Venous Oedema

Do you have swellings of the leg/s related to some problem with your veins? This may be "venous oedema". 'Oedema' is an abnormal accumulation of fluid in the leg tissues. This is due to the fluid being unable to return to the vascular system from where it came or from the lymphatic system being unable to clear it properly.

Venous oedema of the legs is a condition that normally affects older people, however, it can occur at any age. It has been conservatively estimated that 5% of the adult population of developed countries suffers with vein problems and associated swellings of the legs.

How does the venuous system work?

The venous system in the legs can be described as being two channels, the superficial (surface) veins and the deep veins (which run through the thigh area and transports 80-90% of the venous blood from the legs). These two channels are connected to one another via interconnecting veins called perforating veins. Blood from the skin and subcutaneous tissues in the leg collects in venules which drain into the superficial veins. It is then transported into the deeper veins for return to the heart.

The lymphatic system also helps remove some fluid and other materials from the tissues, eventually returning it to the blood circulation. The lymphatics however, remove and pump fluids out of the leg at a much slower rate then the veins. Nevertheless, they too are critically important in the removal of fluid from the leg tissue.

How does the venuous system work?

For effective removal of fluids from the leg, the veins rely upon muscular contractions and valves of the veins to overcome the forces of gravity. This is unlike the arteries, which the blood is moved along by the pumping force of the heart.

Valves can be found in both the superficial and deep veins, with the number of venous valves varying from person to person. These valves stick out from the vein walls acting like gates, shutting behind the blood as it goes past. This prevents backflow of blood and ensures that it normally moves in one direction (towards the heart).

The contraction of skeletal muscles (your walking/moving muscles) near a vein, compresses it, helping to push blood towards the heart. During standing and walking, the cycles of leg muscle contraction that accompanies normal movement assist venous return.

The venous valves and leg muscle generally work in unison, with the muscles helping to squeeze the blood towards the heart and the valves ensuring that the blood moves in one direction. However, this process relies upon the valves in the veins functioning properly.

What causes the venous system to not function properly?

The main conditions that lead to the venous system not working effectively are varicose veins, deep vein thrombosis and congestive cardiac failure.

Other conditions such as leaking perforating veins (the veins that connect the superficial and deep veins) and a diseased or inactive pumping muscle can also contribute. All these conditions result in either blockage of blood flow or the veins being unable to empty out properly.

Varicose Veins

Are quite common; it is estimated at 20% of the general population and as many as 50% of people over the age of 50 suffer from them. Varicose veins can often be identified as unsightly bluish bulges in the leg veins.

Varicose veins occur when the walls of the vein near the valves weaken or become stretched this causes the valves not to meet properly (like gates that don't close properly). Blood pools in the veins and the vessels become grossly swollen. This results in the inadequate removal of fluid from the leg tissues, with fluid stagnating in the area and eventually leaking back into the tissues of the limb. The cells that make up these tissues are then immersed in conditions like a stagnant swamp.

There are various things that contribute to varicose veins. One of these is heredity. If members of your family have suffered with varicose veins then you are likely to suffer with them as well. Prolonged standing in one position (without moving the leg muscles), obesity and pregnancy can also contribute. In pregnancy, the baby exerts a downward pressure on the veins of the groin, restricting return of the blood from the leg to the heart. In obesity, it is the abdominal fat that exerts the downward pressure. Blood then pools in the limbs, weakening the valves and making the vein walls stretched and floppy.

Deep Vein Thrombosis (DVT)

A deep vein thrombosis is a blood clot that forms in the deep veins, generally in the lower leg region. The clot is normally accompanied by pain, redness, warmth, swelling and deep muscle tenderness in the effected area.

Sometimes clots form because the blood flow through the vein is sluggish, leaving more time for the blood to clot onto vein wall damage. This "damage" is normally a rough patch on the vein wall called a plaque. The blood has a tendency to clot onto plaques because they are rough and not smooth like the rest of the vein wall. Other times clots form which cause the blood flow to become sluggish or to stop altogether. These clots generally form because the blood clots abnormally (either the blood clots too quickly or clots when it is not meant to). Either way the end result is the same, the blood in the vein is not moved forward, the veins become congested and the fluid leaks out from the veins and back into the limb tissues.

Clots are generally treated with anti-coagulant drugs, which slow down the rate at which the blood costs. This prevents the existing clot from getting any bigger and gives the body's anti-clotting mechanisms a chance to dissolve the clot. A clot may also leave permanent damage; the congestion it causes in the veins can contribute to varicose veins and chronic swelling.

Congestive Cardiac Failure

This is where the pumping action of the right side of the heart is reduced due to heart muscle weakness or damage (e.g. after a heart attack). This results in congestion (a backlog of blood waiting to be pumped) occurring in the veins returning the blood to the heart. The blood then pools in the veins, putting more pressure on the valves whose job is to direct the blood forward. Eventually the valves fail, with more blood pooling in the veins and the fluid leaking out of the vein and back into the tissues. This results in oedema, which is most noticeable in the extremities (such as the ankles, legs and fingers).

Reference Source: Recognition, Treatment and Management of Venous Oedema by Prof Neil Piller, Lymphoedema Assessment Clinic, Flinders Medical Centre, South Australia. Information is Copyrighted ©