How veins work – issues

What goes wrong with veins?

There are of course many things that can go wrong with veins but for the purposes of phlebology, we concentrate on the most common issues that cause the most common clinical problems for our patients.

The two major problems that affect veins are:

  • blood clotting within the veins
  • the venous pump not working
Blood clotting within the veins:
Although the veins are made specifically to transport venous blood, there are certain circumstances where the blood can clot within the veins.

If the blood clots within the deep venous system, it is called a deep vein thrombosis (DVT) (please click on the previous link to learn more about DVTs).

If blood clots within the superficial venous system, it is called superficial thrombophlebitis or more commonly “phlebitis” (please click on the link to learn more about phlebitis).

Failure of the venous pump:
The venous pump can fail in one of two main ways:
  • Failure of movement
  • Failure of valves
It is less common to have failure of movement as a cause of the venous leg pump to fail, but it does happen. One of the commoner ways is when patients get old or infirm and stop walking – becoming chair-bound or bed bound. Other causes can be paralysis of the limb, stroke or fusion of the ankle or knee joint (or both) stopping any movement of the joint.

Failure of the venous valves of the legs affects about 40% of adults. When these valves fail, usually in the superficial venous system, blood is still pumped up the leg on movement, but it falls back down the affected veins (called incompetent veins and the blood is said to “reflux” back down the veins). This refluxing blood can have several effects depending on how much blood is refluxing and which veins are involved.

Most of phlebology is concerned with venous reflux – ie: what happens when the valves fail and what the refluxing blood does to the venous system. The effect of this blood falling down the incompetent veins and hitting the vein walls might be dilation of veins near the surface (thread veins or varicose veins), inflammation of the vein walls making them leak fluid (aching or “heavy” legs, or swollen ankles) or inflammation spreading from the vein walls and out into the tissues of the lower leg (venous eczema, red or brown stains or venous leg ulcers).

Although most people are able to picture that blood falling the wrong way down a vein can cause stretching of the vein walls and hence varicose veins, most people (including many doctors and nurses) do not understand that this same venous reflux can cause thread veins and the skin damage seen in many people and often mis-treated with steroid creams.

To try to help people understand venous reflux, we have started to use the term “hidden varicose veins” to make the problem easier to visualise, and to sound easier than the more technical sounding “venous incompetence” or “venous reflux”.

Older doctors and nurses who do not understand veins still use the term “venous hypertension”, meaning the increased pressure of blood in these veins due to the valves not working. However research has shown that there is no increase in pressure – the blood flows the wrong way, but the maximum pressure is the same whether the valves are working or not. Hence the term “venous hypertension” is a nonsense in phlebology and should not be used anymore.

This is explained more fully in “Understanding Venous Reflux – the cause of varicose veins and venous leg ulcers”.

Next page: How can venous reflux be treated?