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Infrapopliteal Intervention for the Treatment of the Claudicant
Infrapopliteal Intervention for the Treatment of the Claudicant Matthew T. Menard, MD and Michael Belkin, MD As the associated risks of infrainguinal balloon angioplasty and stenting have fallen and the relative success rates have risen in recent years, the threshold for offering endovascular treatment to patients with claudication has significantly decreased. Patients once considered appropriate only for risk-factor modification, exercise therapy, and medical treatment are now increasingly being offered percutaneous revascularization as a primary treatment option. Similarly, occlusive disease of the tibial vessels, once thought to be the exclusive domain of operative bypass, is increasingly being treated percutaneously. Over this same period, results of operative infrainguinal arterial reconstruction have also considerably improved. In modern times, excellent outcomes following bypass grafting with autogenous vein to the tibial level have been demonstrated, with morbidity, mortality, and long-term patency equivalent to that of more proximal bypasses. Evidence supports the view that the anatomic level of the distal anastomosis is less critical to the long-term outcome of the procedure than factors such as operative indication and conduit quality. Within the context of this changing climate, it is an appropriate time to examine and potentially redefine the role of both endovascular and open surgical intervention for a population that has not traditionally been offered revascularization, patients with claudication secondary to infrageniculate occlusive disease. Semin Vasc Surg 20:42-53 © 2007 Elsevier Inc. All rights reserved.
T
HE RECENT ERA in vascular surgery has been marked by a significant paradigm shift in the treatment of atherosclerotic occlusive disease. The changes have been driven, in part, by continued advances in the perioperative treatment of cardiac and comorbid medical disease, anesthetic management, and surgical technique. This progress has allowed surgical reconstruction to be routinely undertaken on older and sicker patients, and bypass grafts to tibial and pedal targets carried out with fewer complications and improved durability. Newer treatment patterns have also been considerably impacted by ongoing technological advances and an increasing use of endovascular techniques. Similar to the influence that introduction of endovascular aortic aneurysm repair has had on treatment of aneurysmal disease, the management of peripheral vascular occlusive disease has increasingly moved to a less operative and more percutaneous approach. In recent years, angioplasty and stenting have become the firstline therapy in patients with aortoiliac, renal, subclavian, and
Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital, Boston, MA. Address reprint requests to Michael Belkin, Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115. E-mail: mbelkin@ partners.org
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0895-7967/07/$-see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1053/j.semvascsurg.2007.02.007
coronary atherosclerotic disease. It also plays an increasing role in treatment of mesenteric and carotid occlusive disease and of the femoropopliteal and infrageniculate arterial segments. Illustrating these trends in our own institution, for example, we performed 75% fewer aortobifemoral and extraanatomic bypass grafts in the period from 1994 to 2004, compared with the prior decade. We have also performed 30% fewer infrainguinal bypass grafts since establishing our endovascular program, in comparison to the equivalent time interval prior to that point. In a report typical of many vascular surgery divisions, Sullivan and Langan1 reported a 324% increase in the annual endovascular case volume between 1996 and 2000 in their Greenville, South Carolina academic practice. Further highlighting the impact of the treatment changes taking place, some senior British surgeons have even called into question whether tibial-level bypass should remain an index procedure for vascular surgical trainees. Within this backdrop, the appropriate role for surgery and endovascular therapy for intermittent claudication remains controversial. Based on our own and others accumulated experience with femorotibial reconstruction, we have come to believe that infrageniculate surgical bypass is appropriate for a carefully selected subgroup of healthy patients with
Infrapopliteal intervention for treatment of claudicant
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symptomatic impairment from claudication. In certain patients with a favorable anatomic disease pattern, we have also come to support judicious utilization of endovascular therapy for claudicants with tibioperoneal or proximal tibial arterial occlusive disease.
neous therapy,10 particularly in the face of the current fiscal crisis within our healthcare system.
Claudication
Diagnosis of infrainguinal occlusive disease is generally made based on patient symptomatology and physical examination. Noninvasive hemodynamic testing in the form of segmental pressure measurements, pulse volume recordings, and treadmill exercise testing helps to objectively document the degree of disease severity. Claudication remains a relative indication for intervention, with functional quality-of-life improvement the goal of therapy. The anticipated benefits must be carefully weighed against the specific comorbid limitations imposed by concomitant cardiac impairment, pulmonary disease, and musculoskeletal conditions in a given patient. Following diagnosis of symptomatic lower-extremity occlusive disease and the decision to pursue intervention, additional imaging is warranted. Duplex ultrasonography, magnetic resonance imaging (MRA), and computerized tomographic angiography (CTA) are increasingly being utilized as first-line modalities in planning the optimal revascularization approach, and have supplanted contrast angiography as the initial imaging study of choice. Given the quality of current-generation machines, there has been recent support for use of duplex scanning as a stand-alone preoperative mapping modality.11 One group has even advocated for duplex-guided angioplasty and stenting of femoral and tibial level occlusive disease.12 As this practice requires a highly dedicated vascular laboratory, it has not, to date, gained wide acceptance. CTA is being used increasingly as a preoperative roadmapping technique in institutions able to provide high-quality three-dimensional reconstructions. MRA is also particularly useful as a noninvasive screening test to determine the suitability for percutaneous therapy, as advances have solved many of the technical limitations of earlier studies (see Fig 1). Should a lesion amenable to percutaneous therapy be identified, angiography is then pursued. In some instances, when the distal target for a planned surgical reconstruction is at the tibioperoneal trunk or proximal tibial level, we have proceeded directly to surgery based solely on MRA scanning if high-quality time-offlight and gadolinium-enhanced images are obtained.13 Given persistent limitations with both CTA and MRA technology, however, we have usually been reluctant to give up the confirmation afforded by standard contrast angiography when the bypass target is at the more distal tibial or pedal level.
Arterial occlusive disease is highly prevalent in Western society, and constitutes the leading overall cause of death in the United States. With the aging of the American population, the prevalence of lower-extremity occlusive disease has increased steadily in recent decades. Chronic obliterative atherosclerosis of the infrainguinal vessels is the most prevalent manifestation of arterial occlusive disease encountered by the vascular surgeon. Claudication is the cardinal presenting symptom and affects 5% of people over 55 years of age. Another 10% of those in this age group have asymptomatic peripheral atherosclerotic disease, while 1% has critical leg ischemia in the form of rest pain or gangrene.2 Natural history studies, such as the Framingham Heart Study, indicate patients with claudication have increased rates of cardiovascular mortality, but an overall low risk of associated limb loss.3,4 The majority of claudicants will demonstrate a stable pattern of disease throughout their lifetime, or have improvement in their symptoms as a result of risk-factor modification, while 20% to 30% will come to operation within 5 years as a result of disease progression. The annual rates of mortality and limb loss in patients with claudication are typically reported to be 5% and 1%, respectively.5 Risk factors consistently shown to be associated with disease progression in patients with claudication have included continued smoking, diabetes mellitus, low or declining ankle brachial index (ABI), and presence of multilevel disease.6 Diabetic patients represent a particularly challenging cohort, given their known predilection for multisegment and diffuse disease and high degree of popliteal trifurcation and tibial vessel involvement. They are at up to a 10-fold higher risk of progression to critical ischemia compared with nondiabetics7 and often display a more tenuous collateral network with compromised reserve, of importance when considering the implications of a tibial level intervention. Of relevance to a discussion on where the appropriate threshold for intervention for claudication should be set, Rutherford has called into question the commonly quoted estimates of death and loss of limb associated with claudication. Citing evidence based on objective hemodynamic confirmation of the diagnosis rather than clinical assessment alone, he believes the actual rate of limb loss per year for claudicants is more in the range of 5%, particularly in those with ABIs in the range of 0.4 to 0.6.8 Recent studies have indicated that between 17% to 41% of patients with objective clinical evidence of arterial occlusive disease will progress to critical ischemia.6,7,9 Some have pointed to the increasing prevalence of diabetes and the growing burden imposed by infrainguinal occlusive disease in our more sedentary and aging population to justify a wider applicability of percuta-
Diagnosis and Pretherapeutic Assessment
Management Risk-factor modification remains the cornerstone of management for lower-extremity occlusive disease. Smoking cessation, blood pressure control, and aggressive efforts at cholesterol-lowering should be addressed with every patient with atherosclerotic disease. Lipid-lowering therapy
M.T. Menard and M. Belkin
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Figure 1 Magnetic resonance angiogram identifying long-segment occlusion of superficial femoral artery, heavily diseased popliteal artery, and intact peroneal artery runoff, a disease pattern amenable to femorotibial bypass reconstruction.
involves both dietary modification and, more recently, increasing use of 3-hydroxy-3-methylglutaryl coenzyme A reductase⫺inhibitor medication, particularly given recent evidence demonstrating the beneficial effects of statins over and above that associated with their cholesterol-lowering properties. Strong evidence exists supporting the efficacy of a structured walking program14 in increasing the walking distance of patients with claudication. The value of walking outside of a structured regimen with close follow-up is more debatable.15 Medical management with pentoxifylline (Trental, Aventis Pharmaceuticals, Inc, Bridgewater, NJ) or, more recently, cilostazol (Pletal, Otsuka America Pharmaceuticals, Inc, Rockville, MD) has benefit in a subset of patients and remains a reasonable first-line approach to improve claudication symptoms.16 Finally, antiplatelet therapy, either aspirin or clopidogrel, is a critically important element of the treatment of established occlusive disease,17 given its documented ability to prevent thrombosis and embolization and possibly even to arrest the progression of atherosclerosis. Angiography is typically undertaken via a retrograde femoral approach after accessing the femoral artery from the contralateral limb. In patients in whom noninvasive imaging indicates a widely patent common femoral and proximal superficial femoral artery and body habitus is not prohibitive, an antegrade approach can serve as useful alternative. In ambiguous lesions, pull-back pressure measurements, both before and after administration of a systemic vasodilator such as papaverine or nitroglycerine, can be useful in documenting the hemodynamic significance of a particular stenotic zone.18 The use of gadolinium (Magnevist, Berlex Laborato-
ries, Inc, Montville, NJ)19 or carbon dioxide20 as contrast agents in patients with compromised renal function, although somewhat less effective in the periphery than in the aortoiliac vasculature, can minimize or eliminate the nephrotoxic effects associated with standard iodinated contrast medium.
