Chapter 36_ Arteries.pdf

EUROPEAN UNIVERSITY CYPRUS Access Provided by: Current Diagnosis & Treatment: Surgery, 15e Chapter 36: Arteries Gaurav Sharma; Samir K. Shah INTRODUCTION Arterial disease can be broadly classified into two categories: occlusive and aneurysmal. The major sequelae of arterial obstruction are tissue ischemia and necrosis, whereas those of aneurysmal disease are typically rupture and hemorrhage in the aortic position and thrombosis and embolization in the peripheral arteries. ARTERIAL OCCLUSIVE DISEASE Although atherosclerosis is the dominant cause of arterial occlusive disease in Western countries, other etiologies such as congenital and anatomical anomalies, autoimmune diseases, and remote thromboembolism can also result in arterial obstruction. Symptoms of occlusive vascular disease primarily are endorgan dysfunction and, in the muscle beds, pain with exercise and tissue necrosis. ATHEROSCLEROSIS Atherosclerosis can occur in any artery, with plaques most commonly developing in areas of low shear stress, such as at arterial branch points. Lesions are usually symmetrically distributed, although the rate of progression may vary. Early lesions are confined to the intima. In advanced lesions, both intima and media are involved, but the adventitia is spared. Preservation of the adventitia is essential for the vessel’s structural integrity and is the basis for all cardiovascular interventions. When hemodynamically significant disease affects a major artery, a parallel system of collateral vessels may preserve flow to the peripheral runoff bed. Collateral vessels are smaller, more circuitous, and always have a higher resistance than the original unobstructed artery. The stimuli for collateral development include abnormal pressure gradients across the collateral system and increased flow velocity through intramuscular channels that connect to reentry vessels. Adequate collateral vessels take time to develop but often maintain tissue viability in patients with chronic major arterial occlusions. Generally, arterial insufficiency occurs in mediumsized and large arteries with at least a 50% reduction in arterial diameter. This correlates with a 75% narrowing of crosssectional area and enough resistance to decrease downstream flow and pressure. Early in the process, compensatory dilation of the vessel wall may preserve lumen diameter as the atherosclerotic lesion develops, but with continued growth, lesions overcome this adaptation and result in flowlimiting stenoses. If there is adequate collateral flow, single stenoses or even occlusions are reasonably welltolerated. Severe ischemia occurs when there are inadequate collaterals or there are multiple levels of disease. Davì G, Patrono C: Platelet activation and atherothrombosis. N Engl J Med. 2008;358:1638. [PubMed: 18403776] Libby P, Ridker PM, Hansson GK: Inflammation in atherosclerosis: from pathophysiology to practice. J Am Coll Cardiol. 2009;54:2129. [PubMed: 19942084] CHRONIC LOWER EXTREMITY OCCLUSIVE DISEASE General Considerations Peripheral arterial insufficiency is predominantly a disease of the lower extremities. Upper extremity arterial lesions are uncommon and confined Downloaded 5:55 A Your is 82.116.202.56 mostly to the 2024131 subclavian arteries. EvenIP when present, upper extremity atherosclerosis rarely produces symptoms due to abundant collateral pathways. Page 1 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shahare distributed widely, with lesions of the superficial femoral and iliac arteries the most In the lower extremities, however, obstructive lesions common ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility (Figure 36–1). Symptoms are related to the location and number of obstructions. Figure 36–1. CHRONIC LOWER EXTREMITY OCCLUSIVE DISEASE EUROPEAN UNIVERSITY CYPRUS Access Provided by: General Considerations Peripheral arterial insufficiency is predominantly a disease of the lower extremities. Upper extremity arterial lesions are uncommon and confined mostly to the subclavian arteries. Even when present, upper extremity atherosclerosis rarely produces symptoms due to abundant collateral pathways. In the lower extremities, however, obstructive lesions are distributed widely, with lesions of the superficial femoral and iliac arteries the most common (Figure 36–1). Symptoms are related to the location and number of obstructions. Figure 36–1. Common sites of stenosis and occlusion of the visceral and peripheral arterial systems. Peripheral arterial disease affects at least 20% of individuals older than 70 years, with the incidence increasing with the increasing incidence of diabetes. Although most patients with this disorder do not develop gangrene or require amputations, adverse outcomes of systemic atherosclerosis, including myocardial infarction and/or stroke, are common. Even after adjustment for known risk factors, individuals with peripheral arterial disease exhibit a severalfold higher risk of mortality than the nonaffected population. A low anklebrachial index is one of the strongest risk factors for all cause mortality. Peripheral arterial disease is more a marker of a more virulent form of atherosclerosis and early death from cardiovascular or cerebrovascular disease than an indicator of imminent limb loss; thus, identifying and treating associated atherosclerotic risk factors is essential (Figure 36–2). Figure 36–2. Odds ratios for risk factors for allcause mortality. ABI, anklebrachial index; CAD, coronary artery disease. (Reproduced with permission from Dormandy JA, Rutherford RB: Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic InterSociety Consensus (TASC), J Vasc Surg 2000 Jan;31[1 Pt 2]:S1S296.) Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 2 / 47 Figure 36–2. EUROPEAN UNIVERSITY CYPRUS Odds ratios for risk factors for allcause mortality. ABI, anklebrachial index; CAD, coronary artery disease. (Reproduced with permission from Access Provided by: Dormandy JA, Rutherford RB: Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic InterSociety Consensus (TASC), J Vasc Surg 2000 Jan;31[1 Pt 2]:S1S296.) Clinical Findings A. Symptoms 1. Intermittent claudication Intermittent claudication refers to pain in muscles of the lower extremity associated with walking that is relieved by rest. Tissue perfusion is adequate at rest, and so tissue loss (ie, ulceration or gangrene) does not occur. The risk of major limb amputation is low. The pain is described as a muscle ache, cramp, or fatigue that progresses with exertion and that can be severe enough to force the patient to stop walking. The pain occurs one anatomic level distal to the principal area of disease; thus, disease in the aorta and iliac and common femoral arteries produces buttocks and thigh claudication, and disease in the superficial femoral and popliteal arteries creates calf claudication. Gluteal pain indicates lesions in or proximal to the hypogastric arteries and is often accompanied by impotence. Leriche syndrome occurs in men with aortoiliac disease and includes claudication of calf, thigh, and buttock muscles; erectile dysfunction; and diminished or absent femoral pulses. Occasionally, patients describe transient numbness of the extremity accompanying the pain and fatigue of claudication as nerves and muscles become ischemic. Features of vasculogenic claudication that help in distinguishing it from other diseases include its occurrence only with exertion and the constant relationship between its onset and exertion and lack of relief with positional changes. The two conditions that most often mimic claudication are osteoarthritis of the hip or knee and neurospinal compression due to congenital or osteophytic narrowing of the lumbar neurospinal canal (spinal stenosis). Osteoarthritis can be differentiated from claudication because pain occurs predominantly in joints, the amount of exercise required to elicit symptoms varies, symptoms are characteristically worse in the morning and upon initiating exercise, rest does not relieve symptoms promptly, the severity of symptoms changes from day to day, and antiinflammatory agents may relieve the pain. Impingement on the spinal canal or nerve root produces neurospinal compression symptoms; therefore, the pain is typically burning or shooting in nature, and symptoms may occur with sitting or standing. Neurogenic pain may follow a dermatomal distribution, a key factor in differentiating it from vasculogenic claudication. Uncommon conditions such as coarctation of the aorta, chronic compartment syndrome, popliteal artery entrapment, and vasculitis can mimic symptoms of atherosclerotic arterial insufficiency. Age at presentation and associated findings may aid in diagnosing these conditions. The correct diagnosis of vascular claudication should be easily established by determining the location of pain with exercise (buttocks, thigh, calf), the quality of the pain (aching or cramping), the length of time required for relief of symptoms after stopping exercise (immediate or nearly immediate), the reproducibility of the5:55 distance walked symptoms begin (initial claudication distance), and most importantly, the reduction or loss of pulses Downloaded 2024131 A Your IP isbefore 82.116.202.56 Page 3 / 47 with exercise. Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility 2. Critical limb ischemia Uncommon conditions such as coarctation of the aorta, chronic compartment syndrome, popliteal artery entrapment, and vasculitis can mimic EUROPEAN UNIVERSITY CYPRUS symptoms of atherosclerotic arterial insufficiency. Age at presentation and associated findings may aid in diagnosing these conditions. Access Provided by: The correct diagnosis of vascular claudication should be easily established by determining the location of pain with exercise (buttocks, thigh, calf), the quality of the pain (aching or cramping), the length of time required for relief of symptoms after stopping exercise (immediate or nearly immediate), the reproducibility of the distance walked before symptoms begin (initial claudication distance), and most importantly, the reduction or loss of pulses with exercise. 2. Critical limb ischemia With extensive disease, patients move beyond claudication and develop critical limb ischemia, which includes ischemic rest pain and ulceration. Critical limb ischemia carries a high risk of major limb loss, unlike claudication, and is an indication for revascularization. Rest pain is severe and burning, usually confined to the forefoot distal to the metatarsals. It may be localized to the vicinity of an ischemic ulcer or pregangrenous toe. It is aggravated by elevation of the extremity. Thus, patients often report a worsening at night while attempting to sleep with improvement with dangling of the limb, which enlists the help of gravity to improve perfusion. In patients who must keep the foot constantly dependent to relieve pain, the leg and foot may be swollen, causing some confusion in diagnosis. The ischemic neuritis of rest pain is severe and resistant to opioids for relief. Patients with rest pain may give a history of claudication, but rest pain also may occur de novo in diabetics with distal tibial disease or embolic occlusion of the distal tibial arteries and in patients whose walking is limited by other conditions. Differentiating ischemic rest pain from neuropathy in diabetics is critical and may require vascular testing to clarify the diagnosis. Patients with severe lower extremity arterial insufficiency often develop ulcers or wounds on the feet even from seemingly trivial trauma. These lesions are most commonly located on the distal foot and toes, but on occasion, they can be in the upper foot or ankle. Typically, the wounds are excruciatingly painful, deep, and devoid of any evidence of healing such as contraction or formation of granulation tissue. 3. Erectile dysfunction Inability to attain or maintain an erection may be produced by lesions that obstruct blood flow through both hypogastric arteries and is commonly found in association with narrowing of the terminal aorta, common iliac, or hypogastric arteries. Vasculogenic erectile dysfunction is less common than that due to other causes. B. Signs Physical examination is of paramount importance in assessing the presence and severity of vascular disease. The physical findings of peripheral atherosclerosis are related to changes in the peripheral arteries and to tissue ischemia. 