The rehabilitation professional is often asked to evaluate the patient with a painful, swollen, or ulcerated limb. A thorough understanding of the pathophysiology, available diagnostic testing, and clinical evaluation help the practitioners choose the appropriate vascular diagnosis and treatment program.
Arterial Diseases
Arterial diseases include those acute and chronic disorders that result in partial or complete, functional or anatomic occlusion, or aneurysmal dilatation of the arteries. An example of functional occlusion is abnormal vascular reactivity of the arteries supplying a given tissue, such as vasospasm. Recognition of the broad differential diagnosis of lower extremity arterial disease is important to optimize management.
Peripheral arterial disease (PAD) affects more than 8 million adults in the United States alone. PAD is a disease of aging with an increase in disease prevalence from 10% in individuals age 65 years to more than 30% in octogenarians. Patients with PAD commonly present with symptoms of intermittent claudication or critical limb ischemia. In general, symptoms occur distal to the level of stenosis. If the patient is active, intermittent claudication is the typical presenting complaint. If the patient is inactive, rest pain, ulceration, dependent rubor, or gangrene may be the presenting finding ( Figure 25-1 ).
Patients with intermittent claudication have a significantly higher mortality than age-matched controls, approximately 12% per year. Of these deaths, 66% are caused by heart disease, and 10% are caused by strokes. Only one in four patients with intermittent claudication will develop critical limb ischemia. Longitudinal studies have shown that the amputation rate in this group of patients is only 1% to 7% at 5 to 10 years.
Arteriosclerosis Obliterans
The clinical presentation of acute arterial occlusion is described as “6 Ps,” pain, pallor, paresthesias, paralysis, pulselessness, and polar (cold). Some or all of these findings may be present. The limb with acute arterial occlusion is at risk if blood flow is not restored quickly.
Historically, it has been thought that 4 to 6 hours (following the onset of symptoms) is the maximal length of tolerable ischemia. However, patients with previous chronic limb ischemia tend to tolerate longer periods of acute ischemia. The physiologic state of the limb, determined mainly by a balance between metabolic supply and demand, rather than the elapsed time from the onset of occlusion, is actually the best predictor of limb salvage.
Intermittent claudication indicates an inadequate supply of arterial blood to contracting muscles. It occurs primarily in chronic arterial occlusive disease or severe arteriospastic disease. Intermittent claudication is brought on by walking and is relieved promptly by rest without change of position of the affected limb. Patients describe claudication as leg numbness, weakness, buckling, aching, cramping, or pain. It may change in character as the underlying lesions progress. Claudication occurs at a predictable distance or time. When the workload is increased (rapid pace, walking up hills, or walking over rough terrain), the time to claudication decreases. Claudication may worsen over a period of inactivity (when the patient is hospitalized) but usually returns to baseline with reconditioning. When claudication abruptly increases, one must consider thrombosis in situ or an embolic event. Claudication at the arch of the foot suggests occlusion at or above the ankle; claudication at the calf suggests occlusion at or above this region. Claudication is less frequent above the knee (probably because of the rich collateral circulation in the thigh); however, occlusion of the iliac arteries or aorta may cause thigh, lumbar region, and buttock claudication.
Although many other disorders can cause symptoms of lower extremity arterial insufficiency (thromboangiitis obliterans, arterial thromboemboli), these conditions account for only a small percentage of lower extremity arterial disease.
Vasculitic Syndrome
Vasculitis or angiitis is an inflammatory disease of blood vessels. It often causes damage to the vessel wall, stenosis, or occlusion of the vessel lumen by thrombosis, and progressive intimal proliferation. Vasculitic symptoms reflect systemic inflammation and the ischemic consequences of vascular occlusion. The distribution of the vascular lesions and the size of the blood vessels involved vary considerably in different vasculitic syndromes and in different patients with the same syndrome. Vasculitis can be transient, chronic, self-limited, or progressive. It can be the primary abnormality or secondary to another systemic process. Histopathologic classification does not distinguish local from systemic illness or secondary from primary insult.