Infrageniculate Surgical Reconstruction Based largely on the natural history studies outlined here, a conservative approach has typically been advocated for the majority of patients with claudication. Unlike the scenario in patients with critical limb ischemia, an aggressive approach was thought to place patients without a limb-threatening condition at an unnecessary risk of limb loss. Given that the majority of claudicants remain stable for years, it was thought preferable to allow for collateral pathways to develop, with the hope that many patients would improve to an extent that intervention would prove unnecessary.2 Aortofemoral reconstruction for claudication, however, gained acceptance as a viable therapeutic option in good-risk patients given both the excellent long-term patency rates and the perception that those with aortoiliac level are at higher risk of progression to critical ischemia. With subsequent reports documenting minimal associated operative mortality, excellent long-term palliation and absence of added risk of limb loss beyond that expected from the expected course of the disease process, femoropopliteal bypass for claudication also gained widespread acceptance.
Infrapopliteal intervention for treatment of claudicant
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Table 1 Comparative 5-Year Patency and Limb-Loss Results of Vascular Reconstructions in Patients with Claudication
Conte et al27 Femorotibial Femoropopliteal Femorotibial* Byrne et al28 Femorotibial Fem-AK-pop Fem-BK-pop
n
Operative Mortality (%)
Primary 5-Year Patency (%)
Secondary 5-Year Patency (%)
Limb Loss 5-Year (%)
57 261 369
0 0 0
81 74 51
86 81 61
0 3 25
94 165 150
0 0 0
79 48 70
83 50 78
0 .6 0
Abbreviations: AK, above the knee; BK, below the knee. *Operative indication of limb salvage.
In distinction, traditional teaching has held that tibial-level surgical reconstruction for the treatment of claudication is unduly aggressive. Over and above concerns that long-distance revascularization might fail to provide symptomatic relief in patients with either multilevel disease or tibial occlusive disease in isolation, there was a general view that the potential morbidity of extensive reconstructive surgery to the infrapopliteal vessels would not sufficiently offset the expected clinical benefit. Further underlying the conservative approach was a belief that graft failure might result in distal arterial thrombosis, with the potential to convert a situation of relatively benign claudication to the far more ominous situation of limb threat. Given initial patency rates for tibial bypass performed for critical ischemia that failed to match those of femoropopliteal grafts,21,22 and at least one report of up to a 46% amputation rate associated with femorotibial bypass,23 the recommended caution appeared well-founded. In recent years, however, as techniques for distal infrainguinal reconstruction have evolved and tibial level bypass has proven increasingly successful for patients with critical limb ischemia, the aforementioned dogma has come under challenge. In the current era, low mortality rates and 5-year patency rates for single-segment saphenous vein bypass grafts of ⬎80% can be expected at institutions devoted to peripheral bypass surgery.24-26 Given improved outcomes in claudicants compared with those with critical limb ischemia, and comparable if not slightly improved results for tibial bypass compared with popliteal bypass for claudicants, it now appears appropriate to offer tibial level surgical reconstruction to carefully selected patients with limiting claudication and appropriate anatomy. Two specific reports describing favorable results with this patient population serve the basis for our current recommendations.27,28 In 1995, Conte and colleagues27 reviewed the experience at the Brigham and Women’s Hospital in the small subset of patients who had undergone femorotibial bypass for claudication in the 16-year period leading up to 1993. Comparison subgroups to the 53 study patients included 261 patients who underwent femoropopliteal bypass for claudication and 369 patients who underwent femorotibial bypass for limb salvage indications. There was no perioperative mortality and the major morbidity rate was 9% for the study group. Fiveyear primary and secondary patency rates were 81% and
86%, respectively; these results were similar to those for patients undergoing femoropopliteal bypass for claudication, but significantly improved compared to the group undergoing femorotibial bypass for limb salvage (see Table 1). Of particular note, there were no major amputations in the study cohort, while 3% of the femoropopliteal group and 25% of the limb-salvage subgroup had required an amputation by 5 years. Also of interest, the 5-year survival rate for claudicants undergoing femorotibial bypass was only 54%, a level not significantly different from the group with limb salvage as an indication. Finally, successful palliation was achieved in 71% of patients, and as many as 86% expressed overall satisfaction with the operation and would recommend it to others in a similar condition. Several years later, a similar experience was published by the group from Albany, New York. Their series reviewed the outcomes of 409 patients undergoing infrainguinal bypass for claudication over the period from 1987 to 1997, which included 94 patients with infrageniculate outflow targets.28 Operative mortality was 0% for the entire cohort, and a single limb was lost secondary to distal embolization. The 5-year primary and secondary patency rates of 79% and 83% seen for those patients undergoing tibial bypass was better than that seen for patients bypassed to either the above-knee or below-knee popliteal artery (Table 1). Taken together, these studies support the conclusion that arterial reconstruction for disabling claudication to the tibial level can be performed safely and with excellent durability. They also suggest that concern for limb loss with an aggressive surgical approach for claudication may be unfounded. It is important to note that both series represented a highly selected and small minority of patients within the much larger group of patients undergoing lower-extremity bypass at the respective institutions (eg, just 2.1% out of a series of nearly 4,500 bypasses in the Albany group were tibial reconstructions for claudication). This point underscores the fact that the majority of patients likely to be good candidates for femorotibial bypass manifest tibioperoneal or proximal tibial disease as an extension of concomitant superficial femoral and/or popliteal disease, as isolated proximal tibial disease in isolation is relatively rarely encountered in clinical practice. It also highlights both the importance of patient selection and the reality that only small numbers of patients will likely
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Figure 2 (A) Lower-extremity arteriogram in patient with long history of smoking and severe claudication identifying occlusion of distal superficial femoral and popliteal arteries, an anatomic pattern of disease amenable to femorotibial bypass grafting. (B) Completion angiogram following femoral to anterior tibial artery bypass grafting with nonreversed saphenous vein demonstrating a good technical result.
prove suitable for this approach. Figure 2 demonstrates an example of a disease pattern amenable to surgical revascularization, while Figures 3 and 4 represent patients appropriate for an initial attempt at percutaneous therapy.
Percutaneous Therapy The recent decade has seen a dramatic increase in the use of endolumenal therapy for the treatment of infrainguinal occlusive disease. While the reasons for this trend are multifactorial, the increasingly favorable risk-to-benefit profile secondary to lower rates of procedural morbidity and mortality associated with percutaneous intervention in comparison to surgical revascularization is one of the most important factors. While operative mortality rates for infrainguinal bypass average 2% to 3% in recent series,24,29 the death rate was 0.2% in one review of 4,662 noncoronary angioplasty procedures.30 Results of the recently completed PREVENT III trial, the largest blinded, controlled assessment of lower-extremity bypass grafting to date, revealed a major morbidity rate of 18% for patients undergoing revascularization for limb salvage.29 The three most prevalent complications, graft occlusion, myocardial infarction, and major-wound complications, were each seen in 5% of cases. When considering the potential negative impact of surgical intervention for a given patient with claudication, it is important to also take into
consideration the less commonly discussed, more long-term complications of vein bypass surgery, among them chronic incisional pain, saphenous nerve pain, and persistent leg edema. Percutaneous transluminal angioplasty is generally performed under local anesthesia with minimal intravenous sedation and as either an outpatient procedure or involving an overnight admission. Contrast-induced acute renal failure remains the most common complication. With the development of hypo- and iso-osmolor contrast agents, the overall incidence has fallen to under 6%,31 although higher rates are found in patients with preexisting renal failure and diabetes.32,33 Access-site complications, predominately pseudoaneurysms and arteriovenous malformations, occur in 1% of patients34 and the majority of these can be managed conservatively. Maldeployment leading to thromboembolic complications or delayed infection following placement of newer percutaneous closure devices, which are quickly becoming the preferred means of puncture-site control, also occur in low numbers. Additional well-recognized benefits associated with infrainguinal percutaneous therapy helping to fuel its increasing popularity include shorter procedural times, shorter hospital length of stay, substantially reduced time to return to work, and preservation of saphenous vein conduit for potential later cardiac or peripheral bypass surgery. Another fea-
Infrapopliteal intervention for treatment of claudicant
Figure 3 (A) Arteriogram in patient with disabling claudication demonstrating critical stenoses within the superficial femoral, distal popliteal and proximal anterior tibial and peroneal arteries, a pattern of disease amenable to percutaneous therapy. (B) Completion arteriogram following percutaneous balloon angioplasty and stenting of the superficial femoral artery and angioplasty of the infrageniculate lesions.
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48 ture often claimed by endovascular enthusiasts as a benefit, but one that remains a source of debate, is that of reduced procedural cost. Those who believe endotherapy is overutilized argue that true costs are underestimated, given the poor associated durability and more frequent need for additional procedures in the event of recurrent disease. Of note, one of the secondary findings in the BASIL trial,35 the only multicenter, randomized, controlled trial directly comparing surgery to angioplasty in patients with critical limb ischemia, was the costs of patients assigned to a surgery-first strategy were one-third higher than the angioplasty-first cohort over the first 12 months of the trial. To what extent the results of this trial, which did not utilize stents, and which was carried out in patients with severe ischemia, will hold up at longer endpoints or can be extrapolated to the population of those with claudication alone is unknown. There is little question that “nonclinical” forces are also contributing to the shift toward greater adoption of minimally invasive treatment of infrainguinal occlusive disease. Foremost among these factors is the increasingly diverse number of subspecialists with a competitive interest in treatment of peripheral vascular disease. Following their initial sluggish acceptance of endovascular therapy as a viable treatment option through the 1990s and early 2000s, the vascular surgical community has steadily reclaimed this therapeutic territory from interventional radiologists, who had enjoyed a near monopoly since Charles Dotter first introduced the concept of peripheral angioplasty in 1964. Vascular surgeons have, in turn, more recently seen their own therapeutic domain encroached upon by colleagues in interventional cardiology, interventional neuroradiology, and cardiothoracic surgery. As an illustration of current trends, a recent industry poll indicates the number of superficial femoral artery interventions in the United States has increased from 100,000 to 200,000 in the span from 2002 to 2007.36 Globally, the increase has been from 165,000 to 300,000 in the same time period. Table 2 documents the striking concomitant shift in the profile of interventionalists performing peripheral interventions over the course of the previous decade in this country.36 This unwelcomed increase in competition by practitioners new to the peripheral vascular field has been difficult to digest when accompanied by the perception that minimally symptomatic or even asymptomatic patients have been inappropriately treated by interventionalists ill-informed as to the natural history of arterial occlusive disease. It is difficult to determine to exactly what degree the increasing numbers of wire-trained interventionalists, among them those eager to push the endovascular envelope and/or those unable to offer an operative alternative, is helping to drive the wider application of endovascular technology. In the absence of compelling data indicating patients are being poorly served, however, it appears unlikely current trends will abate anytime soon.
Infrageniculate Angioplasty With the advent of endovascular treatment as a viable therapeutic alternative to either medical management or surgical
M.T. Menard and M. Belkin revascularization, long-established resistance to tibial-level intervention for those with claudication has been still further challenged. Because of reasons already enumerated and its proven efficacy in other vascular beds, interventionalists have continued to lower the threshold at which they offer endolumenal therapy to patients at all points along the spectrum of infrainguinal occlusive disease. The results of the BASIL trial,35 where 1- and 3-year amputation-free survival rates were found to be similar for groups randomized to either surgery or angioplasty for critical limb ischemia, will no doubt strengthen this impulse, despite the finding that angioplasty was associated with a higher reintervention rate. Perhaps not surprisingly, reliable published data on tibiallevel angioplasty for treatment of claudication is limited. There is no level I data, and while there has been a growing number of single-institution series of infrageniculate angioplasty for the treatment of lower-extremity occlusive disease,37-39 almost all are mixed series combining a majority of patients with critical limb ischemia with small numbers of patients with severe claudication. Other authors have combined their endovascular experience of femoropopliteal lesions with tibial-level disease without stratifying the results for indication, making meaningful interpretation of the results difficult. In nearly all series, documentation of hemodynamic and functional follow-up is poor, and assessment of site-specific restenosis is lacking, confounding the ability to determine if treated lesions were responsible for recurrent symptoms. While Dotter and Judkins40 first reported infrageniculate dilation as far back as 1964, it was not until Gruntzig and Hopff41 described their use of a coaxial balloon catheter in 1974 that angioplasty of the popliteal and tibioperoneal trunk was more widely adopted. In one representative early experience published in 1995 of 20 patients with critical limb ischemia and 5 patients with claudication, the technical success rate was 88%.42 The clinical and hemodynamic success rates were 59% at 1 year, 32% at 2 years, and 20% at 3 years, and 14 patients ultimately required surgical bypass. Only one of the five claudicants in the series experienced sustained symptomatic relief. Additional series of patients undergoing infrageniculate balloon dilation for either claudication or critical limb ischemia from this time period describe 1-year patency rates that vary widely, ranging anywhere from 13% to 80%.43-47 In 1990, Dorros et al48 published his initial experience with tibial angioplasty in 111 patients, 47% of which were claudicants. Ninety percent of patients had no complications and 95% were clinically improved at the time of discharge. Forty percent of patients either experienced a restenosis or underwent a second angioplasty procedure at a mean of 9 months, with claudication being the predominant recurrent symptom in 86%. Recurrence at the site of the initial stenosis was present in only 36% of cases, while the remaining 64% had evidence of new lesions as the source of their recurrent symptoms. Of those patients undergoing a second percutaneous angioplasty, the angiographic and clinical success rate was 96%. Dorros et al49 subsequently reported their immediate outcomes in a consecutive group of 312 patients with
Infrapopliteal intervention for treatment of claudicant
Figure 4 (A) Arteriogram in patient with diabetes and disabling claudication demonstrating intact femoropopliteal inflow and occlusion of the distal tibioperoneal trunk and proximal segment of posterior tibial and peroneal runoff. (B) Wire traversal across tibioperoneal trunk and proximal peroneal occlusion. (C) Appearance following balloon angioplasty to 2.5 mm and (D) placement of 4 ⫻ 60 mm Xpert stent, demonstrating prompt flow through the peroneal artery and delayed filling of the posterior tibial artery.
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M.T. Menard and M. Belkin
50
Figure 4 (Continued)
either critical ischemia or claudication, the largest experience of tibial angioplasty to date. In the 133 patients with 208 lesions treated for claudication, the technical success rate was 98%. Immediate treatment success was better for claudicants than for those with critical ischemia, and for stenotic lesions (98%) compared with total occlusions (86%). It is worthwhile to note that these results were attained at a time when the profile and range of available wires and balloons was significantly more limited than that available today. A more recent series from Germany detailed 104 infrapopliteal percutaneous interventions in 78 patients with claudication. The excimer laser was used in 18% of cases in which noncalcified totally occluded vessels were encountered and stents were placed in 25% of patients following
suboptimal results with angioplasty. The overall complication rate was low at 6%, with all complications being minor and treated conservatively; there were no periprocedural deaths, amputations, or need for emergent surgical intervention. Both ABI and walking distance significantly improved over baseline measurements. At 12 months, duplex-assessed primary patency was 66%, cumulative primary assisted patency was 82%, and secondary patency was 92%. No patient underwent amputation or surgical bypass during the follow-up period.50
Infrageniculate Stenting A recent technologic advance that will undoubtedly impact vascular surgical practice patterns is the introduction of a
Table 2 National Profile of Providers Performing Percutaneous Interventions for Peripheral Arterial Disease Over a Recent 10-Year Period US Peripheral Interventions
1996 (%) (n ⴝ 340,000)
2000 (%) (n ⴝ 550,000)
2005 (%) (n ⴝ 750,000)
Interventional cardiologists Interventional radiologists Vascular surgeons
25 65 10
40 45 15
55 30 15
Infrapopliteal intervention for treatment of claudicant
Figure 5 (A) Strut profile of stent designed for large vessel placed within a small vessel. (B) Strut profile of stent designed for smaller vessel.
self-expanding stent dedicated for use in the tibial arterial tree. Prior to this point, options in the face of a suboptimal angioplasty result were limited to short-segment balloon expandable stents designed for the coronary arteries. Apart from potential tracking difficulties, the use of drug-eluting stents (DESs) rendered a procedure undertaken solely for lifestyle improvement prohibitively expensive, particularly if more than one stent was used. The Xpert stent (Abbott Vascular Devices, Redwood City, CA) is a 3.8Fr low-profile nitinol device capable of tracking through a 4Fr delivery sheath. The stents targeted for tibial use range in diameter from 3 to 6 mm and in length from 20 to 60 mm. Figure 5 illustrates the low-strut profile of this novel stent. While data on tibial artery stenting is even more sparse than that supporting angioplasty, several small published series with early follow-up have demonstrated efficacy.51 In one study comparing sirolimus-eluting stents (Cypher, Cordis Corporation, Miami, FL) to bare-metal stents following suboptimal angioplasty secondary to lesion recoil or severe dissection in patients with critical limb ischemia, 6-month primary patency rates were 68% in the bare-metal group versus 92% in the drug-eluting stent group.52 Scheinert et al53 also found significantly better 6- to 12-month patency rates, 84% versus 53% respectively, when comparing DESs to PTA alone for infrapopliteal lesions. Although a theoretical concern, crush damage to the balloon expandable stents proved not to be problematic in either series. While the results of these reports are encouraging, it is important to remember that impressive suppression of restenosis was also demonstrated in the early time points following use of DESs in the superficial femoral artery during the SIROCCO trials, but the effect was not sustained over time.54 The preliminary experience with absorbable metal stents and carbon-lined stents,55,56 while anecdotal, has also been positive to date. Paralleling the recent progress in stent technology, there have also been marked improvements in the wires and balloons accessible to the peripheral interventionalist. Tibial artery atherosclerosis frequently manifests as long-segment occlusions in heavily calcified arteries, and a variety of wires now in existence are specifically designed to cross-challenging total occlusions. At present, specialty “re-entry devices” that facilitate successful navigation back into the vessel lumen following subintimal traversal of an occluded arterial segment, particularly useful in the subclavian, iliac, and su-
51 perficial femoral arterial beds, are not practical for the smaller tibial arteries. However, a range of support catheters and low-profile, longer-segment balloons with enhanced trackability have noticeably improved the ability to cross and successfully treat many infrageniculate lesions, and helped to lower the rate of technical failures in recent years. The ev3 Amphirion (ev3 Inc, Plymouth, MN) balloon, which ranges in diameter from 1.5 to 4 mm in diameter and is available in a .014-inch platform in lengths up to 120 mm, is an example of a new-generation balloon particularly well-suited to tibial angioplasty.
