Find over 200 print-friendly fact sheets about heart disease and related health topics.
Find definitions for thousands of medical terms, treatments, and tests -- even health-related abbreviations, prefixes, and suffixes.
Illegal drugs are those that are not prescribed by a doctor or
bought at a drugstore. They are sometimes also called "street drugs."
Some examples of illegal drugs include heroin (a narcotic); cocaine
(a stimulant); LSD, mescaline, PCP, methamphetamine, and psilocybin
(hallucinogens); marijuana and hashish (cannabis); and gamma-hydroxybutyrate
(GHB). Although GHB is legal in Europe for anesthetic uses and in the United
States for government-approved clinical trials for treating narcolepsy, it has
been otherwise illegal in the United States since 1990.
The effects of illegal drugs can be unpredictable because:
October 13, 2011
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Peter Monti, PhD - Alcohol and Addiction
The immune system is the body's natural defense system that helps
fight infections. The immune system is made up of antibodies, white blood
cells, and other chemicals and proteins that attack and destroy substances such
as bacteria and viruses that they recognize as foreign and different from the
body's normal healthy tissues.
The immune system is also responsible for allergic reactions and
allergies, which may occur when the immune system incorrectly identifies a
substance (allergen), such as pollen, mold, chemicals, plants, and medicines,
Sometimes the immune system also mistakenly attacks the body's own
cells, which is known as an autoimmune disease.
April 5, 2012
E. Gregory Thompson, MD - Internal Medicine & Peter Shalit, MD, PhD - Internal Medicine
An implantable cardioverter-defibrillator (ICD) is a small device
that uses electrical pulses or shocks to help control abnormal heart rhythms,
especially ones that can be life-threatening. An ICD is also known as an
automatic implantable cardioverter-defibrillator (AICD).
An ICD is implanted under the skin in the chest. A wire threaded
through a large vein connects the device to the heart.
An ICD is always checking your heart rate and rhythm. If the ICD detects a life-threatening rapid heart rhythm, it tries to slow the rhythm to get it back to normal. If the dangerous rhythm does not stop, the ICD sends an electric shock to the heart to restore a normal rhythm. The device then goes back to its watchful mode. If your heart is beating too slowly, the ICD acts as a pacemaker, sending mild electrical pulses to bring your heart rate back up to normal.
June 2, 2011
E. Gregory Thompson, MD - Internal Medicine & Rakesh K. Pai, MD, FACC
Infectious disease specialists are medical doctors who specialize
in the diagnosis and treatment of complex infections. They also treat people
who have long-term (chronic) infections or disorders such as HIV or
Infectious disease specialists may further specialize in treating
people in certain age groups, such as pediatric infectious disease specialists,
who only treat children.
Infectious disease specialists are internists or pediatricians who
further specialize in infectious diseases. They can be board-certified in
infectious disease through the Board of Internal Medicine, which is recognized
by the American Board of Medical Specialties.
August 17, 2012
Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine
Infertility means not being able to make a baby. Your doctor usually won't say you have infertility until you've tried for at least a year to get pregnant.
It can be caused by problems inside the woman's body or the man's body. But sometimes no cause can be found.
Being told that you have this problem doesn't necessarily mean that you will never get pregnant. Often, couples eventually conceive without help. But medical treatments do help many couples.
September 26, 2012
Adam Husney, MD - Family Medicine
Inflammation is the body's response to injury or infection. It may
result in pain, swelling, redness, warmth, or loss of function of the affected
In some cases inflammation develops as part of a disease process,
such as the inflammation that occurs in rheumatoid arthritis, inflammatory
bowel disease, asthma, or an allergic reaction.
November 23, 2012
Kathleen Romito, MD - Family Medicine & Sarah Marshall, MD - Family Medicine
An aortic aneurysm is a bulging section in the wall of the
aorta—the large blood vessel delivering blood from the heart to the body—that
has become stretched-out and thin. Where the wall of the blood vessel bulges
out, it becomes weaker and may burst or rupture, causing bleeding.
Most aortic aneurysms are caused by a combination of hardening of
the arteries (atherosclerosis), genetics, and aging. But a small number
are caused by inflammation or infection. These are called inflammatory aneurysms.
inflammatory aneurysm can cause complications, such as
fever, weight loss, and symptoms of a chronic disease. A massive inflammatory
response may affect body parts close to the aneurysm, including part of the small intestine, the
ureter, or the veins to the kidney. Any of these
structures can become obstructed by the inflammation.
February 22, 2012
E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery
Inflammatory bowel disease (IBD) is a condition that causes ongoing
inflammation of the intestines. The condition can affect only the large
intestine (ulcerative colitis) or any part of the entire digestive tract, from
the mouth to the anus (Crohn's disease).
Symptoms of inflammatory bowel disease may include abdominal pain,
frequent diarrhea that may contain blood or pus, fever, chills, weight loss,
and fatigue. The condition may be mild or severe. The inflammation can also
affect other parts of the body, such as the eyes or joints, and may cause a
form of arthritis.
Inflammatory bowel disease may recur many times in a person's life.
It is treated with medicines and sometimes with diet changes. If the disease
is in remission (not causing symptoms), treatment may not be needed, although
medicines may help keep the disease in remission. A severe attack may require
that the person be hospitalized for treatment. In some cases, surgery may be
October 8, 2012
E. Gregory Thompson, MD - Internal Medicine & Arvydas D. Vanagunas, MD - Gastroenterology
Influenza (flu) is an infection, caused by a virus, that makes you feel very sick, often with fever, headache, body aches, and coughing.
