Oxygen-rich blood enters the leg via the leg arteries, travel via the multiple branches of the major arteries until it enters the arterioles and then the capillaries. Here the exchange of gas, nutrients and waste between the blood in the capillaries and the tissue of the leg ensures that the leg structures are provided with an adequate oxygen and nutrients. Carbon dioxide and waste substances pass out of the tissue spaces and into the capillary blood where it collects into the venules, empties into the leg veins and returns to the heart.
The circulation of blood through the leg is exactly the same as any other part of the peripheral circulation. The only major difference with leg blood circulation is that due to the distance of the lower legs and feet from the heart, the veins have adapted to ensure that blood is returned to the heart efficiently. This involves the musculovenous pump of the heart where the contractions of the leg muscles helps to propel blood back to the heart. At the same time, valves of the leg veins ensure that blood does not flow backwards away from the heart.
Problems with Leg Blood Circulation
A number of problems can arise with either the incoming blood in the arteries (arterial circulation) or outgoing blood traveling back to the heart in the leg veins (venous circulation). The most common of these problems are :
- Peripheral arterial disease (P.A.D) is where the leg arteries are narrowed, either as a result of :
- Venous insufficiency is where the blood flow from the leg to the heart is impaired either due to :
Signs and Symptoms of Poor Leg Blood Circulation
When blood flow to an area is impaired, the supply of oxygen and nutrients are compromised. This leads to tissue injury (ischemia), shrinking of the tissues (atrophy) or even death of the tissue (necrosis). This often develops gradually and during the course of the disease a number of signs and symptoms will be evident as the functioning of the nerves, muscles, skin, bone and even the local immune mechanisms are hampered to varying degrees.
The signs and symptoms are covered under :
Although the signs and symptoms of a problem in either the leg artery or vein are similar, there are some features which are unique to each case and may assist with a diagnosis prior to investigations like a Doppler study or angiography.
Leg Artery vs Leg Vein Problems
- Leg pain while walking which starts up shortly after activity and eases quickly after rest. Pain may increase when lying flat and eases upon standing.
- Cramping, crushing pain prominent in the calf muscles but can extend to the thigh muscles and buttock muscles (gluteals).
- Usually one sided
- Leg pain while sitting and standing for long periods of time but can also occur with excessive walking. This starts up gradually after activity, standing or sitting and eases long after resting. Pain may only ease when elevating legs.
- Burning, aching and tightness of the lower leg or foot.
- Usually one-sided
- Swelling is rarely present.
- Swelling is almost always present. Initially swelling may only be noticed upon standing or sitting for long periods. As the condition progresses, the swelling is constant although aggravated by standing and sitting for long periods unless the legs are elevated.
- Normal to pale in color.
- Loss of hair on legs.
- Itching and dryness of the skin
- Skin cool to touch.
- Normal to dark discoloration (purple, blue, dark brown or black)
- Skin thickening and hardening in later stages (liposcleratodermatosis)
- Itching and dry flaking skin in the early stages
- Skin normal temperature or even slightly warm to touch.
- Tend to occur on the lower part of the leg and foot, typically on the front part (dorsum).
- Painful especially at night when lying flat which eases upon standing or hanging the leg over the side of the bed.
- Surrounding tissue may typically red and inflamed.
- Tends to occur below the knee on the inner side of the leg (medial aspect), often just above the ankle joint.
- Painless ulcer
- Tissue around ulcer is dark and severely discolored.
- No visible distension of the artery.
- Leg pulses are reduced or absent.
- Superficial veins are visible, enlarged and tortuous.
- No change in the leg pulses.