Adjunctive Endolumenal Therapies Beyond novel balloons and stents, a growing array of innovative adjunctive treatment devices has helped fuel the shift toward increased use of endovascular therapy for infrainguinal occlusive disease. While not new, the excimer laser has been refined and can now be applied via smaller-profile fibers compatible with infrageniculate anatomy. The laser uses ultraviolet energy at 308 nm to photoablate plaque. Although marketed as a “stand-alone” treatment, follow-up balloon angioplasty or stenting is often required to obtain an acceptable angiographic result. It currently has a niche role in allowing stepwise entry through chronic occlusions refractory to intralumenal or subintimal wire passage. The Silverhawk (Foxhollow Technologies, Redwood City, CA) is a new-generation atherectomy device that allows controlled debulking of atheroma, theoretically obviating the need for balloon angioplasty or stenting and removing the triggers for intimal hyperplasia-mediated restenosis. Vessel perforation and distal embolization have been reported in low rates, and current devices have overcome earlier difficulty tracking through the angulation of the proximal anterior tibial artery. In one of the few reviews that included patency data, a small series of 33 patients undergoing directional atherectomy for chronic ischemia, a 22% restenosis rate of ⱖ70% at 6 months was reported.57 Balloon cryoplasty and cutting balloons are two additional novel technologies that aim to minimize the trauma associated with traditional balloon angioplasty, and thereby lower the vexing problem of restenosis. The PolarCath (Boston Scientific Corporation, Natick, MA) uses nitrous oxide to transmit temperatures as low as ⫺10°C to the vessel wall, theoretically reducing arterial wall inflammation and resulting in less intimal dissection and lesion recoil. By inducing apoptosis rather than cell necrosis, the proliferative remodeling that underlies restenosis is also theoretically lessened. Cutting balloons, on the other hand, use either longitudinally oriented microtomes or a spiral nitinol cage mounted onto a balloon to affect a more controlled vessel wall expansion. By incising rather than shattering the plaque, dilation can be achieved at lower pressure, again with theoretic less-resultant dissection, recoil, and barotrauma. While several reports have demonstrated efficacy with vein graft stenoses,58 in our own recent experience with over 20 patients, we have found
52 no advantage over conventional balloon angioplasty in this setting. None of the described adjunctive devices are supported by objective comparative data or any degree of long-term angiographic follow-up demonstrating reliable durability. Enthusiastic endorsement from industrial sponsors notwithstanding, the evidence substantiating their utility is, at present, largely anecdotal. As such, awareness of their associated cost is important in the face of potential local pressure to demonstrate use of cutting-edge technology.
Current Recommendations In summary, we believe an aggressive approach to claudication is warranted in good-risk patients with disabling symptoms and minimal comorbidities. Given available data demonstrating excellent early outcomes and sustained durability with femorotibial reconstruction, operative bypass in carefully selected patients whose anatomy obligates an infrageniculate distal target should not be withheld. A target vessel continuously patent to the level of the ankle would be considered a prerequisite for operative bypass, and reconstruction should be restricted to those patients with a single segment of adequate saphenous vein, given the compromised outcomes and added complexity associated with prosthetic and ectopic conduits. Further, patients with significant cardiopulmonary, neurologic, musculoskeletal, or other conditions likely to compromise their functional capacity or longevity would be poor candidates for reconstruction in the absence of critical ischemia. Percutaneous therapy is an attractive and appropriate therapeutic alternative for claudicants with focal lesions limited to the tibioperoneal trunk or proximal tibial arteries. Paralleling the experience with operative tibial revascularization, early fears that endolumenal therapy would accelerate the disease process or adversely impact available surgical options do not appear to have been borne out in clinical practice. In the absence of reliable long-term patency data to suggest otherwise, patients with long-segment femoral, popliteal, or proximal tibial total occlusions, and who are otherwise good operative candidates, should be offered surgery as their firstline reconstructive option. The presence of multiple polypoid, calcific lesions at potentially higher risk of embolism with wire manipulation or lesions that have responded poorly to initial endolumenal treatment are also relative contradictions to an endovascular approach.
References 1. Sullivan TM, Langan EM: The impact of endovascular interventions on the number of open vascular surgical procedures: the Greenville, SC experience (1996-2000). Perspect Vasc Surg Endovasc Ther 16:65-70, 2004 2. Halperin JL: Evaluation of patients with peripheral vascular disease. Thromb Res 106:303-311, 2002 3. Dawber TR: Framingham Study. London, Harvard University Press, 1980 4. Imparato AM, Kim GE, Davidson T, et al: Intermittent claudication: its natural course. Surgery 78:795-799, 1975
M.T. Menard and M. Belkin 5. Walsh DB, Gilbertson JJ, Zwolak RM, et al: The natural history of superficial femoral artery stenoses. J Vasc Surg 14:299-304, 1991 6. Rosenbloom MS, Flanigan P, Schuler JJ, et al: Risk factors affecting the natural history of intermittent claudication. Arch Surg 123:867-870, 1988 7. Jonason T, Ringqvist I: Diabetes mellitus and intermittent claudication. Acta Med Scand 218:217-221, 1985 8. Rutherford RB: Evaluation and selection of patients for vascular interventions, in Rutherford RB (ed): Vascular Surgery, vol 1 (ed 5). Philadelphia, PA, Saunders, 2000 9. Cronenwett JL, Warner KG, Zelenock GB, et al: Intermittent claudication: current results of nonoperative management. Arch Surg 119:430436, 1984 10. Nanjundappa A, Laird JR: Critical limb ischemia. Endovasc Today 5:36-40, 2006 11. Grassbaugh JA, Nelson PR, Rzucidlo EM, et al: Blinded comparison of preoperative duplex ultrasound scanning and contrast arteriography for planning revascularization at the level of the tibia. J Vasc Surg 37:1186-1190, 2003 12. Ascher E, Marks NA, Hingorani AP, et al: Duplex-guided balloon angioplasty and subintimal dissection of infrapopliteal arteries: early results with a new approach to avoid radiation exposure and contrast material. J Vasc Surg 42:1114-1121, 2005 13. Koelemay MJ, Lijmer JG, Stoker J, et al: Magnetic resonance angiography for the evaluation of lower extremity arterial disease: a meta-analysis. JAMA 285:1338-1345, 2001 14. Nehler MR, Hiatt WR: Exercise therapy for claudication. Ann Vasc Surg 13:109-114, 1999 15. Regensteiner JG, Meyer TJ, Krupski WC: Hospital versus home-based exercise rehabilitation for patients with peripheral arterial occlusive disease. Angiology 48:291-300, 1997 16. Dawson DL, Cutler BS, Hiatt WR, et al: A comparison of Cilostazol and Pentoxifylline for treating intermittent claudication. Am J Med 109: 523-300, 2000 17. Antiplatelet Trialists’ Collaboration: Collaborative overview of randomised trials of antiplatelet therapy-II. Maintenance of vascular graft or arterial patency by antiplatelet therapy. BMJ 308:159-168, 1994 18. Udoff EJ, Barth KH, Harrington DP, et al: Hemodynamic significance of iliac artery stenosis: pressure measurements during angiography. Radiology 132:289-293, 1979 19. Spinosa DJ, Kaufmann JA, Hartwell GD: Gadolinium chelates in angiography and interventional radiology: a useful alternative to iodinated contrast media for angiography. Radiology 223:326-327, 2002 20. Back MR, Caridi JG, Hawkins IF, et al: Angiography with carbon dioxide (CO2). Surg Clin North Am 78:575-591, 1998 21. Veith FJ, Gupta SK, Samson RH, et al: Progress in limb salvage by reconstructive arterial surgery combined with or improved adjunctive procedures. Ann Surg 194:386-400, 1981 22. Conte MS, Belkin M, Upchurch GR, et al: Impact of increasing comorbidity on infrainguinal reconstruction: a 20-year perspective. Ann Surg 233:445-452, 2001 23. Wyatt MG, Kernick VF, Clark H, et al: Femorotibial bypass: the learning curve. Ann R Coll Surg Engl 77:413-416, 1995 24. Belkin M, Knox J, Donaldson MC, et al: Infrainguinal arterial reconstruction with nonreversed greater saphenous vein. J Vasc Surg 24:957962, 1996 25. Shah DM, Darling RC, Chang BB, et al: Long-term results of in situ saphenous vein bypass: analysis of 2058 cases. Ann Surg 222:438-446, 1995 26. Taylor LM, Edwards JM, Porter JM: Present status of reversed vein bypass grafting: five-year results of a modern series. J Vasc Surg 11:193205, 1990 27. Conte MS, Belkin M, Donaldson MC, et al: Femorotibial bypass for claudication: Do results justify an aggressive approach? J Vasc Surg 21:873-881, 1995 28. Byrne J, Darling RC, Chang BB, et al: Infrainguinal arterial reconstruction for claudication: is it worth the risk? An analysis of 409 procedures. J Vasc Surg 29:259-269, 1999
