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.
Deep vein thrombosis is a blood clot in a deep vein, usually in the legs. It can break loose and travel through the bloodstream to the lung. This is called pulmonary embolism and can be very dangerous.
October 9, 2012
E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology
Deep veins are the veins that are near the bones and surrounded by
muscle. These veins lie deeper under the skin and return more blood to the
heart than surface (superficial) veins.
December 28, 2011
Severe dehydration means:
Severe dehydration is a medical emergency and requires
emergency treatment. Call 911 or other emergency services immediately.
Moderate dehydration means:
Mild dehydration means:
Mild to moderate dehydration is treated at home by
drinking more fluids. Treatment for moderate to severe dehydration may include
IV fluids and a stay in the hospital.
Dehydration is very
dangerous for babies, small children, and older adults. It is most dangerous
for newborns. Watch closely for early symptoms anytime there is an illness that
causes a high fever, vomiting, or diarrhea.
May 2, 2011
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
Dementia is a loss of mental skills—such as memory, problem solving, and learning—that's bad enough to interfere with your daily life. It usually gets worse over time. But how long this takes is different for each person.
There are medicines you can take for dementia. They don't cure it, but they can slow it down for a while and make it easier to live with.
Anne C. Poinier, MD - Internal Medicine & Peter J. Whitehouse, MD - Neurology
Demyelination is a process in which the insulating coating (myelin
sheath) around the nerve fibers is destroyed, slowing or halting the passage of nerve
impulses. The myelin sheath allows nerve impulses to be sent between the brain,
the spinal cord, and the nerves in the rest of the body smoothly and quickly.
Demyelination occurs in diseases such as multiple sclerosis (MS),
Guillain-Barré syndrome, and chronic inflammatory demyelinating polyneuropathy
February 15, 2012
Adam Husney, MD - Family Medicine & Anne C. Poinier, MD - Internal Medicine & Barrie J. Hurwitz, MD - Neurology
Depression is an illness that makes you feel sad, lose interest in things you used to enjoy, withdraw from others, and have little energy. It's more than normal sadness, grief, or low energy. Most people get better with medicine, counseling, or a combination of the two.
After you have had an episode of depression, you are more likely to have it again.
January 11, 2013
Kathleen Romito, MD - Family Medicine & Lisa S. Weinstock, MD - Psychiatry
Dermatologists are medical doctors who specialize in diagnosing and
treating diseases and conditions of the skin, hair, or nails, such as acne,
psoriasis, warts, or skin cancer.
Dermatologists may prescribe medicines as well as perform surgery
for skin disorders. They may specialize in treating specific age groups, such
as a pediatric dermatologist, who only treats children.
Dermatologists can be board-certified through the Board of
Dermatology, which is recognized by the American Board of Medical
August 17, 2012
Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine
Diabetes is a condition in which sugar (glucose) remains
in the blood rather than entering the body's cells to be used for energy. This
results in high blood sugar. Over time, high blood sugar can damage many
Symptoms of diabetes include increased thirst and frequent
urination (especially at night); unexplained increase in appetite; unexplained
weight loss; fatigue; erection problems; blurred vision; and tingling, burning,
or numbness in the hands or feet.
People who have high blood sugar over a long period of time are at increased risk for many serious
health problems, including hardening of the arteries (atherosclerosis) and
heart problems, eye problems that can lead to blindness, circulation and nerve
problems, and kidney disease and kidney failure.
Women with diabetes and high blood sugar who become pregnant have an increased risk of
miscarriage and birth defects.
Diabetes is treated with diet and lifestyle changes and with
medicines. If blood sugar levels are
kept within the recommended range, the risk for many complications from
September 20, 2012
E. Gregory Thompson, MD - Internal Medicine & Jennifer Hone, MD - Endocrinology, Diabetes and Metabolism
Diabetic ketoacidosis (DKA) is a life-threatening blood
chemical (electrolyte) imbalance that develops in a person with diabetes when
the cells do not get the sugar (glucose) they need for energy. As a result, the
body breaks down fat instead of glucose and produces and releases substances
called ketones into the bloodstream.
