Premature ventricular contractions (PVCs)

Premature ventricular contractions (PVCs) Definition: Premature ventricular contractions (PVCs) are extra, abnormal heartbeats that begin in one of your heart's two lower pumping chambers (ventricles). These extra beats disrupt your regular heart rhythm, sometimes causing you to feel a flip-flop or skipped beat in your chest. Premature ventricular contractions are very common — they occur in most people at some point. Premature ventricular...

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Pulmonary embolism

Pulmonary embolism Definition: Pulmonary embolism is blockage in one or more arteries in your lungs. In most cases, pulmonary embolism is caused by blood clots that travel to your lungs from another part of your body — most commonly, your legs. Pulmonary embolism is a complication of deep vein thrombosis (DVT), which is clotting in the veins farthest from the surface of the body. Pulmonary embolism can occur in otherwise healthy people....

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DiGeorge syndrome

DiGeorge syndrome Definition  : DiGeorge syndrome (22q11.2 deletion syndrome), a disorder caused by a defect in chromosome 22, results in the poor development of several body systems. Medical problems commonly associated with DiGeorge syndrome include heart defects, poor immune system function, a cleft palate, complications related to low levels of calcium in the blood and behavioral disorders. The number and severity of problems...

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Vasovagal syncope

Vasovagal syncope Definition  : Vasovagal syncope (vay-zo-VAY-gul SING-cuh-pee) is the most common cause of fainting. Vasovagal syncope occurs when your body overreacts to triggers, such as the sight of blood or extreme emotional distress. The trigger results in vasovagal syncope — a brief loss of consciousness caused by a sudden drop in your heart rate and blood pressure, which reduces blood flow to your brain. Vasovagal syncope...

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Nonallergic rhinitis

Nonallergic rhinitis Definition  : Nonallergic rhinitis involves chronic sneezing or having a congested, drippy nose with no apparent cause. The symptoms of nonallergic rhinitis are similar to those of hay fever (allergic rhinitis), but there's no allergic reaction involved. Nonallergic rhinitis can affect children and adults, but is more common after age 20. Although nonallergic rhinitis is more annoying than harmful, it can make ...

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Vasculitis

Vasculitis Definition  : Vasculitis is an inflammation of your blood vessels. Vasculitis causes changes in the walls of your blood vessels, including thickening, weakening, narrowing and scarring. There are many types of vasculitis. Some forms last only a short time (acute) while others are long lasting (chronic). Vasculitis, which is also known as angiitis and arteritis, can be so severe that the tissues and organs supplied by the...

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Smallpox

Smallpox Definition: Smallpox is a contagious, disfiguring and often deadly disease that has affected humans for thousands of years. Naturally occurring smallpox was eradicated worldwide by 1980 — the result of an unprecedented global immunization campaign. Stockpiles of smallpox virus have been kept for research purposes. This has led to concerns that smallpox could someday be used as a biological warfare agent. There's no treatment...

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Esophageal varices

Esophageal varices Definition: Esophageal varices are abnormal, enlarged veins in the lower part of the esophagus — the tube that connects the throat and stomach. Esophageal varices occur most often in people with serious liver diseases. Esophageal varices develop when normal blood flow to your liver is slowed. The blood then backs up into nearby smaller blood vessels, such as those in your esophagus, causing the vessels to swell. Sometimes,...

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Chickenpox

Chickenpox Definition: Chickenpox (varicella) was once considered a rite of passage for most children. Before routine chickenpox vaccination, virtually everyone had been infected by the time they reached adulthood, sometimes with serious complications. Today, the number of cases and hospitalizations is down dramatically. However, when chickenpox does occur, it's highly contagious among people who aren't immune. Most people think of chickenpox...

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Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease Definition: Creutzfeldt-Jakob (KROITS-felt YAH-kobe) disease is a degenerative brain disorder that leads to dementia and, ultimately, death. Symptoms of Creutzfeldt-Jakob disease (CJD) sometimes resemble those of other dementia-like brain disorders, such as Alzheimer's, but Creutzfeldt-Jakob disease usually progresses much more rapidly. Creutzfeldt-Jakob disease captured public attention in the 1990s when some people...

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Plague

Plague Definition: Plague was known as the Black Death during medieval times, when it killed up to a third of the population of Europe. Currently, plague occurs in fewer than 3,000 people per year worldwide. It can be deadly if not treated promptly with antibiotics. The organism that causes plague, Yersinia pestis, lives in a variety of small rodents on every continent except Australia. The organism is transmitted to humans when they are...

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