomiting, lightheadedness or sudden weakness, or a fast or irregular heartbeat.
Angina can be stable or unstable. Stable angina happens at fairly predictable times, usually with
activity or exertion. It also may occur during exposure to cold or times of
emotional stress. Stable angina can be relieved by rest or nitroglycerin. Unstable angina is a change in your usual pattern of stable angina. Unstable angina is a warning sign
that a heart attack may soon occur.
If you have angina, pay attention to
your symptoms, know what is typical for you, learn how to control it, and
understand when you need to get treatment.
April 4, 2011
E. Gregory Thompson, MD - Internal Medicine & John M. Miller, MD, FACC - Cardiology, Electrophysiology
An angiogram is an X-ray test that provides pictures of the
blood flow in a blood vessel. During an angiogram, a material that shows up on
an X-ray (contrast material) is put into a blood vessel through a thin tube
An angiogram may be done to look for problems such as
a tear in a blood vessel that can cause blockage or bleeding, aneurysms (which
are weaknesses in the blood vessel wall), and blood clots or the buildup of
Sometimes a problem can be treated during
angiography. For example, a catheter can be used to open a blocked blood
vessel, deliver medicine to a tumor, or stop bleeding in the intestines.
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Howard Schaff, MD - Diagnostic Radiology
Angioplasty is a procedure done to open a partially blocked blood
vessel so that blood can flow through it more easily. It is most often done on
arteries that deliver blood to the heart (coronary arteries) when they are
narrowed by plaque buildup (atherosclerosis) or blood clots.
During the angioplasty procedure, a thin flexible tube (catheter)
is inserted through an artery in the groin, arm, or wrist and is carefully guided into the
artery that is narrowed. After the tube reaches the narrowed artery, a small
balloon at the end of the tube is inflated. The balloon may remain inflated
for a short time. The pressure from the inflated balloon presses
fat and calcium deposits (plaque) against the wall of the artery to improve
After the fat and calcium buildup is compressed, a small, expandable
tube called a stent is sometimes inserted into the artery to hold it
open. The artery is less likely to get narrow again (restenosis) after
angioplasty with stenting than after angioplasty alone.
April 5, 2012
An anterior cruciate ligament (ACL) injury is a tear in one of the knee ligaments that join the upper leg bone to the lower leg bone. The ACL helps keep your knee stable.
When you twist, bend, or over-straighten your knee, you can injure your ACL. This can cause knee pain, swelling, and weakness. Rest and physical rehabilitation (rehab)—and sometimes surgery—are important to prevent a long-lasting knee problem.
ACL injuries range from mild, such as a small tear, to severe, such as when the ligament tears completely or when the ligament and part of the bone separate from the rest of the bone.
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Freddie H. Fu, MD - Orthopedic Surgery
Antiarrhythmic medicines may be used to return an irregular
heartbeat (arrhythmia) to its normal rhythm, prevent an arrhythmia, or control
the heartbeat during an arrhythmia. These drugs work mostly by slowing the
heart rate or by helping the heart muscle tissue become stable.
Many antiarrhythmic medicines have side effects, and many interact with
other medicines. A person taking any of these medicines should talk often with
his or her doctor.
August 9, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & John M. Miller, MD, FACC - Cardiology, Electrophysiology
Antibiotics are medicines used to kill bacteria that cause infections.
A doctor will choose an antibiotic to treat an illness
March 14, 2011
E. Gregory Thompson, MD - Internal Medicine & Theresa O'Young, PharmD - Clinical Pharmacy
Anticoagulant medicines, often called blood thinners, do not
actually thin the blood but increase the time it takes a blood clot to form.
Anticoagulants help prevent existing blood clots from becoming larger and may
be used to prevent deep vein blood clots or to treat certain blood vessel,
heart, or lung conditions.
December 28, 2011
E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology
Antihypertensives are medicines that help keep blood pressure
within normal limits.
Examples of antihypertensive medicines are diuretics,
beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, calcium channel
blockers, and angiotensin II receptor blockers (ARBs).
April 26, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Margaret Hetherington, PHM, BsC - Pharmacy
Antioxidants protect the body from damage caused by harmful
molecules called oxygen free radicals. Most antioxidants are vitamins (such as
beta-carotene and vitamins E and C) that are naturally found in many fruits and
vegetables or are available as supplements.
Oxygen free radicals are normal by-products of cell metabolism.
But at high levels they can cause damage to cells. Antioxidants may
protect the body from cell damage.
Anxiety is an uncomfortable feeling of fear, uneasiness, or concern
that something bad may happen. Anxiety can cause physical symptoms such as
trembling, shaking, muscle aches, restlessness, insomnia, rapid heartbeat,
sweating, and clammy hands.
If anxiety interferes with your daily activities, you may need
treatment with medicines (such as antidepressants or antianxiety medicines)
and/or professional counseling.
