Circulation disorders includes a large number of different problems with one thing in common, they result in poor blood flow. Specifically, the term peripheral vascular disease refers to blood flow impairment into the feet and legs (although it could include the arms and hands as well).
Blood is circulated throughout the human body by the strong, muscular pump called the heart. With each heartbeat, blood is pushed along through blood vessels called arteries that carry the oxygen and nutrient rich blood to all parts of the body including the legs and the feet. The individual cells in the body take up the oxygen and nutrients. Then a second set of blood vessels known as veins carry the oxygen depleted blood back to the heart and lungs to get more oxygen, and again be pumped throughout the body. Peripheral vascular disease may refer to arterial inflow disorders, (arterial insufficiency) or venous outflow disorders (venous insufficiency).
Arterial inflow disorders are categorized by the size of the artery involved. If a large artery in the thigh or behind the knee becomes blocked by cholesterol deposits this is referred to as large vessel disease or atherosclerosis. The result may be a painful ischemic foot, which means there is a severe lack of arterial blood flow from the heart into the foot. If smaller arteries like those in the lower leg or foot is blocked, this is referred to as small vessel disease, or arteriosclerosis. This too can result in ischemia of the foot. Small vessel disease is seen more often in diabetics, but can affect non-diabetics as well. If the skin of the feet or legs lacks adequate blood flow a sore will develop which may be difficult to heal. These sores are known as ischemic ulcers. Any blockage to arterial inflow will result in a circulation problem to the body tissues down stream. Occasionally a small blockage will occur in the small arteries that supply blood to a toe. This is known as a "Blue Toe Syndrome." Another arterial inflow problem may result when the smooth muscles that control the size of the arteries go into spasm. The arterial muscle spasm can block the blood from circulating into the foot. One common vasospastic disorder is called Raynaud's Syndrome. A second vasospastic disorder is called acrocyanosis.
Venous outflow disorders refer to problems getting blood from the foot back to the heart. There are two sets of veins in the feet and legs to help bring the blood back toward the heart. The superficial venous network refers to veins located just beneath the skin. The deep venous networks are veins located closer to the bones and are not visible when looking at the foot or legs.
Varicose veins refer to an enlargement of the veins and a loss in the ability of the vein to properly maintain blood flow back toward the heart. When this occurs blood can collect in the feet and legs. Superficial varicose veins may appear as unsightly cords or a small bunch of grapes, which usually appear on the tops of the feet, around the ankles and may extend upward to the knees and thighs. Deep varicose veins while usually not visible will result in chronic swelling of the feet, ankles and legs. When the blood is not circulated from the feet back to the heart gravity will cause the fluid to collect in the feet and ankles. This results in swelling, called edema. Chronic edema over a long period of time may cause a discoloration of the skin around the ankles. The skin can become inflamed, and is know as venous stasis dermatitis. If left untreated the skin will become weakened and a weeping sore will develop, usually on the inside of the ankle called a venous stasis ulcer.
A potentially serious consequence of blood collecting in the feet and legs is the formation of blood clots in the veins. A superficial vein blood clot will result in a painful, inflamed superficial vein called superficial phlebitis. When a blood clot forms in a deep vein, it is called deep venous thrombosis, or deep phlebitis. This is a serious condition that causes painful swelling of the leg and may result in part of the clot breaking free. If the clot should travel back up to the heart and get caught in the lungs, it is referred to as a pulmonary embolus which can be life threatening and requires emergency treatment.