Rheumatoid Vasculitis
Rheumatoid vasculitis manifests almost exclusively in patients with rheumatoid autoantibodies and often occurs in the context of other extraarticular manifestations. The vasculitis is mediated by the deposition of circulating immune complexes on the blood vessel wall with activation of complement. Proliferation of the vascular intima and media causes an obliterative enteropathy. Leukocytoclastic or small vessel vasculitis produces palpable purpura or cutaneous ulceration. The presence of HLA-C3 (human leukocyte antigen-C3) and smoking are independent predictors of vasculitis in patients with rheumatoid arthritis. Smoking, rheumatoid factor, and antinuclear antibodies are all associated with severe extraarticular disease manifestations.
Cryoglobulinemia
Cryoglobulins are immunoglobulins that reversibly precipitate at reduced temperatures. Type I consists of monoclonal immunoglobulin, generally IgM or IgG. Type II cryoglobulins are a mixture of monoclonal IgM and polyclonal IgG. Type III cryoglobulins are a mixture of polyclonal IgM and IgG. Cryoglobulinemia is associated with many illnesses, which can be broadly grouped into infections (hepatitis C), autoimmune disorders, and malignancy. More than 90% of cases of cryoglobulinemia have a known underlying cause; treatment is focused on the cause of the disorder rather than merely symptomatic relief.
Polyarteritis
Polyarteritis occurs by itself (polyarteritis nodosa [PAN]) or in association with another disease (secondary polyarteritis). PAN is an acute necrotizing vasculitis that affects primarily medium-sized and small arteries. It is a systemic disorder that may involve the kidneys, joints, skin, nerves, and various other tissues. The prognosis of PAN is heavily dependent on the severity and organ distribution at the time of diagnosis. PAN has a tendency to involve medium-sized muscular arteries. It spares the aorta and its major branches as well as capillaries and small arterioles that lack muscular coats. PAN also spares the venous system. Vasculitis of medium-sized arteries usually produces one of the following: livedo reticularis, nodules, ulcerations, and digital ischemia. For cases of idiopathic PAN, corticosteroids and cytotoxic agents remain the cornerstone of treatment.
Other Vasculitides
A wide variety of other vasculitides may affect small and medium-sized vessels. These include allergic angiitis (Churg-Strauss syndrome), Henoch-Schönlein purpura, various forms of hypersensitivity vasculitis, and numerous nonspecific necrotizing and nonnecrotizing vasculitides.
Thromboangiitis Obliterans (Buerger Disease)
Thromboangiitis obliterans (TAO) or Buerger disease is a nonatherosclerotic segmental vasculitis that affects small and medium-sized arteries and veins of the extremities and is strongly associated with tobacco exposure. The immunopathogenesis of TAO remains largely unknown. The first manifestation of Buerger’s disease may be superficial phlebitis. TAO occurs predominantly in young adult male smokers. Few, if any, cases occur in the absence of tobacco use. If smoking is discontinued, the process is frequently arrested.
Raynaud Syndrome
Raynaud syndrome is characterized by episodic attacks of vasospasm in response to cold or emotional stress. The fingers and hands are most often affected. In certain patients, the toes and feet may be involved. Classic episodes of vasospasm cause an intense pallor of the distal extremity followed in sequence by cyanosis and rubor on rewarming. Most patients do not experience the complete triple color response. Typically, only pallor or cyanosis is noted during attacks. Generally, the attacks are over within 30 to 60 minutes and these episodes are usually bilateral. Attacks may occur infrequently, for example, some may only have symptoms during the winter, whereas other patients may have a significant impairment/disability with multiple daily episodes. Digital ulcerations are rare but may occur. Females are affected more commonly than males.