August 29, 2012
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & David Messenger, MD
The aorta is a large blood vessel that carries oxygen-rich blood
from the heart to the rest of the body. It leaves the heart, arches upward,
then travels down through the chest and into the abdomen.
The aorta has two main portions:
November 2, 2011
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & John A. McPherson, MD, FACC, FSCAI - Cardiology
An aortic aneurysm (say "a-OR-tik AN-yuh-rih-zum") is a bulge in part of the aorta, your main artery. If the bulge gets large enough, it can rupture. If it does, your life is in danger.
Aortic aneurysms are usually caused by hardening of the arteries (atherosclerosis). But other causes include genetic conditions, infections, and injury.
Aneurysms need to be repaired if they are large or fast-growing or if they cause symptoms. Smaller ones are usually just checked regularly to see if they are getting bigger.
September 26, 2012
Adam Husney, MD - Family Medicine
Aortic dissection is a tear between the inner and outer layers of
the aortic wall. The tear can cause the wall to separate and rupture, resulting
in life-threatening bleeding and death.
The aorta, like all arteries, is made up of three layers, which are
fused together. If the layers begin to separate, it causes bleeding into and
around the tear. The bleeding widens the tear and causes the layers to
separate. Typically, an aortic dissection occurs in the section of the aorta
that leaves the heart and curves down through the chest.
Aortic dissection can be caused by atherosclerosis (hardening of
the arteries) and high blood pressure; traumatic injury to the chest, such as
hitting the car steering wheel during an accident; and conditions that are
present at birth, such as Marfan's syndrome or Ehlers-Danlos syndrome.
Symptoms usually include sudden and severe chest or upper back
pain, anxiety, pallor, sweating, and nausea. Aortic dissection usually requires
emergency surgery to repair the tear.
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
The aortic valve separates the lower left chamber (left ventricle)
of the heart and the aorta, the large artery that carries blood from the heart
to the rest of the body.
The aortic valve works like a one-way gate, opening so that blood
from the left ventricle—the heart's main pump—can be pushed into the aorta.
When the heart rests between beats, the aortic valve closes to keep blood from
flowing backward into the heart.
Aortic valve regurgitation is the backflow of blood from the aorta
through the aortic valve into the left ventricle. If enough blood flows back
into the heart, it can increase the workload on the left ventricle (lower left
chamber), causing damage.
When the heart pumps, the aortic valve opens to let oxygen-rich
blood flow from the left ventricle into the aorta. When the heart rests
between beats, the aortic valve closes to keep blood from flowing backward into
the heart. In aortic valve regurgitation, the aortic valve does not close
properly. With each heartbeat, some of the blood pumped into the aorta leaks
back (regurgitates) through the faulty valve into the left ventricle.
Medical therapy may delay or minimize the damage caused by aortic
valve regurgitation. In some cases, surgery to replace the valve is needed, to
avoid damage to the heart chambers and to keep an adequate blood flow to the
Aortic valve stenosis is a narrowing of the aortic valve between
the lower left chamber of the heart and the aorta, which supplies blood to the
body. A narrowed aortic valve forces the lower left chamber of the heart to
pump harder to get enough blood through the valve.
Aortic valve stenosis can be caused by a structural problem called
bicuspid aortic valve, which develops before a baby is born (congenital heart
defect). In these cases, the valve has only two flaps, or leaflets, instead of
the normal three.
Aortic valve stenosis also occurs as a person ages and the valve
becomes hard and thick from calcium buildup. Most cases of aortic valve
stenosis caused by calcium buildup occur in people who are older than
An arterial blood gas (ABG) test measures the levels of oxygen and
carbon dioxide in the blood to find out how well the lungs are working. An ABG
test checks how well the lungs can move oxygen into the blood and remove carbon
dioxide from the blood.
As blood passes through the lungs, oxygen moves into the blood
while carbon dioxide moves out of the blood into the airspace of the lungs. An
ABG test uses blood drawn from an artery, where the oxygen and carbon dioxide
levels can be measured before they enter body tissues and become changed. An
ABG test measures pH (acidity or alkalinity) and the levels of oxygen and carbon dioxide in the blood. Abnormal values for pH, oxygen, and carbon dioxide can be caused by changes in:
An arterial blood gas test is often done for a person who is in the
hospital because of severe injury or illness.
April 28, 2011
E. Gregory Thompson, MD - Internal Medicine & Mark A. Rasmus, MD - Pulmonology, Critical Care Medicine, Sleep Medicine
An arteriovenous malformation is an abnormal network of blood vessels
and veins in the body. It is present at birth
The vessel walls of an arteriovenous malformation may become weak and
leak or burst, causing bleeding in or around important parts of the body, such as the brain or spinal cord.
January 11, 2012
Arthritis is inflammation of a joint. Symptoms of arthritis may
include pain, swelling, redness, warmth, and limitation of movement.
