Glossary

Find definitions for thousands of medical terms, treatments, and tests -- even health-related abbreviations, prefixes, and suffixes.

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A Valsalva maneuver is an effort to exhale without letting air escape through the nose or mouth. People often use a Valsalva maneuver during some common activities, such as straining to have a bowel movement or blowing a stuffy nose.

A Valsalva maneuver is not normally harmful. But it may cause irregular heart rhythms in some people who have certain types of heart disease.

A person may be asked to do a Valsalva maneuver during certain medical tests or exams. During the test, a person is asked to try to breathe using the stomach muscles and diaphragm but not let any air out through the nose or mouth.

Last Revised: August 9, 2012

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & John M. Miller, MD, FACC - Cardiology, Electrophysiology

Varicose veins are twisted, enlarged veins near the surface of the skin. They're most common in the legs and ankles. They usually aren't serious.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery

Vascular (or multi-infarct) dementia refers to a decline in a person's mental abilities that results from a series of strokes. A stroke occurs when blood flow to part of the brain is blocked, cutting off the blood supply to the brain.

Vascular dementia often progresses step by step, with declines in memory and mental functions occurring each time another stroke occurs. The specific symptoms a person has depend on which area of the brain the strokes have affected. Not all strokes cause symptoms.

Vascular dementia is often associated with hardening of the arteries (atherosclerosis) caused by high cholesterol, high blood pressure, or diabetes. A person can reduce the risk of future strokes by controlling high blood pressure, reducing cholesterol, quitting smoking, and taking aspirin and other drugs used to treat these conditions.

Last Revised: June 23, 2011

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Peter J. Whitehouse, MD - Neurology

Vascular surgeons are medical doctors who specialize in the diagnosis, medical management, and surgical treatment of diseases of the blood vessels (vascular disease).

Vascular surgeons can be board-certified through the Board of Surgery, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

A vena cava filter is an umbrella-shaped barrier device that is inserted into the large vein that returns blood to the heart from the abdomen and legs (inferior vena cava). This filter helps prevent blood clots that form in the deep veins of the lower limbs from traveling to the lungs and heart where they may block blood flow.

Vena cava filters are inserted into the vena cava using a catheter inserted through a vein in the neck or groin.

Last Revised: January 10, 2013

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology

Venous insufficiency occurs when the veins in the legs do not return blood to the heart and upper body normally. Causes include long-term high blood pressure inside leg veins and blood clots in leg veins (deep vein thrombosis or phlebitis).

The veins in the body have valves that prevent blood from flowing the wrong way. These valves keep blood flowing toward the heart. Venous insufficiency means that the valves in the veins have become damaged, allowing blood to flow backward and pool in the leg veins. This results in swelling of the legs (lower extremities) and may cause varicose veins.

Symptoms of venous insufficiency include swollen ankles, tight calves, and an aching or heaviness in the legs.

Self-care measures may relieve symptoms. These measures include exercising regularly, wearing compression stockings, avoiding long periods of standing, and elevating the legs.

Last Revised: August 31, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Margaret Doucette, DO - Physical Medicine and Rehabilitation, Wound Care, Hyperbaric Medicine

A venous skin ulcer is a shallow wound caused by venous insufficiency, a condition in which the valves in the blood vessels are damaged and allow some blood to back up in the veins. The slowed circulation causes fluid to seep out of the overfilled veins into surrounding tissues, causing tissue breakdown and ulcers.

Venous skin ulcers, also called stasis leg ulcers, typically develop on either side of the lower leg, above the ankle and below the calf.

The first sign of a skin ulcer is an affected area of skin that turns dark red or purple. It may also become thickened and dry and itchy. Without treatment, an open wound (ulcer) may form. Venous skin ulcers often weep clear fluid and are covered with yellowish film.

The most effective treatment for venous skin ulcers is frequent elevation of the legs above the level of the heart and use of compression stockings during waking hours.

Last Revised: August 31, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Margaret Doucette, DO - Physical Medicine and Rehabilitation, Wound Care, Hyperbaric Medicine

The ventricles are the two lower chambers of the heart, one on the right and one on the left. The ventricles receive blood from the heart's upper chambers (atria) and pump it to the rest of the body.

The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the rest of the body.

Last Revised: April 4, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & John M. Miller, MD, FACC - Cardiology, Electrophysiology

Ventricular septal defect (VSD), the most common heart problem that develops before birth (congenital), is an opening in the wall that separates the lower chambers of the heart. Most ventricular septal defects are small and do not cause a problem.

The opening of a ventricular septal defect can be as small as a pinhole, or the wall between the heart chambers may be completely missing. This defect is usually found when a baby is 1 to 4 weeks old.

A large, untreated ventricular septal defect may result in the lower left heart chamber's inability to pump enough blood to the body and too much blood going to the lungs. Large ventricular septal defects usually cause heart problems and symptoms by the time a baby is 3 to 6 months old.

Treatment is not needed in cases where a ventricular septal defect is small or closes on its own. Some children and adults need surgery or a catheter procedure to close the defect, especially if it is large.

Last Revised: October 11, 2011

Author: Healthwise Staff

Medical Review: John Pope, MD - Pediatrics & Larry A. Latson, MD - Pediatric Cardiology

Vertigo (dizziness) is an uncomfortable feeling of motion when there is no actual movement. The feeling of motion is commonly described as spinning or whirling. But it also may include sensations of falling or tilting.

