Varicose veins are one of the most common diseases worldwide
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The vein system
How does the blood circulation work?
In order to function properly, all organs and tissues of our body need regular supplies of oxygen and nutrients. The cardiovascular system, consisting of the heart, a network of blood vessels and the blood itself, is the transport system responsible for this supply.
The heart is the motor and the blood vessels form the pipeline through which the blood flows. An adult has 4-6 litres of blood, which circulates throughout the body all day long. Our blood vessels therefore transport about 10,000 litres of blood each day.
The blood vessels consist of arteries and veins. The arteries transport bright red blood, rich in oxygen and nutrients, to all the organs and tissues of the body. The veins are the blood vessels that transport blood from the body back to the heart. Venous blood is dark red and contains waste products and less oxygen than arterial blood.
Animation: Blood circulation
The heart is a muscle, which contracts and relaxes to pump blood out into the arteries and through the whole body, so that every single cell is supplied with oxygen and essential nutrients. The blood leaves the left side of the heart through the main artery, called the aorta, which then branches into increasingly smaller arteries, thus carrying the blood to all organs and tissues of the body.
The small arteries end in so-called capillaries, which are the smallest branches of the vascular tree. In the capillaries oxygen and nutrients are released from the blood into the surrounding tissues. In exchange, the blood takes up carbon dioxide and other waste products from the body. The blood, now depleted of oxygen and full of waste products, is first collected in the smaller veins and then transported back to the heart through the larger veins. The circulation of blood from the heart around the body and back is known as the systemic circulation.
The blood returns to the right side of the heart and is then pumped out through arteries into the lungs. Unlike all the other arteries in the body, the pulmonary arteries carry oxygen-depleted blood. Once in the lungs, the blood is again enriched with oxygen and taken back to the left side of the heart through the pulmonary veins. These veins are likewise the exception to the rule, as the blood they carry from the lungs to the heart is rich in oxygen. The blood flow from the heart to the lungs and back is known as the pulmonary circulation.
The left side of the heart then pumps the blood round the body and the circulation starts over again.
Healthy veins for beautiful legs
The veins are those blood vessels, which transport oxygen-depleted blood and waste products from the body back to the heart.
For this, our veins have to work extremely hard every day. They transport all the blood from the legs to the heart against gravity. A sophisticated system of valves and the muscle pump help the veins to overcome the force of gravity and transport the blood back up to the heart.
Venous valves – the quintessential element for healthy veins
The walls of the arteries and veins have the same basic structure. Both have a thin inner lining, the endothelium, after which comes a connective tissue layer and a muscle layer. Finally there is another layer of connective tissue.
Arteries have a thick muscle layer because the blood pressure inside them is higher. The blood pressure in the veins is low, so the muscle layer is thin and the vein wall is overall thinner.
Valves extending from the inner wall are a particular feature of the veins. A large leg vein has up to 20 of these valves. These connective tissue structures act as non-return valves and ensure that the blood flows only in the direction of the heart. The valves open when blood flows towards the heart, but close when it starts to flow the wrong way.
The blood flows in what is virtually a one-way street leading up towards the heart.
Animation: How the valves function
When the valves no longer function properly and are unable to close tightly, some of the blood flows in the wrong direction, namely towards the feet, and pools in the veins there. Left untreated, this causes irreversible damage to the veins with subsequent complications, such as varicose veins.
No flow without the muscle pump
Besides the valves, the so-called muscle pump ensures that blood is transported against gravity from the legs to the heart.
The deep veins in the leg are surrounded by muscles that are automatically activated on moving the feet or when walking and that together form the muscle pump. On movement the muscle bellies contract and compress the veins running between them, thus forcing the blood they contain upwards in the direction of the heart. The valves prevent any backflow of blood in the wrong direction.
The muscles therefore act on the veins as a pump. Depending on the location, a differentiation is made between the pumps for the toes and soles of the feet, the pumps for the ankles and knee joints, the extremely important calf muscle pump and the thigh muscle pump.
All these pumps require movement in order to be effective. From the soles of the feet to the calves and the thighs, an alternating push-pull effect is exerted on the veins each time the muscles contract.
Animation: How the muscle pump works
Movements of the feet and legs are thus essential to keep the leg veins fit. Special vein training is therefore recommended – it is good for the veins and encourages the flow of blood, particularly when sitting or standing for prolonged periods.
Important veins for blood transport
The leg veins can be divided into superficial and deep vein systems. The two systems are separated by connective tissue and muscles, but are joined together at certain points by perforating veins, also known as perforators.
The deep veins lie deep within the tissues, between the muscles in the legs, and usually run with the artery of the same name. The deep vein system is crucial for the return flow of blood and is responsible for transporting about 90% of the venous blood from the legs back to the heart. Thus, there may be far-reaching consequences if, following a thrombosis, the valves of a major deep vein no longer function properly and the vein is no longer available to transport blood. In such cases, patients then frequently have to wear compression stockings for the rest of their lives, in order to assist the blood flow back to the heart.
As the name implies, the veins of the superficial vein system run more superficially (nearer the surface) than the deep veins and lie within and just beneath the skin. They transport blood from the skin and subcutaneous tissues into the deep vein system, accounting for about 10% of the return blood flow. The blood thus usually flows from the superficial veins through the perforating veins into the deep veins, from where it is transported back to the heart. Varicose veins are diseased superficial veins. The deep veins alone can take over the return blood flow to the heart, so it is not a problem if during treatment a superficial vein has to be removed or sealed.
The great and the small saphenous veins
The two main superficial veins in the leg are known as trunk veins. These veins lie somewhat deeper in the connective tissue beneath the skin than the other veins of the superficial system. Each leg has two trunk veins – a great and a small saphenous vein.
The great saphenous vein (Latin: vena saphena magna), formerly called the long saphenous vein, is the longest vein in the leg. It runs up the inside of the leg from the medial malleolus of the ankle to the groin, where it empties into the deep vein system. The veins of the two systems meet at the so-called saphenofemoral junction (in the past, this area was also referred to as the ‘crosse’). Several other superficial veins also empty into the deep vein system here, giving the junction a star-like appearance. In the groin, a healthy trunk vein is as thick as a straw, although its precise diameter varies from person to person. The valve found in the trunk veins directly before the confluence in the deep venous system has a particular relevance to the development of varicose veins. If this valve no longer closes tightly, varicose veins are inevitable.
If necessary, the great saphenous vein can also be used for coronary artery bypass grafting in the heart and should therefore only be removed or occluded completely if there is a strict medical indication to do so.
The small saphenous vein (Latin: vena saphena parva), formerly known as the short saphenous vein, runs from the outside of the ankle to just above the hollow of the knee, where it usually empties into veins of the deep vein system. The confluence of the veins may, however, be at a higher or lower level and must be considered individually in each patient.
Both trunk veins may be affected by varicose disease. If their valves no longer function properly, some blood will flow downwards and collect in the leg veins until varicose veins develop.
Side branch veins
Side branch or tributary veins are superficial veins that empty into the trunk veins. The side branch veins run through the lower leg and the thigh; there are many veins connecting them with each other and also to the deep vein system. The term ‘side branch veins’ is not really accurate, as they do not branch out of but rather enter the trunk veins into which they empty the blood. For the sake of simplicity, however, ‘side branch veins’ continues to be used, as it is such a well-established term.
Should the valves in these tributary veins no longer function properly, particularly large and unsightly varicose veins may develop.