The Ischemic Lower Extremity

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•To discuss the indications for amputation and choice of amputation level.

5.To describe the etiologies and presentation of acute arterial occlusion.

•To discuss embolic versus thrombotic occlusion.

•To discuss the signs and symptoms of acute arterial occlusion (the “Ps”).

•To discuss the medical and surgical management.

•To discuss the complications associated with prolonged ischemia and revascularization.

•To discuss the diagnosis and treatment of compartment syndrome.

Case

An 80-year-old woman presents to her primary care physician with a several-hour history of pain in her left foot. The pain was rather sudden in onset and has progressed to the point that she is having difficulty moving and feeling her toes. She states that in the past she has had difficulty walking more than a block or two without severe pain in her calves bilaterally. She also has an extensive past medical history that includes coronary artery bypass surgery, hypertension, smoking, and insulin-dependent diabetes mellitus (IDDM). She is on multiple medications, but, unfortunately, she forgot to bring her list of medications.

Introduction

The most important question to ask when evaluating someone with an ischemic or painful leg is the following: Is the leg ischemic? Put a better way: Is the pain that the patient is experiencing caused by decreased blood flow? As we shall discuss in this chapter, determining the adequacy of blood flow is relatively easy using history, physical exam, and simple, noninvasive tests.

As in all physical conditions, the cornerstone of medical therapy begins and sometimes ends with a thorough history and a thorough physical exam.

History

The leading cause of lower extremity ischemia usually is related to some form of or complication of atherosclerotic disease, known as “hardening of the arteries” in lay terms. With that in mind, it is helpful to elicit very early in a patient’s history the risk factors for atherosclerotic disease. These risk factors include smoking, hypertension, elevation of cholesterol, diabetes, obesity, and a sedentary lifestyle. Finding

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out about these risk factors early in the evaluation helps to narrow the diagnosis and helps to stratify risk for possible surgical intervention. It has been estimated that the prevalence of intermittent claudication is about 15% for patients older than 50, and about 1% of this population has critical limb ischemia.

Unfortunately, patients, even in this age of information overload, do not always have tremendous insight into their underlying health problems. Despite one’s best efforts, patients frequently are unable to provide an accurate listing of their past medical history and associated comorbidities. To obtain the proper answers concerning a particular condition, it is vital for a physician to ask the correct questions. For example, the question “Do you have high blood pressure?” may be appropriately answered by the patient on hypertensive medications with “No.” The more appropriate question is “Are you currently being treated for high blood pressure?” Very often, the knowledgeable physician can piece together accurately the salient points of patients’ history based on the medications that they are on. Always encourage your patients to carry a list of their current medications and the doses.

Along with the information regarding medications, it is helpful to obtain a history of any adverse drug reactions or allergies. When dealing with patients who have cardiovascular disease, it also is helpful to obtain a history of “dye” reactions or allergies to iodine. This is due to the fact that the patient with the acutely ischemic extremity may require an angiogram with iodinated intraarterial contrast. A previous contrast reaction does not rule out the use of angiography as a diagnostic or therapeutic tool. It simply means that appropriate precautions need to be taken.

As in all conditions, the acuity of the problem also must be taken into account. The reasons for this should be obvious. Patients with chronic ischemia rarely seem to present with acute limb-threatening ischemia. This is not to say that they are not at risk for limb loss or that they will not require aggressive revacularization procedures, but it is rare for these patients to require urgent/immediate surgical intervention. If the onset of the ischemia is acute and particularly if it is unilateral, then an embolic or thrombotic etiology must be considered. This is especially true in a patient such as the one in the case presented who has a long-standing history of lower extremity ischemia and who has a sudden change. You must ask: Why? What has happened that has led to the acute change? For patients with chronic symptoms of leg pain, it is important to elicit the nature of the pain. Is it exercise induced? Does it go away at rest? What part of the leg does the pain affect? How far can one walk before the pain starts? Has it been getting better or worse? Does it affect both legs equally? What we are looking for here is a history of claudication. We generally refer to intermittent claudication, which is a complex of symptoms characterized by absence of pain or discomfort in a limb when at rest, the commencement of pain, tension, and weakness after walking is begun, intensification of the condition until walking becomes impossible, and the disappearance of the symptoms after a period of rest.

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Epidemiologic studies suggest that up to 5% of men and 2.5% of women over 60 years of age have symptoms of claudication.1,2 The natural history of claudication, fortunately, is that of a generally benign course, with 70% of patients reporting no change in symptoms over 5 to 10 years, with 20% to 30% eventually progressing to require some form of intervention, and with less than 10% eventually requiring amputation. However, it is important to recall that intermittent claudication reflects systemic vascular disease, with affected patients carrying a threefold increase in cardiovascular mortality.

