Varicose Veins – Cause

What causes varicose veins?

As a very simple explanation, varicose veins and “hidden varicose veins” are caused by the valves not working in veins.
Very simply, blood is pumped from the heart to the feet by the muscular action of the heart beating.
When lying down, venous blood which is much lower pressure than arterial blood, can flow back from the feet to the heart.
However blood cannot get back from the feet to the heart against gravity when you’re standing up.
To do this, the blood needs to be pumped from the feet and lower leg back to the heart.
To pump blood, it is necessary to have both movement to make the blood move, and valves to stop the blood falling back down the veins once the movement has stopped.
In normal people, movement of the foot and calf during activities such as walking pumps blood up the veins of the legs towards the heart.
When the legs are not actively pumping (such as when the leg is being swung forward for the next step) or when standing still, gravity works on the blood and it tries to fall down the leg veins. Provided the valves are working, it cannot fall down the veins.
If the valves have stopped working, blood falls down the leg veins – this being the “reflux” of the blood down the veins due to the valves being “incompetent”.
When the valves have stopped working in one or more veins, blood refluxing the wrong way down the veins causes damage lower down the leg in one or more ways.
03 valves failing in great saphenous vein - venous incompetence - causing venous reflux and varicos
  • Blood being pumped normally up the deep vein
  • Blood refluxing from deep vein, out of the saphenofemoral junction into the Great Saphenous Vein (GSV) due to valve failure
  • Blood refluxing down the Great Saphenous Vein (GSV) due to the valves not working
  • Turbulence of the refluxing blood causes veins to dilate, which are called varicose veins
If the falling blood just stretches the walls of the surface veins, then these will bulge and varicose veins will be visible on the surface of the legs. This is the cause of varicose veins.
06 valve failure in the Great Saphenous Vein (GSV) - venous incompetence - causes venous reflux and
  • Reflux of blood in the superficial truncal veins causes inflammation of subcutaneous fat in the lower leg
  • Valve failing at the Sapheno-Femoral junction allowing blood to reflux from the deep vein to the Great Saphenous Vein (GSV)
  • Valves working normally in the deep vein
However, if the blood falls straight down the veins and does not make the vein wall dilate, intead it will hit the capillaries around the ankles causing inflammation. Over the years, this inflammation causes the ankles to swell and, if it continues, will slowly start damaging the skin causing itching (venous eczema), red stains, brown stains and then eventually leg ulcers. This is the cause of “hidden varicose veins”.
Varicose veins (left leg)
Hence both varicose veins and “hidden varicose veins”, are caused by the failure of the valves in the veins in the legs (called ‘venous incompetence’) and blood falling the wrong way down these veins by gravity (called venous reflux).
Treament of the incompetent veins, stopping the venous reflux, can reverse all of the changes that it has caused.

Next page: What are the symptoms of varicose veins?

This website was last updated on 11/10/16.