Porth's Essentials of Pathophysiology, 4e

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Circulatory Function

U N I T 5

Diagnosis and Treatment. The diagnosis of vari- cose veins often can be made after physical inspec- tion. Primary varicose veins should be differentiated from those secondary to chronic venous insufficiency, retroperitoneal venous obstruction, or congenital venous malformations. The Doppler ultrasonic flow probe also may be used to assess flow in the large ves- sels. Angiographic studies using a radiopaque contrast medium also are used to assess venous function. Treatment measures for varicose veins focus on improving venous flow and preventing tissue injury. When correctly fitted, elastic support stockings or leggings compress the superficial veins and prevent distention. The most precise control is afforded by prescription stockings, measured to fit properly. These stockings should be applied before the standing position is assumed, when the leg veins are empty. Sclerotherapy, which often is used in the treatment of small residual varicosities, involves the injection of a sclerosing agent into the collapsed superficial veins to produce fibro- sis of the vessel lumen. Surgical treatment consists of removing the varicosities and the incompetent perforat- ing veins, but it is limited to persons with patent deep venous channels. Chronic Venous Insufficiency Chronic venous disease of the lower extremities is mani- fested by venous hypertension and a range of signs, the most obvious of which are varicose veins and venous ulcers due to venous insufficiency. 74,75 Venous hyperten- sion represents a sustained increase in venous blood pressures. Etiology. Chronic venous insufficiency is most com- monly caused by reflux through incompetent veins, but can also be caused by venous outflow obstruction and impaired function of the skeletal muscle pumps. Pressure in the veins of the legs is determined by two components: a hydrostatic component related to the weight of a column of blood below the level of the heart, and a hydrodynamic component related to the action of the skeletal muscle pump. Prolonged standing increases venous pressure and causes dilation and stretching of the vessel wall. When a person is in the erect position, the full weight of the venous columns of blood is trans- mitted to the leg veins. The effects of gravity are com- pounded in persons who stand for long periods without using their leg muscles to assist in pumping blood back to the heart. Clinical Manifestations. Chronic venous insufficiency is characterized by signs and symptoms associated with impaired venous blood flow. In contrast to the ischemia caused by arterial insufficiency, venous insufficiency leads to tissue congestion, edema, and eventual impair- ment of tissue nutrition. The edema is exacerbated by long periods of standing. Necrosis of subcutaneous fat deposits occurs, followed by skin atrophy. Brown pig- mentation of the skin caused by hemosiderin depos- its resulting from the breakdown of red blood cells is

common. Secondary lymphatic insufficiency occurs, with progressive sclerosis of the lymph channels in the face of increased demand for clearance of interstitial fluid. In advanced venous insufficiency, impaired tissue nutrition causes stasis dermatitis and the development of stasis or venous ulcers 74,76 (Fig. 18-19). Stasis der- matitis is characterized by the presence of thin, shiny, bluish brown, irregularly pigmented, desquamative skin that lacks the support of the underlying subcutaneous tissues. Minor injury leads to relatively painless ulcer- ations that are difficult to heal. The lower part of the leg is particularly prone to development of stasis dermati- tis and venous ulcers. Most lesions are located medially over the ankle and lower leg, with the highest frequency just above the medial malleolus. Treatment of venous ulcers includes compression therapy with dressings and inelastic or elastic bandages.

FIGURE 18-19. Classic appearance of a venous stasis ulcer. A venous stasis ulcer is usually located above the medial malleolus and has an indolent appearance with granulation tissue at the base that does not appear ischemic. Scarring of variable extent usually surrounds chronic and recurrent ulcers. Hyperpigmentation, lipodermatosclerosis (induration involving skin and subcutaneous fat), and stasis dermatitis are variably present in the lower third of the leg. Pedal pulses are usually palpable. If they are not palpable because of induration or swelling, ankle pressures measured by means of Doppler ultrasonography will be normal in the absence of associated ischemic disease. (From Raju S, Neglén P. Chronic venous insufficiency and varicose veins. N Engl J Med. 2009;360(22):2322. Copyright © 2009. Massachusetts Medical Society.)