Pvd

Peripheral Vascular Disease Last Updated: October 27, 2005 Synonyms and related keywords: PVD, arteriosclerosis obliterans, circulation disorder, functional peripheral vascular disease, organic peripheral vascular diseases, atherosclerosis, emboli, thrombi, atheroma, vascular disease, cardiac emboli, coronary artery disease, myocardial infarction, MI, atrial fibrillation, transient ischemic attack, stroke, renal disease

Background: Peripheral vascular disease (PVD) is a nearly pandemic condition that has the potential to cause loss of limb, or even loss of life. PVD manifests as insufficient tissue perfusion caused by existing atherosclerosis that may be acutely compounded by either emboli or thrombi. Many people live daily with PVD; however, in settings such as acute limb ischemia, this pandemic disease can be life threatening and can require emergency intervention to minimize morbidity and mortality. Pathophysiology: PVD, also known as arteriosclerosis obliterans, is primarily the result of atherosclerosis. The atheroma consists of a core of cholesterol joined to proteins with a fibrous intravascular covering. The atherosclerotic process gradually may progress to complete occlusion of medium and large arteries. The disease typically is segmental, with significant variation from patient to patient. Vascular disease may manifest acutely when thrombi, emboli, or acute trauma compromises perfusion. Thromboses are often of an atheromatous nature and occur in the lower extremities more frequently than in the upper extremities. Multiple factors predispose patients for thrombosis. These factors include sepsis, hypotension, low cardiac output, aneurysms, aortic dissection, bypass grafts, and underlying atherosclerotic narrowing of the arterial lumen. Emboli, the most common cause of sudden ischemia, usually are of cardiac origin (80%); they also can originate from proximal atheroma, tumor, or foreign objects. Emboli tend to lodge at artery bifurcations or in areas where vessels abruptly narrow. The femoral artery bifurcation is the most common site (43%), followed by the iliac arteries (18%), the aorta (15%), and the popliteal arteries (15%). The site of occlusion, presence of collateral circulation, and nature of the occlusion (thrombus or embolus) determine the severity of the acute manifestation. Emboli tend to carry higher morbidity because the extremity has not had time to develop collateral circulation. Whether caused by embolus or thrombus, occlusion results in both proximal and distal thrombus formation due to flow stagnation. History: The primary factor for developing PVD is atherosclerosis.

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Other maladies that often coexist with PVD are coronary artery disease, myocardial infarction (MI), atrial fibrillation, transient ischemic attack, stroke, and renal disease.

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Risk factors for PVD include smoking, hyperlipidemia, diabetes mellitus, and hyperviscosity.

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Other etiologies for developing PVD may include phlebitis, injury or surgery, and autoimmune disease, including vasculitides, arthritis, or coagulopathy. o o

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PVD rarely exhibits an acute onset; it instead manifests a more chronic progression of symptoms. Patients with acute emboli causing limb ischemia may have new or chronic atrial fibrillation, valvular disease, or recent MI, whereas a history of claudication, rest pain, or ulceration suggests thrombosis of existing PVD.

Intermittent claudication may be the sole manifestation of early symptomatic PVD. The level of arterial compromise and the location of the claudication are closely related as follows: o o o

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Aortoiliac disease manifests as pain in the thigh and buttock, whereas femoral-popliteal disease manifests as pain in the calf. Symptoms are precipitated by walking a predictable distance and are relieved by rest. Collateral circulation may develop, reducing the symptoms of intermittent claudication, but failure to control precipitant factors and risk factors often causes its reemergence. Claudication also may present as the hip or leg "giving out" after a certain period of exertion and may not demonstrate the typical symptom of pain on exertion. The pain of claudication usually does not occur with sitting or standing.

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Ischemic rest pain is more worrisome; it refers to pain in the extremity due to a combination of PVD and inadequate perfusion. o Ischemic rest pain often is exacerbated by poor cardiac output. o The condition is often partially or fully relieved by placing the extremity in a dependent position, so that perfusion is enhanced by the effects of gravity.

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Leriche syndrome is a clinical syndrome described by intermittent claudication, impotence, and significantly decreased or absent femoral pulses. This syndrome indicates chronic peripheral arterial insufficiency due to narrowing of the distal aorta.

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The patient's medications may provide a clue to the existence of PVD. o Pentoxifylline is a commonly used medication specifically prescribed for PVD. o Daily aspirin commonly is used for prevention of cardiac disease (CAD), but PVD often coexists, to some degree, in patients with CAD.