People often use the term "flu" to describe a cold or a stomach virus. But influenza isn't a stomach problem, and it usually feels much worse than a cold.
October 9, 2012
E. Gregory Thompson, MD - Internal Medicine & Christine Hahn, MD - Epidemiology
Insomnia means not being able to sleep well. Short-term or temporary insomnia is very common and usually isn't a problem. Chronic insomnia lasts a month or longer. It can be caused by other problems, like depression, chronic pain, medicines, or poor sleep habits.
Anne C. Poinier, MD - Internal Medicine & Lisa S. Weinstock, MD - Psychiatry
Insulin is a hormone produced in the pancreas that allows sugar
(glucose) to enter body cells, where it is used for energy. It also helps the
body store extra energy in muscle, fat, and liver cells.
Diabetes develops if the body does not produce enough insulin, does not use insulin properly, or both.
September 20, 2012
E. Gregory Thompson, MD - Internal Medicine & Jennifer Hone, MD - Endocrinology, Diabetes and Metabolism
An insulin pen is a device for giving insulin shots. The insulin
pen looks like a pen.
Inside the pen is a needle and a cartridge filled with insulin. You
can set the dose of insulin with a dial on the outside of the pen. You use the
pen to give the insulin shot. Both disposable and reusable insulin pens are available.
December 4, 2012
John Pope, MD - Pediatrics & Stephen LaFranchi, MD - Pediatrics, Pediatric Endocrinology
An insulin pump is a small computerized device that delivers
insulin into the body. Using an insulin pump is different from injecting insulin throughout the day using insulin syringes and needles.
Insulin pumps can be programmed to deliver very precise amounts of insulin in a
continuous (basal) dose and in carefully planned extra (bolus) doses delivered at
specific times throughout the day, usually when eating.
Some pumps connect to the body through a thin tube and needle inserted under the skin,
usually in the abdomen. Some pumps attach directly to the body and do not need tubing. Some pump systems use a remote control. Most pumps can hold between 200 and 300 units of insulin, depending on the model used. Some pumps also work as a blood glucose meter or communicate with your meter to adjust your bolus dose of insulin.
pumps allow flexibility in how a person times his or her meals and snacks. The
pumps may help some people to have fewer low blood sugar events (hypoglycemic
episodes) than people who inject insulin. The insulin pump is designed to mimic
the normal function of the pancreas.
Insulin resistance is a condition in which body cells do not fully
respond to the action of insulin, a hormone that controls the amount of sugar
(glucose) in the blood. As a result, blood sugar levels become abnormally
Over time, insulin resistance can result in consistently high blood
sugar levels, which increases a person's risk for type 2 diabetes.
Pregnant women who are insulin resistant have an increased risk for gestational diabetes.
Usually, insulin resistance develops in people who are overweight
and not physically active. These characteristics are often associated with
having high cholesterol and high blood pressure. People who are insulin
resistant have an increased risk of heart disease and stroke, especially if
other risk factors, such as being a smoker or having high cholesterol levels,
November 3, 2011
Sarah Marshall, MD - Family Medicine & Alan C. Dalkin, MD - Endocrinology
Intermittent claudication is a tight, aching, or squeezing pain in
the calf, foot, thigh, or buttock that occurs during exercise, such as walking
up a steep hill or a flight of stairs. This pain usually occurs after the same
amount of exercise, intensifies until exercise becomes impossible, and is
relieved by rest.
Intermittent claudication is the main symptom of peripheral
arterial disease. As the condition gets worse, leg pain may occur even at rest
(rest pain or rest claudication). Medicines and procedures are available to
treat this condition.
October 14, 2011
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & David A. Szalay, MD - Vascular Surgery
An internist is a medical doctor who specializes in the care of
adults. People might choose an internist as their primary doctor for regular
checkups and for treating illness.
Internists can further specialize in areas such as:
Internists can be board-certified by the American Board of Internal
Medicine, which is recognized by the American Board of Medical
Interventional cardiologists are medical doctors who specialize in
performing surgical or invasive procedures—such as cardiac catheterization,
angioplasty, and stenting—to diagnose and treat heart disease.
Interventional cardiologists can be board-certified as internists
or interventional cardiologists through the Board of Internal Medicine, which
is recognized by the American Board of Medical Specialties.
An intrauterine device (IUD) is a method of birth control that is
placed inside the uterus to prevent pregnancy. It is not clearly understood how
the IUD prevents pregnancy, and different types of IUDs may prevent pregnancy
in different ways.
All IUDs have a plastic string that extends through the opening of
the cervix into the vagina. The string allows a woman to check that the IUD is
in place. It also allows a health professional to remove the device at the
woman's request or at the end of its effectiveness (usually anywhere from 5 to
10 years, depending on the type).
The IUD is very effective at preventing pregnancy.
May 4, 2012
Sarah Marshall, MD - Family Medicine & Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
Intravenous means occurring within or by way of a vein. Medicines
or fluids may be given by inserting an intravenous (IV) needle into a vein,
usually in the back of the hand or on the forearm.
When the IV needle is in place, medicines or fluids can go quickly into the bloodstream and into the rest of the body.
September 30, 2011
Adam Husney, MD, MD - Family Medicine & John M. Freedman, MD, MD - Anesthesiology
The iris is the colored part of the eye. A circular muscle in the
iris controls the amount of light that enters the eye through the pupil.
Pigment cells (melanin) in the iris produce its color. Each
person's irises have a distinct color, texture, and pattern.
June 9, 2011
Kathleen Romito, MD - Family Medicine & Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology