Vasculitis Health Article

Definition

Vasculitis refers to a condition that causes inflammation of blood vessels (arteries, capillaries, and/or veins). When the blood vessels become inflamed, scarring, thickening of the vessel walls, and narrowing of the vessel caliber decrease the amount of blood flow through the blood vessels. When there is less blood flow, the organs or tissues that should be receiving blood flow are deprived of oxygen, causing damage to them. Because blood vessels anywhere in the body can be affected by vasculitis, organs and tissues anywhere in the body can be damaged by its consequences. Vasculitis can occur very focally (in a relatively small, circumscribed area) or diffusely (a widespread network of blood vessels are inflamed).

Description

Vasculitis describes a large number of conditions. Vasculitis can be primary (the vessel inflammation occurs spontaneously, with no other associated disease process) or secondary (the vessel inflammation occurs due to some other preexisting disease). Secondary vasculitis can be a manifestation of a large number of disease processes, including a variety of connective tissue or autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, Raynaud's phenomenon, Sjogren's syndrome, sclerodactyly, polymyositis, and dermatomyositis, as well as sarcoidosis, malignancy, hepatitis B and hepatitis C infections, allergic reactions to antibiotics and/or diuretics, and severe bacterial infections such as endocarditis, pneumonia, meningitis, gonorrhea, or syphilis.

Normally, inflammation is an immune system response to the presence of either an injury or an infection with an invading organism such as a virus, bacteria, or fungi. When faced with either of these threats, the immune system produces a variety of cells and chemicals that cause blood vessels in the injured or infected area to dilate and then become leaky. Fluid, protein, and blood cells leak out of the blood vessels and into the surrounding tissues, causing swelling. The affected area turns red, warm, and painful.

Inflammation causes a cascade of effects, both in the tissues adjacent to the initial area of inflammation and at distant sites throughout the body. Locally, the process of inflammation causes various chemicals of inflammation to leak out into the neighboring tissues, prompting the same cycle of vessel dilatation and leakiness, resulting in swelling of those neighboring tissues. Chemicals of inflammation traveling through the bloodstream can precipitate the cycle of inflammation in tissues and/or organs at a distance from the initial site of inflammation.

In vasculitis, the inflammation response has gone awry: it may be kicked off initially by the presence of an invader such as vasculitis secondary to a severe bacterial infection; it may be part of an overall immune system over-reactiveness as occurs when vasculitis occurs secondary to an autoimmune disease such as systemic lupus erythematosus and rheumatoid arthritis; or it may erupt spontaneously as in cases of primary vasculitis. The end results, however, are inflammation and destruction of blood vessel walls, blood clot blockages within blood vessels, aneurysms (weakened bulging areas of blood vessel walls which can rupture, causing catastrophic bleeding),

and oxygen deprivation of the affected organs and/or tissues, leading to damage and destruction of various tissue or organs throughout the body.

A variety of classification systems have been developed to describe and organize the various types of vasculitis. These include systems that are based on the specific organs affected, and systems that are based on the size and type of vessels affected, and the kinds of microscopic, cellular changes seen within those vessels. One of the most popular systems for classification of vasculitis is called the Chapel Hill system, named for the creators at the University of North Carolina-Chapel Hill. This system divides the types of vasculitis into three categories: large-vessel vasculitis (including giant cell or temporal arteritis and Takayasu's arteritis); medium-vessel vasculitis (including polyarteritis nodosa and Kawasaki's disease); and small-vessel vasculitis (including Wegener's granulomatosis, Churg-Strauss syndrome, microsopic polynagiitis, Henoch-Schonlein purpura, essential cryoglobulinemic vasculitis, and cutaneous leukocytoclastic angiitis).