There are over 100 types of arthritis. Three common types are
osteoarthritis, rheumatoid arthritis, and gout.
April 8, 2011
Anne C. Poinier, MD - Internal Medicine & Stanford M. Shoor, MD - Rheumatology
An artificial heart valve is made of plastic,
metal, or pig tissue and is surgically implanted to replace a person's
original heart valve. These valves are also called mechanical valves or tissue valves.
A person's heart valve may need to be replaced if it no
longer works properly because of a birth defect or because of damage caused by
a disease or aging.
When a person has an artificial heart valve, he or she may need to
take anticoagulants to prevent blood clots. And he or she may need to take antibiotics
before certain procedures to prevent infection.
November 29, 2011
Asthma is a long-term (chronic) disease of the respiratory system. It causes your airways to tighten and become narrow. This makes it hard to breathe and may cause wheezing and coughing.
Even though asthma is a lifelong disease, most people can lead active lives by following a treatment plan, avoiding things that cause flare-ups, and taking medicine.
The cause of asthma is not clearly known.
Atherosclerosis, sometimes called "hardening of the arteries,"
occurs when fat (cholesterol) and calcium build up in the inner lining of the
arteries, forming a substance called plaque. Over time, the fat and calcium
buildup narrows the artery and blocks blood flow through it.
A major part of treating atherosclerosis and coronary artery
disease involves lifestyle changes (such as quitting smoking) and medicines
to help reduce high cholesterol, control high blood pressure, and manage other
things that increase a person's risk of heart attack, stroke, and other
Atrial fibrillation (say "AY-tree-uhl fih-bruh-LAY-shun") is a type of irregular heartbeat (arrhythmia) in which the heart's upper chambers quiver, or fibrillate. This increases the risk of blood clots, which can cause a stroke or other problems. The lower chambers beat without a regular rhythm and may beat too fast. This can cause symptoms like lightheadedness or chest pain.
Treatment is done to control your heart rate or heart rhythm and to prevent stroke.
December 14, 2012
An atrial septal defect is an opening in the wall that separates
the upper chambers of the heart. It is one of the most common congenital heart
defects, which are structural problems that develop before a baby is born or at
When an atrial septal defect is present, some oxygen-rich blood
that should have been pumped to the body flows from one side of the heart to
the other. This blood is then pumped to the lungs. This creates extra work for
one side of the heart.
If an atrial septal defect is large, heart failure may occur,
although this is not common in children. Many children have no symptoms. So this defect may not be found until a child is older or becomes an adult.
A heart catheterization can typically be used to close the opening. The doctor will put a thin tube called a catheter into a blood vessel in your child's groin. The doctor will move the catheter through the blood vessel to the heart. Then the doctor will guide special tools through the catheter to fix the heart problem. The doctor will insert a small closure device into the heart. This prevents blood from flowing between chambers.
Attention deficit hyperactivity disorder (ADHD) is a problem with paying attention and focusing on tasks. People who have ADHD tend to act without thinking and have trouble sitting still.
ADHD may begin in early childhood and can continue into adulthood. Without treatment, it can cause problems at home, at school, at work, and with relationships.
Adam Husney, MD - Family Medicine & Louis Pellegrino, MD - Developmental Pediatrics
The auditory nerve carries sound impulses from the inner ear to the
brain. The brain "unscrambles" the auditory signals to make them recognizable
January 12, 2012
The immune system is the body's defense against foreign substances,
such as bacteria or viruses, that may be harmful. An autoimmune disease is an
abnormal condition that occurs when a person's immune system attacks its own
tissues as though they were foreign substances.
Why the body attacks its own cells is not known. Autoimmune
diseases include lupus, rheumatoid arthritis, scleroderma, and Sjögren's
syndrome. Certain types of diabetes and thyroid disease are related to
autoimmune reactions. People who have autoimmune diseases are at an increased
risk for infections.
May 10, 2012
Anne C. Poinier, MD - Internal Medicine & Nancy Ann Shadick, MD, MPH - Internal Medicine, Rheumatology
The autonomic nervous system controls all "automatic" body
functions, such as breathing, heart rate, blood pressure, sweating,
mouth-watering (salivating), and the movement of food through the intestines
One part of the autonomic nervous system, called the sympathetic nervous system, reacts when a person is facing a
dangerous or frightening situation and will automatically increase the heart
rate and breathing and move blood to the muscles.
The other part of the autonomic nervous system, the parasympathetic nervous system, helps the body return to normal after the threat is over. It will automatically lower heart rate and breathing and move blood back to the rest of the body (for example, the digestive system or reproductive system).
The autonomic nervous system differs from the voluntary nervous
system, which allows a person to control the muscles and body movements.
December 5, 2012
Anne C. Poinier, MD - Internal Medicine & G. Frederick Wooten, MD - Neurology