People with type 1 diabetes
and some people with type 2 diabetes are at risk for DKA if they do not take
enough insulin, have a severe infection or other illness, or become severely
Symptoms of diabetic ketoacidosis include:
Severe diabetic ketoacidosis can cause difficulty
breathing, brain swelling (cerebral edema), coma, or death.
Treatment involves giving insulin and fluids through a vein and closely
monitoring and replacing electrolytes.
May 21, 2012
E. Gregory Thompson, MD - Internal Medicine & David C.W. Lau, MD, PhD, FRCPC - Endocrinology
Nephropathy means kidney disease or damage. Diabetic nephropathy is damage to your kidneys caused by diabetes.
The kidneys have many tiny blood vessels that filter waste from your blood. High blood sugar from diabetes can destroy these blood vessels. Over time, the kidney isn't able to do its job as well. Later it may stop working completely. This is called kidney failure.
Diabetic nephropathy is treated with medicine to slow or prevent further kidney damage. It can often be prevented by keeping blood sugar levels within a target range.
November 14, 2012
E. Gregory Thompson, MD - Internal Medicine & Tushar J. Vachharajani, MD, FASN, FACP - Nephrology
Diabetic neuropathy is nerve damage caused by diabetes. Over time, high blood sugar can damage nerves throughout your body. Diabetic neuropathy can lead to serious foot problems and, in time, to problems like dizziness, diarrhea or constipation, sexual problems, bladder infections, and vision problems.
The older you get, and the longer you have diabetes, the more likely you are to have nerve damage. Controlling your blood sugar can help keep neuropathy from getting worse.
E. Gregory Thompson, MD - Internal Medicine & Barrie J. Hurwitz, MD - Neurology
Retinopathy means disease of the retina, the nerve layer at the back of your eye. Diabetic retinopathy is related to prolonged high blood sugar, which damages blood vessels in the eyes. It can lead to poor vision or blindness.
Diabetic retinopathy usually gets worse over many years. People who have diabetes need regular eye exams so that this condition can be found early. Keeping your blood sugar and blood pressure under control can help protect your vision.
Adam Husney, MD - Family Medicine & Carol L. Karp, MD - Ophthalmology & Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology
Dialysis is a treatment for kidney failure that helps filter
waste products from the blood when the kidneys are not working properly. The
two main types of dialysis are hemodialysis and peritoneal dialysis.
September 15, 2011
Anne C. Poinier, MD - Internal Medicine & Mitchell H. Rosner, MD - Nephrology
The diaphragm is a large sheet of muscle that separates the chest
cavity (containing the lungs and heart) from the abdominal cavity (containing
the digestive organs).
The diaphragm also serves as a muscle to help draw air into the
lungs as a person breathes. It contracts to expand the lungs when breathing in
(inhaling) and relaxes when breathing out (exhaling). If the diaphragm is not
able to move as it should, breathing may become difficult.
November 29, 2011
E. Gregory Thompson, MD - Internal Medicine & Ken Y. Yoneda, MD - Pulmonology
Diastolic pressure is the pressure of blood against the artery
walls between heartbeats, when the heart is relaxed and filling with blood. It
is the second or lower number in a blood pressure reading.
For example, if the diastolic pressure is 80 millimeters of mercury
(mm Hg) and the systolic pressure is 120 mm Hg, the blood pressure is recorded
as 120/80 and read as "120 over 80."
April 5, 2011
E. Gregory Thompson, MD - Internal Medicine & Robert A. Kloner, MD, PhD - Cardiology
Severe trouble breathing means:
Moderate trouble breathing means:
Mild trouble breathing means:
December 21, 2011
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & David Messenger, MD
Dilated cardiomyopathy is a serious problem that occurs when the
heart muscle has become weak and enlarged. It does not have the strength to
pump enough blood to the rest of the body.
