Is revascularization and limb salvage always the treatment for critical limb ischemia?

Despite marked advances in the technical ability to perform lower extremity revascularization, the decision whether to perform primary amputation or attempt revascularization in high risk patients is a major part of modern vascular care. With an aging population and improved medical care that has increased life expectancy, more patients with severe systemic disease are presenting with critical limb ischemia (CLI). In addition, it is well recognized that CLI patients suffer diagnostic delays and poor risk factor modification, which in part contributes to limb loss and poor patient survival. Unlike other disease entities, CLI does not have a clear clinical pattern that provides consistent entry to medical care and uniform treatment algorithm. In this commentary we will discuss the issue from several viewpoints. The unique features of the antecedent natural history of CLI will be presented. Available data on functional outcomes on both therapies for CLI will be presented. Morbidity and mortality of both approaches will be covered, including the risk of multiple procedures, followed by an examination of specific problematic patient populations. Finally, we will close with some potential approaches to these problems and future studies that are needed to push forward our ability to appropriately make these difficult decisions for an increasingly aging population.

How to avoid cardiac ischemic events associated with aortic surgery.

Whereas there is some degree of coronary artery disease (CAD) in most patients undergoing vascular surgery, there is no consensus regarding how to avoid perioperative cardiac ischemic events. Although this edition of Seminars in Vascular Surgery is devoted to aortic surgery, it must be remembered that the incidence of adverse cardiac outcomes after infrainguinal operations is at least as great as after aortic procedures. Thus, much of the information discussed herein will be applicable to patients undergoing all varieties of vascular surgery. Numerous strategies exist for preoperative cardiac testing before vascular operations. These strategies range from routine evaluation before surgery to a "minimalist" approach, treating all patients as though CAD was present. Although advocates of various algorithms often are unwavering in their convictions, there are no randomized, prospective studies comparing different strategies for evaluation and management of patients with CAD undergoing vascular surgery. Potential adverse effects of evaluation and cardiac intervention should be considered before undertaking screening studies. The authors analyzed the adverse outcomes of preoperative cardiac evaluation and intervention before vascular operations in patients treated at the Denver Department of Veterans Affairs Medical Center. Of 153 patients undergoing vascular procedures, 42 had extended cardiac evaluations. Sixteen (38%) patients had untoward events related to this evaluation. Extensive cardiac evaluation before vascular operations can result in morbidity, delays, and refusal to undergo vascular surgery. The underlying indication for vascular operations and the local iatrogenic cardiac complication rates should be considered before ordering special studies. Several recent randomized, prospective studies have established that perioperative beta-adrenergic blockade is beneficial in vascular patients with CAD. Beta-Blocker therapy can reduce the risk of perioperative adverse cardiac outcomes by 55%. The Coronary Artery Revascularization Prophylaxis (CARP) trial currently underway is a multicenter, prospective comparison of invasive intervention for CAD versus best medical care in patients undergoing aortic and lower extremity vascular surgery funded by the Department of Veterans Affairs Cooperative Studies Program.

Iatrogenic vascular injuries from percutaneous vascular suturing devices.

OBJECTIVE: The purpose of this study was to examine the patterns of injury and the strategies of surgical repair of iatrogenic vascular injuries from a percutaneous vascular suturing device after arterial cannulation. METHODS: We retrospectively reviewed the clinical experience from an academic vascular surgical practice over a 2-year period. The subjects were patients undergoing vascular repair of iatrogenic vascular injury after deployment of a percutaneous vascular suturing device. Interventions were direct repair of arterial injury (with or without device extraction) or arterial thrombectomy and repair. The main outcome variables included patterns of arterial injury, magnitude of arterial repair, limb salvage, hospital stay, and perioperative mortality and morbidity rates. RESULTS: From August 1998 through August 2000, eight patients (4 men, 4 women; median age, 55 years; range, 44-80 years) required vascular operations for complications of percutaneous suturing devices after diagnostic (2) or therapeutic (6) arteriograms through a transfemoral approach. Complications included four pseudoaneurysms (1 infected) due to arterial tear from suture pull through, two entrapped closure devices due to device malfunction, and two arterial thromboses due to narrowing/severe intimal dissection. All patients required operative intervention. Direct suture repair with or without device removal was performed in five patients, arterial debridement with vein patch angioplasty in one patient, and arterial thrombectomy and vein patch angioplasty in two patients. There were no perioperative deaths. The median hospital stay was 5 days (range, 2-33). Limbs were salvaged in all patients with a mean follow-up of 4.8 months (range, 1-13). CONCLUSIONS: Although abbreviated postangiography recovery periods and early ambulation have motivated the widespread use of percutaneous suturing devices, the infrequent occurrence of vascular injuries produced by these devices can be significantly more challenging than simple acute pseudoaneurysms or hemorrhage. In addition, thrombotic complications have a small but finite risk of limb loss.

