”Venous insufficiency” is a complex and chronic process, so I hope the following explanation will give you a simple understanding: The arteries are responsible for transporting nutrient-rich blood from the heart and lungs to the whole body; after oxygen is used by the tissues, the veins are responsible for sending the blood back to the heart and lungs. In the lower extremities, the veins need to overcome gravity to return the blood to the heart, which is the special role of the so-called “water flows higher”. In order to accomplish this role, veins rely on a unique one-way valve structure within them – the venous valve. As shown in Figure A, blood flowing upward through the valve cannot return downward due to the valve’s blocking effect, and this depends on a strong vein wall that can support the pressure of the valve and the blood. Ageing, trauma, genetic factors, fatigue, overload, etc. can cause the valves and walls of the veins to become less functional and thus unable to stop the backflow of blood, with the result that the blood becomes stagnant in the veins of the lower extremities. When the veins are subjected to prolonged stagnant blood, the following phenomena can be simply understood: 1. Stagnant blood cells eventually leak out of the weak vein walls and hemochromatosis is deposited under the skin, resulting in discoloration; 2. The veins lose their function, blood and lymphatic flow is poor, tissue fluid is confined to the subcutaneous tissue, resulting in edema of the lower extremities and a feeling of heaviness in the lower extremities; 3. further leads to loss of normal elasticity of the vein wall. The combination of damage to the venous valves and weakness of the vein walls eventually results in dilated, stretched, and distorted veins, resulting in varicose veins. As in Figure B, dilatation of the venous lumen further aggravates the venous valve closure insufficiency, forming a vicious circle; 4. The high intravenous pressure and the exudation of blood cells lead to nutritional disorders of the skin, eventually leading to skin hardening, dermatitis, abnormal sensation, and long-lasting ulcers. However, please note that not all swelling/heaviness/discoloration/dermatitis/ulcers in lower limbs are caused by venous insufficiency. The specific problem has to be determined by the relevant professional doctor to determine the cause. A brief description of the treatment: If the diseased veins cannot be removed, varicose veins should be artificially helped by varicose veins stockings (medical compression stockings), and some complementary drugs to promote venous reflux can be used. If these methods do not work, or if they do not meet the patient’s expectations, these diseased veins can be surgically stripped, after which the blood will naturally return from the remaining functioning veins, thus circumventing the pathological process described above.