Venous overview

Blood, Veins & Valves:

How it circulates

The circulation of blood is possible based on three major component; the heart,

arteries and veins. The pumping action of the heart forces blood through the arteries and veins of the body. Arteries are the vessels that carry blood from the heart to the body tissues. Veins return the blood back to the heart. 

How they work

Valves, located inside the veins, keep the blood flowing in one direction – toward the heart. Valves open to allow blood to return to the heart. They then close to prevent the blood from flowing backwards.

How vein problems occur

When a valve no longer closes properly or fully, problems can develop. Weak or damaged valves cannot support the blood when the muscle relaxes. This allows blood to flow backwards in the vein, creating pressure on the valves below. These valves can also weaken. Blood return to the heart is reduced and other complications can develop.


A damaged or poorly closing valve in a vein allows blood to flow backwards. This can cause blood to back up and collect in the veins of the lower leg. Pooling of blood in the veins of the lower leg causes swelling, especially near the ankles and calves.

Enlarged veins 

When a valve is damaged or missing, the backup of blood results in higher pressure in the veins below. This higher pressure, which directly affects the superficial veins (those closet to the skin), may strain the walls of the vein, causing them to enlarge and even twist.

As the veins enlarge, the valves within them can no longer close fully. Enlarge superficial veins are visible bulges under the skin of the leg. These “ropy” veins are called varicose veins. 


Blood clot

When blood cells stick together near a valve, a clot can form which may partially or completely block the flow of blood through the vein. Slow moving or poorly flowing blood in the veins is more likely to clot. Clots may be caused by slugging blood flow, injury to a vein, or abnormal blood clotting factors.

A clot in the deep veins, which is the most serious, is called a deep vein thrombosis (DVT). Part of a DVT may break loose and lodge in the lungs or may also cause long-term problems in the leg.

Causes and rick factors of venous disorders.

  • Heredity
  • Slouching or sitting for long periods
  • Age
  • Tight fitting clothing
  • High-heeled shoes
  • Obesity
  • Alcohol consumption during air travel
  • Hot baths and excessive exposure to the sun
  • Dehydration
  • Pregnancy

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