Infrapopliteal (IP) peripheral arterial disease (PAD) often occurs as part of multilevel atherosclerotic disease and is more commonly seen in patients with long-standing diabetes mellitus, patients with chronic kidney disease, or the elderly.1 Presence of moderate stenosis with 1 or 2 critical lesions can disrupt pulsatile flow to the limb. Chronic stable limb ischemia is predominantly asymptomatic, with a minority (20%) of patients complaining of symptoms of claudication. Rest pain and/or tissue necrosis occurs (Figure 36-1) when the compensatory mechanisms that were developed in absence of straight line flow, such as ischemic preconditioning of the limb and development of the collaterals, are no longer capable to meeting the oxygen demands.2 The arterial tree below the knee has relatively smaller-caliber vessels that in this population are often calcified, and stenotic lesions are rather diffuse (Figure 36-2).
Ulcer at the base of the second toe. Note the pale base with very pale margins and clearly demarcated margins.
Below-the-knee arteries of a patient with critical limb ischemia. Note that the posterior tibial artery is totally occluded, the peroneal artery occludes shortly after it originated, and the anterior tibial artery has multiple tandem lesions followed by total blockage. Ant., anterior.
Open vascular repair has been the mainstay of treatment, but given the significant comorbidities and lack of viable distal bypass target, endovascular approach is typically considered first. Patients who do have a patent artery that provides direct flow to the foot without other major comorbid conditions and have good vein conduit for bypass should be considered for surgical bypass. Patients with limited life expectancy and extensive gangrene or necrosis should undergo primary amputation.
Patients with IP disease in conjunction with femoral-popliteal disease have a lower risk for amputation and have longer amputation-free survival when compared with patients who have IP disease only.3 Patients who will benefit from revascularization include patients with Rutherford categories 4 to 6, systolic ankle pressure <50 mm Hg, nonpulsatile plethysmographic tracing, and/or transcutaneous oxygen pressure <30 mm Hg.4,5 Clinically, patients present with limb pain at rest, nonhealing ischemic ulceration, or gangrene. The pain is usually located in the acral portion of the leg, toes, or heels and is severe and persistent. The feet may be insensitive to cold, joints may be stiff, and patients may suffer from hyperesthesia. Patients may complain of pain relief when feet are in dependent position, and conversely, pain may increase if feet are above the level of heart or even when laying in bed with feet at heart level. Patients will often narrate how they have pain in the feet at night that gets better when they hang the feet over the side of the bed. ...