Infrapopliteal intervention for treatment of claudicant 29. Conte MS, Bandyk DF, Clowes AW, et al: Results of PREVENT III: a multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery. J Vasc Surg 43:742-751, 2006 30. Becker G, Katzen B, Dake M: Noncoronary angioplasty. Radiology 170: 921-940, 1989 31. Berkseth RO, Kjellstrand CM: Radiologic contrast-induced nephropathy. Med Clin North Am 68:351-370, 1984 32. Kandzari DE, Rebeiz AG, Wang A, et al: Contrast nephropathy: an evidence-based approach to prevention. Am J Cardiovasc Drugs 3:395405, 2003 33. MacNeill BD, Harding SA, Bazari H, et al: Prophylaxis of contrastinduced nephropathy in patients undergoing coronary angiography. Catheter Cardiovasc Interv 60:458-461, 2003 34. Knight CG, Healy DA, Thomas RL: Femoral artery pseudoaneurysms: risk factors, prevalence, and treatment options. Ann Vasc Surg 17:503508, 2003 35. BASIL trial participants: Bypass versus angioplasty in severe ischaemia of the leg (BASIL): multicentre, randomized controlled trial. Lancet 366:1925-1934, 2005 36. IBM/TG analysis: Interventional News 20:6, 2005 37. Horvath W, Oertl M, Haidinger D: Percutaneous transluminal angioplasty of crural arteries. Radiology 177:565-569, 1990 38. Bosiers M, Hart JP, Deloose K, et al: Endovascular therapy as the primary approach for limb salvage in patients with critical limb ischemia: experience with 443 infrapopliteal procedures. Vascular 14:33-39, 2006 39. Kudo T, Chandra FA, Ahn SS: The effectiveness of percutaneous transluminal angioplasty for the treatment of critical limb ischemia: a 10year experience. J Vasc Surg 41:423-535, 2005 40. Dotter CT, Judkins MP: Transluminal treatment of arteriosclerotic obstruction. Description of a new technique and a preliminary report of its application. Circulation 30:654-670, 1964 41. Gruntzig A, Hopff H: Percutaneous recanalization after chronic arterial occlusion with a new dilator-catheter (modification of the Dotter technique). Dtsch Med Wochenschr 99:2502-2510, 1974 42. Treiman GS, Treiman RL, Ichikawa L, et al: Should percutaneous transluminal angioplasty be recommended for treatment of infrageniculate popliteal artery or tibioperoneal trunk stenosis? J Vasc Surg 24:457463, 1995 43. Brillu C, Picquet J, Villapadierna F, et al: Percutaneous transluminal angioplasty for management of critical ischemia in arteries below the knee. Ann Vasc Surg 15:175-181, 2001
53 44. Soder HK, Manninen HI, Jaakkola P, et al: Prospective trial of infrapopliteal artery balloon angioplasty for critical limb ischemia: angiographic and clinical results. J Vasc Interv Radiol 11:1021-1031, 2000 45. Martin DR, Katz SG, Kohl RD, et al: Percutaneous transluminal angioplasty of infrainguinal vessels. Ann Vasc Surg 13:184-187, 1999 46. Varty K, Bolia A, Naylor AR, et al: Infrapopliteal percutaneous transluminal angioplasty: a safe and successful procedure. Eur J Vasc Endovasc Surg 9:341-345, 1995 47. Sivananthan UM, Browne TF, Thorley PJ, et al: Percutaneous transluminal angioplasty of the tibial arteries. Br J Surg 81:1282-1285, 1994 48. Dorros G, Lewin RF, Jamnadas P, et al: Below-the-knee angioplasty: tibioperoneal vessels, the acute outcome. Cathet Cardiovasc Diagn 19: 170-178, 1990 49. Dorros G, Jaff MR, Murphy KJ, et al: The acute outcome of tibioperoneal vessel angioplasty in 417 cases with claudication and critical limb ischemia. Cathet Cardiovasc Diagn 45:251-256, 1998 50. Krankenberg H, Sorge I, Zeller T, et al: Percutaneous transluminal angioplasty of infrapopliteal arteries in patients with intermittent claudication: acute and one-year results. Catheter Cardiovasc Interv 64:1217, 2005 51. Feiring AJ, Wesolowski AA, Lade S: Primary stent-supported angioplasty for treatment of below-knee critical limb ischemia and severe claudication: early and one-year outcomes. J Am Coll Cardiol 44:23072314, 2004 52. Siablis D, Kraniotis P, Karnadatidis D, et al: Sirolimus-eluting versus bare stents for bailout after suboptimal infrapopliteal angioplasty for critical limb ischemia: 6-month angiographic results from a nonrandomized prospective single-center study. J Endovasc Ther 12:685-695, 2005 53. Scheinert D: The Cypher below the knee pilot study. Presented at EuroPCR, Paris, France, May 2005 54. Duda SH, Bosiers M, Lammer J, et al: Sirolimus-eluting versus bare metal stent for obstructive superficial femoral artery disease: the Sirocco II trial. J Vasc Interv Radiol 16:331-338, 2005 55. Rand T, Basile A, Cejna M, et al: PTA versus Carbofilm coated stents in infrapopliteal arteries pilot study. Cardiovasc Invervent Radiol 29:2938, 2005 56. Bosiers M, Deloose K, Verbist J, et al: Update on advantages and limitations of biodegradable (Biotronik) metal stents: are they better than PTA alone? 12-month results. Vascular 13:S35, 2005 57. Zeller T, Rastan A, Schwarzwalder U, et al: Midterm results after atherectomy-assisted angioplasty or below-knee arteries with use of the Silverhawk device. J Vasc Interv Radiol 15:1391-1397, 2001 58. Kasirajan K, Schneider PA, Hood D, et al: Early outcomes of cutting balloon angioplasty for infrainguinal vein graft stenosis. J Vasc Surg 39:702-708, 2004
T
HE RECENT ERA in vascular surgery has been marked by a significant paradigm shift in the treatment of atherosclerotic occlusive disease. The changes have been driven, in part, by continued advances in the perioperative treatment of cardiac and comorbid medical disease, anesthetic management, and surgical technique. This progress has allowed surgical reconstruction to be routinely undertaken on older and sicker patients, and bypass grafts to tibial and pedal targets carried out with fewer complications and improved durability. Newer treatment patterns have also been considerably impacted by ongoing technological advances and an increasing use of endovascular techniques. Similar to the influence that introduction of endovascular aortic aneurysm repair has had on treatment of aneurysmal disease, the management of peripheral vascular occlusive disease has increasingly moved to a less operative and more percutaneous approach. In recent years, angioplasty and stenting have become the firstline therapy in patients with aortoiliac, renal, subclavian, and
Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital, Boston, MA. Address reprint requests to Michael Belkin, Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115. E-mail: mbelkin@ partners.org
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0895-7967/07/$-see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1053/j.semvascsurg.2007.02.007
coronary atherosclerotic disease. It also plays an increasing role in treatment of mesenteric and carotid occlusive disease and of the femoropopliteal and infrageniculate arterial segments. Illustrating these trends in our own institution, for example, we performed 75% fewer aortobifemoral and extraanatomic bypass grafts in the period from 1994 to 2004, compared with the prior decade. We have also performed 30% fewer infrainguinal bypass grafts since establishing our endovascular program, in comparison to the equivalent time interval prior to that point. In a report typical of many vascular surgery divisions, Sullivan and Langan1 reported a 324% increase in the annual endovascular case volume between 1996 and 2000 in their Greenville, South Carolina academic practice. Further highlighting the impact of the treatment changes taking place, some senior British surgeons have even called into question whether tibial-level bypass should remain an index procedure for vascular surgical trainees. Within this backdrop, the appropriate role for surgery and endovascular therapy for intermittent claudication remains controversial. Based on our own and others accumulated experience with femorotibial reconstruction, we have come to believe that infrageniculate surgical bypass is appropriate for a carefully selected subgroup of healthy patients with
Infrapopliteal intervention for treatment of claudicant
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symptomatic impairment from claudication. In certain patients with a favorable anatomic disease pattern, we have also come to support judicious utilization of endovascular therapy for claudicants with tibioperoneal or proximal tibial arterial occlusive disease.
neous therapy,10 particularly in the face of the current fiscal crisis within our healthcare system.
Claudication
Diagnosis of infrainguinal occlusive disease is generally made based on patient symptomatology and physical examination. Noninvasive hemodynamic testing in the form of segmental pressure measurements, pulse volume recordings, and treadmill exercise testing helps to objectively document the degree of disease severity. Claudication remains a relative indication for intervention, with functional quality-of-life improvement the goal of therapy. The anticipated benefits must be carefully weighed against the specific comorbid limitations imposed by concomitant cardiac impairment, pulmonary disease, and musculoskeletal conditions in a given patient. Following diagnosis of symptomatic lower-extremity occlusive disease and the decision to pursue intervention, additional imaging is warranted. Duplex ultrasonography, magnetic resonance imaging (MRA), and computerized tomographic angiography (CTA) are increasingly being utilized as first-line modalities in planning the optimal revascularization approach, and have supplanted contrast angiography as the initial imaging study of choice. Given the quality of current-generation machines, there has been recent support for use of duplex scanning as a stand-alone preoperative mapping modality.11 One group has even advocated for duplex-guided angioplasty and stenting of femoral and tibial level occlusive disease.12 As this practice requires a highly dedicated vascular laboratory, it has not, to date, gained wide acceptance. CTA is being used increasingly as a preoperative roadmapping technique in institutions able to provide high-quality three-dimensional reconstructions. MRA is also particularly useful as a noninvasive screening test to determine the suitability for percutaneous therapy, as advances have solved many of the technical limitations of earlier studies (see Fig 1). Should a lesion amenable to percutaneous therapy be identified, angiography is then pursued. In some instances, when the distal target for a planned surgical reconstruction is at the tibioperoneal trunk or proximal tibial level, we have proceeded directly to surgery based solely on MRA scanning if high-quality time-offlight and gadolinium-enhanced images are obtained.13 Given persistent limitations with both CTA and MRA technology, however, we have usually been reluctant to give up the confirmation afforded by standard contrast angiography when the bypass target is at the more distal tibial or pedal level.
