Patients with CLI typically present with ischemic rest pain and/or tissue loss or forefoot gangrene. Most of these patients have significant comorbid conditions such as diabetes mellitus, coronary artery disease, hyperlipidemia, and hypertension that will be important for risk stratification and in deciding between different revascularization modalities. Additionally, managing and optimizing these risk factors are keys to successful outcomes following lower extremity revascularization, regardless of the technique used. As such, optimizing lipid profile, glycemic control, smoking cessation; minimizing renal dysfunction; and managing hypercoagulable states are all essential components to the perioperative medical management, in addition to managing any concomitant coronary disease. The majority of patients are already followed by a team of physicians for their comorbidities (primary care physician, cardiologist, endocrinologist, nephrologist), whereas the surgical team is evaluating the peripheral vascular disease. It is imperative that these consultants remain actively involved in the perioperative period for both the short-term and long-term success of limb salvage and overall survival. The age of the patient, functional status, and comorbidities guide the vascular surgeon’s decision making in terms of the type of revascularization offered to the patient.

Most patients presenting as outpatients will have a history of symptoms of disabling claudication, rest pain, or tissue loss. Taking a careful history noting duration of symptoms, level of pain/claudication, areas of tissue loss, and history of traumatic neuropathic ulceration will guide the workup. Young patients, younger than 60 years of age, or patients with multiple arterial/venous thromboses should undergo a thrombophilia evaluation. Physical examination should include a thorough peripheral vascular examination, including assessment of the potential presence of a palpable aortic aneurysm on abdominal exam. The quality and symmetry of pulses and/or handheld Doppler signals between both legs at the femoral, popliteal, and pedal levels assist in determining the anatomic level of disease. Wound documentation, when present, should note location, depth, presence of infection, bone exposure, and extent of soft tissue defects. Neuropathic deformities of the foot should also be taken into careful consideration for offloading purposes. If there is gross purulence or systemic signs of infection, a debridement of the affected area is required prior to revascularization, even if the area is malperfused, for source sepsis control.

The location and appearance of ulcerations will often assist in differentiating ischemic, neuropathic, or decubitus wounds. Location of the ischemic wound is important in determining which target vessel will be chosen for revascularization. If the history and physical examination suggest peripheral vascular disease as the primary diagnosis, then noninvasive vascular testing is the next step in determining need for revascularization and level of disease.

After a thorough history and physical examination, the diagnostic workup of patients with ischemic ulcerations, rest pain, or significant claudication involves noninvasive vascular testing. This involves calculation of ankle-brachial indices and pulsed volume recordings in addition to duplex imaging of the extremity. An ankle-brachial index (ABI) of less than 0.4 is typically seen in patients with CLI (FIG 1). Toe pressures of less than 40 mmHg suggest inadequate perfusion for wound healing. In cases of severely calcified vessels, it is important to obtain associated pulsed volume recordings and toe pressures because ABIs can be falsely elevated due to vessel incompressibility. Transcutaneous oxygen tension (TcPO2) measurement can also be used to determine the severity of ischemia and probability of wound healing.

Once the history, physical examination, and noninvasive testing are complete, the surgeon must determine the next step in imaging, which may be both diagnostic and therapeutic. The patient’s functional status, cardiac risk profile, and other comorbidities (ambulatory status, etc.) will all play an important role in determining whether any revascularization attempt is even feasible. If femoral pulses are not palpable on physical examination and noninvasive testing is also suggestive of inflow disease, computed tomography arteriography (CTA) may be instrumental in evaluating the extent of aortoiliac disease, taking into account renal function and risk of contrast-induced nephrotoxicity. Alternatively, aortography obtained from contralateral femoral access or upper extremity arterial access may suffice. General management approaches to aortoiliac versus infrainguinal disease are discussed elsewhere in this book.

Once the clinical determination is made that the level of disease is infrainguinal, digital subtraction angiography is an excellent diagnostic test and provides access for therapeutic intervention as well. This chapter focuses on patients with multilevel infrainguinal disease who, presumably, have either failed endovascular revascularization, prior open bypass, or who have no endovascular options for revascularization. Therefore, the primary goal of diagnostic angiography is to assess the caliber and quality of inflow vessels and bypass targets.

The contralateral femoral artery is accessed and an aortogram with oblique pelvic views is obtained to rule out the presence of inflow disease that may need treatment prior to evaluating the infrainguinal segment. An ipsilateral oblique magnified projection will be helpful in determining if there is any significant common femoral or profunda femoris stenosis, which is especially important if these vessels are to be chosen as the source of inflow for an open bypass (FIG 2).

Deciding on which type of intervention to perform, endovascular versus open, and how aggressive to be about either approach is determined by multiple considerations as outlined earlier and elsewhere in this section. Patients requiring open bypass typically have multilevel disease. As such, it is critically important to image the runoff with the catheter placed proximal to the profunda origin, as the distal runoff will likely be filling from profunda collaterals that are communicating with geniculate collaterals. With common femoral or profunda disease, the catheter will need to be placed in the common iliac artery to evaluate internal iliac collaterals that are in communication with the profunda and more distal collaterals. Performing magnified, time-delayed digital subtraction angiography will assist in revealing which tibial vessels are patent and filling through collateral networks. It is also essential to identify the primary named crural artery that is in continuity to the foot that will perfuse the tissue affected by ischemic ulceration (FIG 3).

Using full-strength contrast, magnified projections of the foot will help delineate which pedal vessels are patent, which fill the tarsal and plantar branches, and confirm the status of the plantar arch. Occasionally, there are situations in which no suitable target (e.g., “named” artery) is identifiable and
exploration of a tibial vessel at the time of operative intervention may be required. This exercise is fraught with risk, however, especially in the setting of a desperately ischemic foot, and should rarely be undertaken without conclusive pre- or intraoperative arteriography. Duplex ultrasonography may assist in further defining quality, caliber, and patency of tibial vessels in these situations. Choosing a patent posterior tibialis or anterior tibialis artery in direct continuity with the pedal arteries is preferred over a peroneal artery as a distal target when the former is available, especially in cases of forefoot wounds; however, peroneal arteries are perfectly suitable and serviceable in this situation in the absence of other alternatives.

The decision to proceed with open perimalleolar bypass is made in the context of the patient’s overall clinical functional status, cardiopulmonary and renal comorbidities, presence of autogenous saphenous vein conduit, and options for endovascular revascularization. Preoperative autogenous conduit assessment is best performed by detailed ultrasonographic imaging along the length of the vein. Preference is always given to a single segment of greater saphenous vein (GSV) from the ipsilateral leg that is at least 2.5-3 mm in diameter, compressible, and free of thrombus throughout. Assessment of the contralateral GSV is useful in case ipsilateral vein is found to be of poor quality during operative exploration.

Inflow artery selection is usually based on length of available conduit and location of proximal disease. The common, superficial, or deep femoral or popliteal arteries may all serve as suitable inflow arteries in circumstances where minimal or insignificant occlusive disease is present proximally. This determination is best made during diagnostic angiography. The need for concomitant inflow endarterectomy should also be evaluated at this time.