Rest pain is not merely claudication while at rest; rather, it is pain, usually in the forefoot, that occurs at rest and often is relieved by dependency of the affected limb. Rest pain indicates reduced perfusion of the extremity even at rest and portends eventual progression to frank tissue loss.

In the case presented, the patient, by her history, has chronic ischemia of her lower extremity, but she has experienced a rather profound and unfortunately negative change. Did she acutely thrombose already diseased but patent lower extremity vessels, or did she embolize a clot from her heart or from another more diseased proximal vessel leading to her current limb that is in a threatened state? A physical exam will give some clues to the etiology of her current state.

Physical Examination

When treating a patient who presents with an ischemic extremity, it is necessary to examine that extremity. But one must not forget to examine the entire patient. By examining a patient in a head-to-toe manner, one is much less likely to miss important physical findings.

The Ps of acute ischemia are pain, pallor, pulselessness, paresthesia, paralysis, and poikilothermy. It is helpful to think in this order because, generally, it is the order in which the patient complains of symptoms. Patients do not come in saying that their leg is poikilothermic, although they may say that it is cold. Generally, patients present because their leg hurts. The pain coincides with the pallor and the pulselessness. Optimally, the patient is seen prior to the onset of paresthesia and paralysis. The extremity that has been paralyzed secondary to ischemia usually predicts a less than optimal outcome, even if expedient revascularization is performed. Patients with acutely ischemic extremities present with painful, cold, and pale extremities. If they do not improve or are revascularized, they become numb and immobile.

The critical and yet frequently missed physical finding is the presence or absence of pulses. It is critically important to examine and honestly document the presence or absence of all pulses in both the upper

1 Reunanen A, Takkunen H, Aromaa A. Prevalence of intermittent claudication and its effect on mortality. Acta Med Scand 1982;211:249–256.

2 Jelnes R, Gaardsting O, Hougaard Jensen K, Baekgaard N, Tonnesen KH, Schroeder T. Fate in intermittent claudication: outcome and risk factors. Br Med J (Clin Res Ed) 1986;293:1137–1140.

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and lower extremities. It also is helpful to note whether the pulse is regular or not. The presence of a cardiac rhythm other than sinus may have some critical implications to the understanding of the patient’s problem. If pulses are absent to palpation, then it is helpful to employ the aid of a hand-held Doppler. The presence or absence of Doppler signals goes a long way in assessing the degree of limb ischemia. If the leg is absent of both pulses and Doppler signal, it generally is profoundly ischemic and will require revascularization sometime in the near future.

In addition to palpating pulses, it is important to feel for thrills, which are a “buzzing” vibratory sensation above the vessel. If there is a thrill, then you can expect to find an audible bruit. One must listen for bruits over the areas of major pulsation, most notably the neck, abdomen, groin, and occasionally the popliteal fossa. The presence of a bruit generally implies turbulence within the underlying vessel, and that generally is due to atherosclerotic plaque. Documentation and recognition of an irregular pulse are exceedingly important and frequently help to explain the source of embolization as a case of an acutely ischemic extremity.

The chronically ischemic leg has several other salient physical findings: thickened, brittle toenails; thin, fragile, almost shiny skin; absence of hair on the dorsum of the toes; increased capillary refill times; and frequently, dependent rubor.

Diagnostic Tests

Generally, diagnostic tests should form a logical progression from the history and physical exam. The tests should focus and clarify what the physician has found on the physical exam. If an operation is indicated to treat the problem, the tests frequently define the anatomy in question in a better manner. See Algorithm 28.1 for management options for claudication.

In general, one should start with a noninvasive and relatively inexpensive test first before proceeding to more expensive and invasive studies. It is important to individualize the approach to a patient. For example, the patient in the case presented at the start of this chapter, based on her presentation, would benefit from an angiogram, providing an emergent operation is not required. Order the test that the patient needs and that gives the information that is needed to take care of the patient optimally.

The most common and frequently the most valuable noninvasive vascular study is the ankle brachial index (ABI). This is a simple test to perform and is easy to learn. It simply is the ankle systolic pressure taken by Doppler over either the posterior tibial or dorsalis pedis artery (whichever is highest) divided by the brachial systolic pressure, also taken by Doppler. The ratio should be greater than 1.0. Values less than 1.0 suggest some component of peripheral vascular disease. The lower the value, the greater the degree of ischemia, with the important caveat that patients with very calcified lower extremity vessels (e.g., diabetic

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Algorithm 28.1. Algorithm for the management of claudication. ABI, ankle brachial index; DM, diabetes mellitus; HTN, hypertension. (Reprinted from Millikan KW, Saclarides TJ, eds. Common Surgical Diseases: An Algorithmic Approach to Problem Solving. New York: Springer-Verlag, 1998, with permission.)

patients) tend to have noncompressible vessels and, therefore, falsely elevated ABIs.