Epithelioid hemangioendothelioma of the common femoral vein: Case report and review of the literature.

A young competitive skier had venous claudication. A stenosis of the left common femoral vein was revealed by means of an examination. Exploration and vein patch angioplasty were performed, and because of both the unusual appearance (focal thickening of vein wall) and the unclear etiology of the lesion, frozen and permanent sections of the wall were obtained. Epithelioid hemangioendothelioma, a rare intravascular sarcoma, was revealed by means of an examination of the permanent sections. Two additional procedures were required to completely excise the epithelioid hemangioendothelioma. We discuss these rare vascular malignancies and include a review of the available literature. Also, oncologic principles important in both the diagnosis and therapy of intravascular sarcomas are discussed.

Negative impact of cardiac evaluation before vascular surgery.

The optimal preoperative evaluation of cardiac risk in patients with peripheral vascular disease is controversial. In developing a paradigm for preoperative cardiac workup, potential adverse effects of evaluation and cardiac intervention must be considered. This study analyzed the deleterious outcomes of extensive, comprehensive cardiac evaluation and intervention before planned vascular surgery in patients treated at the Denver Department of Veterans Affairs Medical Center. Over a 12-month period between 1994 and 1995, 161 patients were scheduled to undergo major vascular operations; 153 patients came to operation. The decision to pursue a cardiac evaluation was variously made by a combination of surgeons, cardiologists, and anesthesiologists. No defined protocol was followed. Cardiac history, chest X-rays and ECGs were obtained for all patients. Extended cardiac evaluation included these studies plus special tests, including echocardiography (echo), radionuclide ventriculography (RNVG), dipyridamole thallium scintigraphy (DTS), and cardiac catheterization (CC). Extended cardiac evaluations were undertaken in 42 patients. Complications related to percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) were also recorded. Cardiac mortality and morbidity after vascular interventions were itemized in all 153 patients. Forty-two male patients, aged 68 +/- 9 years, underwent extended cardiac evaluations before planned vascular operations. The median elapsed time for cardiac workup was 14 days (mean 30 +/- 59 days). The median and mean times from cardiac workup to vascular surgery were 25 days and 76 +/- 142 days, respectively. Eighteen (43%) patients had echo or RNVG; 22 (52%) patients had DTS; 27 (64%) had CC; 9 (21%) had PTCA; 7 (17%) had CABG. Sixteen (38%) patients had untoward events related to cardiac evaluation. Eight patients (19%: one with cerebrovascular disease, and seven with aortic aneurysms) refused vascular surgery after extended cardiac workup. Complications attributable to CC, PTCA, and CABG included prosthetic graft infection, pseudoaneurysms (two), sternal wound infections (two), renal failure and brain anoxia. Two patients with severe limb ischemia who were candidates for revascularization ultimately required amputations because of delay due to cardiac evaluations. Extensive cardiac evaluation prior to vascular operations can result in morbidity, delays, and refusal to undergo vascular surgery. The underlying indication for vascular operations and the local iatrogenic cardiac complication rates must be considered before ordering special studies.

Reliability of treadmill testing in peripheral arterial disease: a comparison of a constant load with a graded load treadmill protocol.

