Unit 8: Disorders of Venous Circulation PDF

# Unit 8: Disorders of Venous Circulation ## Varicose Veins * **Varicose, or dilated, tortuous veins of the lower extremities are common and often lead to secondary problems of venous insufficiency.** * **Varicose veins can be described as:** * **Primary varicose veins:** originate in the super...

# Unit 8: Disorders of Venous Circulation ## Varicose Veins * **Varicose, or dilated, tortuous veins of the lower extremities are common and often lead to secondary problems of venous insufficiency.** * **Varicose veins can be described as:** * **Primary varicose veins:** originate in the superficial saphenous veins * **Secondary varicose veins:** result from impaired flow in the deep venous channels. * **Secondary Varicose Veins:** become inevitable when flow in these deep channels is impaired or blocked. The most common cause of secondary varicose veins is deep vein thrombosis (DVT). * **Other causes:** include congenital or acquired arteriovenous (AV) fistulas, congenital venous malformations, and pressure on the abdominal veins caused by pregnancy or a tumor. ## Etiology and Pathogenesis * **Prolonged standing and increased intra-abdominal pressure are important contributing factors in the development of primary varicose veins.** * **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 transmitted to the leg veins.** * **The effects of gravity are compounded in people who stand for long periods without using their leg muscles to assist in pumping blood back to the heart.** * **Lifting also increases intra-abdominal pressure and decreases flow of blood through the abdominal veins.** Occupations that require repeated heavy lifting also predispose to development of varicose veins. * **Prolonged exposure to increased pressure causes the venous valves to become incompetent so they no longer close properly.** * **Obesity reduces the support provided by the superficial fascia and tissues, increasing the risk for development of varicose veins.** ## Chronic Venous Insufficiency * **Venous insufficiency refers to the physiologic consequences of DVT, valvular incompetence, or a combination of both conditions.** ## Disorders of Venous Circulation | Disorder | Etiology | Pathogenesis | |--------------------------|---------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------| | Chronic Venous Insufficiency | The most common cause is DVT, which causes deformity of the valve leaflets, rendering them incapable of closure. | Venous insufficiency leads to tissue congestion, edema, and eventual impairment of tissue nutrition. | | | | The edema is exacerbated by long periods of standing. | | | | Necrosis of subcutaneous fat deposits occurs, followed by skin atrophy. | | | | In advanced venous insufficiency, impaired tissue nutrition causes stasis dermatitis and the development of stasis or venous ulcers. | | | | Minor injury leads to relatively painless ulcerations that are difficult to heal. | | | | The lower part of the leg is particularly prone to development of stasis dermatitis and venous ulcers. | ## Signs of Venous Insufficiency A diagram showing the signs of venous insufficiency. There are three images of legs: * The first image shows the legs with edema. * The second image shows varicose veins. * The third image shows skin changes and discoloration. * The fourth image shows skin ulceration. ## Venous Thrombosis, or Thrombophlebitis * **Describes the presence of thrombus in a vein and the accompanying inflammatory response in the vessel wall. Thrombi can develop in the superficial or the deep veins.** * **DVT most commonly occurs in the lower extremities.** A diagram showing the progression of deep vein thrombosis: * The first image shows normal blood flow. * The second image shows deep vein thrombosis. * The third image shows an embolus * **DVT of the lower extremity is a serious disorder, complicated by pulmonary embolism, recurrent episodes of DVT, and development of chronic venous insufficiency.** ## Etiology and Pathogenesis * **Venous thrombosis is associated with stasis of blood, increased blood coagulability, and vessel wall injury.** * **Stasis of blood occurs with immobility of an extremity or the entire body.** * **Hip fracture, joint replacement, or spinal cord injury are prone to develop venous thrombosis.** * **Bed rest and immobilization are associated with decreased blood flow, venous pooling in the lower extremities, and increased risk of DVT.** * **The use of oral contraceptives and hormone replacement therapy appears to increase coagulability and predispose to venous thrombosis.** * **Immune interactions with cancer cells can result in the release of cytokines that can cause endothelial damage and predispose to thrombosis.** * **Vessel injury can result from a trauma situation or from surgical intervention.** * **People with hip replacement are at particular risk because of trauma to the femoral and iliac veins.** * **Consider chart 30.1 page 763**