You are in: eMedicine Specialties > Vascular Surgery > MEDICAL TOPICS Popliteal Artery ThrombosisArticle Last Updated: May 24, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Deron J Tessier, MD, Staff Surgeon, Kaiser Permanente Medical Center, Fontana, CA Deron J Tessier is a member of the following medical societies: American College of Surgeons and American Medical Association Coauthor(s): Russell A Williams, MBBS, Program Director, Professor, Department of Surgery, University of California Medical Center at Irvine Editors: Richard M Stillman, MD, FACS, Honorary Medical Staff, Northwest Medical Center; Former Chief of Staff and Medical Director, Wound Healing Center, Department of Surgery, Northwest Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Vincent Lopez Rowe, MD, Assistant Professor of Surgery, Department of Surgery, Division of Vascular Surgery, University of Southern California Medical Center; Paolo Zamboni, MD, Professor of Surgery, Chief of Day Surgery Unit, Chair of Vascular Diseases Center, University of Ferrara, Italy; William H Pearce, MD, Chief, Division of Vascular Surgery, Violet and Charles Baldwin Professor of Vascular Surgery, Department of Surgery, Northwestern University School of Medicine Author and Editor Disclosure Synonyms and related keywords: popliteal artery thrombosis, popliteal artery occlusion, popliteal artery disease, popliteal artery aneurysm, claudication, cardiovascular disease, cystic adventitial disease, atherosclerosis, peripheral arterial reconstructive operations, lower limb amputations, lower extremity limb ischemia, gangrene INTRODUCTIONSection 2 of 11
  Popliteal artery occlusion is a common occurrence, especially in elderly patients and those with diabetes mellitus and other cardiovascular diseases. Each year, more than 100,000 peripheral arterial reconstructive operations and 50,000 lower limb amputations for lower extremity limb ischemia are performed in the United States. Many of these are related to popliteal artery disease. ProblemPopliteal artery occlusion and the disease processes leading up to it cause morbidity and mortality by decreasing or completely blocking blood supply though the popliteal artery and into the lower leg and foot. Tissue ischemia results. Claudication usually is the first manifestation, followed by rest pain and tissue loss (gangrene). Once a portion of a lower extremity becomes gangrenous, infection becomes a constant mortal threat. FrequencyAtherosclerosis is by far the most common cause of popliteal artery occlusion. Popliteal artery aneurysms are the most common peripheral aneurysms. They occur in 0.01% of all hospitalized patients. From 50-70% of aneurysms are bilateral. These aneurysms are most often caused by either atherosclerosis or trauma. Fifteen percent of lower extremity emboli affect the popliteal artery. Popliteal entrapment is a rare cause of popliteal artery occlusion. This syndrome occurs most commonly in young athletes, such as cyclists. Cystic adventitial disease is another rare cause of popliteal artery occlusion, accounting for only 254 reported cases since the first description by Ejrup and Hiertonn in 1954. EtiologyPopliteal artery thrombosis can be caused by atherosclerosis, popliteal artery aneurysm, emboli, popliteal entrapment syndrome, cystic adventitial disease, and trauma. PathophysiologyDuring exercise, muscles require 2-10 times more blood than when at rest. Mild nonocclusive arterial obstruction minimally affects resting blood flow but severely curtails the body's response to exercise. The first symptom of a decrease in the body's ability to deliver blood is ischemic pain during exercise. As the stenosis worsens, pain at rest and tissue loss follow. As the stenosis progresses and proceeds to occlusion, collateral vessels, via the descending genicular artery, propagate and flourish, providing the distal leg with much needed arterial blood. However, collateral circulation does not provide the amount of blood needed in the exercising leg, and it does not guarantee leg viability. In the absence of sufficient collateral blood flow in the extremity with an occluded popliteal artery, limb viability is tenuous. If the occluded popliteal artery is not treated, significant morbidity and mortality can result. Atherosclerosis Atherosclerotic disease isolated to the popliteal vessels is not common; however, popliteal occlusion as a result of atherosclerosis associated with other lesions is extremely common. As the atherosclerotic lesion enlarges, normal laminar flow in the artery is disrupted, causing eddy currents and thrombus formation. Additionally, ulcerated plaques promote local thrombus formation, and the result is a primary popliteal thrombus that occludes flow. Popliteal artery aneurysm The exact cause of popliteal artery aneurysms is not known. Historically, the common causes were mycotic, syphilitic, or traumatic in nature. As the population ages, arteriosclerosis seems to be the dominant associated factor. Turbulent flow distal to arteriosclerotic lesions is believed to result in distal dilation of the vessel at the adductor hiatus. Decreased wall strength, turbulent flow, and constant kinking and motion from normal movement of the knee joint are believed to result in aneurysm formation. Emboli Fifteen percent of emboli emanating from proximal sources result in popliteal disease. Common sources include mural thrombi in the heart, diseased heart valves, abdominal aortic aneurysms, or iliac aneurysms. Popliteal entrapment syndrome The pathophysiology of popliteal entrapment