Raynaud disease refers to a primary vasospastic disorder where there is no identifiable underlying cause. Raynaud phenomenon refers to vasospasm, secondary to another underlying condition or disease. Predisposing factors include atherosclerosis, arteritis, cancer, collagen vascular disease, thoracic outlet syndrome, embolic occlusion, occupational disease, and certain medications. Secondary Raynaud phenomenon is occasionally unilateral and may produce skin breakdown.
Vibration Syndrome
Vibratory tools, such as chainsaws, grinders, and jack hammers, can induce hand dysesthesias and Raynaud phenomenon when used for several years. Symptoms initially occur during use of the instrument. Subsequently, dysesthesias and cold sensitivity persist when the vibratory tool is not being used. During exposure to vibration, there is a reduction in finger blood flow in both vibrated and nonvibrated fingers. The acute vascular responses during and after exposure to vibration may not be separate independent effects of vibration frequency, magnitude, and duration; there may be complex interactions between the effects of these variables.
Hypothenar Hammer Syndrome
Occlusive disease in the hands can result from trauma to the hypothenar area caused by using the palm of the hand as a hammer in an activity that involves pushing, pounding, or twisting. This results in intimal injury to the ulnar artery as it crosses the hamate bone. Such injuries of the ulnar artery may lead to severe vascular insufficiency in the hand with thrombosis and distal embolization of the digital arteries.
External Iliac Syndrome in Cyclists
Exercise-induced external iliac artery endofibrosis is rare and has been described primarily in endurance male cyclists. Clinically, it presents as claudication during maximal exercise with quick resolution after exercise. Most patients have fibrotic changes within the external iliac artery. Vasospasm may be more important than wall thickening for the reduction of blood flow during extreme exercise in affected athletes.
Arterial Evaluation
Vascular diagnostic testing is typically performed to confirm a clinical diagnosis and document the severity of disease.
Noninvasive Arterial Studies
Vascular diagnostic laboratories can use segmental pressures, Doppler waveform analysis, pulse volume recordings, or Ankle-Brachial Index (ABI) with duplex ultrasonography (or some combination of these methods) to document the presence and location of PAD.
Ankle-Brachial Index
The ABI provides objective data about arterial perfusion of the lower limbs. Pressures are obtained with a blood pressure cuff placed around the patient’s lower calves or ankles. A handheld Doppler detects systolic blood pressure in the dorsalis pedis and the posterior tibial arteries. The brachial (arm) pressure is also obtained. In a healthy individual, because of peripheral amplification of the pulse pressure, the ankle pressure should be higher than the brachial arterial systolic pressure. A normal ankle to arm systolic blood pressure ratio is 1.0 to 1.4. Values greater than 1.4 indicate noncompressible arteries. ABI values of 0.91 to 0.99 are considered “borderline”. ABI values are considered mildly diminished when they are less than or equal to 0.90 and more than or equal to 0.80, moderately diminished between 0.50 and 0.80, and severely decreased when less than 0.50. An ABI identifies individuals who are at risk for developing rest pain, ischemic ulcerations, or gangrene, and it is a marker of generalized atherosclerosis. The risk of death, usually from a cardiovascular event, increases dramatically as the ABI decreases. The 5-year mortality rate in patients with an ABI less than 0.85 is 10%. When the ABI is less than 0.40, the 5-year mortality rate approaches 50%.
The ABI is known to be unreliable in patients with vascular stiffness and fails to detect the early phase of atherosclerotic development. The toe vessels are less susceptible to vessel stiffness, which makes the toe-brachial index (TBI) useful. The incidence of noncompressible (artifactually high), calcified conduit arteries is highest in patients with diabetes, patients with chronic renal failure, and elderly patients. Despite high recorded systolic pressure, these patients may have severe disease. The TBI should be used to establish the lower extremity PAD diagnosis in patients in whom lower extremity PAD is clinically suspected but in whom the ABI test is not reliable as a result of noncompressible vessels (usually patients with long-standing diabetes or advanced age). Other diagnostic tests (arterial duplex studies, segmental pressure measurement, Doppler waveform analysis, pulse volume recording, transcutaneous oximetry [TcPO 2 ], or photoplethysmography) may also be performed to rule out significant arterial occlusive disease.
