The Ischemic Foot
The term “ischemic foot” refers to a lack of adequate arterial blood flow from the heart to the foot. There are a wide variety of possible causes for poor arterial circulation into the foot including arterial blockage from cholesterol deposits, arterial blood clots, arterial spasm, or arterial injury. The ischemic foot is also referred to as having arterial insufficiency, meaning there is not enough blood reaching the foot to provide the oxygen and nutrient needs required for the cells to continue to function.
The result of insufficient blood supply to the foot can manifest itself in a variety of ways depending upon how severe the impairment to circulation. Early symptoms may include cold feet, purple or red discoloration of the toes, or muscle cramping after walking short distances (intermittent claudication). Later findings may include a sore that won’t heal (ischemic ulcer), pain at night while resting in bed, or tissue death to part of the foot (gangrene).
The diagnosis of ischemia is made by reviewing the patient’s symptoms, examination of the foot, and special testing to evaluate the circulation. The examination should reveal cold skin temperature, and skin atrophy that causes the skin to appear shiny or paper thin with loss of normal hair on tops of the toes and on the lower leg. There is often a color change associated with ischemic feet. This may show as a purple discoloration of the toes, white blanching of the toes when the foot is elevated, and red discoloration when the foot is hanging down. Additionally the two arterial pulses in the foot will not be as strong as normal, or may be entirely absent. Certainly the presence of a pale looking ulcer, or black gangrenous toes would be an ominous sign of poor circulation.
When these findings are present further testing is usually required. This will often include arterial Doppler testing. This test uses sound waves to listen to the blood flow through the arteries and is able to record the quality of the blood flow and also the blood pressure. If the quality of blood flow is poor and the pressure is greatly diminished, this would indicate a lack of adequate blood flow. A second test may be required to further determine where the arterial blockage is located and how much blood is able to squeeze past the blockage. This test is known as an arteriogram. The arteriogram requires the injection of a special dye into the artery so that the artery will be visible when an x-ray is taken. This x-ray can then show where the artery is blocked and how much blood can flow past the blockage.
In the early stages of ischemia of the foot, the doctor will often recommend a program of walking exercises to increase blood flow, protective shoes and insoles if necessary, to protect the skin from rubbing producing irritations which may lead to ulcerations. Medications are also available to help improve the blood flow into the feet.
In more advanced stages of ischemia, a referral to a vascular specialist is appropriate for further evaluation. Oftentimes, if the patient is in otherwise good general health, a surgery may be recommended to bypass the blocked artery or to clean out the area of blockage. This can be major surgery, however in these cases, failure to improve the circulation into the foot may result in gangrene, which may ultimately require amputation of part of the foot or leg. The surgery is an attempt to save the foot and leg from the impending amputation. The surgery has improved over the years and the chances for success are now greater than ever before. However, each individual needs to be evaluated as to the potential risks and possible benefits from this type of surgery.