Symptoms can come on gradually, over months or years. They also can
start suddenly, such as after a viral infection or pregnancy. As the heart
muscle weakens, a person may feel short of breath, especially when active.
Other symptoms include fatigue, problems breathing while lying down, and
swelling in the legs. These are symptoms of heart failure.
Most times, dilated cardiomyopathy is treated with several
medicines. Changes in eating habits and lifestyle are also important in
managing symptoms. These changes include limiting how much salt the person gets
from food and drinks.
July 24, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & George Philippides, MD - Cardiology
A diuretic is a substance that removes water from the body by
promoting urine formation and the loss of salt (sodium).
Caffeine and alcohol are common diuretics.
Diuretic medicines include furosemide, hydrochlorothiazide,
metolazone, and spironolactone. These medicines may be used as part of
treatment for conditions that cause swelling from water retention (edema), such
as heart failure, hypertension, or liver or kidney disease.
October 23, 2012
Dizziness, or lightheadedness, is a feeling of unsteadiness.
Dizziness can lead to feeling faint or to fainting (brief loss of
Dizziness can be caused by many things, including stress and/or
problems with brain functions.
Dizziness often goes away or improves after lying down. If it does
not, it may be linked with conditions related to the inner ear or brain
January 2, 2013
A Doppler ultrasound (or duplex scanning) is a medical test
that uses reflected sound waves to estimate the speed and direction of blood as
it flows through a blood vessel. It helps doctors evaluate blood flow through
arteries and veins.
Doppler ultrasound can be used to evaluate the
vessels in several areas of the body. For example, a Doppler ultrasound test of
the blood vessels in the neck (carotid ultrasound) can be done to estimate a
person's risk of a stroke from blockage in those arteries. Renal ultrasound can
help detect kidney problems. Lower extremity ultrasound can be used to detect a
blood clot in the deep veins of the legs. A Doppler ultrasound also may be used
to evaluate problems with the blood flow to the placenta and umbilical cord in
a pregnant woman; problems with this blood flow may point to fetal distress.
November 29, 2012
Kathleen Romito, MD - Family Medicine & Howard Schaff, MD - Diagnostic Radiology
Down syndrome is a genetic condition caused by abnormal cell
division in the egg, sperm, or fertilized egg. This results in an extra or
irregular chromosome in some or all of the body's cells, causing varying levels
of intellectual disability and physical problems.
syndrome is also called trisomy 21, for the specific chromosome that has the
abnormality. A person with Down syndrome has three copies of chromosome 21. Normally, a person has two copies.
Down syndrome usually can be
detected during pregnancy or soon after birth. Chromosome (karyotype) tests and how a baby looks can help make a diagnosis.
Babies usually have distinctive facial characteristics, such as
upward-sloping eyes and a flattened nose. People with Down syndrome have an
increased risk of being born with or developing health problems. For example,
some babies with Down syndrome are born with heart, intestinal, ear, or
respiratory defects. These health conditions often lead to other problems, such
as respiratory infections, sleep apnea, or hearing problems. Other health
issues, such as vision trouble or problems with thyroid function, can also
Children with Down syndrome grow and develop more slowly
than other children. But most are able to attend school, play sports,
socialize, and enjoy active lifestyles. Unless their disabilities are severe,
adults with Down syndrome can care for most of their own needs. Many people
who have Down syndrome live into their 50s and some into their 60s or older.
July 20, 2011
Susan C. Kim, MD - Pediatrics & Louis Pellegrino, MD - Developmental Pediatrics
Dysfunctional uterine bleeding is a type of irregular bleeding from the uterus. For example, your periods may be less than 21 days or more than 35 days apart. They may last longer than 7 days, or they may be very heavy. This type of bleeding isn't serious, but it can be annoying and can disrupt your life.
Sarah Marshall, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology