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Surgery for Peripheral Vascular Diseases
Peripheral vascular disease (PVD) encompasses the pathologies of both the arterial and the venous circulations. Advanced disease of either system can be debilitating and disabling. The clinical presentation and therapeutic choices for patients with PVD vary widely, depending on the vascular distribution involved and the severity of the disease. This chapter focuses on the common problems that require surgical intervention. Although PVD includes venous pathologies, these are less likely to result in serious morbidity and mortality; thus, this chapter focuses on arterial pathologies.
Atherosclerosis involving the infrarenal aorta and the iliac and infrainguinal arteries is the most common cause of arterial insufficiency of the lower extremities, and is typically multifactorial ( Fig. 60.1 ). PVD can be subdivided into categories based on location: inflow (infrarenal aorta, iliac), outflow (femoral, popliteal), and runoff (tibial, peroneal) vessels. These categories help define the risks and benefits of intervention and treatment options.
Multiterritorial Atherosclerotic Disease.
A detailed history and physical examination can identify the anatomical distribution of vascular pathology. Invasive and noninvasive imaging augments clinical findings and aids decision-making. Several open surgical and endovascular interventions, discussed later, provide significant benefits to patients with PVD.
Other important areas of the vascular system affected by occlusive disease include the carotid arteries and the visceral vessels. Surgical and other interventional approaches to treating atherosclerosis of the carotid and visceral arteries are also discussed in this chapter.
Etiology and Pathogenesis
Embolic disease, thrombosis, or trauma may also cause arterial occlusion ( Fig. 60.1 ). However, the most common cause of lower extremity arterial occlusion is atherosclerosis. The etiology and pathogenesis of atherosclerosis are discussed in Chapter 14 .
Lower Extremity Atherosclerosis
Clinical Presentation
With the tendency for development of collateral circulation in the lower extremities, patients with lower extremity atherosclerosis may be asymptomatic despite significant arterial insufficiency. In addition, many of these patients have comorbid conditions (e.g., cardiac disease) that restrict their activity and preclude them from having symptoms until advanced disease is present. For individuals who can ambulate, claudication—muscle “cramping” or discomfort after walking a specific distance, with relief of the pain upon resting—is often the chief complaint. This pain is reproducible and consistent with pathophysiology that limits muscular blood supply during exertion, causing lactic acid accumulation.
Claudication of the proximal muscles of the leg, buttock, or hip usually indicates inflow disease, commonly referred to as aortoiliac occlusive disease. Leriche syndrome may develop in some patients with severe disease. Patients with Leriche syndrome exhibit the characteristic triad of sexual dysfunction, buttock claudication, and absent femoral pulses. The association between aortoiliac occlusive disease and proximal muscle complaints is variable, and some patients may complain of calf claudication despite the presence of significant occlusion more proximally. Atheromatous embolization from aortoiliac lesions can lodge in the distal vessels, creating localized ischemia of the digits with resulting cyanosis. Because this is an embolic process, patients with the “blue toe syndrome” often have palpable distal pulses, and may, depending on the degree of involvement, experience resolution of their clinical symptoms with time or medical therapy, or both.
Patients with atherosclerosis involving the femoropopliteal (outflow) vessels or with multilevel distribution of the disease can present with complaints ranging from claudication, the mildest presentation, to the most severe symptoms of pain at rest and tissue loss. Patients with mild complaints often never seek medical attention because they attribute symptoms to arthritis or old age. However, as the disease worsens and pain at rest ensues, a persistent burning or aching sensation over the dorsum of the foot often prompts individuals to seek help. Although usually of little benefit, patients may keep the ischemic limb in a dependent position, in an attempt to have gravity aid blood flow. Other signs characteristic of severe ischemia include dependent rubor, muscle atrophy, skin changes, lower extremity alopecia, ulcerations, and lack of palpable distal pulses. Although these signs and symptoms of severe ischemia occur in nondiabetic individuals, with the increasing prevalence of diabetes, a higher proportion of patients who present with femoropopliteal disease are diabetic ( Fig. 60.2 ).
Isolated lesions at a single level rarely result in lower extremity pain at rest and nonhealing ulcerations. Patients who present with concomitant lower extremity infections and persistent ulcerations despite medical therapy should be thoroughly evaluated for significant arterial insufficiency. In many instances, these patients require lower extremity revascularization to salvage the limb.
Assessment by a noninvasive vascular laboratory can provide extensive critical information on the location and hemodynamic significance of lower extremity arterial obstruction. The ankle-brachial index provides an overall estimate of limb perfusion pressure, whereas analysis of velocity waveforms in the arteries at the groin, knee, and ankle helps to classify the obstruction location as inflow (aortoiliac), outflow (superficial femoral artery), or runoff (tibioperoneal vessels), as well as its hemodynamic impact of extremity perfusion. Photoplethysmography waveforms in the toes and toe pressures help diagnose even more distal disease. Transcutaneous oxygen measurements aid in the quantification of tissue ischemia, and may be used to analyze ischemia and predict wound healing.
