Venous Incompetence – varicose Veins
One of the most common problems with the veins of the leg is failure of their valves. This occurs frequently in the superficial venous system resulting in varicose veins, which affect 10—20 per cent of the adult population in Westernised countries. In developing countries, where a primitive way of life is maintained, there is a very low incidence of varicose veins. The reasons for this difference are unclear but are probably related to differences in diet. A further major factor is inheritance: women in whom neither parent has varicose veins have a 10 per cent risk of developing varices, but when both parents are affected there is an 80 per cent chance. Men are affected less frequently than women.
The mechanisms that cause the superficial vein valves to fail have not been fully established. What appears to happen is that first a small gap appears between the valve cusps at the commisure (where the valve leaflets join the vein wall). This gap widens and more reverse flow (venous reflux) is allowed. The valve cusps degenerate and holes develop in them. Eventually they disappear completely. The vein below the valve responds by dilating. Varicose veins may eventually reach five times their usual size if left to develop for long enough.
In the past it was thought that varicose veins were caused by anatomical abnormalities in the deep vein valves. It is now clear that this is not true. Varicose veins often develop in the calf when the veins above are normal. This seems to be a process where congenital and environmental factors accumulate to cause valve failure.
Varicose veins are thought to develop more often in people who stand during their work. People who sit or walk are at less risk of developing varices. They often develop during pregnancy under the influence of oestrogen and progesterone which cause the smooth muscle in the vein wall to relax.
Varicose veins are very common; they may either give no symptoms or cause aching and discomfort in the legs. Varices are recognised as tortuous dilated veins in the leg, but physiologically speaking a varicose vein is one which permits reverse flow through its faulty valves. Varices of the major tributaries of the saphenous veins or the saphenous veins themselves are large (5—15 mm diameter) and usually start in the calf. Later varices of the long saphenous system may also appear in the thigh. Patients may develop much smaller varices. These range from 0.5-mm diameter vessels in the skin, which are commonly referred to as thread veins or dermal flares, and are usually purple or red in colour. Slightly larger veins (1—3 mm diameter) lying immediately beneath the skin may also present as small varicosities. These are usually referred to as reticular varices. The association of thread veins and reticular varices is frequently seen, and these probably reflect a type of varicose veins which is confined to the smallest size of vein. These tiny veins are associated with superficial venous incompetence in about 30 per cent of cases. They require different treatment from large varices. The combination of small varicosities and much larger truncal and tributary varices is often seen, but each type may occur on its own. The symptoms reported by patients affected by either type of varices are very numerous. Often there are no specific symptoms but the cosmetic appearance is unsatisfactory. Patients may also report aching especially on standing, itching, ‘restless legs’ and ankle swelling. The severity of the symptoms is unrelated to the size of the veins, and is often more severe during the early stages of development of varices.
Complications of varicose veins
Occasionally complications of varicose veins may develop. These include thrombosis,which is referred to as superficial thrombophlebitis. Usually this remains in the superficial veins and may cause considerable discomfort. Sometimes thrombosis extends into the deep venous system to cause deep vein thrombosis, although this is infrequent. Spectacular haemorrhage can occur when large superficial varices are damaged. This is easily controlled by lying the patient down, elevating the leg and applying a compression bandage. The most serious problem is venous ulceration which complicates varicose veins in less than 5 per cent of patients. However, it is a troublesome and painful condition which requires careful management if the ulcer is to heal.
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