is unknown. In 1985, Mosimann postulated that increased use of the knee joint causes intimal fibrosis of the vessel lumen, thereby decreasing flow and causing claudication and eventual occlusion. Cystic adventitial disease The mechanism of cystic adventitial disease was first thought to be a primary dysplasia of the blood vessel wall. In a 1984 report, Leu and associates suggest that the cysts associated with this disease originate from ectopic tissue of the joint capsule or bursa. Following some type of trauma to the popliteal area, collagenous and muscular fibers in the joint and the myocytes around it undergo focal necrosis. Multiple loculated cysts result, the lumen of which are filled with mucinous material containing amino acids without carbohydrates, cholesterol, or calcium. The cysts compress the popliteal artery, either causing thrombus or directly impinging and occluding arterial blood flow. Trauma Injuries to the popliteal arteries may cause endothelial damage and subsequent thrombus formation. ClinicalWith the exceptions of emboli and trauma, the course of disease culminating in popliteal artery occlusion is insidious. Patients present with claudication symptoms in the calf and foot. Ankle-brachial indices are diminished, the extent of which depends on collateral flow. An index of less than 90% is abnormal, an index of greater than 50% is associated with claudication, and an index of less than 30% is associated with limb threat and rest pain. Atherosclerosis These patients are older (sixth and seventh decades of life) and may be asymptomatic or have claudication, rest pain, or tissue ischemia or loss below the knee. Chronic decreased blood supply also manifests as loss of hair on the affected limb, thickened toenails, dependent rubor, and pallor upon elevation. Popliteal artery aneurysm Approximately one third of patients are asymptomatic at the time of diagnosis. Patients may present with distal embolization or aneurysmal thrombosis that is causing claudication or popliteal occlusion. In addition, the aneurysms can rupture, causing a threat to leg viability and life itself. This occurs much less frequently than thrombosis of the aneurysm. On the contrary, abdominal aortic aneurysms are more likely to rupture than thrombose. Patients typically present in their sixth or seventh decade of life, with a pulsatile mass in the subsartorial or popliteal area, as observed upon physical examination. Popliteal entrapment syndrome These patients are young, otherwise healthy, athletic people who, upon examination, are pain-free at rest. Ankle-brachial indices at rest are normal. Findings from Doppler examinations at rest are normal. Abnormal findings after Doppler examination with dorsiflexion of the foot are diagnostic of popliteal entrapment syndrome. Cystic adventitial disease Patients usually are healthy, nonsmoking, middle-aged men with a sudden onset and rapid progression of intermittent claudication. The only physical examination sign is a loss of foot pulses with knee flexion (Ishizawa sign). Symptoms predominately are unilateral. INDICATIONSSection 3 of 11
Regardless of the reason for popliteal artery occlusion, the indications for performing an operation include severe claudication that alters lifestyle and may threaten tissue viability or lead to tissue loss. Patients with infection or gangrene in deeper tissues require amputation. Amputation is also indicated for those patients who are unable to ambulate because of reasons other than the popliteal artery thrombosis, such as paraplegia and acute lateral sclerosis. However, special consideration should be given to those patients in whom the effect of amputation would have deleterious effects on the ability to transfer to or balance in a wheelchair. Indications for Diagnostic and Therapeutic Interventions (from Veith, 1986)
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The popliteal artery sits on the posterior aspect of the leg, in the popliteal fossa. The superficial femoral artery becomes the popliteal artery as it passes through the adductor hiatus, and it proceeds until it trifurcates into the peroneal, anterior tibial, and posterior tibial arteries. Collateral circulation is achieved through the descending genicular, lateral-superior genicular, middle-superior genicular, lateral-inferior genicular, and medial-inferior genicular arteries. CONTRAINDICATIONSSection 5 of 11
The vast majority of patients with atherosclerotic disease that is severe enough to cause popliteal artery occlusion have atherosclerotic disease elsewhere (including the coronary circulation). These patients require a workup to determine their operative morbidity and mortality risks. Those with coronary artery disease (or any other disease) significant enough to substantially increase morbidity and mortality should be managed by either conservative medical therapies or limb amputation. WORKUPSection 6 of 11
Imaging Studies
Other Tests
TREATMENTSection 7 of 11
