The approach to the patient with CLI, including the choice of revascularization technique, depends on the patient’s presentation and the CLI classification. For example, the patient with extensive foot ulceration and/or gangrene (Fontaine stage IV CLI) will require normal perfusion to the foot for limb salvage, with the goal of restoration of a normal foot pulse. In order to maximize the chances of successful limb salvage, targeted revascularization to the specific angiosome should always be the first choice [1].

As the majority of CLI patients have diabetes, and because diabetic vascular disease tends to be most pronounced in the tibial vessels, this will almost always require infrainguinal surgical bypass to the target vessel. Proximal bypass to the popliteal or tibio-peroneal arteries may restore foot pulses, but the characteristic pattern of occlusive disease in the diabetic patient usually requires more distal bypass grafting, often to the dorsalis pedis, distal posterior tibial, or plantar artery.

In contrast, the patient presenting with ischemic rest pain (Fontaine stage III CLI) without tissue loss may be significantly ameliorated with more proximal revascularization. This may include femoral endarterectomy with profundaplasty alone in the patient with concomitant superficial femoral artery occlusion or bypass to an isolated popliteal segment.

Active infection in the foot is commonly encountered in the complicated ischemic diabetic foot. However, it is not a contraindication to lower extremity revascularization, as long as the infectious process is controlled and located remotely from the proposed incisions. Adequate control implies absence of sepsis and resolution of cellulitis, lymphangitis, and edema, especially in areas of proposed incisions required to expose the distal artery or saphenous vein.

Essential to the success of surgical revascularization is appropriate and accurate preoperative planning. High-quality arteriography should include visualization of planned target vessels, localization and extent of disease in the proximal vessels (including aorta and iliac arteries), and, if needed, pressure measurements across suspected inflow lesions. Based on the pattern of vascular disease in the diabetic patient, with sparing of the pedal vessels, the arteriogram must include the foot vessels in both the lateral and anterior views for a complete assessment (Fig. 36.1). Although others have performed distal revascularization based on duplex ultrasound or CT angiography alone, the author’s preference is to always have a high-quality arteriography prior to any infrainguinal bypass.

Autogenous ipsilateral saphenous vein is the preferred conduit for all infrainguinal bypass grafts. High-quality conduit is central to successful bypass and has direct implications for both short-term and long-term patency results. Preoperative bilateral saphenous vein mapping with duplex ultrasound should always be performed, assessing for caliber and size, phlebitic changes, wall thickening, and accessory branching (Fig. 36.2). Saphenous vein grafts should have a minimum diameter of 2 mm, ideally 3 mm or more, as smaller veins have been shown to yield inferior short- and long-term patency [2]. If the great saphenous vein is inadequate, consideration may be given to either arm vein or prosthetic graft; if the former is chosen, duplex scanning should be performed of the upper extremities as well.

As with any major operation, appropriate medical stabilization and optimization of the patient should be performed prior to proceeding with surgical revascularization. This may involve cardiac stress testing, coronary angiography, and echocardiography. Many patients with long-standing foot ulceration may be nutritionally depleted, and preoperative assessment and intervention may prevent postoperative wound and systemic complications.

Diabetic patients also present unique challenges to the surgeon as hyperglycemia has been linked to poor perioperative outcomes. Good glycemic control around the time of surgery, employing a multidisciplinary team of endocrine and nutrition specialists, can improve chances of success and reduce infection rates. Diabetics have lower rates of limb salvage and reduced long-term survival overall; however, several institutional series and randomized trials have demonstrated that diabetes per se is not a risk factor for graft failure . Vein grafts in diabetics in fact have superior patency, which is explained by the preponderance of shorter distal-origin grafts in those patients [2].

As noted previously, many patients with CLI will present with foot ulceration or gangrene, with concomitant foot infection. Control of infection is mandatory prior to surgical revascularization, to prevent the risk of systemic sepsis, wound, and graft infection. In the patient with diabetes, classical signs of infection may not always be present in the infected foot due to the consequences of neuropathy, alterations in the foot microcirculation, and leukocyte abnormalities. Fever, chills, and leukocytosis may be absent in the majority of diabetic patients with extensive foot infections, and hyperglycemia is often the sole presenting sign [3]. Infections should be adequately drained, as diabetic patients simply cannot tolerate undrained pus or infection. Because most infections are polymicrobial, cultures should be obtained from the base or depths of the wound after debridement so that appropriate antibiotic treatment may ensue. If adequately controlled with antibiotics and surgical drainage (if necessary), the infectious process can be controlled within 5–7 days, even in patients with systemic sepsis, and the patient may subsequently be revacularized.

