Ischemia of the lower extremities will manifest itself in many different ways ranging from asymptomatic (simply the presence of a blockage) to gangrene of the leg or a part of it. Quite often a patient will have an asymptomatic blockage (one that they do not know is there) that is manifested simply by an absent pulse in the footbehind the knee or in the groin or an abnormal angiogram that is usually done at the time that a cardiac catheterization (heart catheterization) is performed. A person will have no symptoms referable to this blockage and will only know of the abnormality because their physician informs them of such! This is generally referred to as Fontaine’s Class I.
The next “level” of ischemia is that of claudication. This is manifest by cramping pain that occurs with walking. It most often affects the calf muscles and generally occurs at a rather fixed distance (usually measured in blocks.) Depending on the severity of the ischemia—either by its level of lifestyle interference or by distance at which symptoms begin—it is referred to as Fontaine’s Class IIa or IIb.
Rest Pain is the next Stage (III) in the Fontaine classification of leg ischemia. This is typified by pain that occurs even in the absence of significant stress on the legs. It often occurs in the evenings awakening the patient from sleep. Quite oftenhanging the leg from the side of the bed will improve the painful symptoms that are experienced. The foot will often turn a light purple or deep red-violet color as it is held in a dependent condition—often referred to as “dependent rubor.” This is a sign of significant leg ischemia and warrants aggressive intervention.
The final stage of leg ischemia (Fontaine Level IV) is tissue loss—seen as a non-healing sore or gangrene. This level (along with rest pain) is appropriately referred to as “limb-threatening ischemia” and must be evaluated appropriately by those with expertise in this area. Ignoring this degree of ischemia will very likely lead to limb loss (amputation) at some point in the future!