Physical: A systematic examination of the peripheral vasculature is critical for proper evaluation. •

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Peripheral signs of PVD are the classic "5 P's": o Pulselessness o Paralysis o Paraesthesia o Pain o Pallor Paralysis and paraesthesia suggest limb-threatening ischemia and mandate prompt evaluation and consultation.

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Assess the heart for murmurs or other abnormalities. Investigate all peripheral vessels, including carotid, abdominal, and femoral, for pulse quality and bruit. Note that the dorsalis pedis artery is absent in 5-8% of normal subjects, but the posterior tibial artery usually is present. Both pulses are absent in only about 0.5% of patients. Exercise may cause the obliteration of these pulses.

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The Allen test may provide information on the radial and ulnar arteries. The skin may have an atrophic, shiny appearance and may demonstrate trophic changes, including alopecia; dry, scaly, or erythematous skin; chronic pigmentation changes; and brittle nails.

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Advanced PVD may manifest as mottling in a “fishnet pattern” (livedo reticularis), pulselessness, numbness, or cyanosis. Paralysis may follow, and the extremity may become cold; gangrene eventually may be seen. Poorly healing injuries or ulcers in the extremities help provide evidence of preexisting PVD. The ankle-brachial index (ABI) can be measured at bedside. Using Doppler ultrasonography, the pressure at the brachial artery and at the posterior tibialis artery is measured. The ankle systolic pressure is divided by the brachial pressure, both measured in the supine position. Normally, the ratio is more than 1. In severe disease, it is less than 0.5.

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A semiquantitative assessment of the degree of pallor also may be helpful. While supine, the degree of pallor is assessed.

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If pallor manifests when the extremity is level, the pallor is classified as level 4.

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If not, the extremity is raised 60°. If pallor occurs within 30 seconds, it is a level 3; in less than 60 seconds, level 2; in 60 seconds, level 1; and no pallor within 60 seconds, level 0.

Lab Studies: •

Routine blood tests generally are indicated in the evaluation of patients with suspected serious compromise of vascular flow to an extremity. CBC, BUN, creatinine, and electrolytes studies help evaluate factors that might lead to worsening of peripheral perfusion. Risk factors for the development of vascular disease (lipid profile, coagulation tests) also can be evaluated, although not necessarily in the ED setting.

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An ECG may be obtained to look for evidence of dysrhythmia, chamber enlargement, or MI.

Imaging Studies: •

Plain films are of little use in the setting of PVD. Doppler ultrasound studies are useful as primary noninvasive studies to determine flow status. Upper extremities are evaluated over the axillary, brachial, ulnar, and radial arteries. Lower extremities are evaluated over the femoral, popliteal, dorsalis pedis, and posterior tibial arteries. Note the presence of Doppler signal and the quality of the signal (ie, monophasic, biphasic, triphasic). The presence of distal flow does not exclude emboli or thrombi because collateral circulation may provide these findings.

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Magnetic resonance imaging (MRI) may be of some clinical benefit due to its high visual detail. Plaques are imaged easily, as is the difference between vessel wall and flowing blood. MRI also has the benefits of angiography to provide even higher detail, and can replace traditional arteriography. The utility of MRI is limited in the emergency setting, often due to location of the device and the technical skill required to interpret the highly detailed images.

Other Tests: •

The ankle-brachial index (ABI) is a useful test to compare pressures in the lower extremity to the upper extremity. Blood pressure normally is slightly higher in the lower extremities than in the upper extremities. Comparison to the contralateral side may suggest the degree of ischemia.

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The ABI is obtained by applying blood pressure cuffs to the calf and the upper arm. The blood pressure is measured, and the systolic ankle pressure is divided by the systolic brachial pressure. Normal ABI is more than 1; a value less than 0.95 is considered abnormal. This test can be influenced by arteriosclerosis and small vessel disease (eg, diabetes), reducing reliability.

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Transcutaneous oximetry affords assessment of impaired flow secondary to both microvascular and macrovascular disruption. Its use is increasing, especially in the realm of wound care and patients with diabetes. Transcutaneous oximetry has not been studied extensively in emergent occlusion.

Procedures: •

The criterion standard for intraluminal obstruction always has been arteriography, although this is both potentially risky and often unobtainable in the emergency setting. The delay associated with obtaining arteriography in the setting of obvious limb ischemia can delay definitive treatment to deleterious effect. If time allows, arteriography can prove useful in discriminating thrombotic disease from embolic disease.