Arterial occlusive disease is highly prevalent in Western society, and constitutes the leading overall cause of death in the United States. With the aging of the American population, the prevalence of lower-extremity occlusive disease has increased steadily in recent decades. Chronic obliterative atherosclerosis of the infrainguinal vessels is the most prevalent manifestation of arterial occlusive disease encountered by the vascular surgeon. Claudication is the cardinal presenting symptom and affects 5% of people over 55 years of age. Another 10% of those in this age group have asymptomatic peripheral atherosclerotic disease, while 1% has critical leg ischemia in the form of rest pain or gangrene.2 Natural history studies, such as the Framingham Heart Study, indicate patients with claudication have increased rates of cardiovascular mortality, but an overall low risk of associated limb loss.3,4 The majority of claudicants will demonstrate a stable pattern of disease throughout their lifetime, or have improvement in their symptoms as a result of risk-factor modification, while 20% to 30% will come to operation within 5 years as a result of disease progression. The annual rates of mortality and limb loss in patients with claudication are typically reported to be 5% and 1%, respectively.5 Risk factors consistently shown to be associated with disease progression in patients with claudication have included continued smoking, diabetes mellitus, low or declining ankle brachial index (ABI), and presence of multilevel disease.6 Diabetic patients represent a particularly challenging cohort, given their known predilection for multisegment and diffuse disease and high degree of popliteal trifurcation and tibial vessel involvement. They are at up to a 10-fold higher risk of progression to critical ischemia compared with nondiabetics7 and often display a more tenuous collateral network with compromised reserve, of importance when considering the implications of a tibial level intervention. Of relevance to a discussion on where the appropriate threshold for intervention for claudication should be set, Rutherford has called into question the commonly quoted estimates of death and loss of limb associated with claudication. Citing evidence based on objective hemodynamic confirmation of the diagnosis rather than clinical assessment alone, he believes the actual rate of limb loss per year for claudicants is more in the range of 5%, particularly in those with ABIs in the range of 0.4 to 0.6.8 Recent studies have indicated that between 17% to 41% of patients with objective clinical evidence of arterial occlusive disease will progress to critical ischemia.6,7,9 Some have pointed to the increasing prevalence of diabetes and the growing burden imposed by infrainguinal occlusive disease in our more sedentary and aging population to justify a wider applicability of percuta-
Diagnosis and Pretherapeutic Assessment
Management Risk-factor modification remains the cornerstone of management for lower-extremity occlusive disease. Smoking cessation, blood pressure control, and aggressive efforts at cholesterol-lowering should be addressed with every patient with atherosclerotic disease. Lipid-lowering therapy
M.T. Menard and M. Belkin
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Figure 1 Magnetic resonance angiogram identifying long-segment occlusion of superficial femoral artery, heavily diseased popliteal artery, and intact peroneal artery runoff, a disease pattern amenable to femorotibial bypass reconstruction.
involves both dietary modification and, more recently, increasing use of 3-hydroxy-3-methylglutaryl coenzyme A reductase⫺inhibitor medication, particularly given recent evidence demonstrating the beneficial effects of statins over and above that associated with their cholesterol-lowering properties. Strong evidence exists supporting the efficacy of a structured walking program14 in increasing the walking distance of patients with claudication. The value of walking outside of a structured regimen with close follow-up is more debatable.15 Medical management with pentoxifylline (Trental, Aventis Pharmaceuticals, Inc, Bridgewater, NJ) or, more recently, cilostazol (Pletal, Otsuka America Pharmaceuticals, Inc, Rockville, MD) has benefit in a subset of patients and remains a reasonable first-line approach to improve claudication symptoms.16 Finally, antiplatelet therapy, either aspirin or clopidogrel, is a critically important element of the treatment of established occlusive disease,17 given its documented ability to prevent thrombosis and embolization and possibly even to arrest the progression of atherosclerosis. Angiography is typically undertaken via a retrograde femoral approach after accessing the femoral artery from the contralateral limb. In patients in whom noninvasive imaging indicates a widely patent common femoral and proximal superficial femoral artery and body habitus is not prohibitive, an antegrade approach can serve as useful alternative. In ambiguous lesions, pull-back pressure measurements, both before and after administration of a systemic vasodilator such as papaverine or nitroglycerine, can be useful in documenting the hemodynamic significance of a particular stenotic zone.18 The use of gadolinium (Magnevist, Berlex Laborato-
ries, Inc, Montville, NJ)19 or carbon dioxide20 as contrast agents in patients with compromised renal function, although somewhat less effective in the periphery than in the aortoiliac vasculature, can minimize or eliminate the nephrotoxic effects associated with standard iodinated contrast medium.
Infrageniculate Surgical Reconstruction Based largely on the natural history studies outlined here, a conservative approach has typically been advocated for the majority of patients with claudication. Unlike the scenario in patients with critical limb ischemia, an aggressive approach was thought to place patients without a limb-threatening condition at an unnecessary risk of limb loss. Given that the majority of claudicants remain stable for years, it was thought preferable to allow for collateral pathways to develop, with the hope that many patients would improve to an extent that intervention would prove unnecessary.2 Aortofemoral reconstruction for claudication, however, gained acceptance as a viable therapeutic option in good-risk patients given both the excellent long-term patency rates and the perception that those with aortoiliac level are at higher risk of progression to critical ischemia. With subsequent reports documenting minimal associated operative mortality, excellent long-term palliation and absence of added risk of limb loss beyond that expected from the expected course of the disease process, femoropopliteal bypass for claudication also gained widespread acceptance.
Infrapopliteal intervention for treatment of claudicant
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Table 1 Comparative 5-Year Patency and Limb-Loss Results of Vascular Reconstructions in Patients with Claudication
Conte et al27 Femorotibial Femoropopliteal Femorotibial* Byrne et al28 Femorotibial Fem-AK-pop Fem-BK-pop
n
Operative Mortality (%)
Primary 5-Year Patency (%)
Secondary 5-Year Patency (%)
Limb Loss 5-Year (%)
57 261 369
0 0 0
81 74 51
86 81 61
0 3 25
94 165 150
0 0 0
79 48 70
83 50 78
0 .6 0
Abbreviations: AK, above the knee; BK, below the knee. *Operative indication of limb salvage.
In distinction, traditional teaching has held that tibial-level surgical reconstruction for the treatment of claudication is unduly aggressive. Over and above concerns that long-distance revascularization might fail to provide symptomatic relief in patients with either multilevel disease or tibial occlusive disease in isolation, there was a general view that the potential morbidity of extensive reconstructive surgery to the infrapopliteal vessels would not sufficiently offset the expected clinical benefit. Further underlying the conservative approach was a belief that graft failure might result in distal arterial thrombosis, with the potential to convert a situation of relatively benign claudication to the far more ominous situation of limb threat. Given initial patency rates for tibial bypass performed for critical ischemia that failed to match those of femoropopliteal grafts,21,22 and at least one report of up to a 46% amputation rate associated with femorotibial bypass,23 the recommended caution appeared well-founded. In recent years, however, as techniques for distal infrainguinal reconstruction have evolved and tibial level bypass has proven increasingly successful for patients with critical limb ischemia, the aforementioned dogma has come under challenge. In the current era, low mortality rates and 5-year patency rates for single-segment saphenous vein bypass grafts of ⬎80% can be expected at institutions devoted to peripheral bypass surgery.24-26 Given improved outcomes in claudicants compared with those with critical limb ischemia, and comparable if not slightly improved results for tibial bypass compared with popliteal bypass for claudicants, it now appears appropriate to offer tibial level surgical reconstruction to carefully selected patients with limiting claudication and appropriate anatomy. Two specific reports describing favorable results with this patient population serve the basis for our current recommendations.27,28 In 1995, Conte and colleagues27 reviewed the experience at the Brigham and Women’s Hospital in the small subset of patients who had undergone femorotibial bypass for claudication in the 16-year period leading up to 1993. Comparison subgroups to the 53 study patients included 261 patients who underwent femoropopliteal bypass for claudication and 369 patients who underwent femorotibial bypass for limb salvage indications. There was no perioperative mortality and the major morbidity rate was 9% for the study group. Fiveyear primary and secondary patency rates were 81% and
86%, respectively; these results were similar to those for patients undergoing femoropopliteal bypass for claudication, but significantly improved compared to the group undergoing femorotibial bypass for limb salvage (see Table 1). Of particular note, there were no major amputations in the study cohort, while 3% of the femoropopliteal group and 25% of the limb-salvage subgroup had required an amputation by 5 years. Also of interest, the 5-year survival rate for claudicants undergoing femorotibial bypass was only 54%, a level not significantly different from the group with limb salvage as an indication. Finally, successful palliation was achieved in 71% of patients, and as many as 86% expressed overall satisfaction with the operation and would recommend it to others in a similar condition. Several years later, a similar experience was published by the group from Albany, New York. Their series reviewed the outcomes of 409 patients undergoing infrainguinal bypass for claudication over the period from 1987 to 1997, which included 94 patients with infrageniculate outflow targets.28 Operative mortality was 0% for the entire cohort, and a single limb was lost secondary to distal embolization. The 5-year primary and secondary patency rates of 79% and 83% seen for those patients undergoing tibial bypass was better than that seen for patients bypassed to either the above-knee or below-knee popliteal artery (Table 1). Taken together, these studies support the conclusion that arterial reconstruction for disabling claudication to the tibial level can be performed safely and with excellent durability. They also suggest that concern for limb loss with an aggressive surgical approach for claudication may be unfounded. It is important to note that both series represented a highly selected and small minority of patients within the much larger group of patients undergoing lower-extremity bypass at the respective institutions (eg, just 2.1% out of a series of nearly 4,500 bypasses in the Albany group were tibial reconstructions for claudication). This point underscores the fact that the majority of patients likely to be good candidates for femorotibial bypass manifest tibioperoneal or proximal tibial disease as an extension of concomitant superficial femoral and/or popliteal disease, as isolated proximal tibial disease in isolation is relatively rarely encountered in clinical practice. It also highlights both the importance of patient selection and the reality that only small numbers of patients will likely
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Figure 2 (A) Lower-extremity arteriogram in patient with long history of smoking and severe claudication identifying occlusion of distal superficial femoral and popliteal arteries, an anatomic pattern of disease amenable to femorotibial bypass grafting. (B) Completion angiogram following femoral to anterior tibial artery bypass grafting with nonreversed saphenous vein demonstrating a good technical result.
