cardiovascular disorders
Chronic Venous Insufficiency and Post Thrombotic Syndrome
Etiology of Chronic Venous Insufficiency
Venous return from the lower extremities relies on contraction of calf muscles to push blood from intramuscular (soleal) sinusoids and gastrocnemius veins into and through deep veins. Venous valves direct blood proximally to the heart. Chronic venous insufficiency occurs when venous obstruction (eg, in Deep Venous Thrombosis (DVT) ), venous valvular insufficiency, or decreased contraction of muscles surrounding the veins (eg, due to immobility) decrease forward venous flow and increase venous pressure (venous hypertension). Fluid accumulation in the lower extremities (eg, in right heart failure) can also contribute by causing venous hypertension. Prolonged venous hypertension causes tissue edema, inflammation, and hypoxia, leading to symptoms. Pressure may be transmitted to superficial veins if valves in perforator veins, which connect deep and superficial veins, are ineffective. Themost common risk factorfor chronic venous insufficiency is Deep venous thrombosis Other risk factorsinclude Trauma Older age Obesity None Sitting or standing for long periods Pregnancy Idiopathic cases are often attributed to a history of occult DVT. Post-thrombotic syndromeis symptomatic chronic venous insufficiency that follows DVT. Risk factors for post-thrombotic syndrome in patients with DVT include proximal thrombosis, recurrent ipsilateral DVT, and body mass index (BMI)≥22 kg/m2. Age, female sex, andestrogentherapy are also associated with the syndrome. 