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| The Surgical Technologist | JANUARY 2017 14 V E I N A N A T O M Y A N D P H Y S I O L O G Y Primary components of the vascular system include the heart, arteries, capillaries and veins. The heart is the pump that forces blood to move away from the heart to the organs and tissues through the arteries. Small arter- ies, called arterioles, connect arteries to the capillaries. Capillaries are thin-walled microscopic vessels that allow transfer of nutrients, oxygen, carbon dioxide and products of cellular metabolism to and from the blood. Small veins called venules connect capillaries to veins. Veins return blood from the organs and tissues to the heart. The wall of a vein consists of three layers: The outer layer is called the tunica externa or the tunica adventitia and is comprised of collagen and elastin to provide strength. The middle layer is called the tunica media or the muscularis and is comprised of smooth muscle and elastin. The thin, smooth muscle layer of the tunica media provides resistance, but is not strong enough to support venous return. Skeletal muscle outside of the veins aids venous return. For exam- ple, contraction of the gastrocnemius and soleus muscles located in the calf force blood from the lower leg upward through the veins toward the thigh. Pairs of unidirection- al valves within the veins are designed to be forced open when the skeletal muscles are contracted to allow blood pass through and close after each contraction to prevent reflux. The inner layer is called the tunica interna or the tunica intima and is comprised of endothelial cells that are in direct contact with the blood. Blood flows through the central canal of the vein which is called the lumen.1 There are three types of veins that are found in the leg: Superficial veins are located near the surface and often can be seen as a bluish discoloration through the skin. Approximately 10% of the blood from the lower leg is carried through the superficial veins. The great saphe- nous vein is considered a superficial vein, and is the most important vein in the lower limbs. The term saphenous is derived from the word safina, which means “hidden,” as in the vein is hidden in a facial compartment. Deep veins are located within the muscles of the leg. Approximately 90% of the blood from the lower leg is car- ried through the deep veins. Perforator veins run perpendicular to the superficial veins and connect the superficial veins to the deep veins by perforating the deep fascia of muscles. Sometimes perfora- tor veins are referred to as communicating veins. 5 T R E A T M E N T O P T I O N S F O R C V I Options for treatment of CVI include compression therapy, vein stripping and ligation, sclerotherapy, endovenous laser treatment and radiofrequency ablation (RFA). Documenta- tion of treatment of varicose veins can be found as early as the fourth century BCE, when Hippocrates writes of treat- ment of varicosed veins with a metal instrument. 9 C O M P R E S S I O N T H E R A P Y Compression therapy is often the first method considered for treatment of CVI and is the most cost effective and least invasive treatment. Compression therapy is classified as static and dynamic. Static (constant) compression therapy involves fitting the patient with compression hosiery or applying compression wraps such as an elastic bandages. Dynamic (intermittent) compression therapy involves appli- cation of half-leg or full-leg inflatable sleeve along with the use of a pneumatic sequential compression pump. V E I N S T R I P P I N G A N D L I G A T I O N The probable advent of vein stripping of the great saphenous vein was reported in 1844 by Madelung and is considered the oldest technique for treatment of CVI. 2 Vein stripping involves making small incisions proximally (usually near the groin) and distally (usually near the ankle) over the saphenous vein, ligating the proximal and distal ends of the vein, inserting a plastic or wire cable called a “vein stripper” through the proximal lumen to the distal lumen of the vein. Following insertion of the cable, a cap called an “olive” is attached proximally and a handle is attached distally allow- ing the vein to be pulled through the distal incision on the stripper. Vein ligation (also called avulsion phlebectomy) involves double ligation and removal of tributary veins. S C L E R O T H E R A P Y Sclerotherapy involves injecting a drug directly into the vein which causes the vein to collapse and disappear. In 1682, D CVI occurs when the pairs of valves in the legs designed to prevent venous stasis and retro- grade blood flow do not close effectively, or the venous wall becomes distended impeding blood flow from the legs back to the heart.