prove suitable for this approach. Figure 2 demonstrates an example of a disease pattern amenable to surgical revascularization, while Figures 3 and 4 represent patients appropriate for an initial attempt at percutaneous therapy.
Percutaneous Therapy The recent decade has seen a dramatic increase in the use of endolumenal therapy for the treatment of infrainguinal occlusive disease. While the reasons for this trend are multifactorial, the increasingly favorable risk-to-benefit profile secondary to lower rates of procedural morbidity and mortality associated with percutaneous intervention in comparison to surgical revascularization is one of the most important factors. While operative mortality rates for infrainguinal bypass average 2% to 3% in recent series,24,29 the death rate was 0.2% in one review of 4,662 noncoronary angioplasty procedures.30 Results of the recently completed PREVENT III trial, the largest blinded, controlled assessment of lower-extremity bypass grafting to date, revealed a major morbidity rate of 18% for patients undergoing revascularization for limb salvage.29 The three most prevalent complications, graft occlusion, myocardial infarction, and major-wound complications, were each seen in 5% of cases. When considering the potential negative impact of surgical intervention for a given patient with claudication, it is important to also take into
consideration the less commonly discussed, more long-term complications of vein bypass surgery, among them chronic incisional pain, saphenous nerve pain, and persistent leg edema. Percutaneous transluminal angioplasty is generally performed under local anesthesia with minimal intravenous sedation and as either an outpatient procedure or involving an overnight admission. Contrast-induced acute renal failure remains the most common complication. With the development of hypo- and iso-osmolor contrast agents, the overall incidence has fallen to under 6%,31 although higher rates are found in patients with preexisting renal failure and diabetes.32,33 Access-site complications, predominately pseudoaneurysms and arteriovenous malformations, occur in 1% of patients34 and the majority of these can be managed conservatively. Maldeployment leading to thromboembolic complications or delayed infection following placement of newer percutaneous closure devices, which are quickly becoming the preferred means of puncture-site control, also occur in low numbers. Additional well-recognized benefits associated with infrainguinal percutaneous therapy helping to fuel its increasing popularity include shorter procedural times, shorter hospital length of stay, substantially reduced time to return to work, and preservation of saphenous vein conduit for potential later cardiac or peripheral bypass surgery. Another fea-
Infrapopliteal intervention for treatment of claudicant
Figure 3 (A) Arteriogram in patient with disabling claudication demonstrating critical stenoses within the superficial femoral, distal popliteal and proximal anterior tibial and peroneal arteries, a pattern of disease amenable to percutaneous therapy. (B) Completion arteriogram following percutaneous balloon angioplasty and stenting of the superficial femoral artery and angioplasty of the infrageniculate lesions.
47
48 ture often claimed by endovascular enthusiasts as a benefit, but one that remains a source of debate, is that of reduced procedural cost. Those who believe endotherapy is overutilized argue that true costs are underestimated, given the poor associated durability and more frequent need for additional procedures in the event of recurrent disease. Of note, one of the secondary findings in the BASIL trial,35 the only multicenter, randomized, controlled trial directly comparing surgery to angioplasty in patients with critical limb ischemia, was the costs of patients assigned to a surgery-first strategy were one-third higher than the angioplasty-first cohort over the first 12 months of the trial. To what extent the results of this trial, which did not utilize stents, and which was carried out in patients with severe ischemia, will hold up at longer endpoints or can be extrapolated to the population of those with claudication alone is unknown. There is little question that “nonclinical” forces are also contributing to the shift toward greater adoption of minimally invasive treatment of infrainguinal occlusive disease. Foremost among these factors is the increasingly diverse number of subspecialists with a competitive interest in treatment of peripheral vascular disease. Following their initial sluggish acceptance of endovascular therapy as a viable treatment option through the 1990s and early 2000s, the vascular surgical community has steadily reclaimed this therapeutic territory from interventional radiologists, who had enjoyed a near monopoly since Charles Dotter first introduced the concept of peripheral angioplasty in 1964. Vascular surgeons have, in turn, more recently seen their own therapeutic domain encroached upon by colleagues in interventional cardiology, interventional neuroradiology, and cardiothoracic surgery. As an illustration of current trends, a recent industry poll indicates the number of superficial femoral artery interventions in the United States has increased from 100,000 to 200,000 in the span from 2002 to 2007.36 Globally, the increase has been from 165,000 to 300,000 in the same time period. Table 2 documents the striking concomitant shift in the profile of interventionalists performing peripheral interventions over the course of the previous decade in this country.36 This unwelcomed increase in competition by practitioners new to the peripheral vascular field has been difficult to digest when accompanied by the perception that minimally symptomatic or even asymptomatic patients have been inappropriately treated by interventionalists ill-informed as to the natural history of arterial occlusive disease. It is difficult to determine to exactly what degree the increasing numbers of wire-trained interventionalists, among them those eager to push the endovascular envelope and/or those unable to offer an operative alternative, is helping to drive the wider application of endovascular technology. In the absence of compelling data indicating patients are being poorly served, however, it appears unlikely current trends will abate anytime soon.
Infrageniculate Angioplasty With the advent of endovascular treatment as a viable therapeutic alternative to either medical management or surgical
M.T. Menard and M. Belkin revascularization, long-established resistance to tibial-level intervention for those with claudication has been still further challenged. Because of reasons already enumerated and its proven efficacy in other vascular beds, interventionalists have continued to lower the threshold at which they offer endolumenal therapy to patients at all points along the spectrum of infrainguinal occlusive disease. The results of the BASIL trial,35 where 1- and 3-year amputation-free survival rates were found to be similar for groups randomized to either surgery or angioplasty for critical limb ischemia, will no doubt strengthen this impulse, despite the finding that angioplasty was associated with a higher reintervention rate. Perhaps not surprisingly, reliable published data on tibiallevel angioplasty for treatment of claudication is limited. There is no level I data, and while there has been a growing number of single-institution series of infrageniculate angioplasty for the treatment of lower-extremity occlusive disease,37-39 almost all are mixed series combining a majority of patients with critical limb ischemia with small numbers of patients with severe claudication. Other authors have combined their endovascular experience of femoropopliteal lesions with tibial-level disease without stratifying the results for indication, making meaningful interpretation of the results difficult. In nearly all series, documentation of hemodynamic and functional follow-up is poor, and assessment of site-specific restenosis is lacking, confounding the ability to determine if treated lesions were responsible for recurrent symptoms. While Dotter and Judkins40 first reported infrageniculate dilation as far back as 1964, it was not until Gruntzig and Hopff41 described their use of a coaxial balloon catheter in 1974 that angioplasty of the popliteal and tibioperoneal trunk was more widely adopted. In one representative early experience published in 1995 of 20 patients with critical limb ischemia and 5 patients with claudication, the technical success rate was 88%.42 The clinical and hemodynamic success rates were 59% at 1 year, 32% at 2 years, and 20% at 3 years, and 14 patients ultimately required surgical bypass. Only one of the five claudicants in the series experienced sustained symptomatic relief. Additional series of patients undergoing infrageniculate balloon dilation for either claudication or critical limb ischemia from this time period describe 1-year patency rates that vary widely, ranging anywhere from 13% to 80%.43-47 In 1990, Dorros et al48 published his initial experience with tibial angioplasty in 111 patients, 47% of which were claudicants. Ninety percent of patients had no complications and 95% were clinically improved at the time of discharge. Forty percent of patients either experienced a restenosis or underwent a second angioplasty procedure at a mean of 9 months, with claudication being the predominant recurrent symptom in 86%. Recurrence at the site of the initial stenosis was present in only 36% of cases, while the remaining 64% had evidence of new lesions as the source of their recurrent symptoms. Of those patients undergoing a second percutaneous angioplasty, the angiographic and clinical success rate was 96%. Dorros et al49 subsequently reported their immediate outcomes in a consecutive group of 312 patients with
Infrapopliteal intervention for treatment of claudicant
Figure 4 (A) Arteriogram in patient with diabetes and disabling claudication demonstrating intact femoropopliteal inflow and occlusion of the distal tibioperoneal trunk and proximal segment of posterior tibial and peroneal runoff. (B) Wire traversal across tibioperoneal trunk and proximal peroneal occlusion. (C) Appearance following balloon angioplasty to 2.5 mm and (D) placement of 4 ⫻ 60 mm Xpert stent, demonstrating prompt flow through the peroneal artery and delayed filling of the posterior tibial artery.
