Mechanisms of varicose vein formation

A varicose vein is a diseased superficial vein of the lower limb. It becomes dilated and blood stagnates in the vein. Varicose veins can lead to cosmetic and even functional disorders.
A is the best examination to assert a vein is diseased and evaluate the degree of seriousness.
Spider veins are not strictly speaking varicose veins, but they can be accompanied by varicose veins, whether they are visible or not, and so they should also be monitored.
A Duplex scan examination is therefore the cornerstone of vein disease evaluation before taking any therapeutic decision.

Varicose veins and the venous systems

There are two venous systems in the lower limbs:

The deep venous system which normally carries about 90% of
venous return

The superficial venous system when in perfect condition carries only about 10% of blood back to the heart.

Varicose veins always belong to the superficial venous system. Varicose veins do not develop in the deep venous system.

Saphenous veins are the main superficial veins: they are collecting trunks which drain venous blood from the superficial into the deep network.
The great saphenous vein (also called internal saphenous vein) is the longest vein; it runs on the inner side of the lower limb, from the to the groin where it flows into the common femoral vein (deep vein).

The small saphenous vein (also called external saphenous vein) runs behind the and joins the popliteal vein (deep vein) situated at the back of the knee.

Anterior and posterior saphenous veins are not always detected by an ultrasound or clinical examination alone: when diseased, they may require a treatment.

Perforating veins form "bridges" that perforate muscles and connect the to the deep system.

Varicose vein formation

A varicose vein is defined as the dilatation of a superficial vein disrupting the unidirectional blood flow back to the heart. Its valves are incontinent and fail in their anti-reflux function.
Valves normally work as one-way flaps allowing blood to flow only upwards, from the foot to the heart; they work against universal gravity, especially in an upright position.

Ostial valves (in the ostium) are the last valves in the saphenous veins before blood reaches the deep network: these are the most important valves as they prevent reflux from the deep network back into the superficial network (the deep network being subjected to higher pressure than the superficial network).

Vein dilatation in itself does not necessarily imply an incontinence of the valves and does not always need to be treated. When significant valvular incontinence occurs, it almost always requires treatment.

Varicose veins symptoms

Varicose veins can be and cause only cosmetic damage: the need for treatment depends on found during a Duplex scan and on the cosmetic discomfort felt by the patient.

Varicose veins can also come with functional signs such as heaviness, pain, , cramps, , and itching: again, a Duplex scan will evaluate the extent of reflux and its level will determine the choice of treatment.

Spider veins

are not really varicose veins. They may or may not be accompanied by more severe varicose veins, whether they are visible or not. In any case they require a consultation and a Duplex scan.
Indeed, some recent studies show that spider veins could serve as a "tank" aggravating from underlying superficial veins and causing further damage to the point of forming varicose veins.

Vein anatomy

The formation of a varicose vein is the consequence of vein wall disease and malfunction.
The vein wall is made of three layers (or tunica, i.e. coat) including from the outside to the inside:

The tunica adventitia (the outermost coat) is made of
connective tissue
which forms a sort of covering of the vein.
The tunica media (the middle coat) is essentially made of smooth muscle fibres, which are not attached to each other but attached to venous collagen, and elastic fibres: the tunica media allows
vasoconstriction
and
vasodilatation
.
Finally, the tunica intima (the innermost coat) is covered with a layer of endothelium which ensures that the vessel is watertight since it is in direct contact with the blood flow, and also allows exchanges with blood.

When a vein becomes varicose, a significant decrease of about 75% of insoluble collagen is observed, and it results in the thickening of the vein wall that can often be detected in early childhood. This process weakens the vein wall and valves.