Prehospital Care: Prehospital care for PVD involves the basics: control ABCs, obtain IV access, and administer oxygen. Generally, do not elevate the extremity. Note and record distal pulses and skin condition. Perform and document a neurological examination of the affected extremities. Emergency Department Care: Attention to the ABCs, IV access, and obtaining baseline laboratories should occur early in the ED visit. Obtain an ECG and chest x-ray. Treatment for either thrombi or emboli in the setting of PVD is similar. Empirically initiate a heparin infusion with the goal of increasing activated partial thromboplastin time to 1.5 times normal levels. Acute leg pain correlated with a cool distal extremity, diminished or absent distal pulses, and an ankle blood pressure under 50 mm Hg should prompt consideration of emergent surgical referral. In some cases of emboli, intra-arterial thrombolytic agents may be useful. The exact technique of administration varies, both in dosage and time of administration. Remember that intra-arterial thrombolysis remains investigational. Obviously, such thrombolytic therapy is contraindicated in the presence of active internal bleeding, intracranial bleeding, or bleeding at noncompressible sites. Consultations: Early surgical consultation in patients with acute limb ischemia is prudent. Depending on the case, the surgeon may involve interventional

radiology or proceed operatively. Emboli may be treated successfully by Fogarty catheter, ie, an intravascular catheter with a balloon at the tip. The balloon is passed distal to the lesion; the balloon is inflated, and the catheter is withdrawn along with the embolus. This technique most commonly is used for iliac, femoral, or popliteal emboli. Definitive treatment of hemodynamically significant aortoiliac disease is usually by aortobifemoral bypass. Its 5-year patency rate is approximately 90%. Those patients in whom PVD becomes significant, however, often have a plethora of comorbid medical conditions, such as cardiovascular disease, diabetes, and chronic obstructive pulmonary disease, which increase procedural morbidity and mortality. Axillobifemoral or femoral-femoral bypass are alternatives, both of which have lower 5-year patencies but have lower procedural mortality. Some areas of arteriostenosis can be revascularized with percutaneous transluminal coronary angioplasty (PTCA). If the occlusion is complete, a laser may be useful in making a small hole through which to pass the balloon. Restenosis is a concern with PTCA, particularly for larger lesions. Stents and lasers are still considered experimental. The goal of pharmacotherapy is to reduce morbidity and prevent complications.

Drug Category: Anticoagulants -- Reduce thrombin generation and fibrin formation and minimize clot propagation.

Drug Name

Adult Dose Pediatric Dose Contraindications

Interactions Pregnancy Precautions

Heparin -- Augments activity of antithrombin III and prevents conversion of fibrinogen to fibrin. Does not actively lyse but is able to inhibit further thrombogenesis. Prevents reaccumulation of clot after spontaneous fibrinolysis. 80 U/kg IV bolus, followed by infusion of 18 U/kg/h Administer as in adults Documented hypersensitivity; subacute bacterial endocarditis, active bleeding, history of heparininduced thrombocytopenia Digoxin, nicotine, tetracycline, and antihistamines may decrease effects; NSAIDs, aspirin, dextran, dipyridamole, and hydroxychloroquine may increase toxicity B - Usually safe but benefits must outweigh the risks. In neonates, preservative-free heparin is recommended to avoid possible toxicity (gasping syndrome) by benzyl alcohol, which is used as

preservative; caution in severe hypotension and shock; recent neurosurgery (within 6 wk), major surgery within 48 h, known bleeding diathesis, childbirth within 24 h, thrombocytopenia Further Outpatient Care: •

Patients who have significant peripheral vascular disease but whose illness is not so severe or acute that it requires inpatient treatment may be discharged with appropriate follow-up. Counsel these patients, however, regarding the potential effects of various activities and medications on the course of their illness. Advise patients to stop smoking and to avoid cold exposures and medications that can lead to vasoconstriction, including medications used for migraines and over-the-counter medications.

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Some recreational drugs (eg, cocaine) may have a deleterious effect on peripheral arterial tone, and beta-blockers may exacerbate the condition.

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Consultation with providers who will be following the patient after ED discharge is advised when making decisions regarding the discontinuation of medications used for chronic medical conditions.

Patient Education: •

For excellent patient education resources, visit eMedicine's Circulatory Problems Center. Also, see eMedicine's patient education article Peripheral Vascular Disease.

Medical/Legal Pitfalls: •

Failure to recognize severe arterial insufficiency may put the patient at risk for serious local ischemic complications. In addition, it is critical that the patient be evaluated for acute cardiac conditions that might have led to peripheral arterial ischemia. Potentially significant legal consequences may ensue if these conditions are missed.