With the limitations of the ABI in mind, more formal, noninvasive testing frequently is indicated. We prefer to use a combination of pulse volume recordings (PVRs) and segmental pressure measurement. These relatively easy-to-perform and inexpensive studies provide very accurate and reproducible information regarding lower extremity ischemia. The PVRs are measurements of the increase in blood volume at a given level of the extremity with each heartbeat. If there is an obstructing lesion or occlusion of a blood vessel proximal to the placement of the PVR cuff, the amount of blood flow to that level will be diminished, and the PVR waveform will be flattened.

It also is important to recognize that the above-mentioned studies also can be performed after the patient has exercised. The normal response to exercise is an increase in heart rate, blood pressure, and

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Table 28.1. Infrapopliteal grafts.

PTFE, polytetrafluoroethylene.

a Anonymous. Comparative evaluation of prosthetic, reversed, and in situ vein bypass grafts in distal popliteal and tibialperoneal revascularization. Veterans Administration Cooperative Study Group 141. Arch Surg 1988;123: 434–438.

b Bandyk DF, Kaebnick HW, Stewart GW, Towne JB. Durability of the in situ saphenous vein arterial bypass: a comparison of primary and secondary patency. J Vasc Surg 1987;5:256–268.

c Barry R, Satiani B, Mohan B, Smead WL, Vaccaro PS. Prognostic indicators in femoropopliteal and distal bypass grafts. Surg Gynecol Obstet 1985;161:129–132.

d Bergan JJ, Veith FJ, Bernhard VM, et al. Randomization of autogenous vein and polytetrafluoroethylene grafts in femoral-distal reconstruction. Surgery (St. Louis) 1982;92:921–930.

e Berkowitz HD, Greenstein SM. Improved patency in reversed femoral-infrapopliteal autogenous vein grafts by early detection and treatment of the failing graft. J Vasc Surg 1987;5:755–761.

f Cantelmo NL, Snow JR, Menzoian JO, LoGerfo FW. Successful vein bypass in patients with an ischemic limb and a palpable popliteal pulse. Arch Surg 1986;121:217–220.

g Dalsing MC, White JV, Yao JS, Podrazik R, Flinn WR, Bergan JJ. Infrapopliteal bypass for established gangrene of the forefoot or toes. J Vasc Surg 1985;2:669–677.

h Flinn WR, Rohrer MJ, Yao JS, McCarthy WJ III, Fahey VA, Bergan JJ. Improved long-term patency of infragenicular polytetrafluoroethylene grafts. J Vasc Surg 1988;7:685–690.

i Harris RW, Andros G, Dulawa LB, Oblath RW, Apyan R, Salles-Cunha S. The transition to “in situ” vein bypass grafts. Surg Gynecol Obstet 1986;163:21–28.

j Hobson RW Jr, Lynch TG, Jamil Z, et al. Results of revascularization and amputation in severe lower extremity ischemia: a five-year clinical experience. J Vasc Surg 1985;2:174–185.

k Kent KC, Whittemore AD, Mannick JA. Short-term and midterm results of an all-autogenous tissue policy for infrainguinal reconstruction. J Vasc Surg 1989;9:107–114.

l Leather RP, Shah DM, Chang BB, Kaufman JL. Resurrection of the in situ saphenous vein bypass. 1000 cases later [see comments]. Ann Surg 1988;208:435–442.

m Leather RP, Shan DM, Karmody AM. Infrapopliteal arterial bypass for limb salvage: increased patency and utilization of the saphenous vein used “in situ.” Surgery 1981;90:1000–1008.

n Rosenbloom MS, Walsh JJ, Schuler JJ, et al. Long-term results of infragenicular bypasses with autogenous vein originating from the distal superficial femoral and popliteal arteries. J Vasc Surg 1988;7:691–696.

o Rutherford RB, Jones DN, Bergentz SE, et al. Factors affecting the patency of infrainguinal bypass. J Vasc Surg 1988;8:236–246.

p Schuler JJ, Flanigan DP, Williams LR, Ryan TJ, Castronuovo JJ. Early experience with popliteal to infrapopliteal bypass for limb salvage. Arch Surg 1983;118:472–476.

q Taylor LM Jr, Edwards JM, Brant B, Phinney ES, Porter JM. Autogenous reversed vein bypass for lower extremity ischemia in patients with absent or inadequate greater saphenous vein. Am J Surg 1987;153:505–510.

r Taylor LM Jr, Edwards JM, Porter JM. Present status of reversed vein bypass grafting: five-year results of a modern series. J Vasc Surg 1990;11:193–205.

s Varty K, Allen KE, Jones L, Sayers RD, Bell PR, London NJ. Influence of Losartan, an angiotensin receptor antagonist, on neointimal proliferation in cultured human saphenous vein. Br J Surg 1994;81:819–822.

t Veith FJ, Gupta SK, Ascer E, et al. Six-year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions. J Vasc Surg 1986;3: 104–114.

