Those disorders that involve the arteries, veins, and lymphatics.
Arteries
Diseases of the large and medium-sized arteries are the major cause of morbidity and mortality in the Western world.
Arteriosclerotic vascular disease, also known as arteriosclerosis, affects large and medium arteries and is particularly common in the arteries supplying the heart, those supplying the brain, and those supplying the lower extremities. Progressive narrowing and finally total occlusion of these arteries lead to the development of angina pectoris, myocardial infarction, stroke, and vascular insufficiency in the limbs. Although the cause of the disease is not known, certain factors appear to predispose to its development. These include cigarette smoking, hypertension, elevated serum cholesterol, and diabetes mellitus. There can also be a genetic predisposition to the disorder. See also Arteriosclerosis; Diabetes; Hypertension; Infarction.
Much less common are diseases that lead to arteritis, an inflammation of the large or medium arteries, with subsequent occlusion or rupture of the artery. The causes include bacterial infection, syphilis, allergic disorders, and hypersensitivity states. See also Hypersensitivity; Syphilis.
Several generalized disorders can involve the small arteries. These include scleroderma, periarteritis nodosa, lupus erythematosus, rheumatoid arthritis, and dermatomyositis. The involvement can produce areas of cell death (necrosis) and ulceration of the skin, particularly of the limbs. This appears to occur because of the occlusion of the involved small arteries, with consequent loss of blood supply. Such involvement often is preceded by a type of hypersensitivity to cold, a condition known as Raynaud's syndrome. See also Connective tissue disease.
Veins
The most common disorder of the venous circulation is varicose veins. It develops because of the loss of function of the valves in the superficial veins of the limbs. The two most commonly involved veins are the greater and lesser saphenous. In this condition, the veins are enlarged and often tortuous. If the deep veins are not involved, the varicose veins are termed primary. Varicose veins tend to cluster in families and are more common in women than men. Primary varicose veins may be cosmetically unpleasing, but they rarely cause serious symptoms in the involved limbs. A more serious problem develops when the varicose veins are associated with destruction of valves in the deep veins, secondary to deep-vein thrombosis. When varicose veins develop because of problems within the deep venous system, they are called secondary varicose veins.
When patients undergo major surgery or are confined to bed because of a serious medical illness, thrombosis of the veins of the leg can occur. The thrombosis occurs most commonly in the deep veins of the calf but can progress and extend proximally to involve the popliteal, femoral, and iliac veins.
Lymphatics
When the drainage function is disturbed by obstruction of the lymphatics by tumors, parasites, or surgical excision, serious swelling (edema) can occur. This condition is called lymphedema. The pattern of swelling involves not only the lower leg but the foot and toes as well. Obstruction of the lymphatics can also be congenital or can appear unexpectedly at the time of the onset of the menses. Regardless of its cause, lymphedema is a permanent condition. See also Edema; Lymphatic system.
Arteriovenous communications
If there are anomalous communications between the arteries and veins proximal to the capillaries, blood is shunted away from the capillary bed. Such shunting can be congenital or acquired.
The congenital form can occur at almost any site in the vascular system. When these communications are present, they may appear as prominent veins that are much larger and more numerous than normal. These are commonly referred to as hemangiomas. The extent to which they cause problems depends upon their location, their size, and numbers of feeding communications that are present. If a foreign body such as a bullet or knife passes between a major artery and vein, an artificial communication can develop that results in the shunting of a large volume of blood. When the communication is between very large vessels such as the abdominal aorta and inferior vena cava, the amount of blood shunted may be so large that heart failure occurs. See also Cardiovascular system.