1. Arterial pulse examination Decreased amplitude of the pulse denotes proximal obstructions to flow, which can help localize disease. For example, an absent femoral pulse usually signifies aortoiliac occlusive disease. It is possible but unusual for collateral flow to be sufficient to produce a pulse distal to an occluded artery. 2. Bruits and thrills A bruit is the sound produced by dissipation of energy as blood flows through a stenotic arterial segment. With extremely high flows, the energy may vibrate the artery, creating a thrill. The bruit or thrill is transmitted distally along the course of the artery. Thus, when a bruit is heard through a stethoscope placed over a peripheral artery, stenosis is present at or proximal to that level. The pitch of the bruit rises as the stenosis becomes more marked, until a critical stenosis is reached or the vessel becomes occluded, when the bruit may disappear. Thus, absence of a bruit does not indicate insignificant disease. 3. Response to exercise Exercise in a normal individual increases the pulse rate without producing arterial bruits or reduction in pulse amplitude. In an individual who complains of claudication, there may be minimal findings at rest, but exercise will produce decreased pulse strength, decreased distal arterial pressure, and possibly an audible bruit unmasking a significant stenosis. Exercise is best used in conjunction with noninvasive vascular testing. 4. Integumentary changes Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Page 4 / 47 Chapter 36: Arteries, Gauravproduces Sharma;loss Samir K. Shah Chronic ischemia commonly of hair over the dorsum of the toes and foot and may be associated with thickening of the toenails ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility (onychomycosis) due to slowed keratin turnover. With more advanced ischemia, there is atrophy of the skin and subcutaneous tissue so that the foot becomes shiny, scaly, and skeletonized. EUROPEAN Exercise in a normal individual increases the pulse rate without producing arterial bruits or reduction in pulse amplitude. In an UNIVERSITY individual whoCYPRUS Access Provided by: complains of claudication, there may be minimal findings at rest, but exercise will produce decreased pulse strength, decreased distal arterial pressure, and possibly an audible bruit unmasking a significant stenosis. Exercise is best used in conjunction with noninvasive vascular testing. 4. Integumentary changes Chronic ischemia commonly produces loss of hair over the dorsum of the toes and foot and may be associated with thickening of the toenails (onychomycosis) due to slowed keratin turnover. With more advanced ischemia, there is atrophy of the skin and subcutaneous tissue so that the foot becomes shiny, scaly, and skeletonized. 5. Pallor Pallor of the foot on elevation of the extremity with a complete absence of capillary refill indicates advanced ischemia. Pallor on elevation does not occur unless advanced ischemia is present. It is always present with ischemic rest pain. 6. Reactive hyperemia When pallor is produced with elevation, the ischemia results in maximum cutaneous vasodilation. When the extremity is returned to a dependent position, blood returning to the dilated vascular bed produces an intense color in the foot, called dependent rubor, and denotes advanced disease. The delay in the appearance of color when the extremities return to a dependent position is proportionate to the impairment in circulation. The purple discoloration due to severe chronic venous insufficiency does not give way to pallor on elevation. 7. Skin temperature With chronic ischemia, the temperature of the skin of the foot decreases. Coolness can best be detected by palpation with the back of the examiner’s hand with comparison to the contralateral foot. 8. Ulceration Ischemic ulcers are usually very painful and accompanied by rest pain in the foot. They occur in toes or at a site where minor trauma can initiate the injury. The margin of the ulcer is sharply demarcated or punched out, and the base is devoid of healthy granulation tissue. The surrounding skin is pale and mottled, and signs of chronic ischemia are invariably present. Neuropathic ulcers are surrounded by a callus and occur frequently at areas of repeated trauma, such as plantar surface of the metatarsal heads. 9. Atrophy Moderate to severe degrees of chronic ischemia produce gradual soft tissue and muscle atrophy and loss of strength. Joint mobility and gait may be altered due to muscle atrophy. Subsequent changes in foot structure and gait increase the possibility of developing foot ulceration. 10. Necrosis Severe tissue ischemia may progress to necrosis with minor injuries, infection, or swelling. Necrosis halts proximally at a line where the blood supply is sufficient to maintain viability and results in dry gangrene. If the necrotic portion is infected (wet gangrene), necrosis may extend into tissues that would normally remain viable. C. Noninvasive Vascular Laboratory Tests Noninvasive assessment is helpful to determine the severity of hypoperfusion and the sites of hemodynamically significant stenoses or occlusions. The anklebrachial index (ABI) is a quick screening test and the cornerstone of the diagnosis of peripheral vascular disease. The ABI is determined by first determining the systolic pressures obtained by Doppler insonation of the dorsalis pedis and posterior tibial arteries and the bilateral brachial arteries. Next, the highest pedal systolic pressure is divided by the highest brachial pressure to determine the ABI. Normally, the ABI is 0.9 or greater; a lower value indicates occlusive disease proximal to the point of measurement. The ABI correlates roughly with the degree of ischemia: claudication occurs with a value less than 0.7, and rest pain usually appears when the ratio is 0.4 or lower. Patients with diabetic vascular disease may have artificially elevated ABI values due to calcified, noncompressible arteries, and toebrachial indices and pulse volume recordings may be used instead to assess arterial perfusion. Blood pressures can be measured at rest after exercise in the ankle, and the effect of exercise can be monitored. Exercise testing confirms and Downloaded 2024131 5:55 A Your IP and is 82.116.202.56 Page 5 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah quantitates the diagnosis of claudication. To perform exercise testing, the patient walks on a treadmill at a standard speed and grade until claudication ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility pain is experienced or a time limit is reached. With significant arterial occlusive disease, there will be a decrease in the ABI with exercise. If the pain is not due to arterial stenosis, no decrease in pressure will occur. This test is particularly useful in differentiating neurogenic pain with walking from arteries. Next, the highest pedal systolic pressure is divided by the highest brachial pressure to determine the ABI. Normally, the ABI is 0.9 or greater; a lower value indicates occlusive disease proximal to the point of measurement. The ABI correlates roughly with theEUROPEAN degree of ischemia: claudication UNIVERSITY CYPRUS occurs with a value less than 0.7, and rest pain usually appears when the ratio is 0.4 or lower. Patients with diabeticAccess vascular disease may have Provided by: artificially elevated ABI values due to calcified, noncompressible arteries, and toebrachial indices and pulse volume recordings may be used instead to assess arterial perfusion. Blood pressures can be measured at rest and after exercise in the ankle, and the effect of exercise can be monitored. Exercise testing confirms and quantitates the diagnosis of claudication. To perform exercise testing, the patient walks on a treadmill at a standard speed and grade until claudication pain is experienced or a time limit is reached. With significant arterial occlusive disease, there will be a decrease in the ABI with exercise. If the pain is not due to arterial stenosis, no decrease in pressure will occur. This test is particularly useful in differentiating neurogenic pain with walking from claudication. D. Imaging Studies Color duplex ultrasound imaging is a mainstay of vascular imaging. It is a painless, relatively inexpensive, and accurate method for acquiring anatomic and functional information (eg, velocity gradients across stenoses). Although the accuracy of this study is operator dependent, it can supply sufficient information to permit intervention in selected cases. Computed tomography angiography (CTA) is useful for imaging the arterial tree and has the advantage of visualizing crosssections of the vessel lumen. In many instances, this allows for more accurate determination of vessel diameter and stenosis severity than conventional angiography. It does require the administration of contrast dye and is less useful for tibial disease, and its images may be obscured by the presence of calcification or metallic implants. Magnetic resonance angiography (MRA) also can be used to obtain images similar in quality to angiography in most cases. MRA does not show calcifications and gives better visualization of tibial vessels than CTA. MRA also can reveal details of composition of atherosclerotic plaque. Gadoliniumassociated nephrogenic systemic fibrosis limits its use in patients with renal insufficiency. The integrated use of computer workstations with computed tomography (CT) and magnetic resonance imaging (MRI) data can provide threedimensional images that can be useful in visualizing patient anatomy and planning interventional procedures. Conventional arteriography provides detailed anatomic information about peripheral arterial disease. It is reserved for patients warranting invasive intervention such as percutaneous transluminal angioplasty, stent placement, or planning for open vascular surgery. Complications of angiography are related to technique and contrast media. Technical complications such as puncture site hematomas, arteriovenous fistulas, and false aneurysms are uncommon (1%). Contrast agents may precipitate allergic reactions (0.1%). Patients with renal failure, proteinuria, diabetes, and dehydration are at increased risk for contrastinduced renal failure. Adequate hydration of patients before and after angiography and use of N acetylcysteine may reduce the incidence of this complication. Contrastsparing techniques and even carbon dioxide–based angiography, which may avoid administration of iodinated contrast altogether, are also in use. Treatment & Prognosis The objectives of treatment for lower extremity occlusive disease are relief from symptoms and prevention of limb loss. A. Nonoperative Treatment In general, patients with peripheral vascular disease have shortened life expectancies because of their severe atherosclerotic disease. Nondiabetic patients with ischemic disease of the lower extremity have a 5year survival rate of 70%. The survival rate is 60% in patients with associated ischemic heart disease or cerebrovascular insufficiency. Patients with peripheral vascular disease and renal failure have a 2year survival rate of less than 50%. Most deaths are due to myocardial infarctions and strokes. Only 20% of deaths are due to nonatherosclerotic causes. Nonoperative treatment consists of (1) medical management of cardiovascular risk factors, (2) exercise rehabilitation, (3) foot care, and (4) pharmacotherapy. 1. Reduction of cardiovascular risk factors See Table 36–1. Managing cardiovascular risk in patients with chronic lower extremity ischemia is critical. Although nondiabetics with intermittent claudication carry a less than 5% risk of major amputation at 5 years, in some series, the risk of mortality over that same period exceeds 40%, primarily due to cardiovascular events. Critical limb ischemia (characterized by rest pain and/or tissue loss) patients are at even higher risk of cardiovascular events; mortality in this subset of peripheral arterial disease patients may exceed 25% at 1 year, again primarily due to cardiovascular causes. Cigarette smoking is the single most important risk factor for peripheral vascular disease, and all patients should stop smoking. At high levels of consumption (eg, 23 packs per day), claudicants who successfully cease smoking will experience immediate improvement in walking distance. Table 36–1. Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Summary of risk factor modification in peripheral vascular disease. Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Risk Factor Therapy Clinical Effect Page 6 / 47 due to cardiovascular events. Critical limb ischemia (characterized by rest pain and/or tissue loss) patients are at even higher risk of cardiovascular EUROPEAN UNIVERSITY CYPRUS events; mortality in this subset of peripheral arterial disease patients may exceed 25% at 1 year, again primarily due to cardiovascular causes. Cigarette Access Provided by: smoking is the single most important risk factor for peripheral vascular disease, and all patients should stop smoking. At high levels of consumption (eg, 23 packs per day), claudicants who successfully cease smoking will experience immediate improvement in walking distance. Table 36–1. Summary of risk factor modification in peripheral vascular disease. Risk Factor Therapy Clinical Effect Tobacco use Counseling Reduced overall mortality Pharmacotherapy Reduced cardiovascular events Nicotine replacement Bupropion, varenicline Antiplatelet Aspirin Antiplatelet therapy gives > 20% reduction in Ml, stroke, or vascular death Clopidogrel (Plavix) Hyperlipidemia Statin 20%30% reduction in cardiovascular and allcause mortality in CAD patients Lipid goals in PAD patients: LDL < 100 mg/dL Hypertension Target BP < 140/90 in Betablocker and ACE inhibitors each associated with > 20% reduction in cardiovascular PAD patients mortality Betablocker ACE inhibitor Diabetes Goal hemoglobin A1c < 7% Benefits in vascular disease unproven Lifestyle Daily aerobic exercise Reduced lipid levels Weight loss Reduced cardiovascular events Healthy, lowfat diet ACE, angiotensinconverting enzyme; BP, blood pressure; CAD, coronary artery disease; LDL, lowdensity lipoprotein; Ml, myocardial infarction; PAD, peripheral artery disease. In the past, elevated lipids were not usually associated with peripheral vascular disease. Hyperlipidemia, however, is often present, especially in patients with early onset of disease. Elevated triglyceride levels and low highdensity lipoprotein (HDL) cholesterol levels are more prevalent than elevated levels of lowdensity lipoprotein (LDL) cholesterol. Reduction of elevated lipid levels is associated with stabilization or regression of arterial plaques. Highintensity, highdose statin regimens are recommended for all patients with peripheral arterial disease. Statins have other pleiotropic effects that may reduce inflammation, stabilize plaques, and independently increase walking distance in claudicants. Both type 1 and type 2 diabetes increase the prevalence and severity of cardiovascular disease. Intensive glycemic control reduces the incidence of nephropathy, neuropathy, and retinopathy in diabetes, but it does not correlate with the severity or progression of peripheral arterial disease. In order to reduce allcause mortality, however, it is recommended that fasting blood sugars should be controlled with hemoglobin A1c levels less than 7%. 2. Exercise rehabilitation For claudicants, exercise ranging from unsupervised walking to formal supervised exercise on a treadmill significantly improves walking ability. A 21 study metaanalysis of exercise programs showed an average 180% increase in initial claudication distance and a 120% increase in maximal walking distance achieved through exercise. The precise mechanism behind this improvement is not firmly established. Collateral development seems unlikely because ankle pressures and limb flow do not increase substantially. Possible explanations include improved metabolic capacity and conditioning of the muscles. Because patients with claudication are at a twofold to fourfold greater risk of dying from complications of generalized atherosclerosis than people without claudication, an additional benefit of exercise in these patients is that an improvement in walking distance as part of an aggressive risk factor Downloaded 2024131 5:55 A Your IP is 82.116.202.56 modification regimen Gaurav results inSharma; an overall decrease in cardiovascular risk. Page 7 / 47 Chapter 36: Arteries, Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility 3. Foot care distance achieved through exercise. The precise mechanism behind this improvement is not firmly established. Collateral development seems unlikely EUROPEAN UNIVERSITY CYPRUS because ankle pressures and limb flow do not increase substantially. Possible explanations include improved metabolic capacity and conditioning of the muscles. Access Provided by: Because patients with claudication are at a twofold to fourfold greater risk of dying from complications of generalized atherosclerosis than people without claudication, an additional benefit of exercise in these patients is that an improvement in walking distance as part of an aggressive risk factor modification regimen results in an overall decrease in cardiovascular risk. 3. Foot care The feet of patients with neuropathy or with critical limb ischemia should be inspected and washed daily and kept dry. Mechanical and thermal trauma to the feet should be avoided. Toenails should be trimmed carefully, and corns and calluses should be attended to promptly. Even minor foot infections or injuries should be treated aggressively. Educating the patient to understand neuropathy, peripheral vascular insufficiency, and the importance of foot care is a central aspect of treatment. 4. Pharmacotherapy The Antiplatelet Trialists Collaboration found an overall 25% decrease in fatal and nonfatal myocardial infarctions, strokes, and vascular deaths in those treated with antiplatelet agents. Aspirin at dosages ranging from 75 to 350 mg/d is the firstline antiplatelet agent recommended, although clopidogrel, which blocks the activation of platelets by adenosine diphosphate (ADP), is a viable alternative. Clopidogrel is also an important adjunctive therapy in reducing thrombogenicity at locations of endovascular arterial treatment. All patients with cardiovascular disease, whether symptomatic or asymptomatic, should be considered for antiplatelet therapy to reduce the risk of cardiovascular morbidity and mortality. Cilostazol is a phosphodiesterase III inhibitor with vasodilator, antiplatelet, and antilipid activity approved for treatment of intermittent claudication. Randomized, placebocontrolled, blinded trials have shown an increase of about 50% in absolute claudication distance in patients treated with cilostazol. Congestive heart failure is an absolute contraindication, and significant side effects limit its use. Aboyans V, Criqui MH, Abraham P, et al: Measurement and interpretation of the anklebrachial index: a scientific statement from the American Heart Association. Circulation. 2012;126:2890. [PubMed: 23159553] Alonso Coello P, Bellmunt S, McGorrian C, et al: Antithrombotic therapy in peripheral artery disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians EvidenceBased Clinical Practice Guidelines. Chest. 2012;141(2 Suppl):e669S. [PubMed: 22315275] Critchley JA, Capewell S: Mortality risk reduction associated with smoking cessation in patients with coronary heart disease: a systematic review. JAMA. 2003;290:86. [PubMed: 12837716] Dormandy JA, Murray GD: The fate of the claudicant: a prospective study of 1969 claudicants. Eur J Vasc Surg. 1991;5:131. [PubMed: 2037083] Hamburg NM, Balady GJ: Exercise rehabilitation in peripheral artery disease: functional impact and mechanisms of benefits. Circulation. 2011;123:87– 97. [PubMed: 21200015] McCullough PA: Contrastinduced acute kidney injury. J Am Coll Cardiol. 2008;51:1419. [PubMed: 18402894] Mills EJ, Wu P, Chong G, et al: Efficacy and safety of statin treatment for cardiovascular disease: a network metaanalysis of 170,255 patients from 76 randomized trials. QJM. 2011;104:109. [PubMed: 20934984] Momsen AH, Jensen MB, Norager CB, et al: Drug therapy for improving walking distance in intermittent claudication: a systematic review and meta analysis of robust randomised controlled studies. Eur J Vasc Endovasc Surg. 2009;38:463. [PubMed: 19586783] Murphy TP, Cutlip DE, Regensteiner JG, et al: Supervised exercise versus primary stenting for claudication resulting from aortoiliac peripheral artery disease: sixmonth outcomes from the claudication: exercise versus endoluminal revascularization (CLEVER) study. Circulation. 2012;125:130. [PubMed: 22090168] Rehring TF, Stolcpart RS, Hollis HW Jr: Pharmacologic risk factor management in peripheral arterial disease: a vade mecum for vascular surgeons. Society for Vascular Surgery. J Vasc Surg. 2008;47:1108. [PubMed: 18372155] Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah B. Operative Treatment ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 8 / 47 Interventional procedures, open or endovascular, are performed both for limb salvage and for lifestylelimiting claudication. The choice of operative disease: sixmonth outcomes from the claudication: exercise versus endoluminal revascularization (CLEVER) study. Circulation. 2012;125:130. [PubMed: 22090168] EUROPEAN UNIVERSITY CYPRUS Access Provided by: Rehring TF, Stolcpart RS, Hollis HW Jr: Pharmacologic risk factor management in peripheral arterial disease: a vade mecum for vascular surgeons. Society for Vascular Surgery. J Vasc Surg. 2008;47:1108. [PubMed: 18372155] B. Operative Treatment Interventional procedures, open or endovascular, are performed both for limb salvage and for lifestylelimiting claudication. The choice of operative procedure depends on the location and distribution of arterial lesions and the patient’s comorbidities. Recognition of coexistent cardiopulmonary disease is particularly relevant, because many patients with peripheral vascular disease also have ischemic heart disease or chronic lung disease associated with tobacco use. Preoperative cardiac functional assessment is sometimes necessary, but preoperative myocardial revascularization is not beneficial in patients with reasonable cardiac reserve. All patients undergoing vascular surgery should have preoperative risk assessment. Randomized trials have shown that perioperative betablocker, angiotensinconverting enzyme (ACE) inhibitor, and statins may reduce cardiac morbidity in patients undergoing vascular surgery. 