Data from McCann RL. Peripheral artery aneurysms. In: Porter JM, Taylor LM Jr, eds. Basic Data Underlying Clinical Decision Making in Vascular Surgery. St. Louis: Quality Medical, 1994:137–140. Source: Reprinted from Neschis DG, Golden MA. Arterial disease of the lower extremity. In: Norton JA, Bollinger RR, Chang AE, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001, with permission.

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Table 28.2. Percutaneous transluminal angioplasty patency.

a Gallino A, Mahler F, Probst P, Nachbur B. Percutaneous transluminal angioplasty of the arteries of the lower limbs: a 5-year follow-up. Circulation 1984;70:619–623.

b Hewes RC, White RI, Jr., Murray RR, et al. Long-term results of superficial femoral artery angioplasty. AJR 1986; 146:1025–1029.

c Johnston KW, Rae M, Hogg-Johnston SA, et al. 5-year results of a prospective study of percutaneous transluminal angioplasty. Ann Surg 1987;206:403–413.

d Krepel VM, van Andel GJ, van Erp WF, Breslau PJ. Percutaneous transluminal angioplasty of the femoropopliteal artery: initial and long-term results. Radiology 1985;156: 325–328.

e Spence RK, Freiman DB, Gatenby R, et al. Long-term results of transluminal angioplasty of the iliac and femoral arteries. Arch Surg 1981;116:1377–1386.

Data from Wilson SE, Sheppard B. Results of percutaneous transluminal angioplasty for peripheral vascular occlusive disease. In: Porter JM, Taylor LM Jr, eds. Basic Data Underlying Clinical Decision Making in Vascular Surgery. St. Louis: Quality Medical, 1994:144–148. Source: Reprinted from Neschis DG, Golden MA. Arterial disease of the lower extremity. In: Norton JA, Bollinger RR, Chang AE, et al, eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001, with permission.

Case Discussion

The most appropriate first step in dealing with the presented patient would be to anticoagulate her with systemic heparin. If she is a reasonable operative candidate, then one could go to the operating room and, under local anesthesia, perform a diagnostic angiogram. Depending on the findings, a decision could be made as to whether the ischemia could be resolved with either endovascular techniques (e.g., thrombolytic therapy) or limited open surgery. Caution should be taken, however, to avoid lengthy emergent surgical procedures on these very elderly patients with significant comorbidities.

Summary

Lower leg ischemia as a manifestation of peripheral arterial disease is common. Frequently, it can be noninvasively diagnosed and conservatively managed. Patients, like the patient in our case, may present with acute ischemia and warrant more aggressive management. The level of intervention, however, always must be tailored to the overall condition of the patient. Given the presences of significant comorbidities in our patient, significant caution is warranted before

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embarking on aggressive surgical intervention. Fortunately, with the advent of less invasive endovascular techniques, vascular interventionalists have more and potentially safer options.

Selected Readings

Chew DE, Conte MS, Belkin M, et al. Arterial reconstruction for lower limb ischemia. Acta Chir Belg 2001;101(3):106–115.

Cikrit DF, Dalsing MC. Lower extremity arterial endovascular stenting. Surg Clin North Am 1998;78(4):617–629.

Cronenwett JL, Warner KG, Zelenock GB, et al. Intermittent claudication. Current results of nonoperative management. Arch Surg 1984;119:430–436.

Dalman RL, Taylor LM Jr. Infrainguinal revascularization procedures. In: Porter JM, Taylor LM Jr, eds. Basic Data Underlying Clinical Decision Making in Vascular Surgery. St. Louis: Quality Medical, 1994:141–143.

Kannel WB, Skinner JJ Jr, Schwartz MJ, Shurtleff D. Intermittent claudication. Incidence in the Framingham Study. Circulation 1970;875–883.

Mills JL, Porter JM. Acute limb ischemia. In: Porter JM, Taylor LM Jr, eds. Basic Data Underlying Clinical Decision Making in Vascular Surgery. St. Louis: Quality Medical, 1994:134–136.

Neschis DG, Golden MA. Arterial disease of the lower extremity. In: Norton JA, Bollinger RR, Chang AE, et al., eds. Surgery: Basic Science and Clinical Evidence. New York: Springer-Verlag, 2001.

Ouriel K, Veith FJ, Sasahara AA. A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. Thrombolysis or Peripheral Arterial Surgery (TOPAS) Investigators [see comments]. N Engl J Med 1998;338:1105–1111.