Medical therapyAtherosclerosis Atherosclerotic popliteal thrombosis in which the limb is not imminently threatened is best treated medically, with smoking cessation and exercise. These lifestyle changes help maintain high flows in, and patency of, collateral vessels. Short-term results are attained with clot lysis using, for example, tissue plasminogen activator (TPA), urokinase, or streptokinase. Popliteal artery aneurysm Because of the high rate of complications from aneurysms, medical therapies such as clot lysis are not routinely initiated except to identify an artery for distal anastomosis or when the patient is critically ill and cannot withstand an operation. If a vascular bypass operation is impossible, amputation is usually performed. Emboli Treatment with lysis, such as with urokinase and TPA, can be efficacious. However, emboli are likely to recur if definitive therapy is not undertaken for the underlying problem. Popliteal entrapment syndrome Aside from surgical intervention, rest is the only other treatment shown to decrease symptoms. Cystic adventitial disease No effective medical treatments are available for cystic adventitial disease. Surgical therapyPopliteal artery occlusion Surgical therapy for popliteal artery occlusion is bypass of the occlusion, which can be achieved with grafts, including in situ greater saphenous, reversed, or polytetrafluoroethylene (PTFE) grafts. For bypasses reaching below the knee joint, vein grafts have superior patency (3-y patency of 70% vs 50% for PTFE). The reverse vein bypass graft, first described by Kunlin in 1949, has become the favored operation for bypass of a thrombosed popliteal artery. The ipsilateral greater saphenous vein is the conduit of first choice. If that is unavailable, the contralateral greater saphenous vein, arm veins, the lesser saphenous vein, or the popliteal vein can be used. The popliteal artery is accessible from medial thigh and calf incisions. The anastomosis can be performed either end-to-end or side-to-side. If the latter is chosen in the case of an aneurysm, the aneurysm must be excluded from the circulation by ligature. Emboli Emboli may be evacuated from distal vessels by either the use of a balloon catheter or intraoperative thrombolysis. Popliteal entrapment syndrome Popliteal entrapment syndrome can be treated with endofibrosectomy (endarterectomy) with enlargement of the artery with a saphenous vein patch, which has been shown to alleviate symptoms. Cystic adventitial disease Cystic adventitial disease has been treated in numerous ways. Evacuation with removal of the cyst wall has had a 94% initial success rate in 68 operations performed. Evacuation with a vein patch has had a 66% initial success rate in 9 operations performed. Evacuation with a synthetic patch has had a 75% initial success rate in 4 operations performed. Aspiration has had a 66% initial success rate in 3 operations performed. Resection with a vein graft has had a 95% initial success rate in 54 operations performed. Resection with synthetic graft placement has had a 90% initial success rate in 10 operations performed. Resection with end-to-end anastomosis of primary vessel has had a 100% initial success rate in 3 operations performed. Resection with homograft placement has a 100% initial success rate in 2 operations performed. Three cases resolved spontaneously. Angioplasty has not been successful. Preoperative detailsThe majority of patients with occlusion of the popliteal artery have some component of coronary artery disease or another comorbid condition. Preoperative ECG, chest radiography, and coagulation studies are recommended. In nonemergent cases, performing lower extremity angiography is important for identifying the site of occlusion, any collateral circulation, and possible target vessels for bypass. If the use of a vein is anticipated, Doppler studies should be performed to assess the caliber and patency of the veins. Those patients with gangrene of the affected leg require a course of antibiotics and wound care prior to the bypass operation. Although not an absolute contraindication, leg infections increase the incidence of graft infections and subsequent failure. Intraoperative detailsCareful cardiac monitoring must be employed in the operative intervention of popliteal artery thrombosis. These patients usually have significant comorbid conditions (eg, coronary artery disease, chronic obstructive pulmonary disease) that increase the risk of stroke, myocardial infarction, or bleeding episodes. Upon completion of the bypass, some form of confirmation of technical competency must be performed (eg, completion angiography, intraoperative duplex ultrasonography, continuous-wave Doppler ultrasonography). Postoperative detailsOn the first postoperative day, patients should begin aspirin therapy and, if indicated, beta-blockers. Postoperative ankle-brachial indices should be obtained before the patient is discharged from the hospital. These serve as a baseline to which subsequent ankle-brachial indices can be compared in the event of restenosis. Postoperative visits for duplex scanning of the graft are undertaken every 3 months for a year and every 6 months thereafter. Follow-upFollow-up should be performed at regular intervals to assess for restenosis, which usually results from technical failures, intimal hyperplasia, or disease (particularly atherosclerosis) progression at other sites. COMPLICATIONSSection 8 of 11
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The use of endovascular stents in vascular surgery has opened a new realm of microinvasive possibilities. Although still preliminary, initial results for infrainguinal endovascular stent deployment are extremely promising. Some have advocated intravascular thrombolytics in the acute setting; however, aggressive and close monitoring should be instituted. ACKNOWLEDGMENTSSection 10 of 11
The authors and editors of eMedicine gratefully acknowledge the contributions of previous author Yale D Podnos, MD, MPH to the development and writing of this article. REFERENCESSection 11 of 11
Popliteal Artery Thrombosis excerpt Article Last Updated: May 24, 2006 |
