About Venous Disease
Calf Muscle Pump
Arteries deliver nutrients and oxygen from the heart to the extremities at relatively high blood pressures (usually 120/80 mmhg). Only a little of this pressure is left after the blood filters through the capillaries. Veins convey cellular waste from the extremities back to the heart at relatively low blood pressures (10-15 mmhg when lying down).
Gravitational force on a column of blood creates a downward pressure known as "hydrostatic pressure". When standing upright hydrostatic pressure assists arterial flow to the feet, but impedes venous return from the feet back to the heart.
The low venous blood pressure pushing upward cannot overcome the downward hydrostatic pressure without assistance. This assistance comes in two forms:
- Delicate venous valves occur at regular intervals within all leg veins that force the blood to flow only upwards in the deep and superficial veins and inwards through the perforator veins
- The deep leg veins run within the calf muscle, which is sheathed in layers of fibrous "fascia" Each time the calf muscle contracts, it squeezes the deep veins, emptying these veins of blood. Because of the one-way venous valves, the blood can only go "up" or back toward the heart. Thus, the calf muscles and the veins within them form a calf muscle pump. The calf muscle pump provides upward propulsion to overcome the downward hydrostatic pressure and send venous blood back to the heart.
Calf muscle pump problems generally begin when the delicate valves in the deep veins malfunction. These faulty valves allow blood to reflux and pool in the veins, resulting in venous insufficiency. There are no good procedures to cure this problem. Fortunately, the calf muscle pump is extremely durable and resistant to malfunction. Fewer than 10% of our patients have calf muscle pump dysfunction.
The calf pump is idle when you stand still or sit with your legs in a dependent position. In these positions, gravity causes blood to pool in the lower legs. This pooling of blood makes your legs feel tired, heavy and achy. Prolonged standing still or sitting with legs dependant are therefore bad for your veins. Exercise and leg elevation are good for your veins because they prevent pooling of blood.