1. Endovascular therapy Endovascular therapy consists of imageguided techniques to treat diseased arterial segments from within the lumen of the vessel. Access to the arterial system is established by the insertion of valved sheaths, usually percutaneously, into the access vessel, often the common femoral artery. Steerable wires and catheters are then passed through the vasculature under fluoroscopic guidance to the target lesion (Figure 36–3). Once the target lesion is accessed, therapeutic maneuvers including angioplasty (plain, cutting, or drugcoated balloons), atherectomy (mechanical or laser), and stenting (bare metal or drugeluting) can be performed. Continued technologic advances have resulted in the everexpanding application of these interventions to patients with disease characteristics once thought to preclude endovascular interventions, such as highgrade TransAtlantic Inter Society Consensus (TASC) D lesions, chronic total occlusions, infrapopliteal disease, and even common femoral and profunda femoral occlusive disease. In many arterial beds, endovascular therapy is more commonly used than open surgical therapy because of its minimally invasive nature and reduction of shortterm morbidity and mortality. However, many questions remain concerning the longterm durability of endovascular repairs, and open surgery still plays a major role in the treatment of patients with arterial disease. Figure 36–3. Endovascular gear. A : Sheath. Inserted using Seldinger technique into access vessel. Wires, catheters, and devices pass through the sheath. Sheaths provide stable working access points and protect the artery. B : Catheter. Variable length, stiffness, coating, and shape (examples: B.1, cobra; B.2, pigtail; B.3, mesenteric selective). Catheters help steer wires through vasculature and also maintain access in vessel. C : Guidewire. Variable diameter, length, stiffness, and shape. Used to gain access into vasculature, crosslesions, and deliver devices. D : Balloon catheter. E: Peripheral stent graft. F : Peripheral nitinol selfexpanding stent. G : Aortoiliac stainless steel/Dacron stent graft. Percutaneous transluminal angioplasty, with or without placement of an intravascular stent, is often the treatment of choice when stenoses or Downloaded 2024131 5:55 A Your IP is 82.116.202.56 even occlusions are relatively and Samir localized. As the angioplasty balloon expands, it stretches the adventitia, fracturing and compressing plaque Page 9 / 47 Chapter 36: Arteries, Gaurav short Sharma; K. Shah and expanding artery to widen the lumen. Energy associated with aNotice stenosis are inversely proportionate to the fourth power of the radius; ©2024 McGrawthe Hill. All Rights Reserved. Terms of losses Use Privacy Policy Accessibility therefore, even small increases in radius can result in substantial increases in blood flow, although durability of the procedure is improved with the reestablishment of a normal lumen. Concomitant stenting is frequently performed to improve luminal expansion. Stent grafts or covered stents (stents EUROPEAN UNIVERSITY CYPRUS Access Provided by: Percutaneous transluminal angioplasty, with or without placement of an intravascular stent, is often the treatment of choice when stenoses or even occlusions are relatively short and localized. As the angioplasty balloon expands, it stretches the adventitia, fracturing and compressing plaque and expanding the artery to widen the lumen. Energy losses associated with a stenosis are inversely proportionate to the fourth power of the radius; therefore, even small increases in radius can result in substantial increases in blood flow, although durability of the procedure is improved with the reestablishment of a normal lumen. Concomitant stenting is frequently performed to improve luminal expansion. Stent grafts or covered stents (stents lined with an impermeable material) may also be used in selected cases, based on anatomic location of the lesion, or to repair the inadvertent rupture of an artery during angioplasty (Figure 36–4). Figure 36–4. Aortoiliac occlusive disease. A : Aorta. B : Severely stenotic/occluded iliac arteries. B.1: Widely patent iliac arteries following balloon angioplasty and stenting (C). Both stents and stent grafts are commonly used from the aortic bifurcation to the distal popliteal artery. Stenting is performed less commonly below the knee, but angioplasty of tibial disease is now increasingly common. Metaanalytic data suggest that infrapopliteal angioplasty in this patient population is associated with less than 50% midterm primary patency, but 82% limb salvage at 3 years; thus, it may be a viable option in patients who are not candidates for open bypass. Percutaneous mechanical and laser atherectomy are other options in removing obstructing lesions in lower extremity atherosclerotic occlusive disease, although their durability has not been proven. For short, stenotic segments in larger, more proximal vessels, the results of endovascular therapies are good, with 1year success rates of 85% in common iliac disease and 70% in external iliac disease. The results with superficial femoral and popliteal lesions are lower (Figure 36–5). The success of endovascular therapy for lower extremity occlusive disease is inversely related to the complexity of the lesion, defined by the number and length of stenoses treated. Figure 36–5. Superficial femoral artery occlusion, angioplasty, and stent graft. A : Common femoral artery. B : Occluded superficial femoral artery. B.1: Recannalized, stentgrafted superficial femoral artery. C : Profunda femoris artery. D : Stent graft. Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 10 / 47 Figure 36–5. EUROPEAN UNIVERSITY CYPRUS Access Provided by: Superficial femoral artery occlusion, angioplasty, and stent graft. A : Common femoral artery. B : Occluded superficial femoral artery. B.1: Recannalized, stentgrafted superficial femoral artery. C : Profunda femoris artery. D : Stent graft. Close followup of patients after endovascular therapy is required because disease may recur more frequently after angioplasty than after bypass surgery, and the patient should be followed using noninvasive tests. Repeat angioplasty or stenting may be indicated for recurrent disease, but the improvement in morbidity and mortality of endovascular interventions may be offset by the need for multiple repeat procedures. In general, minimally invasive percutaneous treatment of lower extremity occlusive disease is best used in patients with high operative risk and severe, limbthreatening ischemia (Figure 36–6). Figure 36–6. Comparison of outcomes for surgical and endovascular intervention in lower extremity occlusive disease. 2. Surgical treatment Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Page 11 / 47 Chapter 36: RECONSTRUCTION Arteries, Gaurav Sharma; Samir K. Shah A. AORTOILIAC ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Open operations are indicated for aortoiliac occlusive disease in younger patients with low operative risk or patients with severe disease not amenable to endovascular therapy. To completely bypass the aortoiliac segment, an inverted Yshaped (bifurcated) prosthesis is interposed between the infrarenal abdominal aorta and the femoral arteries, creating an aortofemoral bypass. The goal of operation is restoration of blood flow to the EUROPEAN UNIVERSITY CYPRUS Access Provided by: 2. Surgical treatment A. AORTOILIAC RECONSTRUCTION Open operations are indicated for aortoiliac occlusive disease in younger patients with low operative risk or patients with severe disease not amenable to endovascular therapy. To completely bypass the aortoiliac segment, an inverted Yshaped (bifurcated) prosthesis is interposed between the infrarenal abdominal aorta and the femoral arteries, creating an aortofemoral bypass. The goal of operation is restoration of blood flow to the common femoral artery or, when occlusive disease of the superficial femoral artery is present, to the profunda femoris artery. The clinical results of aortofemoral reconstruction are excellent, although the mortality and morbidity clearly are higher than for endovascular therapy. The operative death rate is less than 5%; the early patency rate is 95%; and the late primary patency rate (510 years postoperatively) ranges from 72% to 98%. Late complications may be as high as 10% and include graftintestinal fistula formation, anastomotic aneurysm formation, renal failure, and erectile dysfunction. Lower risk procedures may be preferable in highrisk patients. If the clinically important lesions are confined to one side, a femoralfemoral or iliofemoral bypass graft can be used. A graft from the axillary to the femoral artery (ie, axillofemoral graft) can be used for bilateral disease. Unfortunately, these “extraanatomic” methods of arterial reconstruction are more prone to late occlusion than are direct reconstructions. B. FEMOROPOPLITEAL RECONSTRUCTION When disease is confined to the femoropopliteal segment of the superficial femoral artery, femoropopliteal bypass is used. The principal indication for these operations is limb salvage. In patients with claudication alone, the indications for femoropopliteal bypass are more difficult to define but must include substantial disability from claudication. For limited lesions of the superficial femoral artery, endovascular therapy is often attempted first, with surgery reserved for extensive disease or angioplasty failure. The best conduit for femoropopliteal bypass is an autologous greater saphenous vein. The saphenous vein may be left in situ or removed and reversed. Expanded polytetrafluoroethylene (PTFE) may also be used as a conduit, albeit with lower patency. Below the popliteal artery, PTFE conduits produce much lower patency rates than saphenous veins. Operative death rates are low (2%), and 5year patency rates range from 60% to 80%. Limb salvage rates are higher than graft patency rates. The profunda femoris artery perfuses the thigh and acts as an important source of collateral flow to the more distal leg when the superficial femoral artery is diseased. When there is a stenosis of the profunda femoris, profundoplasty alone can be performed for limb salvages with success rates of 80% when the suprageniculate popliteal artery is patent and 40%50% when the popliteal artery is occluded. Isolated profundoplasty is typically inadequate as an isolated procedure for treating claudication. C. TIBIOPERONEAL ARTERIAL RECONSTRUCTION Reconstruction of tibial arteries (ie, distal bypass to the tibial, peroneal, or pedal vessels) is performed only for limb salvage. Advancing technology allows better endovascular therapy in the tibial vessels, with decreased shortterm morbidity and mortality and similar gains in limb salvage when compared to bypass surgery. However, bypass still remains an important mode of therapy for these patients. Autogenous saphenous veins are preferred because prosthetic conduits have high failure rates. Due to smaller vessel size, extensive disease, and probably the length of the bypass conduit, these grafts are not as durable as femoropopliteal bypass, so the limb salvage rate is substantially higher than graft patency. The operative death rate for these procedures is about 5% due to extensive comorbidities. D. AMPUTATION Amputation of the limb is necessary within 510 years in less than 5% of nondiabetic patients presenting with claudication. Amputation is more common if patients continue to smoke cigarettes. Patients with multiple risk factors for atherosclerosis and shortdistance claudication are also at increased risk for eventual limb loss. Of patients who present with ischemic rest pain or ulceration, 5%10% require amputation as initial therapy, and most eventually will require amputation if not revascularized. Successful revascularization results in lower costs than primary amputation and an improvement in quality of life. Occasionally, primary amputation may be preferable to revascularization if the likelihood of successful bypass is low, extensive foot infection is present, or the patient is nonambulatory. Amputation levels, options, and the special needs of amputees are covered in the section on lower extremity amputation. Ambler GK, Twine CP: Graft type for femoropopliteal bypass surgery. Cochrane Database Syst Rev. 2018;2:CD001487. [PubMed: 29429146] Bradbury AW, Adam DJ, Bell J, et al: Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial: an intentiontotreat analysis of amputationfree and overall survival in patients randomized to a bypass surgeryfirst or a balloon angioplastyfirst revascularization strategy. J Vasc Downloaded 2024131[PubMed: 5:55 A Your IP is 82.116.202.56 Surg. 2010;51:5S–17S. 20435258] Page 12 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Chung SW, Sharafuddin MJ, Chigurupati R, et al: Midterm patency following atherectomy for infrainguinal occlusive disease: a word of caution. Ann Vasc Surg. 2008;22:358–365. [PubMed: 18411033] section on lower extremity amputation. EUROPEAN UNIVERSITY CYPRUS Access Provided by: Ambler GK, Twine CP: Graft type for femoropopliteal bypass surgery. Cochrane Database Syst Rev. 2018;2:CD001487. [PubMed: 29429146] Bradbury AW, Adam DJ, Bell J, et al: Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial: an intentiontotreat analysis of amputationfree and overall survival in patients randomized to a bypass surgeryfirst or a balloon angioplastyfirst revascularization strategy. J Vasc Surg. 2010;51:5S–17S. [PubMed: 20435258] Chung SW, Sharafuddin MJ, Chigurupati R, et al: Midterm patency following atherectomy for infrainguinal occlusive disease: a word of caution. Ann Vasc Surg. 2008;22:358–365. [PubMed: 18411033] de Vries SO, Hunink MG: Results of aortic bifurcation grafts for aortoiliac occlusive disease: a metaanalysis. J Vasc Surg. 1997;26:558–569. [PubMed: 9357455] GerhardHerman MD, Gornik HL, Barrett C, et al: 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2017;135(12):e791–e792. [PubMed: 28320816] Jacobs DL, Motaganahalli RL, Cox DE, et al: True lumen reentry devices facilitate subintimal angioplasty and stenting of total chronic occlusions: initial report. J Vasc Surg. 2006;43:1291–1296. [PubMed: 16765258] Nieves JT, Singh G, Laird J, et al: Endovascular versus open bypass surgery for TASC D femoropopliteal lesions in patients with critical limb ischemia. J Vasc Surg. 2016;64:545–546. Norgren L, et al: InterSociety consensus for the management of peripheral arterial disease (TASC II). TASC II Working Group. J Vasc Surg. 2007;45(Suppl S):S5. [PubMed: 17223489] RochaSingh KJ, Jaff M, Joye J, et al: Major adverse limb events and wound healing following infrapopliteal artery stent implantation in patients with critical limb ischemia: the XCELL trial. Catheter Cardiovasc Interv. 