Vasospastic claudication

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Vasospasm occurring in the digital circulation is also known as Raynaud's phenomenon. Raynaud's phenomenon is caused by abnormal vascular reactivity precipitated by exposure to cold or by emotional stress. Peripheral vasospasm was first described by the French clinician, Maurice Raynaud in 1862 (91). Usually in peripheral vasospasm there are three phases: first, the main arterial branches of the digits constrict causing a marked reduction of the blood flow to the tissues; the skin of the digits becomes pale and the patient complains of numbness, pain or paresthesias. The second phase is the cyanotic phase; the digits appear blue, purple or even black in extreme cases. The cyanotic phase continues until the blood flow is re-established as the arterial branches open up again. The cyanotic color is caused by deoxygenated hemoglobin in the post arteriolar capillaries. The third and final phase, is the post-ischemic hyperemia; the increased blood flow to the skin gives a blushed coloration. Many years ago, Allen and Brown (92) described the minimal requisites for the diagnosis of Raynaud's disease or syndrome.

It should be noted that several patients do not exhibit the classical color changes. They may complain only of cold and numb fingers or toes; thumbs are usually spared.

As with claudication caused by atherosclerosis, Raynaud's phenomenon is a clinical diagnosis. No practical laboratory test exists to diagnose peripheral vasospasm. The physician should elicit the symptoms by taking a detailed history. Color charts can also be used. The patient is asked to identify the color of the skin during a typical episode by choosing colors from actual photographs of Raynaud's attacks. Patients with peripheral vasospasm are classified as having primary or secondary Raynaud's phenomenon. In primary Raynaud's phenomenon, the patient has symmetrical attacks in the absence of digital pitting, ulceration, or gangrene. The nailfold capillaries are normal and screening tests for connective tissue disease, like erythrocyte sedimentation rate, antinuclear antibodies, immunoglobulin electrophoresis, etc. are normal. The prognosis of primary vasospasm is usually benign, provided the appropriate protective measures from direct exposure to cold are taken. The situation is different in secondary Raynaud's phenomenon. The most common cause of secondary Raynaud's phenomenon is an underlying collagen vascular disease. Several conditions are associated with Raynaud's (91-97). CREST consists of Calcinosis, Raynaud's phenomenon, Esophageal changes, Sclerodatyly, and Telangiectasias. Raynaud's phenomenon may precede a connective tissue disorder for years (94). The prognosis in secondary Raynaud's phenomenon depends on the underlying connective tissue disease. The most common cause of secondary Raynaud's phenomenon is scleroderma. Approximately 90% of patients with scleroderma have Raynaud's phenomenon and it can be the first clinical expression of the disease. Peripheral vasospasm has also been associated with systemic lupus erythematosus in about 30 to 40% of patients. Approximately 20% of patients with dermatomyositis describe Raynaud's phenomenon. An association of Raynaud's phenomenon with Sjogren's syndrome has been described. The existence of Raynaud's phenomenon in collagen vascular diseases may adversely influence their prognosis. In lupus erythematosus, for example, the presence of Raynaud's symptomatology has been associated with pulmonary hypertension. Any kind of vasculitis or vascular injury can be subsequently associated with Raynaud's phenomenon. Raynaud's symptoms in patients with giant cell arteritis (polyarteritis nodosa) can evolve to cutaneous gangrene (93-96).

Hyperviscocity states like cryoglobulinemia have been associated with Raynaud's phenomenon: from reversible vasospasm to frank pur-

pura. Certain pharmacologic agents can cause or aggravate Raynaud's phenomenon. The most notorious for that toxicant is nicotine. Smoking can cause both coronary and peripheral vasoconstriction and has been associated with coronary spasm in men and women (61). Cocaine is another cause of both coronary and peripheral vasospasm. Ergotamine derivatives can also produce both coronary and peripheral vasospasm. Raynaud's phenomenon occurs in about 30% of cases following chemotherapy with Vinca alkaloids and bleomycin. ^-Blockers have also been reported to cause Raynaud's phenomenon, but very rarely as have certain sympathomimetic agents used as over-the-counter cold preparations.

The pathophysiology of peripheral vasospasm is unclear. The author of this chapter would like to propose the hypothesis that it is a result of endothelial dysfunction. In the late 1920s, Sir Thomas Lewis hypothesized that Raynaud's disease is a result of a local vascular fault (99), but after all these years, the fault has not been adequately defined. An attractive hypothesis is an imbalance of the endothelial function, involving endothelin (100-106). Endothelin (107) that is produced by the endothelial cells is a potent vasoconstrictor, whereas nitric oxide, an endothe-lium-derived relaxing factor (EDRF), is a potent vasodilator (104). Prostacycline and prostaglandins also produced by the endothelial cells normally counteract thrombaxene, which is a potent platelet derived-vasoconstrictor. A parallel mechanism leading to peripheral vasospasm can be increased sensitivity to a-adenoceptor agonists (102).

Individuals with primary Raynaud's phenomenon are more likely to respond well to therapy than individuals with secondary Raynaud's phenomenon. Many patients with mild Raynaud's phenomenon are minimally disabled, but often frightened by the cutaneous color changes. The majority of patients do not need pharmacologic intervention. Protection of the upper and lower extremities from direct exposure to cold is a practical approach. Although Raynaud's phenomenon is more severe during the winter, recurrent attacks do occur in any season upon a sudden cold stimulus. Often a rapidly changing temperature is more likely to precipitate peripheral vasospasm than exposure to a lower, but constant temperature. A central body chill is as likely to provoke an attack of Raynaud's as is a direct cold exposure to the hands. In a number of patients, emotional stress is a major precipitating factor. All known aggravating factors should be avoided and by all means smoking. Ketanserin has been tried in the treatment of Raynaud's phenomenon occurring with scleroderma (109).

Calcium channel blockers (CCBs) are the most widely used pharmacologic agents for the treatment of peripheral vasospasm (110-112). Sympatholytic agents have also been used in the treatment of Raynaud's phenomenon. Topical nitroglycerin ointment can be applied with a nocturnal nitrate-free interval to avoid nitrate tolerance.

The treatment of claudication due to LEAD is multifacted: aggressive risk factor modification, regression therapy of the atheromas, pharmacotherapy, exercise therapy, endovascular transcatheter therapeutic interventions, angiogenesis, and vascular graft procedures.

In any patient with documented LEAD, risk assessment for cerebrovascular, and coronary heart disease of utmost importance.

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