Management and Therapy
Optimum Treatment
All patients should undergo aggressive evaluation and treatment for hyperlipidemia and other genetic disorders associated with progressive atherosclerosis. Reducing risk factors, most importantly, cessation of smoking, will slow disease progression. In addition, patients should integrate diet modification, exercise regimens that encourage collateral circulation, and prevention of lower extremity trauma and infection into their lifestyles. Drug therapy with an antiplatelet drug or cilostazol can provide symptomatic improvement in some patients.
Ischemic pain at rest, ulceration, and gangrene of the digits are indications for arterial reconstruction if anatomically feasible. Decisions about operations for lifestyle-impairing claudication must be based on patient comorbidities and the anatomical distribution of the disease. The decision as to which operative approach is best for an individual (and whether a surgical approach is indicated) should be based on the natural history of the disease, the overall condition of the patient, and the risks and benefits specific to the procedure and individual ( Fig. 60.3 ). The goal of the procedure (e.g., limb salvage, wound healing, relief of pain at rest, exercise tolerance) must be determined before surgical intervention. The Best Surgical Therapy in Patients with Critical Limb Ischemia (BEST-CLI) trial is an on-going multicenter, open label, randomized trial that is comparing best endovascular therapy with best open surgical treatment in patients eligible for both. The trial hopes to establish primary endpoints that include amputation rates, repeat interventions, and mortality with a full evaluation of cost-effectiveness and quality-of-life outcomes between each modality. Endovascular procedures such as balloon angioplasty or stenting increase the options for therapy and are discussed in detail in Chapter 59 .
If inflow disease is present, it should be addressed first, because surgical correction can relieve symptoms and obviate the need for the less successful infrainguinal bypass surgery. Patients with symptomatic inflow disease can be treated with endovascular therapies, in-line arterial reconstructions, or extra-anatomic bypass. In making the decision about surgical therapy, consideration of both the perioperative risk of the patient and the influence of anatomy and comorbidities of the patient on graft survival is important. For instance, comorbidities may exclude one approach or another. Other issues, such as cigarette smoking, may also influence therapeutic decisions. Many vascular surgeons will not perform reconstructive surgery on patients who are still smoking, because smoking lowers bypass patency rates dramatically.
Bilateral aortoiliac disease is best treated with aortobifemoral grafting, using a prosthetic graft. The patency of this graft is approximately 80% to 90% at 5 years and approximately 70% at 10 years. Mortality risks for this procedure are <5%. The descending thoracic aorta can be used as an alternative inflow source in patients with a history of abdominal infection, previous irradiation, abdominal stomas, or multiple abdominal operations (all of which increase operative morbidity rates). The thoracobifemoral bypass achieves patency rates of 75% to 85% at 5 years, with perioperative mortality rates of <5% when experienced vascular surgeons perform the bypasses. Extra-anatomic bypasses (grafts that course through an anatomic pathway that is significantly different from the native arteries) should be performed in patients who cannot tolerate major aortic reconstructive surgery because of comorbidities. The most common extra-anatomic procedures are axillobifemoral and femorofemoral bypass grafts. Axillobifemoral reconstruction, used for aortoiliac occlusive disease, has a 5-year patency rate of 50% to 60%. For patients with unilateral iliac disease not amenable to angioplasty, femorofemoral bypass has a 5-year patency rate of 50% to 80%.
Critical ischemia or tissue loss from infrainguinal occlusive disease is best treated with arterial reconstruction. With respect to patency and resistance to infections, autologous vein grafts are superior to other conduits, especially when reconstruction below the knee is necessary. Availability, quality, and length requirements may necessitate a search for alternate sites for veins, such as the arms (basilic, cephalic) or the posterior leg (lesser saphenous vein). If possible, an autologous graft rather than synthetic material should be used for infrainguinal bypasses. Prosthetic material in lower extremity bypass procedures is reserved mainly for patients without other conduit options. In some cases, prosthetic material may be used for reconstructions above the knee.
Comparison of the use of an autologous saphenous vein with polytetrafluoroethylene grafts in above-the-knee (femoropopliteal) and below-the-knee (distal femoropopliteal and femorodistal) bypass procedures showed equivalent 2-year patency rates in grafts to the same level, but patency rates were significantly different at 4 years for infrapopliteal bypasses but not for above-the-knee procedures. Prosthetic graft material for distal bypasses is a better option than primary amputation in patients with suboptimal autologous vein options.
An excellent summary of the diagnosis and treatment of patients with lower extremity ischemia may be found in the American College of Cardiology/American Heart Association 2011 Practice Guidelines for the management of patients with peripheral arterial disease.
Avoiding Treatment Errors
Patients often attribute calf or thigh pain to orthopedic conditions. Individuals with lower extremity pain associated with exercise should have a complete vascular evaluation.
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