Vertigo can cause nausea and vomiting. You may find it difficult to walk, stand, or keep your balance.

Causes for vertigo include problems with nerves, blood flow, and the inner-ear.

Infrequent episodes of vertigo may not require treatment. If vertigo is severe or frequent, treatment will depend on the specific cause.

Last Revised: December 19, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Aerobic fitness means increasing how well the body uses oxygen, which depends on the condition of the heart, lungs, and muscles. Experts tend to describe aerobic activity in three ways: light, moderate, and vigorous.

When people do vigorous-intensity activities, they breathe faster and have a much faster heartbeat than at rest. To get the benefits of vigorous activity, a person can:

  • Jog or run.
  • Cycle fast (at least 12 miles per hour [mph]).
  • Hike.
  • Play soccer.
  • Cross-country ski.
  • Swim moderately to hard.
  • Play a game of basketball or volleyball.
  • Carry heavy loads, such as bricks.

The goal of aerobic fitness is to increase the amount of oxygen that goes to the heart and muscles, which allows them to work longer. Any activities, including many kinds of daily activities, that raise the heart rate and keep it up for an extended period of time can improve aerobic fitness. If the activities are done regularly and long enough, they can help improve fitness.

Experts recommend that adults try to do vigorous activity for at least 1¼ hours a week. Or they can do moderate activity for at least 2½ hours a week. People can choose to do one or both types of activity. And it's fine to be active in blocks of 10 minutes or more throughout the day and week. Teens and children (starting at age 6) should do moderate to vigorous activity at least 1 hour every day.

It's always a good idea to talk to your doctor before starting an exercise program.

Last Revised: October 25, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Heather Chambliss, PhD - Exercise Science

Vitamin B12 (cobalamin) is important in the formation of all cells in the body, especially red blood cells and the covering of nerve cells (myelin). The body needs myelin for nerves to function properly.

Vitamin B12 is found in animal products such as meat, shellfish, milk, cheese, and eggs. Most people who eat meat are not likely to develop a vitamin B12 deficiency. There is normally enough vitamin B12 stored in a person's liver to last a year or more, even if the person does not eat any foods that contain the vitamin during that time.

Some people have a disease that makes their bodies unable to absorb vitamin B12. These people need either to get an injection of B12 once a month, to take high-dose B12 pills, or to use a nasal spray containing B12.

Strict vegetarians (vegans) who do not eat meat, milk, cheese, or eggs are at risk for vitamin B12 deficiency. They need a vitamin supplement containing vitamin B12.

Last Revised: December 10, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Joseph O'Donnell, MD - Hematology, Oncology

Vitamin B12 deficiency anemia is a blood problem that occurs when there is not enough of this vitamin in the body. Vitamin B12 helps make red blood cells. Without enough vitamin B12, the body does not produce enough red blood cells, and cells throughout the body do not get the oxygen they need.

Vitamin B12 (also called cobalamin) is found in animal products such as meat, eggs, and milk products. Most people get more than enough of this vitamin from the food they eat. Vitamin B12 deficiency anemia usually occurs when the body cannot absorb this vitamin from food. It can also occur if a person's diet does not include enough of this vitamin.

A mild deficiency may not cause symptoms. As the anemia becomes worse, symptoms may include weakness, fatigue, diarrhea or constipation, numbness or tingling in the fingers and toes, poor sense of balance, thinking and memory problems, and/or depression. If the condition is not treated right away, symptoms caused by damage to the brain and nerve cells may become permanent.

If vitamin B12 deficiency anemia is suspected, the doctor will do a physical exam, take a medical history, and order blood tests that can help diagnose this condition.

Vitamin B12 deficiency anemia is treated with supplements of vitamin B12. These may be given as shots, pills, or a nasal spray. Vitamin B12 pills contain a higher dose of vitamin B12 than a regular vitamin pill. There is no need for any worry about getting too much vitamin B12, because the body passes extra vitamin B12 out in the urine. Most people need to take supplements for the rest of their lives to keep the condition from coming back.

Last Revised: December 10, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Joseph O'Donnell, MD - Hematology, Oncology

Vitamins are certain chemicals the body needs in small amounts to function properly. They work in a variety of ways, mostly as "helpers"; for example, many of the B vitamins help the body use protein, carbohydrate, and fats.

Vitamins are divided into two categories:

  • Water-soluble vitamins include all the B vitamins and vitamin C. Water-soluble vitamins travel freely through the body, and the part that the body doesn't use passes through the kidneys and leaves the body as urine or stool. The body needs water-soluble vitamins in frequent, small doses, and they are unlikely to reach toxic levels.
  • Fat-soluble vitamins include vitamins A, D, E, and K. Fat-soluble vitamins are stored in the body's cells and are not passed out of the body as easily as water-soluble vitamins. They do not need to be taken in as frequently as water-soluble vitamins (although adequate amounts are needed). And they are more likely to reach toxic levels if a person takes in too much.

Last Revised: August 29, 2011

Author: Healthwise Staff

Medical Review: John Pope, MD - Pediatrics & Rhonda O'Brien, MS, RD, CDE - Certified Diabetes Educator

Vitreous gel (also called vitreous humor) is a thick, colorless, gel-like fluid that fills the large space in the middle of the eye, behind the lens. It helps the eyeball maintain its shape.

Last Revised: August 7, 2011

Author: Healthwise Staff

Medical Review: Adam Husney, MD, MD - Family Medicine & Carol L. Karp, MD - Ophthalmology