This study aims to evaluate the reliability of repeated graded workload treadmill testing (G-test; 2 mph; 0% grade, increasing 2% every 2 min) and to compare the reliability of a constant workload treadmill protocol (C-test; 2 mph; 12% grade) versus the graded workload treadmill protocol in patients with intermittent claudication, studied longitudinally. A clinical trial investigating an orally stable prostacycline derivative that included 330 patients with intermittent claudication was performed. The trial employed three active treatment groups and one placebo group. Because there were no significant inter-group differences at baseline or after treatment, data from all groups were pooled for the evaluation of treadmill test reliability. Treadmill data were obtained from a 2-week run-in phase where three G-tests were performed, as well as from the beginning and the end of a 3-month double-blind phase where a G-test and a C-test were performed in random order. Treadmill test reliability was described through test process-related and between-subject variances and also using variance-derived parameters such as the reliability coefficient (RC) and the relative precision (RP). A higher value for the RC and a lower value for the RP indicate that the test variability is predominantly due to between-subject variance and not to test process-related variance. Estimates of variance were described for both the maximal or absolute claudication distance (ACD) and the initial claudication distance (ICD) with each treadmill test. Reliability estimates are reported for the total study sample and for patients with baseline claudication distances < or =300 feet and >300 feet (approximately < or =100 m; >100 m), as measured with the C-test. The cut-off value was empirically chosen to separate severely diseased from mild to moderately diseased claudicants. Theoretical considerations suggest that reliability measures may differ in these subgroups. With repeated testing during the run-in phase for the measure of ACD, the G-test had an RC of 0.952 and an RP of 21.9%. With the comparison of both test protocols in the entire study population for the measurement of ACD, the G-test had an RC of 0.902 and an RP of 31.3%, while the C-test had an RC of 0.876 and an RP of 35.2%. The results for ICD on the G-test were an RC of 0.809 and an RP of 43.7%, while the C-test had an RC of 0.737 and an RP of 51.3%. The reliability of the ACD measurement for RC and RP was numerically superior to those for the ICD for both protocols. In patients with a baseline ACD < or =300 feet, the RC for ACD on the G-test was 0.827 and the RP was 41.4%. In contrast, on the C-test the RC decreased to 0.250 and the RP increased to 86.6%. These changes in RC and RP were due to a marked decrease in the between-subject variance, demonstrating the inability of the C-test to separate appropriately the different claudication distances in populations with highly limited baseline claudication distances. During a run-in phase, the G-test has excellent test characteristics. During the longitudinal phase of a trial, the reliability of G-tests and C-tests are comparable in the entire study population. However, in patients with low claudication distances, the G-test should be given preference over the C-test.

Intermediate-term outcome of primary digit amputations in patients with diabetes mellitus who have forefoot sepsis requiring hospitalization and presumed adequate circulatory status.

PURPOSE: The intermediate success and outcome of primary forefoot amputations in patients with diabetes mellitus who have sepsis limited to the forefoot and presumed adequate forefoot perfusion, as determined by means of noninvasive methods, was studied. METHODS: Cases of a university hospital-based practice from January 1984 to April 1998 were retrospectively reviewed. Patients included had diabetes mellitus with forefoot sepsis requiring immediate hospitalization for digit amputations who had adequate arterial circulation for healing based on noninvasive and clinical assessment: palpable pedal pulses (29%), "compressible" ankle pressure of 70 mm Hg or higher (48%), pulsatile metatarsal waveforms (67%), and/or toe pressure higher than 55 mm Hg (36%). All patients underwent a primary single- or multiple-digit amputation (through the interphalangeal joint, metatarsal head, or metatarsal shaft). Additional forefoot procedures (debridement, digit amputation) were performed during the follow-up period as needed for persistent or recurrent infection. The main outcome variables were recurrent or persistent foot infection (defined as requiring rehospitalization for antibiotics, wound care, and/or reoperation), the number of repeat operations and hospitalizations for salvage of limbs with recurrent or persistent infections, and time to complete forefoot healing or foot amputation. RESULTS: Ninety-two patients who had diabetes mellitus with 97 forefoot infections comprised the study group. Ninety-seven primary digit amputations (34 through interphalangeal joints, 28 through metatarsal heads, 35 through metatarsal shafts) were performed. The median length of hospital stay was 10 days. There were no operative deaths. The mean follow-up period was 21 months (range, 3 days to 105 months). The primary amputation healed (without persistent infection) in only 38 limbs (39%), at a mean time of 13 +/- 10 weeks. Twenty-three limbs (24%) had not healed the primary amputation without evidence of persistent infection at last follow-up (mean, 12 weeks). Infection persisted in 35 limbs (36%), and infection recurred in 15 of 38 (40%) healed limbs. An average of 1.0 reoperations (range, 0 to 3) and 1.6 rehospitalizations (range, 1 to 4) were involved in salvage attempts in these recurrent/persistent infections. Five persistent and five recurrent infections ultimately healed (mean, 53 weeks). Complete healing was achieved in only 33 of 97 limbs (34%). Twenty-two foot amputations (20 transtibial, two Syme's) were performed (mean, 49 +/- 74 weeks; 20 for persistent infection). Eighteen persistent/recurrent infections remained unhealed at the last follow-up examination (mean, 105 weeks). CONCLUSION: Patients with diabetes mellitus who have sepsis limited to the forefoot requiring acute hospitalization and undergoing primary digit amputations have a high incidence of intermediate-term, persistent, and recurrent infection, leading to a modest rate of limb loss, despite having apparently salvageable lesions and noninvasive evidence of presumed adequate forefoot perfusion.

