DEFINITION An arteriovenous (AV) fistula is an abnormal connection between an artery and a vein. Normally, blood flows from your arteries to your capillaries to your veins. Nutrients and oxygen in your blood travel from your capillaries to tissues in…
DEFINITION Acute respiratory distress syndrome (ARDS) occurs when fluid builds up in the tiny, elastic air sacs (alveoli) in your lungs. More fluid in your lungs means less oxygen can reach your bloodstream. This deprives your organs of the…
DEFINITION Aplastic anemia is a condition that occurs when your body stops producing enough new blood cells. Aplastic anemia leaves you feeling fatigued and with a higher risk of infections and uncontrolled bleeding. A rare and serious…
DEFINITION Aortic valve disease is a condition in which the valve between the main pumping chamber of your heart (left ventricle) and the main artery to your body (aorta) doesn’t work properly. Aortic valve disease sometimes may be a condition…
DEFINITION Aortic valve regurgitation — or aortic regurgitation — is a condition that occurs when your heart’s aortic valve doesn’t close tightly. Aortic valve regurgitation allows some of the blood that was just pumped out of your heart’s main pumping…
DEFINITION Aphasia is a condition that robs you of the ability to communicate. It can affect your ability to speak, write and understand language, both verbal and written. Aphasia typically occurs suddenly after a stroke or a…
DEFINITION Zollinger-Ellison syndrome is a complex condition in which one or more tumors form in your pancreas or the upper part of your small intestine (duodenum). These tumors, called gastrinomas, secrete large amounts of the hormone gastrin, which causes your…
DEFINITION Yips are involuntary wrist spasms that occur most commonly when golfers are trying to putt. However, the yips can also affect people who play other sports — such as cricket, darts and baseball. It was once thought that the…
DEFINITION Wrinkles, a natural part of aging, are most prominent on sun-exposed skin, such as the face, neck, hands and forearms. Although genetics mainly determine skin structure and texture, sun exposure is a major cause of wrinkles, especially for fair-skinned…
DEFINITION In Wolff-Parkinson-White (WPW) syndrome, an extra electrical pathway between your heart’s upper chambers (atria) and lower chambers (ventricles) causes a rapid heartbeat (tachycardia). The extra electrical pathway is present at birth and fairly rare. WPW is detected in about…
DEFINITION Wilson’s disease is a rare inherited disorder that causes too much copper to accumulate in your liver, brain and other vital organs. Symptoms typically begin between the ages of 12 and 23. Copper plays a key role in the…
DEFINITION Wilms’ tumor is a rare kidney cancer that primarily affects children. Also known as nephroblastoma, Wilms’ tumor is the most common cancer of the kidneys in children. Wilms’ tumor most often affects children ages 3 to 4 and becomes…