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The term peripheral vascular disease can be applied to a variety of illnesses associated with blood vessels outside the heart, but it generally refers to diseases of the blood vessels of the arms and legs (the extremities). These illnesses can be subdivided into two types based on arterial or venous origin: (1) peripheral arterial diseases; and (2) venous disorders, such as acute deep vein thrombosis (see Chapter 27). The arterial disorders are subdivided into those that result from arterial narrowing and occlusion (obstructive) and those caused by arterial spasm (vasospastic).

The most common form of obstructive arterial disease is arteriosclerosis obliterans, also called atherosclerosis obliterans. It results from atherosclerotic plaque formation, with narrowing of the lower aorta and the major arteries that provide circulation to the legs. As with atherosclerosis of the coronary arteries, the risk factors that play an important role in the development of this disease are high levels of low-density lipoprotein cholesterol (LDL-C), hypertension, cigarette smoking, low levels of high-density lipoprotein cholesterol (HDL-C), and diabetes mellitus.

Patients tend to remain free of symptoms until there is significant narrowing (75% to 90%) in key locations of the major arteries and arterioles of the legs. The typical pain pattern described is one of aching, cramping, tightness, or weakness that occurs during exercise. The primary pathophysiology is obstruction of blood flow through the arteries, resulting in ischemia to the tissues supplied by those arteries. A term commonly applied to this condition is intermittent claudication; it manifests as pain secondary to lack of oxygen to the muscles during exercise. During the early stages of symptoms, the patient finds relief by stopping the exercise for a few minutes. Without treatment, as the disease progresses over time, the arteries become obstructed, resulting in thrombosis and the potential for gangrene. Additional symptoms that develop are pain at rest, numbness, and paresthesias (numbness with a tingling sensation). The disease is often accompanied by increased blood viscosity. Physical findings on the lower extremities are reduced arterial pulsations on palpation; systolic bruits over the involved arteries; waxy, pale, and dry skin; a lower temperature of the skin of the extremity; edema; and numbness to sensation.

Peripheral vascular disease caused by arterial vasospasm is known as Raynaud’s disease, named after the man who first described the illness in 1862. It is unfortunate that, more than a century later, the pathophysiology and treatment of this condition are still not well defined. Raynaud’s disease is classified as either primary, in which the cause is unknown, or as secondary, in which other conditions contribute to the symptoms. Secondary causes are frequent exposure to cold weather, obstructive arterial disease, occupational trauma (e.g., pneumatic hammer users, pianists), and certain drugs (e.g., beta blockers, imipramine, nicotine, bromocriptine, vinblastine, clonidine). Heredity may also play a role in this disease. The onset of Raynaud’s disease is usually during the teenage years to the 40s, and it occurs four times more frequently in women.

Raynaud’s disease is thought to be caused by vasospasm (vasoconstriction of blood vessels) and subsequent ischemia of the arteries of the skin of the hands, fingers, and sometimes toes. The physiologic mechanisms that trigger the vasospasm are unknown. Sudden coldness applied to the extremity, such as cold water, can induce an attack. The signs and symptoms associated with Raynaud’s disease are numbness, tingling, a sense of skin tightness in the affected area, and blanching of the skin because of sudden vasoconstriction followed by cyanosis. As the attack subsides, vasodilation causes a redness, or rubor, to the pale skin. The skin appears normal except during spasm. During the early years of the illness, only the fingertips of both hands are involved. However, as the disease progresses, the skin on the hands is also affected by the arteriospasm.