Contemporary management of isolated iliac aneurysms.

OBJECTIVE: Because isolated common iliac artery aneurysms are infrequent, are difficult to detect and treat, and have traditionally been associated with high operative mortality rates in reported series, we analyzed the outcomes of operative repair of 31 isolated common iliac artery aneurysms in 21 patients to ascertain morbidity and mortality rates with contemporary techniques of repair. METHODS: A retrospective review study was conducted in a university teaching hospital and a Department of Veterans Affairs Medical Center. Perioperative mortality and operative morbidity rates were examined in 17 men and four women with isolated common iliac artery aneurysms between 1984 and 1997. Ages ranged from 38 to 87 years (mean 69 +/- 8 years). Slightly more than half of the cases were symptomatic, with abdominal pain, neurologic, claudicative, genitourinary, or hemodynamic symptoms. One aneurysm had ruptured and one was infected. There was one iliac artery-iliac vein fistula. All aneurysms involved the common iliac artery. Coexistent unilateral or bilateral external iliac aneurysms were present in four patients; there were three accompanying internal iliac aneurysms. Overall, 52% of patients had unilateral aneurysms and 48% had bilateral aneurysms. Aneurysms ranged in maximal diameter from 2.5 to 12 cm (mean 5.6 +/- 2 cm). No patients were unavailable for follow-up, which averaged 5.5 years. RESULTS: Nineteen patients underwent direct operative repair of isolated iliac aneurysms. One patient had placement of an endoluminal covered stent graft; another patient at high risk had percutaneous placement of coils within the aneurysm to occlude it in conjunction with a femorofemoral bypass graft. Patients with bilateral aneurysms underwent aortoiliac or aortofemoral interposition grafts, whereas unilateral aneurysms were managed with local interposition grafts. There were no deaths in the perioperative period. Only one elective operation (5%) resulted in a significant complication, compartment syndrome requiring fasciotomy. The patient treated with the covered stent required femorofemoral bypass when the stent occluded 1 week after the operation. The patient treated with coil occlusion of a large common iliac aneurysm died 2 years later when the aneurysm ruptured. CONCLUSIONS: Isolated iliac artery aneurysms can be managed with much lower mortality and morbidity rates than aneurysm previously been reported by using a systematic operative approach. Percutaneous techniques may be less durable and effective than direct surgical repair.

Interposition grafting for reoperation on the common femoral artery.

PURPOSE: This report details our experience with common femoral artery resection and Dacron interposition grafting in the management of vascular reoperations involving the common femoral artery. DESIGN: Retrospective review. SETTING: University teaching hospital. SUBJECTS: Consecutive reoperative patients who had common femoral artery interposition grafting for arteriosclerotic occlusive disease from 1986 to 1997. INTERVENTIONS: Common femoral artery resection and interposition grafting. MAIN OUTCOME MEASURES: Operative morbidity and mortality rates and long-term patency, limb salvage, patient survival, freedom-from-graft-infection, and freedom-from-reoperation rates. RESULTS: Ninety-nine common femoral arteries (16 bilateral) were resected and replaced with Dacron interposition grafts in 83 patients (50 male, 33 female; mean age, 65 years) who had had 237 previous ipsilateral common femoral artery operations (mean, 2.4 operations; range, 1-9 operations). Simultaneous infrainguinal bypass grafts were performed in 52 operations (53%), and 60 operations (61%) were performed in patients who had had previous ipsilateral proximal bypass grafts. Operative mortality was 2%, with a 14% rate of perioperative wound complications. Mean follow-up time was 22 months. One- and 3-year assisted primary patency rates for the interposition grafts were 90% and 77%, respectively. Both 1- and 3-year life-table-determined limb salvage rates were 95%. One- and 3-year life-table-determined freedom-from-reoperation rates were 74% and 43%, respectively. One- and 3-year life-table-determined freedom-from-infection rates were 99% and 92%, respectively. One- and 3-year life-table-determined survival rates were 82% and 73%, respectively. CONCLUSIONS: Common femoral artery resection and Dacron interposition grafting are safe, and they obviate many difficulties associated with reoperative common femoral artery surgery with satisfactory long-term results.