Segmental Pressure Measurements
Segmental pressure is the arterial closing and opening pressure at a specific anatomic location. Systolic blood pressure obtained in this manner can be indexed relative to the brachial artery pressure in a manner analogous to the ABI. Segmental pressure analysis is often used to determine the location of arterial stenosis. Arterial pressure can be measured with blood pressure cuffs placed at various levels (upper thigh, lower thigh, upper calf, and lower calf above the ankle) sequentially along the limb. The presence of a significant systolic pressure gradient (greater than 10 to 15 mm Hg) between the brachial artery pressure and the upper thigh systolic pressure usually signifies the presence of aortoiliac obstruction. A pressure gradient located between the upper and lower thigh cuffs signifies obstruction in the superficial femoral artery. A gradient between the lower thigh and upper calf cuffs indicates distal superficial femoral or popliteal artery obstruction. A gradient between the upper and lower calf cuffs identifies infrapopliteal disease. Gradients of 10 to 15 mm Hg between adjacent sites may represent physiologically important obstruction.
Continuous Wave Doppler (See )
A normal continuous wave Doppler is triphasic, with a rapid upstroke or forward flow, a downstroke to below baseline as flow reverses, and finally a short period of forward flow is seen again. When stenosis is present, and as it increases, the reversal of flow is lost and the upstroke may be delayed. With greater stenosis, the upstroke becomes smaller, further delayed, sinusoidal, and eventually absent. A change from triphasic to monophasic waveforms provides reasonable, accurate information about the location and extent of specific lower extremity lesions. Doppler waveform analyses are reliable even in highly calcified vessels that are not amenable to pressure determinations ( Table 25-1 ).
| Right | Left | |
|---|---|---|
| Common femoral | Biphasic | Biphasic |
| Superficial femoral | Biphasic | Biphasic |
| Popliteal | Reduced biphasic | Biphasic |
| Posterior tibial | Monophasic | Monophasic |
| Dorsalis pedis | Monophasic | Monophasic |
Transcutaneous Oximetry
TcPO 2 determinations provide a very sensitive means to assess skin perfusion and the potential for cutaneous healing at a specific site. TcPO 2 values less than 20 to 30 mm Hg suggest inadequate perfusion for healing. A decrease in the TcPO 2 value of 10 mm Hg with leg elevation also suggests tenuous perfusion ( Table 25-2 ).
| Electrode Site | Supine | Elevated | Dependent |
|---|---|---|---|
| Chest (reference) | 58 | 66 | 65 |
| R foot | 58 | 58 | 64 |
| L above knee | 60 | 59 | 64 |
| L below knee | 38 | 35 | 44 |
| L foot proximal | 2 | 1 | 7 |
| L foot distal | 3 | 1 | 3 |
Photoplethysmography
Photoplethysmography is a noninvasive optical technique used to measure changes in the cutaneous microcirculation by detecting the reflection of infrared light. The amount of blood under the source beam affects the absorption of light.
Duplex Scanning
Duplex scanning with B-mode imaging combined with directional Doppler can visualize and assess arterial aneurysms and detect flow velocity changes at sites of localized stenosis or occlusion. Duplex scanning is particularly helpful in assessing proximal iliofemoral stenosis that may be amenable to angioplasty, providing follow-up data to assess continued patency of both venous and prosthetic arterial grafts, and evaluating the patency of previous angioplasty sites or intravascular stents.
Imaging Techniques
Advances in technology are enabling computed tomography angiography (CTA) and magnetic resonance angiography (MRA) to replace conventional angiography as a means of identifying arterial stenoses and occlusions.
Computed Tomography Angiography
CTA has become a standard noninvasive imaging modality for vascular anatomy and pathology ( Figure 25-2 ). With continued improvement in spatial resolution, CTA is now a mainstay for preoperative imaging of abdominal aortic aneurysms. It provides accurate information not only of the size of an aneurysm but also the exact location and critical measurements needed for repair.