2012;80:1042–1051. [PubMed: 22605682] Romiti M, Albers M, BrochadoNeto FC, et al: Metaanalysis of infrapopliteal angioplasty for chronic critical limb ischemia. J Vasc Surg. 2008;47:975– 981. [PubMed: 18372148] ACUTE LIMB ISCHEMIA General Considerations Sudden occlusion of a previously patent artery is a dramatic event characterized by the abrupt onset of severe pain and absent pulses in the involved extremity. Tissue viability depends on the extent to which flow is maintained by collateral circuits. When ischemia persists, motor and sensory paralysis and muscle infarction become irreversible in a matter of hours. Acute major arterial occlusion may be caused by an embolus, primary arterial thrombosis, trauma, or dissection. The heart is the embolic source in 80%90% of episodes, with the remainder from proximal arterial lesions. Aortic aneurysms often contain thrombus, but this material rarely causes symptomatic emboli. In contrast, femoral and particularly popliteal aneurysms embolize frequently. Ulceration in atherosclerotic plaques also can lead to formation of thrombus, which may fragment. Miscellaneous infrequent sources of emboli include cardiac tumors (including cardiac myxoma) and paradoxical emboli (venous thrombi migrating through a patent foramen ovale). Up to 5%10% of spontaneous emboli originate from a source that remains unidentified despite thorough diagnostic interrogation. It may be difficult to differentiate between sudden thrombosis of an atherosclerotic peripheral artery and embolic occlusion. The former patients usually have preexisting atherosclerotic stenosis and low blood flow, which predisposes to stagnation and thrombosis. One should also keep in mind the clinical setting and a history of preexisting symptoms such as atrial fibrillation (embolus) or claudication (primary thrombosis). Clinical Findings Acute arterial occlusion is characterized by the five Ps: pain, pallor, pulselessness, paresthesias, and paralysis. Severe sudden pain is present in 80% of patients, and its onset usually indicates the time of vessel occlusion. Pain is absent in some patients because of prompt onset of anesthesia and Downloaded Your IP is 82.116.202.56 paralysis and 2024131 portends a 5:55 poorAprognosis. Page 13 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility On examination, the key finding is a lack of palpable pulses in a diffusely painful extremity. Prognosis and management are heavily dependent on physical exam findings, which should include sensorimotor assessment (Table 36–2). Sensory fibers associated with light touch are highly susceptible the clinical setting and a history of preexisting symptoms such as atrial fibrillation (embolus) or claudication (primary thrombosis). EUROPEAN UNIVERSITY CYPRUS Access Provided by: Clinical Findings Acute arterial occlusion is characterized by the five Ps: pain, pallor, pulselessness, paresthesias, and paralysis. Severe sudden pain is present in 80% of patients, and its onset usually indicates the time of vessel occlusion. Pain is absent in some patients because of prompt onset of anesthesia and paralysis and portends a poor prognosis. On examination, the key finding is a lack of palpable pulses in a diffusely painful extremity. Prognosis and management are heavily dependent on physical exam findings, which should include sensorimotor assessment (Table 36–2). Sensory fibers associated with light touch are highly susceptible to ischemia, and their dysfunction heralds the beginning of irreversible ischemic changes. The onset of motor paralysis implies progression to unsalvageable tissue necrosis if not treated immediately. Early intervention is critical. Skin and subcutaneous tissues have greater resistance to hypoxia than nerves and muscles, which may demonstrate irreversible histologic changes after 3 hours or less of ischemia. Table 36–2. Rutherford classification of acute limb ischemia. Stage Limb Description Prognosis Sensory Loss Muscle Arterial Venous Weakness Doppler Doppler I Viable Not immediately threatened None None Audible Audible IIA Marginally Salvageable if promptly treated Minimal (toes) or None Often Audible threatened IIB III none inaudible Immediately Salvageable with immediate More than toes, pain Mild or moderate threatened revascularization at rest Irreversibly Major tissue loss/permanent nerve Profound, Profound, paralysis damaged damage inevitable anesthetic (rigor) Usually Audible inaudible Inaudible Inaudible Reproduced with permission from Rutherford RB, Baker JD, Ernst C, et al: Recommended standards for reports dealing with lower extremity ischemia: revised version, J Vasc Surg. 1997 Sep;26(3):517538. Treatment & Prognosis A. Embolism and Thrombosis Immediate anticoagulation by intravenous heparin slows the propagation of thrombus and allows time for assessment of adequacy of collateral flow and preparation for operation. Nonoperative management is rarely indicated except in debilitated patients and patients with emboli to major arteries in the upper extremities, which generally have good collateral circulation. If light touch is intact (Rutherford stage I or IIA; Table 36–2), CTA or conventional angiography sometimes may be useful to define the anatomy and assist in planning the operation. Diagnosis of acute embolic occlusion is based on an abrupt cessation of contrast opacification of the artery with little accompanying arterial disease; conversely, acute in situ thrombosis is associated with extensive atherosclerosis and a wellestablished collateral network. The operative treatment for an embolus, embolectomy, differs from that of preexisting atherosclerosis, which may require bypass. For patients presenting with more advanced ischemia but salvageable limbs (Rutherford stage IIB; Table 36–2), imaging should be deferred in favor of expeditious operative intervention. Therapeutic options include catheterdirected thrombolysis, percutaneous mechanical thrombectomy, and surgical embolectomy. For patients with severe acute ischemia, operative therapy is preferable because it is usually associated with the least delay in reestablishing perfusion. Surgical embolectomy may be performed through an arteriotomy at the site of the embolic occlusion or, most commonly, by clot extraction with a balloon catheter inserted through a remote arteriotomy. Successful embolectomy requires removal of the embolus and the “tail” of thrombus that extends distally or proximally from it. If operation is not performed within the first few hours, the clot may become adherent, and subsequent revascularization is less successful. Intraoperative infusion of thrombolytic agents is often a useful adjunct to embolectomy. In patients who will tolerate a delay in revascularization (Rutherford stage I; Table 36–2), particularly in the setting of thromboembolic bypass graft occlusion or extensive tibial involvement, intraarterial thrombolysis should be considered. The usual regimen involves selective intraarterial Downloaded 2024131 5:55artery A Your IP is 82.116.202.56 PageThis 14 / 47 infusion of doses of thrombolytic agent (eg,K.tissue Chapter 36:low Arteries, Gaurav Sharma; Samir Shahplasminogen activator) directly into the clot via a remotely placed, indwelling catheter. ©2024 McGraw Hill.plasminogen All Rights Reserved. Termsallows of Usehigh Privacy Policy Notice Accessibility activates thrombus more efficiently, concentrations in the clot while limiting systemic effect, and has acceptable complication rates. In cases of thrombosis on preexisting atherosclerotic lesions, thrombolysis reveals the underlying lesions that will require treatment to prevent recurrent thrombosis. catheter inserted through a remote arteriotomy. Successful embolectomy requires removal of the embolus and the “tail” of thrombus that extends EUROPEAN UNIVERSITY CYPRUS distally or proximally from it. If operation is not performed within the first few hours, the clot may become adherent, and subsequent revascularization Access Provided by: is less successful. Intraoperative infusion of thrombolytic agents is often a useful adjunct to embolectomy. In patients who will tolerate a delay in revascularization (Rutherford stage I; Table 36–2), particularly in the setting of thromboembolic bypass graft occlusion or extensive tibial artery involvement, intraarterial thrombolysis should be considered. The usual regimen involves selective intraarterial infusion of low doses of thrombolytic agent (eg, tissue plasminogen activator) directly into the clot via a remotely placed, indwelling catheter. This activates thrombus plasminogen more efficiently, allows high concentrations in the clot while limiting systemic effect, and has acceptable complication rates. In cases of thrombosis on preexisting atherosclerotic lesions, thrombolysis reveals the underlying lesions that will require treatment to prevent recurrent thrombosis. If revascularization is successful, a reperfusion injury may develop with significant swelling requiring fasciotomy to treat the compartment syndrome that may accompany the reperfusion injury. Vigilance for compartment syndrome is thus critical, and prophylactic twoincision, fourcompartment leg fasciotomies may be undertaken if the period of acute ischemia exceeded 46 hours or, even in the presence of lesser durations, if the ischemia was severe. Renal insufficiency from myoglobin release should be anticipated after reperfusion of ischemic muscle. Treatment consists of vigorous hydration and alkalinization of the urine. Administration of free radical scavengers such as mannitol may be helpful in this disorder. Patients with clearly irreversible limb ischemia (Rutherford stage III; Table 36–2) should undergo amputation without an attempt at revascularization because revascularization may expose the patient to the serious hazards of reperfusion caused by release of acidic and hyperkalemic venous blood from the dying extremity with little benefit given the futility of limb salvage attempts in this setting. B. Traumatic Arterial Occlusion An ABI of less than 0.9 in otherwise healthy, peripheral arterial disease–free patients with suspicion of traumatic arterial injury should prompt CTA. Traumatic arterial occlusion must be corrected within a few hours to avoid development of gangrene. Repair of arterial injury is usually performed in conjunction with repair of other injuries. Occasionally, temporary shunts are used to restore flow to the injured extremity while other injuries are addressed and repaired, until definitive vascular reconstruction can be undertaken. PERIPHERAL MICROEMBOLI Microemboli are most dramatic when they occlude a digital artery perfusing a toe or finger. This causes sudden pain, cyanosis, and coldness or numbness in the affected digit. These changes characteristically improve over several days. If there are multiple emboli, these symptoms may reappear in a different area of the hand or foot. In the lower extremity, this clinical entity has been called blue toe syndrome or trash foot. The sudden onset of pain