What Causes Varicose Veins?
This question is best answered in two parts, discussing 1) conditions that predispose someone to develop varicose veins, and 2) the actual structural abnormality that results in the development of varicose veins.
Predisposing Conditions: Gender. Hereditary. Pregnancy. Trauma.
The Actual Structural Abnormalities: Bad Venous Valves.
There are a number of veins in the lower leg that may have damaged venous valves. The most common place for this to happen is the great saphenous vein, which starts in the groin and runs down the anterior-medial aspect of the leg.
To understand how bad venous valves cause varicose veins, it is important to understand how good venous valves perform. The animated depiction on the right demonstrates how a venous valve functions. The flexible membranes that make up the valves allow the valve leaflets to collapse against the wall when blood is flowing toward the heart. However, if the blood flow is reversed the valve leaflets expand and close the vein to any further blood flowl. |
Damaged venous valves allow the blood to flow in both directions. Normally movement in the leg causes blood in the leg veins to flow upward toward the heart. If the venous valves are injured, blood will flow in the wrong direction -- from the abdomen down into the lower leg -- when the leg is not in motion. |