Magnetic Resonance Angiography
MRA can be used to determine the morphology of blood vessels, assess blood flow velocity, evaluate the lumen for the presence of thrombosis, and evaluate for the presence of hemorrhage, infection, or the status of the end organ. Unlike ultrasound, MRA is not compromised by overlying bone, bowel gas, or calcification. MRA is relatively expensive and its use is limited in situations in which metallic instrumentation may be required. MRA is the optimum imaging alternative in patients who are pregnant and patients with severe iodinated contrast allergy. Reports that gadolinium may play a role in inducing nephrogenic systemic fibrosis (NSF) are a concern. Although rare, NSF, can be catastrophic. Caution is recommended in patients with reduced glomerular filtration rate (GFR) (definitely a GFR less than 30, possibly less than 60).
Contrast Arteriography
Contrast angiography has been the traditional “gold standard” for lower extremity arterial evaluation. Angiography remains the definitive approach for perioperative evaluation in patients requiring revascularization. Preprocedure arteriography is an essential part of endovascular procedures ( Figure 25-3 ).
Management
The goals of management in patients with PAD should be to reduce cardiovascular risk and alleviate symptoms. Medical therapies can effectively modify both the natural history of atherosclerotic lower extremity arterial occlusive disease and significantly reduce the morbidity of this disorder.
On average, an age-matched control group has an all-cause mortality rate of 1.6% per year. This rate increases to 4.8% per year for patients with PAD. Cardiovascular mortality rates are similarly affected with an overall event rate of 0.5% per year in controls and 2.5% per year in patients with PAD. The presence of PAD is an independent risk factor for mortality even when other known risk factors are controlled. Treatment needs to focus on both the effects of atherosclerosis in the peripheral circulation and the systemic nature of the disease. Appropriate therapy should be instituted to decrease the risk for both peripheral progression and cardiovascular mortality. The increased cardiac event rate in patients with PAD underscores the importance of intensive medical management to reduce the risk for cardiovascular morbidity and mortality.
Risk Factor Management
A transition in the pattern of atherosclerotic risk factors in the United States and worldwide is being witnessed. Certain traditional atherosclerotic risk factors are on the wane (as a result of decreased rates of smoking, antihypertensive medications, statins). The astounding increase in obesity in the U.S. population has led to a significant increase in the prevalence of the components of the clustered risk factors often referred to as the metabolic syndrome. The metabolic syndrome is characterized by a constellation of interrelated pathologic conditions of a metabolic or hemodynamic nature (abdominal obesity, atherosclerosis, impaired glucose control, or hypertension) that appear to directly promote the development of cardiovascular disease.
All patients presenting for treatment of PAD should have their risk factors rigorously assessed. Patients with known PAD should be treated aggressively with a combination of an HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitor (statin), an angiotensin-converting enzyme (ACE) inhibitor, an antiplatelet agent, and a beta-blocker (if there is a history of coronary disease). Blood pressure and glucose control is imperative and aggressive smoking cessation counseling is recommended for every medical interaction.
Diabetes is a strong independent predictor for stroke, myocardial infarction (MI), and PAD. The need for amputation in patients with diabetes for lower extremity arterial occlusive disease is 10 times that for patients who do not have diabetes. In patients with diabetes, for every 1% increase in hemoglobin A1c, there is a corresponding 26% risk of PAD.
Cigarette smoking has been identified as an independent predictor of vascular disease and the reason why vascular procedures and interventions fail. More than 80% of patients with PAD are current or former smokers.
Patients with PAD consistently have higher levels of homocysteine when compared with controls. The data suggest that hyperhomocysteinemia may either be a marker of PAD or etiologically implicated in the development of PAD. Elevated homocysteine levels can be lowered by folic acid and other vitamin supplementation. Randomized trials that have used vitamin treatments to lower homocysteine levels have not documented improvement in cardiovascular outcomes.
