Acute lower limb ischemia may be caused by distal embolization from a more proximal source or by thrombosis of an underlying atherosclerotic lesion or previously constructed bypass graft. The clinical presentation is often an emergency situation with varying degrees of limb-threatening ischemia. If a patient's ischemia is not as severe and allows more time for treatment, catheter-based thrombolytic therapy may be preferred as first line because lysis may reveal an underlying lesion that also requires treatment. If ischemia is more profound, then proceeding to emergency surgical intervention is the best, most expeditious approach.
Preoperative imaging, such as catheter-based angiography, computed tomographic angiography, and duplex ultrasound, can be helpful to localize the extent of the thrombus/embolus but is not always necessary depending on the urgency of the procedure. Because these are often emergency surgeries, rapid preparation of the patient is essential to increase the chances of limb salvage. Because patients with embolic phenomena often have a cardiac source, including acute myocardial infarction, dysrhythmia, and aneurysm, attention should be paid to close hemodynamic monitoring and maximizing cardiac function as much as possible in an emergency situation.
History of prior claudication or previous surgical bypass graft points more toward a diagnosis of thrombotic disease. An understanding of the patient's vascular disease history is critical to determining the underlying etiology. Heparin administration is extremely important as soon as a diagnosis of thromboembolic phenomena is made. Prophylactic antibiotic therapy is administered just before the operation and continued for 24 hours.
General or regional anesthesia is generally employed, but local with monitored anesthesia care is sometimes preferred in this group of patients, who may have other significant comorbidities. The feasibility of local anesthesia depends on the location of the incision and the extent of surgery. Careful attention should be given to maintaining satisfactory hemodynamic parameters.
Patients are positioned supine on the operating table. It is usually best to prep and drape the lower abdomen and contralateral groin area in case an adjuvant in-flow procedure such as a femorofemoral bypass becomes necessary. The entire affected leg should be circumferentially prepped and draped as well, with the foot preferentially placed in a sterile plastic (Lahey) bag so that it may be inspected at the end of the case (FIGURE 1). Anticoagulation with heparin is usually not interrupted; often, an extra dose is given during surgery. Then a time-out is performed.
DETAILS OF THE PROCEDURAL
A vertical groin incision is made, and the femoral vessels are dissected free from surrounding structures. Silastic vessel loops are placed around the arteries proximally and distally (FIGURE 2). If additional heparin is warranted, a dose is given a few minutes prior to occluding the vessels.