49
M.T. Menard and M. Belkin
50
Figure 4 (Continued)
either critical ischemia or claudication, the largest experience of tibial angioplasty to date. In the 133 patients with 208 lesions treated for claudication, the technical success rate was 98%. Immediate treatment success was better for claudicants than for those with critical ischemia, and for stenotic lesions (98%) compared with total occlusions (86%). It is worthwhile to note that these results were attained at a time when the profile and range of available wires and balloons was significantly more limited than that available today. A more recent series from Germany detailed 104 infrapopliteal percutaneous interventions in 78 patients with claudication. The excimer laser was used in 18% of cases in which noncalcified totally occluded vessels were encountered and stents were placed in 25% of patients following
suboptimal results with angioplasty. The overall complication rate was low at 6%, with all complications being minor and treated conservatively; there were no periprocedural deaths, amputations, or need for emergent surgical intervention. Both ABI and walking distance significantly improved over baseline measurements. At 12 months, duplex-assessed primary patency was 66%, cumulative primary assisted patency was 82%, and secondary patency was 92%. No patient underwent amputation or surgical bypass during the follow-up period.50
Infrageniculate Stenting A recent technologic advance that will undoubtedly impact vascular surgical practice patterns is the introduction of a
Table 2 National Profile of Providers Performing Percutaneous Interventions for Peripheral Arterial Disease Over a Recent 10-Year Period US Peripheral Interventions
1996 (%) (n ⴝ 340,000)
2000 (%) (n ⴝ 550,000)
2005 (%) (n ⴝ 750,000)
Interventional cardiologists Interventional radiologists Vascular surgeons
25 65 10
40 45 15
55 30 15
Infrapopliteal intervention for treatment of claudicant
Figure 5 (A) Strut profile of stent designed for large vessel placed within a small vessel. (B) Strut profile of stent designed for smaller vessel.
self-expanding stent dedicated for use in the tibial arterial tree. Prior to this point, options in the face of a suboptimal angioplasty result were limited to short-segment balloon expandable stents designed for the coronary arteries. Apart from potential tracking difficulties, the use of drug-eluting stents (DESs) rendered a procedure undertaken solely for lifestyle improvement prohibitively expensive, particularly if more than one stent was used. The Xpert stent (Abbott Vascular Devices, Redwood City, CA) is a 3.8Fr low-profile nitinol device capable of tracking through a 4Fr delivery sheath. The stents targeted for tibial use range in diameter from 3 to 6 mm and in length from 20 to 60 mm. Figure 5 illustrates the low-strut profile of this novel stent. While data on tibial artery stenting is even more sparse than that supporting angioplasty, several small published series with early follow-up have demonstrated efficacy.51 In one study comparing sirolimus-eluting stents (Cypher, Cordis Corporation, Miami, FL) to bare-metal stents following suboptimal angioplasty secondary to lesion recoil or severe dissection in patients with critical limb ischemia, 6-month primary patency rates were 68% in the bare-metal group versus 92% in the drug-eluting stent group.52 Scheinert et al53 also found significantly better 6- to 12-month patency rates, 84% versus 53% respectively, when comparing DESs to PTA alone for infrapopliteal lesions. Although a theoretical concern, crush damage to the balloon expandable stents proved not to be problematic in either series. While the results of these reports are encouraging, it is important to remember that impressive suppression of restenosis was also demonstrated in the early time points following use of DESs in the superficial femoral artery during the SIROCCO trials, but the effect was not sustained over time.54 The preliminary experience with absorbable metal stents and carbon-lined stents,55,56 while anecdotal, has also been positive to date. Paralleling the recent progress in stent technology, there have also been marked improvements in the wires and balloons accessible to the peripheral interventionalist. Tibial artery atherosclerosis frequently manifests as long-segment occlusions in heavily calcified arteries, and a variety of wires now in existence are specifically designed to cross-challenging total occlusions. At present, specialty “re-entry devices” that facilitate successful navigation back into the vessel lumen following subintimal traversal of an occluded arterial segment, particularly useful in the subclavian, iliac, and su-
51 perficial femoral arterial beds, are not practical for the smaller tibial arteries. However, a range of support catheters and low-profile, longer-segment balloons with enhanced trackability have noticeably improved the ability to cross and successfully treat many infrageniculate lesions, and helped to lower the rate of technical failures in recent years. The ev3 Amphirion (ev3 Inc, Plymouth, MN) balloon, which ranges in diameter from 1.5 to 4 mm in diameter and is available in a .014-inch platform in lengths up to 120 mm, is an example of a new-generation balloon particularly well-suited to tibial angioplasty.
Adjunctive Endolumenal Therapies Beyond novel balloons and stents, a growing array of innovative adjunctive treatment devices has helped fuel the shift toward increased use of endovascular therapy for infrainguinal occlusive disease. While not new, the excimer laser has been refined and can now be applied via smaller-profile fibers compatible with infrageniculate anatomy. The laser uses ultraviolet energy at 308 nm to photoablate plaque. Although marketed as a “stand-alone” treatment, follow-up balloon angioplasty or stenting is often required to obtain an acceptable angiographic result. It currently has a niche role in allowing stepwise entry through chronic occlusions refractory to intralumenal or subintimal wire passage. The Silverhawk (Foxhollow Technologies, Redwood City, CA) is a new-generation atherectomy device that allows controlled debulking of atheroma, theoretically obviating the need for balloon angioplasty or stenting and removing the triggers for intimal hyperplasia-mediated restenosis. Vessel perforation and distal embolization have been reported in low rates, and current devices have overcome earlier difficulty tracking through the angulation of the proximal anterior tibial artery. In one of the few reviews that included patency data, a small series of 33 patients undergoing directional atherectomy for chronic ischemia, a 22% restenosis rate of ⱖ70% at 6 months was reported.57 Balloon cryoplasty and cutting balloons are two additional novel technologies that aim to minimize the trauma associated with traditional balloon angioplasty, and thereby lower the vexing problem of restenosis. The PolarCath (Boston Scientific Corporation, Natick, MA) uses nitrous oxide to transmit temperatures as low as ⫺10°C to the vessel wall, theoretically reducing arterial wall inflammation and resulting in less intimal dissection and lesion recoil. By inducing apoptosis rather than cell necrosis, the proliferative remodeling that underlies restenosis is also theoretically lessened. Cutting balloons, on the other hand, use either longitudinally oriented microtomes or a spiral nitinol cage mounted onto a balloon to affect a more controlled vessel wall expansion. By incising rather than shattering the plaque, dilation can be achieved at lower pressure, again with theoretic less-resultant dissection, recoil, and barotrauma. While several reports have demonstrated efficacy with vein graft stenoses,58 in our own recent experience with over 20 patients, we have found
52 no advantage over conventional balloon angioplasty in this setting. None of the described adjunctive devices are supported by objective comparative data or any degree of long-term angiographic follow-up demonstrating reliable durability. Enthusiastic endorsement from industrial sponsors notwithstanding, the evidence substantiating their utility is, at present, largely anecdotal. As such, awareness of their associated cost is important in the face of potential local pressure to demonstrate use of cutting-edge technology.
Current Recommendations In summary, we believe an aggressive approach to claudication is warranted in good-risk patients with disabling symptoms and minimal comorbidities. Given available data demonstrating excellent early outcomes and sustained durability with femorotibial reconstruction, operative bypass in carefully selected patients whose anatomy obligates an infrageniculate distal target should not be withheld. A target vessel continuously patent to the level of the ankle would be considered a prerequisite for operative bypass, and reconstruction should be restricted to those patients with a single segment of adequate saphenous vein, given the compromised outcomes and added complexity associated with prosthetic and ectopic conduits. Further, patients with significant cardiopulmonary, neurologic, musculoskeletal, or other conditions likely to compromise their functional capacity or longevity would be poor candidates for reconstruction in the absence of critical ischemia. Percutaneous therapy is an attractive and appropriate therapeutic alternative for claudicants with focal lesions limited to the tibioperoneal trunk or proximal tibial arteries. Paralleling the experience with operative tibial revascularization, early fears that endolumenal therapy would accelerate the disease process or adversely impact available surgical options do not appear to have been borne out in clinical practice. In the absence of reliable long-term patency data to suggest otherwise, patients with long-segment femoral, popliteal, or proximal tibial total occlusions, and who are otherwise good operative candidates, should be offered surgery as their firstline reconstructive option. The presence of multiple polypoid, calcific lesions at potentially higher risk of embolism with wire manipulation or lesions that have responded poorly to initial endolumenal treatment are also relative contradictions to an endovascular approach.
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