Lipid Management
Effective lipid management should be considered a mandatory component of the medical therapy of patients with objective evidence of atherosclerotic peripheral arterial occlusive disease. Statins have favorable effects on multiple interrelated aspects of vascular biology important in atherosclerosis. In particular, they have beneficial effects on inflammation, plaque stabilization, endothelial function, and thrombosis.
Lipid-lowering therapy is effective in reducing the cardiovascular mortality and morbidity associated with PAD and likely improves the most common symptoms of PAD, intermittent claudication. The goal for hyperlipidemia management is to maintain a low-density lipoprotein level of less than 100 mg/dL in the general population and less than 70 mg/dL in patients with atherosclerotic disease.
Health care providers should increase statin therapy in a graduated manner to adequately determine the patient’s response and tolerance. Because statins are cleared hepatically, it is recommended that liver enzymes be tested before initiating the medication, 12 weeks following initiation of therapy, upon any elevation of the medication dose, and every 6 months. Other side effects of HGM-CoA reductase inhibitors include myopathy and rhabdomyolysis with acute renal failure secondary to myoglobinuria. Statins should be prescribed with caution in patients with predisposing factors for myopathy and they should be discontinued if markedly elevated creatine kinase levels or myopathy is diagnosed or suspected.
Angiotensin-Converting Enzyme Inhibitors
The Heart Outcomes Prevention Evaluation (HOPE) study showed that ACE inhibitors reduce cardiovascular events by 25% in patients with symptomatic PAD. In addition, treatment with ACE inhibitors improves walking ability in patients with intermittent claudication. This was not associated with significant improvement in the ABI. Patients with intermittent claudication may benefit from treatment with a high tissue affinity ACE inhibitor for a period of 6 months. The overall treatment effect achieved by ACE inhibitors is more than that of other therapeutic agents for intermittent claudication, such as cilostazol and pentoxifylline, but less than that of a supervised exercise program.
Antiplatelet Therapy
Antiplatelet therapy may decrease the rate of atherosclerotic disease progression, decrease the incidence of thrombotic events in the limbs, and decrease the rate of adverse coronary and cerebrovascular ischemic events. Aspirin in doses of 75 to 325 mg is recommended as safe and effective platelet therapy to reduce the risk of MI, stroke, or vascular death in individuals with atherosclerotic lower extremity PAD.
Antiplatelet therapy is indicated to reduce the risk of MI, stroke, and vascular death in individuals with symptomatic atherosclerotic lower extremity PAD including those with intermittent claudication or critical limb ischemia, previous lower extremity revascularization (endovascular or surgical), previous amputation or lower extremity ischemia. Long-term administration of clopidogrel in patients with atherosclerotic vascular disease has been reported to be more efficient than aspirin in reducing the combined risk for ischemic stroke, MI, or vascular death.
Agents for Intermittent Claudication
Cilostazol and pentoxifylline have been shown to modestly improve walking distances in patients with intermittent claudication. Cilostazol has significant antiplatelet, vasodilatory, and vascular antiproliferative properties. It is contraindicated in patients with either systolic or diastolic heart failure. Cilostazol (100 mg orally two times per day) is indicated as an effective therapy to improve symptoms and increase walking distances in patients with lower extremity PAD and intermittent claudication (in the absence of heart failure). Pentoxifylline has diminished estimated efficacy when compared with cilostazol. Minimal efficacy and caffeine-like side effects limit use of this medication.
