Veins

Veins are part of our cardiovascular system whose function it is to move blood and transport nutrients to the cells in our body. Veins are the blood vessels that move oxygen-depleted blood from around the body back towards the right atrium of the heart. The smallest veins are called venules and range from 1mm in diameter up to just over 2cm which is the diameter of the largest vein, the vena cava. The tiny venules are responsible for collecting oxygen-depleted blood from the capillaries. Veins are made up of several layers of thin tissue and are thinner and more elastic than arteries, and because of this, veins can hold more blood. Within a vein there are valves which help to prevent any backflow of blood and to keep it flowing towards the heart. Valves are very important in the arms and legs as they must fight gravity to prevent backflow. Veins work under a low-pressure system, relying on muscle contractions to return blood to the heart.

There are four different types of veins – deep veins which are found in muscle tissue and have a corresponding artery nearby, superficial veins which are found closer to the skin surface and don’t have corresponding arteries, pulmonary veins which are found in the lungs (and are the only exception to the rule of veins carrying deoxygenated blood as these veins actually carry blood that has been filled with oxygen from the lungs to the heart). Systemic veins are the rest of the veins throughout the body that deliver deoxygenated blood to the heart.

Problems with veins usually occur due to a blockage (from a blood clot) or a defect in the vein itself. Blood clots can form when blood cells called platelets or thrombocytes stick together if the vein has been damaged in some way. A clot in a deep vein is called a thrombosis (DVT), and a clot in a superficial vein closer to the skin is given the term thrombophlebitis.

Varicose veins are actually superficial veins near the surface of the skin that have become swollen. This can happen when the one-way valves inside the vein break down or the vein wall becomes weak, allowing the back flow of blood. When valves don’t work as well it allows blood to pool in the veins causing inflammation and bulging.

Chronic venous insufficiency is when the blood collects in superficial and deep veins of the legs due to improper functioning one-way valves. This condition is very similar to varicose veins but causes other symptoms such as coarse skin and ulcers.

While varicose veins can look unsightly they don’t tend to be a serious concern. A deep vein thrombosis (DVT) however can be life threatening. DVTs occur when a blood clot forms, usually in a deep leg vein. If the clot breaks free it can potentially travel to the lungs and cause a pulmonary embolism.

Symptoms of venous conditions are swelling and inflammation, pain or tenderness, veins that feel warm or an itching or burning sensation. These symptoms are most common in the legs.

A DVT can have similar symptoms as other venous conditions, however they can sometimes even be symptomless. Generally there will be pain and swelling in the affected leg. The pain can start in the calf muscle and feel like cramp. The skin on the affected leg can appear red or discoloured. See your doctor promptly for unexpected pain or swelling in your leg.

To keep your veins healthy remember the following advice:

• Keep the blood moving by doing regular exercise.
• Avoid standing or sitting for long periods. Get up and change position frequently.
• Keep to a healthy weight to decrease your risk of developing high blood pressure. High blood pressure will weaken veins over time due to the added pressure on their walls.
• Don’t cross your legs.
• When flying make sure you keep hydrated, move around as often as you can and flex your ankles frequently while you are sitting.

This blog provides general information and discussion about medicine, health and related subjects. The information contained in the blog and in any linked mate­ri­als, are not intended nor implied to be a substitute for professional medical advice.