and purple discoloration of a toe in the presence of palpable pulses is recognized as a potentially limbthreatening arterial problem. With each succeeding episode, recovery is slower and less complete. The most common source of microembolization is cardiac valvular disease. However, if no cardiac valvular lesions are found, a careful examination of the proximal arterial tree must be done to identify an arterial source shedding atheroemboli. Sudden onset may differentiate peripheral microembolism from other causes of blue toes, such as vasculitis, thromboangiitis obliterans, trauma, or chronic ischemia. If a single toe is affected, it is more likely to be the result of emboli, whereas multiple cyanotic toes are more likely to be the result of vasculitis or chronic ischemia. It is important to remember that a patent proximal artery is required to serve as a conduit for the embolus, so pulses are intact. Furthermore, a normal blood supply is present in adjacent tissue segments. The appearance of a normally perfused foot with a cyanotic toe is characteristic. However, the waxing and waning symptoms of repeated emboli can make the diagnosis difficult. Unless the syndrome is recognized, alternative diagnoses investigated, and the lesion of origin corrected, survival of the foot or hand may be in peril. Workup may include echocardiography, crosssectional imaging (eg, CTA), peripheral arterial duplex ultrasonography, and serology if vasculitides are suspected based on history and physical examination. Dean SM: Atypical ischemic lower extremity ulcerations: a differential diagnosis. Vasc Med. 2008;13:47. [PubMed: 18372440] DIABETIC VASCULAR DISEASE Atherosclerotic arterial disease in patients with diabetes mellitus is more diffuse and more severe than in nondiabetics. In diabetic patients, the tibioperoneal vessels frequently contain atherosclerotic changes, and the vessels are often heavily calcified. The degree of ischemia may be severe and extensive, and noninvasive tests (ABIs) may be falsely elevated. Fortunately, in many diabetics, the small arteries in the foot are relatively spared, making distal 2024131 bypass to these and allowing foot salvage in cases of threatened limb loss. Downloaded 5:55 arteries A Your possible IP is 82.116.202.56 Page 15 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah DiabeticMcGraw patientsHill. alsoAll have a high incidence Terms of neuropathy are more apt to ignore minor foot injuries, which can develop into ulcerations. ©2024 Rights Reserved. of Use and Privacy Policy Notice Accessibility Ulcerations associated with diabetic neuropathy typically occur at pressure points, such as the classic malum perforans ulcer on the plantar surface of the metatarsal heads. In contrast, classic arterial insufficiency ulcers occur at the tips of the toe. Patients often have comorbid arterial insufficiency and DIABETIC VASCULAR DISEASE EUROPEAN UNIVERSITY CYPRUS Access Provided by: Atherosclerotic arterial disease in patients with diabetes mellitus is more diffuse and more severe than in nondiabetics. In diabetic patients, the tibioperoneal vessels frequently contain atherosclerotic changes, and the vessels are often heavily calcified. The degree of ischemia may be severe and extensive, and noninvasive tests (ABIs) may be falsely elevated. Fortunately, in many diabetics, the small arteries in the foot are relatively spared, making distal bypass to these arteries possible and allowing foot salvage in cases of threatened limb loss. Diabetic patients also have a high incidence of neuropathy and are more apt to ignore minor foot injuries, which can develop into ulcerations. Ulcerations associated with diabetic neuropathy typically occur at pressure points, such as the classic malum perforans ulcer on the plantar surface of the metatarsal heads. In contrast, classic arterial insufficiency ulcers occur at the tips of the toe. Patients often have comorbid arterial insufficiency and neuropathy contributing to complex lesions. Daily foot inspections are essential to avoid progression of minor injuries into limbthreatening lesions. Neuropathy is also responsible for loss of tone of intrinsic foot muscles that leads to subluxation of the metatarsal phalangeal joints, resulting in a “rockerbottom” foot and ultimately producing complete joint destruction termed Charcot arthropathy. These architectural changes also make skin breakdown more likely to occur and require referral to a foot and ankle clinic. In addition to local foot care and glycemic control, assessment for concomitant peripheral arterial disease is essential to ensure that perfusion is optimized for wound healing. Conte MS: Diabetic revascularization: endovascular versus open bypass—do we have the answer? Semin Vasc Surg. 2012;25:108. [PubMed: 22817861] Gibbons GW, Shaw PM: Diabetic vascular disease: characteristics of vascular disease unique to the diabetic patient. Semin Vasc Surg. 2012;25:89. [PubMed: 22817858] Prompers L, et al: Predictors of outcome in individuals with diabetic foot ulcers. Diabetologia. 2008;51:747. [PubMed: 18297261] NONATHEROSCLEROTIC DISORDERS CAUSING LOWER LIMB ISCHEMIA Thromboangiitis Obliterans Thromboangiitis obliterans (Buerger disease) is characterized by multiple segmental occlusions of obliterating tibial and pedal arteries. The most distal arteries are affected, making bypass impossible. Migratory phlebitis may be present. In contrast to atherosclerosis, which involves the intima and media, thromboangiitis obliterans is manifested by infiltration of round cells in all three layers of the arterial wall. The disease occurs principally in young male smokers. Smoking cessation is the cornerstone of therapy. Patients with Buerger disease may have specific cellular immunity against arterial antigens, specific humoral antiarterial antibodies, and elevated circulatory immune complexes, but a precise diagnosis can be made only by tissue histology. Arteriographic findings are distinctive but not pathognomonic. Arterial bypass is not typically feasible because of the lack of distal targets. Amputation is indicated for persistent pain or gangrene and can be performed adjacent to the line of demarcation with satisfactory primary healing. The disease may become dormant if the patient can stop smoking. Unfortunately, smoking cessation seems particularly difficult in these patients, and many ultimately require multiple amputations. Popliteal Artery Entrapment Syndrome This rare cause of popliteal artery stenosis or occlusion occurs as a result of an anomalous course of the popliteal artery. The popliteal artery normally passes between the two heads of the gastrocnemius muscle as it enters the lower leg. In the entrapment syndrome, the artery passes medial to both heads of the gastrocnemius, causing compression of the popliteal artery when the knee is extended. There are five anatomic variants of popliteal artery entrapment, but all produce similar clinical effects. Fibrous thickening of the intima occurs at the site of compression and gradually progresses to total occlusion. Symptoms vary from calf claudication to those of more severe ischemia, depending on lesion severity and embolization. Popliteal artery entrapment should be considered when a young, otherwise healthy patient presents with calf claudication. Until the artery becomes occluded, the only finding is a decrease in strength of the pedal pulses, which is most evident when using provocative maneuvers such as foot passive dorsiflexion or active plantarflexion. Conventional angiography may be useful in demonstrating arterial pathology developing from the repetitive trauma to the vessel and may support the diagnosis by demonstrating stenosis or occlusion with provocative maneuvers but fails to demonstrate the causative extraarterial, anatomic pathology. MRI and CT studies are most useful in confirmation of the diagnosis (provocative positioning may be performed during image acquisition). Atherosclerotic changes are notably absent. Given the extrinsic pathology responsible for the disorder, open surgery is the mainstay of therapy. Treatment consists of returning the popliteal artery to its normal anatomic course by dividing the aberrant muscle fibers or fibrous band and/or bypass with saphenous vein. Surgery can be performed from a medial or posterior (prone) approach (Figure 36–7). Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Figure 36–7. Page 16 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Popliteal entrapment syndrome. A : Gadoliniumenhanced magnetic resonance imaging demonstrating aberrant slip of muscle and fibrous tissue (arrow) overlying the popliteal artery (arrowhead) in a symptomatic patient. B : Posterior approach via prone positioning demonstrating fibromuscular trauma to the vessel and may support the diagnosis by demonstrating stenosis or occlusion with provocative maneuvers but fails to demonstrate the causative extraarterial, anatomic pathology. MRI and CT studies are most useful in confirmation of the diagnosis (provocative mayCYPRUS be EUROPEANpositioning UNIVERSITY performed during image acquisition). Atherosclerotic changes are notably absent. Given the extrinsic pathology responsible Access Provided for by: the disorder, open surgery is the mainstay of therapy. Treatment consists of returning the popliteal artery to its normal anatomic course by dividing the aberrant muscle fibers or fibrous band and/or bypass with saphenous vein. Surgery can be performed from a medial or posterior (prone) approach (Figure 36–7). Figure 36–7. Popliteal entrapment syndrome. A : Gadoliniumenhanced magnetic resonance imaging demonstrating aberrant slip of muscle and fibrous tissue (arrow) overlying the popliteal artery (arrowhead) in a symptomatic patient. B : Posterior approach via prone positioning demonstrating fibromuscular abnormality (right angle clamp) with popliteal artery coursing underneath (forceps tip). Cystic Degeneration of the Popliteal Artery Arterial stenosis is produced by a mucoid cyst in the adventitia, usually located in the middle third of the artery. Calf claudication is the most common symptom, and the only finding is the disappearance of the pedal pulses with knee flexion (Ishikawa sign). Arteriography shows a sharply localized zone of popliteal stenosis with a smooth concentric tapering. Ultrasound or CT scans can be used to demonstrate the cyst within the vessel wall (displacement of the arterial flow lumen, or socalled “scimitar sign” of large lesions). The stenosis may be missed on conventional anteroposterior films and may appear only on lateral exposures. Treatments range from simple cyst aspiration to cyst excision to excision and replacement of the affected arterial segment; more radical treatments appear to reduce the risk of recurrence. Abdominal Aortic Coarctation Coarctations of the thoracic or abdominal aorta are rare. They may be congenital or may result from an inflammatory largevessel arteritis such as Kawasaki or Takayasu disease. These rare disorders may produce symptoms of lower extremity, mesenteric, or renal ischemia depending on the location of the constriction. The congenital variant of this condition is best managed surgically when it is recognized; autogenous repair may be preferable to the use of prosthetic grafts. Surgical repair in the presence of ongoing inflammation is not recommended because those patients do poorly. However, if the disease is quiescent with a normal sedimentation rate, standard surgical operations appear to produce satisfactory results. LOWER EXTREMITY AMPUTATION General Considerations More than 90% of the 110,000 amputations performed in the United States each year are for ischemic disease or infective gangrene. More than half of lower extremity amputations are performed for complications of diabetes mellitus, and 15%50% of diabetic amputees will lose a second leg within 5 years. Recent retrospective review has suggested that overall diseaseassociated amputation rates may actually be increasing. This risk is about two times higher for men than for women. Other indications for amputations are nondiabetic infection with ischemia (15%25%), ischemia without infection (5%10%), osteomyelitis (3%5%), trauma (2%5%), and frostbite, tumors, neuromas, and other miscellaneous causes (5%10%). Many patients facing amputation are near the end of life because of systemic cardiovascular disease. Approximately 20%30% of patients undergoing major amputation (belowknee or aboveknee) will be dead within 2 years. The prevalence of many comorbidities in this population is also reflected in the perioperative mortality rates for major amputation, ranging from 5% to 10% for belowknee amputations to 10% or higher for aboveknee amputations. The level of amputation is determined by assessing the likelihood of healing of the limb in association with the functional potential of the patient. Compared with normal walking, energy expenditure is increased by 10%40% with a belowknee prosthesis, 50%70% with an aboveknee prosthesis, Downloaded 5:55 A Your IP is 82.116.202.56 and 60% with 2024131 crutches. The clinical conundrum in patients with limb ischemia is twofold: (1) determining which limbs have adequate blood supply to Page 17 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K.which Shah patients with vascular disease have reasonable rehabilitation potential. The best predictions heal at the belowknee level and (2) determining ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility are based on clinical assessment by an experienced surgeon, assisted by one of the several noninvasive techniques, such as segmental Doppler pressures or transcutaneous measurement of oxygen tension. major amputation (belowknee or aboveknee) will be dead within 2 years. The prevalence of many comorbidities in this population is also reflected in EUROPEAN UNIVERSITY CYPRUS the perioperative mortality rates for major amputation, ranging from 5% to 10% for belowknee amputations to 10% or higher for aboveknee amputations. Access Provided by: The level of amputation is determined by assessing the likelihood of healing of the limb in association with the functional potential of the patient. Compared with normal walking, energy expenditure is increased by 10%40% with a belowknee prosthesis, 50%70% with an aboveknee prosthesis, and 60% with crutches. The clinical conundrum in patients with limb ischemia is twofold: (1) determining which limbs have adequate blood supply to heal at the belowknee level and (2) determining which patients with vascular disease have reasonable rehabilitation potential. The best predictions are based on clinical assessment by an experienced surgeon, assisted by one of the several noninvasive techniques, such as segmental Doppler pressures or transcutaneous measurement of oxygen tension. Lower Extremity Amputation Levels Lower extremity amputations are done most commonly at one of the following levels: toe (called digit amputations, which may be extended to include resection of the metatarsal and called ray amputations), transmetatarsal, belowknee, and aboveknee. Amputations at other levels (Syme amputation, Chopart amputation, and hip disarticulation) are infrequently performed for vascular disease. 1. Toe and ray amputations Toe amputations are the most frequently performed amputation (Figure 36–8). Over twothirds of amputations in diabetics involve the toes and forefoot. A guiding principle is midphalangeal or metatarsal resection to assure that all cartilaginous articular surfaces are removed because this material has no blood supply. The indications include gangrene, infection, neuropathic ulceration, frostbite, and osteomyelitis limited to the middle or distal phalanx. Contraindications to digit amputation include indistinct demarcation, infection at the metatarsal level, pallor on elevation, or dependent rubor indicating ischemia of the forefoot. Figure 36–8. Toe and ray amputations. For dry, uninfected gangrene of one or more toes, autoamputation may be allowed to occur. During this process, epithelialization occurs beneath the eschar, and the toe spontaneously detaches, leaving a clean residual limb at the most distal site. Although preferable in many patients, autoamputation sometimes requires months to complete. Ray, or wedge, amputation includes removal of the toe and metatarsal head; occasionally, two adjacent toes may be amputated by this method. As with toe amputation, there is modest and a prosthesis is not required. Ray amputation of the great toe leads to unstable weight bearing Downloaded 2024131 5:55 A cosmetic Your IP isdeformity 82.116.202.56 Page 18 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah and some difficulty with ambulation resulting from loss of the first metatarsal head. ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Complications that may require amputation at higher levels include infection, osteomyelitis of remaining bone, and nonhealing of the incision. These complications have been reported in up to onethird of diabetic patients. For dry, uninfected gangrene of one or more toes, autoamputation may be allowed to occur. During this process, epithelialization occurs beneath the EUROPEAN UNIVERSITY CYPRUS eschar, and the toe spontaneously detaches, leaving a clean residual limb at the most distal site. Although preferable in many patients, Access Provided by: autoamputation sometimes requires months to complete. Ray, or wedge, amputation includes removal of the toe and metatarsal head; occasionally, two adjacent toes may be amputated by this method. As with toe amputation, there is modest cosmetic deformity and a prosthesis is not required. Ray amputation of the great toe leads to unstable weight bearing and some difficulty with ambulation resulting from loss of the first metatarsal head. Complications that may require amputation at higher levels include infection, osteomyelitis of remaining bone, and nonhealing of the incision. These complications have been reported in up to onethird of diabetic patients. 2. Transmetatarsal amputation Transmetatarsal forefoot amputations preserve normal weight bearing. The principal indication is gangrene of several toes or the great toe, with or without soft tissue infection or osteomyelitis. Good blood supply is needed because the incision creates a generous plantar flap. There is no dorsal flap. On the plantar surface, the incision is continued medially to laterally just proximal to the metatarsophalangeal crease. The metatarsal bones are divided, with the medial and lateral shafts cut shorter than those in the middle to preserve the normal architecture of the foot and assist with orthotic fitting postoperatively, and the tendons are pulled down and transected as high as possible. Transmetatarsal amputation produces an excellent functional result. Walking requires no increase in energy expenditure, and the gait is usually smooth. A prosthesis is not mandatory, but to achieve optimal gait, the shoes must be modified. 3. Major leg amputations An attempt at performing a belowknee amputation is warranted in almost any patient who appears to be a potential candidate for rehabilitation. A. BELOWKNEE AMPUTATION The most common procedure for belowknee amputation is the Burgess technique, which uses a long posterior flap (Figure 36–9). The blood supply to a posterior flap is generally better than the supply to an anterior flap or to sagittal flaps, because the sural arteries (which supply the gastrocnemius and soleus muscles) arise high on the popliteal artery, an area not often diseased. The use of rigid dressings and immediate postoperative prostheses has proved advantageous. Application of a rigid cast bandage has several potential advantages: (1) It controls postoperative edema, which may reduce pain; (2) it protects the stump from trauma, particularly when a patient falls during attempts at mobilization; and (3) it allows the patient to be ambulatory with a temporary prosthesis much sooner. Figure 36–9. Belowknee amputation. B. ABOVEKNEE AMPUTATION Absolute indications for primary aboveknee amputation include contracture at the knee joint (observed in debilitated patients with longstanding extremity pain who have been in a prolonged withdrawal posture with the knee flexed) and nonviable calf muscle or skin for creation of the below knee flap. Patients unlikely to ambulate after belowknee amputation (eg, because of general deconditioning) and those unable to comply with physical therapy and thus at risk for development of a flexion contracture should be considered for aboveknee amputation even if able to heal a belowknee amputation. Aboveknee amputation may be performed at several levels, including knee disarticulation. Although it is advantageous to preserve as long a lever arm Downloaded 2024131 5:55 A Your IP is 82.116.202.56 as possible, disarticulation is technically demanding than transfemoral amputation at a higher level. The technique for standard above Page 19 / 47 Chapter 36:knee Arteries, Gaurav Sharma; Samir more K. Shah knee amputation is straightforward. Short anterior and posterior flaps, sagittal flaps, Accessibility or a circular incision may be used. The bone is divided ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice substantially higher than the skin and soft tissue to avoid tension when the wound is closed and later when the muscles of the thigh atrophy. A simple dressing is then applied. extremity pain who have been in a prolonged withdrawal posture with the knee flexed) and nonviable calf muscle or skin for creation of the below EUROPEAN UNIVERSITY CYPRUS knee flap. Patients unlikely to ambulate after belowknee amputation (eg, because of general deconditioning) and those unable to comply with Access Provided by: physical therapy and thus at risk for development of a flexion contracture should be considered for aboveknee amputation even if able to heal a belowknee amputation. Aboveknee amputation may be performed at several levels, including knee disarticulation. Although it is advantageous to preserve as long a lever arm as possible, knee disarticulation is technically more demanding than transfemoral amputation at a higher level. The technique for standard above knee amputation is straightforward. Short anterior and posterior flaps, sagittal flaps, or a circular incision may be used. The bone is divided substantially higher than the skin and soft tissue to avoid tension when the wound is closed and later when the muscles of the thigh atrophy. A simple dressing is then applied. SPECIAL PROBLEMS OF AMPUTEES Thromboembolism The amputee is at great risk for deep venous thrombosis (15%) and pulmonary embolism (2%) postoperatively because (1) amputation often follows prolonged immobilization during treatment of the primary disease, and (2) the operation involves ligation of large veins, causing stasis of blood, a situation that predisposes to thrombosis. If immediatefit prosthetic techniques are not employed, an additional period of inactivity follows the operation, further increasing the risk of thromboembolism. Rehabilitation After Amputation The rehabilitation goals following amputation are highly variable. Younger patients universally want to regain ambulatory status and frequently return to work. Elderly patients with significant comorbid conditions may remain wheelchairbound, and much of their rehabilitation is focused on providing wheelchair access in their living situations and working on independent transfers. It is important to understand that amputation in an elderly patient is frequently an event that occurs near the end of life. For these people, relief of pain and provision for modest function may be the most appropriate outcome in the limited amount of time they have left. The length of the residual limb correlates well with regaining the ability to walk. Cardiopulmonary disease and physical weakness make walking an overwhelming effort for some patients; this emphasizes the importance of preserving a belowknee amputation if possible, so that walking will require the least possible amount of energy. Pain & Flexion Contracture Physical therapy consultation is an important adjunct to prevent contracture. Flexion contractures of the knee or hip occur rapidly in the painful limb because of the relative strength of the flexors over the extensors. Measures to prevent contracture