Iatrogenic vascular trauma.

With the increasing performance of percutaneous transluminal angioplasty and insertion of an increasing number of intravascular devices, the size of arterial punctures has been increasing. A consistent minority of these procedures will result in vascular injuries requiring treatment. At the same time, the regionalized nature of trauma care in the United States has resulted in a large number of vascular surgeons who are exposed to vascular trauma only when iatrogenic. The most common injuries observed are caused by percutaneous vascular instrumentation and include hemorrhage and pseudoaneurysm that may compress adjacent structures, fistula, acute occlusion, and embolization. Injuries unique to balloon angioplasty/stenting include arterial rupture and dissection. Indwelling intravascular devices are another common source of iatrogenic vascular injury ranging from arterial rupture to thrombosis and embolization. Much less common injuries are observed in orthopedic and abdominal/laparoscopic operations but show reproducible causes/patterns. Finally, pediatric iatrogenic vascular trauma is relatively common because of the small size of the vasculature, but the natural history and management is markedly different from that in adults.

Upper extremity ischemia from subclavian artery aneurysm caused by bony abnormalities of the thoracic outlet.

OBJECTIVE: To describe our experience with surgical therapy for upper extremity ischemia incident to emboli from aneurysms of the subclavian artery. DESIGN: Retrospective review case series. SETTING: Vascular surgery practice at a university hospital-based tertiary referral center. PATIENTS: All patients treated for upper extremity ischemia caused by embolism from a subclavian artery aneurysm from January 1, 1990, to July 31, 1996. INTERVENTION: All patients underwent detailed history and physical examination, screening for immunologic and hypercoaguable disorders, noninvasive vascular laboratory evaluation, and arteriography of the aortic arch in both arms and hands. Surgical treatment consisted of rib excision or fracture plating, aneurysm excision, and interposition vein grafting, with additional saphenous vein bypasses to brachial or forearm arteries as needed to provide uninterrupted circulation to the wrist. RESULTS: Twelve patients (6 males; mean age, 37 years) were treated. All had episodic upper extremity ischemia with an initial misdiagnosis of primary vasospastic disorder. Rest pain and/or ischemic ulceration developed in 3. Duration of symptoms before correct diagnosis averaged 7 months (range, 1-36 months). All patients had bony abnormalities of the thoracic outlet (8 cervical ribs, 3 abnormal first ribs, and 1 unstable clavicular fracture). All aneurysms contained intraluminal thrombus, and all patients had multiple ipsilateral distal arm, forearm, and/or hand arterial occlusions indicating chronic and repeated embolization. All patients underwent aneurysm excision and interposition vein grafting, with additional vein bypass to the brachial (3 patients) and/or forearm arteries (5 patients). Mean follow-up was 18 months (range, 2 weeks to 63 months). Eleven patients had complete symptomatic relief, and 1 patient improved. All subclavian interposition grafts remained patient. Two distal bypass grafts occluded in patients with preoperative arteriograms demonstrating no patient forearm arteries. There has been no limb loss. CONCLUSIONS: Hand ischemia caused by embolization from a subclavian artery aneurysm occurs in young patients without atherosclerosis and is frequently misdiagnosed as vasospasm. Despite advanced disease and multiple chronic distal arterial occlusions, surgical treatment by resection of bony abnormalities, aneurysm excision and grafting, and distal bypass grafting produces excellent results.

Homocysteinemia as a risk factor for atherosclerosis: a review.

Elevation in plasma homocysteine has been widely studied as an independent risk factor for atherosclerosis. Animal laboratory models have demonstrated rapid onset vascular lesions with homocysteine infusion. A large body of data indicates a consistent relationship between plasma homocysteine and symptomatic atherosclerotic disease involving the coronary, peripheral, and cerebral circulations. Elevated plasma homocysteine can be predictably normalized with oral folate in most patients. Despite the wealth of published clinical data on this topic, it is unknown if normalization of plasma homocysteine in patients with symptomatic atherosclerosis will prevent or arrest the disease process.