The term “inflow operation” refers to any procedure performed on a vessel at or proximal to the inguinal ligament, which restores normal flow into the femoral segment. These include aortobifemoral bypass, iliac-femoral bypass, common femoral endarterectomy, and profundaplasty, as well as extra-anatomic bypass es such as axillo-femoral and femoral-femoral bypass. Because they are performed on larger vessels with expected higher patency rates, prosthetic grafts are utilized for almost all inflow bypasses. With greater success and application of endovascular procedures, especially in the aortoiliac segment, these procedures are being performed with less frequency. Nevertheless, they continue to be an important component of the treatment plan for revascularization, especially after endovascular failure or infection.

Aortobifemoral bypass represents the “gold standard” of patency and durability for inflow operations, with 5-year primary patency of approximately 85 % [4]. The aorta is exposed via a midline or retroperitoneal incision, and the proximal anastomosis may be performed to the infrarenal aorta in almost all cases. Even if there is occlusive disease present, endarterectomy of the infrarenal aorta may be performed, followed by the proximal anastomosis to the endarterectomized aorta (Fig. 36.3). Each limb of the graft is tunneled anatomically to the respective groin and the distal anastomoses are performed to the common femoral arteries. The author’s preference is to extend the anastomosis onto the profunda, so as to prevent late thrombosis of the limb secondary to unrecognized stenoses at the profunda or superficial femoral artery origins. In instances of redo operations or groin infection, the anastomosis may be performed onto the profunda directly, with a lateral approach to the profunda, which avoids the femoral region altogether (Fig. 36.4).

A hybrid approach to the aortoiliac segment involving aortouniiliac angioplasty with concomitant femoral-femoral bypass is another option for patients who are poor candidates for open aortic surgery. This approach is associated with similar patency to open aortafemoral bypass in patients with focal iliac occlusive disease (<5 cm) [5].

Because of the challenges associated with percutaneous endovascular treatment of common femoral artery disease, common femoral endarterectomy and profundaplasty is utilized commonly and may be combined with concomitant iliac or superficial femoral-popliteal-tibial angioplasty. The femoral vessels are exposed, and as the occlusive process often extends proximally to the external iliac artery, the distal external iliac artery above the circumflex branches is also exposed (Fig. 36.5). Arteriotomy is made extending onto the profunda and all plaque is removed (Figs. 36.6 and 36.7), followed by patch closure with vein, prosthetic patch, or bovine pericardium (Fig. 36.8). If concomitant iliac or distal endovascular intervention is planned, a sheath may be placed directly through the patch after restoration of flow (Fig. 36.9), and a simple suture used to close the hole after the sheath is removed. In some cases, the occlusive process within the profunda may be too bulky for endarterectomy or may result in extensive thinning of the artery. In these instances, a short bypass from the common femoral to the profunda may be performed, with excellent results (Fig. 36.10).

Although axillo-femoral and femoral-femoral bypasses are associated with lower patency rates as compared to the aortobifemoral bypass, their principal advantages lie in the fact that they are markedly less invasive. By avoiding an abdominal incision and aortic cross clamping, these operations may be performed in high-risk patients with poor cardiopulmonary reserve; in some cases, the operation may be performed under local anesthesia in those patients in whom general anesthetic is contraindicated. In addition, by virtue of their extra-anatomic location, they may be utilized in instances of groin sepsis when placement of a prosthetic graft is undesirable.

Infrainguinal bypass is the most commonly performed surgical revascularization among patients with CLI. Several principles are noteworthy. Autogenous saphenous vein is the preferred conduit for all infrainguinal bypass operations, even to the above-knee popliteal artery. In addition to its superior primary patency compared to prosthetic, autogenous vein also carries less risk of graft infection, which can be devastating.

The saphenous vein graft can be prepared in several ways. The simplest is a reversed configuration, in which the vein is harvested off its bed, reversed, and then placed either subcutaneously or deep to the muscle and fascia after the proximal anastomosis is performed. Because of the inherent disadvantage of the size discrepancy between the smaller distal portion of the vein and the larger proximal artery, the non-reversed and in situ techniques may be employed, in which the valves are rendered incompetent by cutting them with an atraumatic valvulotome. The non-reversed translocated technique is identical to the reversed technique except that the valves are cut, whereas the in situ technique leaves the vein in the bed, with mobilization only of the proximal and distal portions and tributary ligation without harvesting the vein. In both of these, the larger proximal vein is utilized for the proximal anastomosis, allowing for an easier anastomosis both proximally and distally.

The type of configuration utilized—reversed, non-reversed translocated, or in situ—has no effect on patency, and multiple series have confirmed that all yield virtually identical results when performed correctly [6]. Ultimately the decision as to the type of configuration should depend on the surgeon’s experience with each technique and vein graft size. My preference is either a reversed graft when the vein is of a uniformly large caliber and for shorter bypasses or non-reversed translocated for smaller veins and for long bypasses (such as femoral-tibial). If a non-reversed configuration is used, I prefer to inspect the vein with an angioscope and cut all the valves under direct angioscopic guidance, which allows for precise valve lysis without any risk of intimal injury or retained valve, both of which can have an adverse effect on patency and outcome (Fig. 36.11) [7].