Rehabilitation
Patients with PAD should be instructed to wear protective footwear at all times (never walk barefoot or in socks) and monitor their extremities carefully for redness or skin breakdown. Extremes of temperature should be avoided. The feet should be washed carefully with mild soap and warm water. Drying is best performed by blotting or patting with a soft clean towel (rubbing should be avoided because it may injure the skin). The skin between the toes should be carefully dried to avoid maceration. Emollients without preservatives or perfume should be used (avoid between the toes) to prevent cracking of the skin. Proper footwear, which does not produce areas of point pressure, should be used. Whenever new shoes are purchased, the patient should gradually (over a period of a week) wear-in shoes to make sure that there are no areas of point pressure with the new footwear. Warm outer footwear should be used in the winter to protect against thermal injury. Decreased activity secondary to symptomatic lower extremity arterial occlusive disease can result in deconditioning, which further contributes to disease impairment. Deconditioning may also be “iatrogenic” as a result of a prolonged period of limited mobility to avoid trauma to ischemic wounds.
Regular lower extremity exercise in the form of a structured or a supervised walking program is critical for patients with PAD. Ambulation can help to develop collateral blood flow and in time may lead to resolution or improvement of intermittent claudication. A minimum of 30 minutes of moderate activity at least three times per week is beneficial. Regular training has been shown to improve oxygen extraction from blood, muscle enzyme activity, and hemorheology. Regular exercise training produces a reduction in the inflammatory markers associated with endothelial damage. Evidence suggests that patients following an exercise regimen improve both their claudication distance and cardiovascular risk profile. Exercise improves maximal walking ability by an average of 150%. Remarkably, increased walking capacity increased further 6 months after supervised exercise training cessation, suggesting an ongoing benefit of the intervention.
In summary, current recommendations are that all patients with PAD should receive antiplatelet therapy, stop smoking, exercise, and be screened and treated for hyperlipidemia, hypertension, diabetes, and hypercoagulability in accordance with national guidelines and community standards.
Gene Therapy
Molecular therapies to induce angiogenesis are appealing in the claudicant population because ischemia is subacute, time is available for angiogenesis to occur, and collateral development is associated with increased walking distance.
Revascularization
Ischemic rest pain and tissue necrosis, including ischemic ulcerations or gangrene, are well-accepted indicators of advanced ischemia and threatened limb loss. Without treatment, most limbs with these symptoms experience disease progression and require major amputation. Previously, surgical revascularization was considered for patients with rest pain, impending tissue loss, or significant limitations of lifestyle who failed medical treatment. Endovascular intervention coupled with aggressive proactive medical management is replacing this conventional paradigm. The multicenter BASIL (Bypass Versus Angioplasty in Severe Ischaemia of the Leg) trial found no significant difference between surgical and endovascular revascularization in amputation-free survival or overall survival. A bypass surgery first approach, was associated with a significant increase in overall survival of 7.3 months and a trend toward improved amputation-free survival of 5.9 months for those patients who survived for at least 2 years after randomization. If early and long-term patency is to be achieved, it is important that the site for vascular reconstruction has a relatively unobstructed inflow and a patent distal runoff.
Attempts at revascularization should be avoided in the presence of life-threatening sepsis, chronic flexion contracture, paralysis, and in patients with markedly reduced life expectancy. Revascularization should be delayed in most individuals with a significant acute comorbidity (recent MI), unless the limb is imminently threatened and high perioperative morbidity is acceptable.
Intermittent Pneumatic Compression
Intermittent pneumatic foot and calf compression has been shown to improve walking distance comparable with supervised exercise. External compression briefly raises the tissue pressure, emptying the underlying veins and transiently reducing the venous pressure without occluding arterial blood flow. The proposed mechanism to explain the increased flow is analogous to the pumping action of the calf muscle during walking. The transient inflation (quick impulse) imitates the effects of normal gait by generating a vigorous hemodynamic impulse throughout the veins each time the lower extremity is compressed. An increase in the hydrostatic pressure gradient is thought to be a major mechanism for the enhancement of arterial leg inflow. In addition, the altered flow and shear forces generated by the inflation of the pneumatic cuff may mediate the release of endothelial and humeral factors having local and systemic effects. A direct reduction in the peripheral resistance is also postulated via release of nitrous oxide secondary to shear stress across the vessel wall.
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