Veins – Vacular szstem of legs
A body of an adult contains 4-5 liters of blood. Of those, the largest part – up to 85% – is in the veins.
Vascular system has a primary task of maintaining blood flow in our organism. It contains arteries and veins.
Arteries are blood vessels with exit the heart and conduct blood to every part of our organism. Arterial blood is rich in oxygen which is necessary to sustain life.
Veins depart from the furthermost parts of the body – from tissue and organs, and all blood that is spent, that is poor in oxygen and saturated with carbon dioxide – is returned back to the heart, and then the lungs, where the blood is enriched with oxygen again, and then again, returned to the heart and the same cycle starts again via the arteries.
Blood flows in arteries thanks to the heart which acts as a pump – from heart toward periphery. In veins, blood flows in a different direction, from tissue to the heart. By moving in such manner, it has to overcome very strong gravitational force, which is especially evident in leg veins. In humans, due to their evolutionary upright stance, there are mechanisms developed for normal return of venous blood: venous valves and muscles of the lower leg – muscle pump.
What is the function of veins?
Blood flows through the arteries into the tissue cells and replenishes them. Veins take blood back from the periphery into the heart. Venous blood is enriched with carbon dioxide and decomposed products of tissue metabolism; it returns back via veins to be cleaned in the lungs.
In the legs, there are deep and superficial veins.
About 2% of blood flows via superficial veins, and the rest via deep veins.
Deep veins are placed between muscles in the depth of a leg; they are separated from superficial veins by a membrane – a muscle fascia. Function of deep veins is to transport venous blood in the legs – they are responsible for hemodynamics of venous blood, because over 90% of venous blood in legs is transported right through the deep veins.
With evolutionary development of human upright walk, veins developed special structures which do not exist in arteries, called venous valves.
Venous valves have a shape of two pockets which are found in the inner side of the vein, and they function as semi permeable valves. That means that when the valves are opened, they let blood through only in one direction – towards the heart. Closed valves prevent blood in veins from returning towards the feet.
While walking, running, or any other activity, lower leg muscles contract and press deep veins – the valves open and direct blood towards the heart. And vice versa – while sitting, standing, or generally, while we are inactive, muscles are relaxed and valves stay closed to prevent blood from returning towards the feet.
Synchronized operation of venous valves and lower leg muscles is called a muscle pump.
Superficial veins are found right under the skin, placed in the subcutaneous fat tissue where there are no muscles. Their role in transporting venous blood in legs is very slight; they collect peripheral blood filled with carbon dioxide and decomposed products of tissue metabolism and enable their elimination from the organism. Such blood is collected by superficial veins, and then it is transported via deep veins to the heart, and then the lungs, where carbon dioxide is thrown out of the body by exhaling.
Communicating veins (perforating, connecting) are veins of ‘medium caliber’ which connect deep and superficial vascular system.
- congenital weakness of venous valves – a genetic predisposition
- disruption of posture – low instep
- being overweight
- prolonged standing and sitting
- lack of physical activity
- sex – hormonal status, pregnancy, oral contraceptives
- earlier thromboses or vein trauma (secondary varicosities)
More about causes and pathogenesis of the vein diseases.
Causes and pathogenesis
The most common cause of primary varicosities is usually genetic predisposition – congenital weakness of venous valves. However, they are usually caused by the lifestyle, obesity, prolonged sitting and standing and lack of physical activity.
In women, vascular diseases are enhanced by pregnancy, hormonal status and wearing high heels.
What also contributes to a marked progression of the disease is the disruption of posture: gradual lowering of the cross arch of the foot, which is usually not even noticed. Achilles tendon does not stand under 90 degrees anymore, but moves its angle inwards; on footwear, there is a visible detrition of the inner side of the sole. In that way, venous valves in the inner leg are strained. When the valves relax, blood starts returning due to gravitational force. If the valve is small, capillaries open; if the valve is ‘main’ – in the groin, i.e. if it is a venous confluence – large veins open. They become wide, curved and visible, or they, immersed into softened muscles and connective tissue – make lower legs feel heavy, swollen and overloaded.
The process is faster and more intense in overweight people.
- heavy, painful, swollen lower legs
- leg fatigue
- cramps in lower legs, especially during the night
- dry, thin, atrophic skin; dark sports as a sign of hyperpigmentation
- itching, skin redness
Classification of the stage of disease – CEAP
0 stage – no visible or palpable signs of vein disease
1st stage – telangiectasias (slight, spider-web veins) or mesh veins (‘capillaries’)
2nd stage – varicose veins (‘baggy’, ‘expanded’)
3rd stage – edema (swollen leg), but without skin changes
4th stage – skin changes: pigmentation, eczema, lipodermatosclerosis – dark, hardened skin
5th stage – skin changes + healed ulcer
6th stage – skin changes + unhealed, open ulcer