are indicated preoperatively, and application of a rigid dressing postoperatively decreases the incidence of this complication. Phantom Pain Persistent sensations in a residual limb are almost universal. Unfortunately, phantom limb pain also is common. Treatment is difficult; improvement has been reported using tricyclic antidepressants and other medications used for neuropathic pain, transcutaneous electrical nerve stimulation, and calcitonin. The incidence and severity of phantom limb pain are increased if there was prolonged ischemia before amputation and decreased if postoperative rehabilitation is rapid. Brown BJ, Crone CG, Attinger CE: Amputation in the diabetic to maximize function. Semin Vasc Surg. 2012;25:115. [PubMed: 22817862] Fleury AM, Salih SA, Peel NM: Rehabilitation of the older vascular amputee: a review of the literature. Geriatr Gerontol Int. 2013;13:264. [PubMed: 23279009] Humphries MD, Brunson A, Li CS, et al: Amputation trends for patients with lower extremity ulcers due to diabetes and peripheral artery disease using statewide data. J Vasc Surg. 2016;64:1747–1755. [PubMed: 27670653] Landry GJ, Silverman DA, Liem TK, et al: Predictors of healing and functional outcome following transmetatarsal amputations. Arch Surg. 2011;146:1005. [PubMed: 21930995] Downloaded 2024131 5:55 A Your IP is 82.116.202.56 CEREBROVASCULAR DISEASE Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility General Considerations Page 20 / 47 using statewide data. J Vasc Surg. 2016;64:1747–1755. [PubMed: 27670653] EUROPEAN UNIVERSITY CYPRUS Landry GJ, Silverman DA, Liem TK, et al: Predictors of healing and functional outcome following transmetatarsalAccess amputations. Arch Surg. Provided by: 2011;146:1005. [PubMed: 21930995] CEREBROVASCULAR DISEASE General Considerations Unlike in the other vascular beds, symptoms of extracranial carotid disease are most often caused by embolization. Arterial emboli account for approximately onequarter of strokes in Europe and North America, and 80% of these originate from atherosclerotic lesions in a surgically accessible artery in the neck. The most common lesion is at the bifurcation of the carotid artery. Transcranial Doppler studies have shown that emboli are seen in approximately 20% of patients with moderate (> 50% stenosis) lesions at the carotid bifurcation and even higher rates with more than 70% stenoses. The incidence and frequency of emboli are increased in recently symptomatic patients. The neurologic dysfunction associated with microemboli may appear as sudden “shortlived,” or transient, neurologic symptoms that may include unilateral motor and sensory loss, aphasia (difficulty with understanding and expressing language), or dysarthria (difficulty speaking due to motor dysfunction). These are termed transient ischemic attacks (TIAs). Most TIAs are brief, but by convention, a duration of 24 hours is the limit of a TIA. If the symptoms persist, it is a stroke, or cerebrovascular accident (CVA). An embolus to the ophthalmic artery, the first branch of the internal carotid artery, produces a temporary monocular loss of vision called amaurosis fugax or permanent blindness. Atherosclerotic emboli may be visible as small bright flecks (Hollenhorst plaques) lodged in arterial bifurcations in the retina. Characteristically, lesions of atherosclerosis in the internal carotid artery occur along the wall of the carotid bulb opposite to the external carotid artery origin (Figure 36–10). The enlargement of the bulb just distal to this major branch point creates an area of low wall shear stress, flow separation, and loss of unidirectional flow. Presumably, this allows greater interaction of atherogenic particles and the vessel walls at this site and accounts for the localized plaque at the carotid bifurcation. Figure 36–10. Cerebrovascular circulation anatomy. Downloaded 2024131 5:55 A Your IP is 82.116.202.56 The accessibility of thisGaurav localized atheroma allows effective removal of the plaque and a dramatic reduction in stroke risk. Landmark trial data the Pagefrom 21 / 47 Chapter 36: Arteries, Sharma; Samir K. Shah ©2024demonstrated McGraw Hill. that All Rights Reserved. Use Privacy Policy26% Notice Accessibility 1990s with even the best Terms medicaloftherapy at that time, of patients with TIAs and 70% or greater stenosis of the carotid artery develop permanent neurologic impairment (CVA) from continued embolization at 2 years. The risk of CVA can be reduced to 9% with plaque removal. The risk of CVA is lower for patients presenting with amaurosis fugax. localized plaque at the carotid bifurcation. EUROPEAN UNIVERSITY CYPRUS Figure 36–10. Access Provided by: Cerebrovascular circulation anatomy. The accessibility of this localized atheroma allows effective removal of the plaque and a dramatic reduction in stroke risk. Landmark trial data from the 1990s demonstrated that with even the best medical therapy at that time, 26% of patients with TIAs and 70% or greater stenosis of the carotid artery develop permanent neurologic impairment (CVA) from continued embolization at 2 years. The risk of CVA can be reduced to 9% with plaque removal. The risk of CVA is lower for patients presenting with amaurosis fugax. Clinical Findings A. Symptoms Patients with cerebrovascular disease can be grouped into three categories based on symptoms at presentation. 1. Asymptomatic disease An audible bruit heard in the neck may be the only manifestation of cerebrovascular disease. Severe carotid stenosis may also occur in the absence of a bruit with markedly reduced blood flow. Ultrasound screening may identify these patients. 2. Transient ischemic attacks Sudden onset of a neurologic deficit in the distribution of the anterior or middle cerebral arteries requires investigation of the carotid arteries. Symptoms depend on the ischemic area of the brain, the size of the embolus, and the condition of collaterals to the affected area. Hypoperfusion rarely causes transient neurologic and visual attacks. In symptomatic patients, stroke risk after TIA correlates with the severity of internal carotid artery stenosis. Patients with multiple TIAs, particularly if these are increasing in frequency or severity, stroke in evolution, or waxing and waning neurologic deficits and highgrade stenoses should be treated urgently, because otherwise they may suffer irreversible deficits. 3. Stroke (CVA) Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Page 22 / 47 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah Intervention is indicated for patients after stroke who have either complete mild to moderate deficits, because up to onehalf will suffer ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy recovery Notice or Accessibility another stroke with further loss of neural function. The timing of intervention is controversial. In select patients, endarterectomy is now recommended within 14 days of the initial neurologic event or earlier. If the infarct is large and the stenosis severe, a healing period prior to revascularization may be stenosis. EUROPEAN UNIVERSITY CYPRUS Access Provided by: Patients with multiple TIAs, particularly if these are increasing in frequency or severity, stroke in evolution, or waxing and waning neurologic deficits and highgrade stenoses should be treated urgently, because otherwise they may suffer irreversible deficits. 3. Stroke (CVA) Intervention is indicated for patients after stroke who have either complete recovery or mild to moderate deficits, because up to onehalf will suffer another stroke with further loss of neural function. The timing of intervention is controversial. In select patients, endarterectomy is now recommended within 14 days of the initial neurologic event or earlier. If the infarct is large and the stenosis severe, a healing period prior to revascularization may be advisable to prevent hemorrhage into the necrotic area with restoration of systemic pressure. In stroke patients, the perioperative risk of additional neurologic deficit is higher than in patients after TIA. 4. Distribution TIAs and strokes attributable to the carotid typically occur in the middle cerebral artery distribution. In the posterior circulation, emboli are less common and hypoperfusion is the dominant pathology. Reduction of flow in the vertebral and basilar arteries may cause drop attacks, clumsiness, and a variety of sensory phenomena. Frequently, the symptoms are bilateral. Vertigo, diplopia, or dysequilibrium occurring individually is rarely due to vertebrobasilar disease, but when these symptoms occur in combination, the diagnosis becomes more likely. It is unusual for dizziness alone to be due to cerebrovascular disease. B. Signs A thorough neurologic exam is necessary in all patients both to ensure that the findings are attributable to a carotid stenosis (eg, findings of left arm and leg weakness are not likely to be secondary to highgrade left carotid artery stenosis) and to establish a baseline for comparison on subsequent exam, including after any intervention. Auscultation of the carotid and subclavian arteries is of questionable value because bruits are nonspecific findings. C. Imaging 1. Doppler ultrasound The most useful test for the diagnosis of extracranial carotid artery disease is the duplex ultrasound. As the stenosis encroaches on the lumen of the vessel, the velocity of blood increases in the area of the stenosis to maintain distal flow. Doppler spectral velocity analysis determines the flow rate rapidly and with reasonable accuracy. This allows an estimate of the degree of stenosis. Ultrasound can also display plaque morphology but with less reproducibility than stenosis. 2. CTA and MRA CTA and MRA are often used for confirmation of duplex findings and planning interventional procedures (Figure 36–11). Both types of imaging can assess the degree of stenosis at the carotid bifurcation, providing information on the configuration of the aortic arch and identifying additional disease in the proximal supraaortic trunk and intracerebral vessels. These studies also delineate regions of ischemic damage in the brain. Diffusion weighted MRI of the brain is particularly sensitive and will define areas of injury as well as areas of infarction. CTA also displays calcifications, the visualization of which can assist in planning clamp placement and the extent of distal exposure necessary should carotid endarterectomy be undertaken. Figure 36–11. Carotid bifurcation occlusive disease. A : Threedimensional computed tomography (CT) angiogram of neck demonstrating carotid bifurcation stenosis. B : Axial CT view demonstrating the lesion. Downloaded 2024131 5:55 A Your IP is 82.116.202.56 Chapter 36: Arteries, Gaurav Sharma; Samir K. Shah ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 23 / 47 Figure 36–11. EUROPEAN UNIVERSITY CYPRUS Access Provided by: Carotid bifurcation occlusive disease. A : Threedimensional computed tomography (CT) angiogram of neck demonstrating carotid bifurcation stenosis. B : Axial CT view demonstrating the lesion. 3. Arteriography Cerebral arteriography is occasionally performed in patients with symptomatic or asymptomatic cerebrovascular disease. It is most useful for cases in which noninvasive studies are in disagreement or in those patients who are candidates for carotid angioplasty and stenting. Cerebral diagnostic arteriography is invasive and has a low but significant risk of stroke (0.5%1.0%) due to wire and catheter manipulation within the aortic arch and carotid artery itself. Treatment Stroke risk is highest immediately after a TIA, returning to baseline at approximately 6 months. Consequently, in symptomatic patients with carotid stenosis, early intervention is mandatory. Antiplatelet therapy, usually in the form of aspirin or clopidogrel, is particularly important in cerebrovascular patients. Cardiovascular risk factor modification is also imperative in reducing stroke and overall mortality. After a completed stroke, caution must be exercised when planning an intervention. A. Carotid Endarterectomy Carotid endarterectomy, the removal of the atherosclerotic lesion at the carotid bifu

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