Homocysteinemia as a risk factor for atherosclerosis: a review.

In industrialized nations, the leading cause of death and disability is atherosclerosis. Despite a widespread research effort spanning decades, there remains no clearly defined cause or cure for this disease that directly or indirectly affects the lives of almost all individuals in the western world. Autopsy findings show atherosclerosis to some degree in nearly all aged people, suggesting it should be regarded as a normal aging process as well as a disease. Any investigation of atherosclerosis etiology therefore requires a distinction between atherosclerosis normally observed with aging, and pathologic atherosclerosis causing disease and/or death. Atherosclerosis is most appropriately regarded as a disease when associated with both rapid progression and clinical symptoms. Widely accepted risk factors for atherosclerotic disease include advanced age, diabetes, tobacco use, arterial hypertension, hypercholesterolemia, hypertriglyceridemia, decreased high-density lipoprotein, some hypercoaguable states, sedentary life-style, and elevated plasma homocysteine. The study of lipid metabolism has dominated research into atherosclerosis etiology for decades, although now it is widely recognized that a large number of people with symptomatic atherosclerotic disease have no detectable evidence of abnormal lipid metabolism. Elevation in plasma homocysteine has also been widely studied as an independent risk factor for atherosclerosis. A description of the metabolism of homocysteine, its relationship to vascular disease, evidence supporting its role as an independent risk factor for atherosclerotic vascular disease, and the potential role of treatment will form the basis for this review.

Improving selection of patients with less than 60% asymptomatic internal carotid artery stenosis for follow-up carotid artery duplex scanning.

PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) indicated significant benefit from endarterectomy compared with medical therapy for patients with 60% to 99% asymptomatic internal carotid artery (ICA) stenoses. To date, optimal selection of patients for vascular laboratory follow-up to determine progression from < 60% to > or = 60% asymptomatic ICA stenosis is unknown. To determine which patients with < 60% asymptomatic ICA stenoses are at greatest risk for short-term progression to > or = 60% without symptoms, we reviewed vascular laboratory results and clinical risk factors of consecutive patients who were prospectively observed in a study of atherosclerosis progression. METHODS: Carotid duplex studies were obtained every 6 months and were reviewed for progression from < 60% to > or = 60% asymptomatic ICA stenosis by using criteria that were developed and reported by our laboratory. Clinical risk factors and velocities from initial duplex scans were analyzed for association with progression from < 60% to > or = 60% ICA stenoses without symptoms. RESULTS: Two hundred sixty-three patients (mean age, 66 years) with 434 asymptomatic < 60% ICA stenoses were prospectively observed for a mean of 20 months, with a mean of four examinations per patient. Seventeen patients (6.5%) and 18 ICAs (4%) progressed without symptoms to > or = 60% ICA stenoses at a mean of 18 months. Clinical risk factors associated with progression to > or = 60% asymptomatic ICA stenosis included elevated systolic blood pressure and decreased ankle-brachial index (p = 0.05). The mean initial ICA peak systolic velocity (PSV) in ICAs that progressed to > or = 60% asymptomatic stenoses was 180 cm/sec, compared with 104 cm/sec in asymptomatic ICAs that did not progress to > or = 60% (p = 0.0003). Thirty-one percent of asymptomatic ICAs that had initial PSVs of 175 cm/sec or greater progressed to > or = 60% stenosis, whereas only 1.8% that had initial PSVs less than 175 cm/sec progressed to > or = 60% asymptomatic stenoses (p < 0.001). The life-table-determined rate of freedom from progression to > or = 60% stenosis was 94% at 4 years for asymptomatic ICA lesions that had initial PSVs less than 175 cm/sec, compared with 14% at 3 years for lesions that had initial PSVs > or = 175 cm/sec. CONCLUSIONS: Early progression from < 60% asymptomatic ICA stenoses to > or = 60% asymptomatic ICA stenoses occurs infrequently. Patients who are at the greatest risk of early progression without symptoms to an ACAS-positive lesion can be identified from the ICA PSV at their initial duplex examination. Early vascular laboratory follow-up of asymptomatic ICA stenoses may be limited to a relatively small group.