”Venous insufficiency” is a complex and chronic process, which 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 the 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 blood to the heart, which is the special role of the so-called “water flows higher”. To accomplish this role, veins rely on a unique one-way valve structure within them – the venous valve. As shown in Figure A, the upward flow of blood through the valve is prevented from returning downward by the valve’s blocking effect, and this depends on a strong vein wall that supports the valve and the pressure of 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 veins are subjected to prolonged stagnant blood action, the following phenomena can be simply understood: 1. Stagnant blood cells eventually leak out of the weak vein walls and blood pigments are deposited under the skin, forming discoloration. 2. When the veins lose their function, both blood and lymph flow are poorly returned and tissue fluid is confined to the subcutaneous tissues, resulting in edema of the lower extremities and a feeling of heaviness in the lower extremities. 3, The stagnant blood makes to generate excessive pressure, which further leads to the loss of normal elasticity of the vein wall. With the dual alteration of damaged venous valves and weak vein walls, the veins eventually dilate, stretch, and twist, forming varicose veins. As in Figure B, dilatation of the venous lumen further aggravates the venous valve closure insufficiency, forming a vicious circle.