Endovascular Popliteal Aneurysm Repair: Are the Results Comparable to Open Surgery?

Eur J Vasc Endovasc Surg 32, 149–154 (2006) doi:10.1016/j.ejvs.2006.01.009, available online at http://www.sciencedirect.com on

Endovascular Popliteal Aneurysm Repair: Are the Results Comparable to Open Surgery?* I.V. Mohan, 1* P.J. Bray, 1,2 J.P. Harris,1 J. May,1 M.S. Stephen,1 A.E. Bray2 and G.H. White1 a

Royal Prince Alfred Hospital, Missenden Road, Camperdown, Sydney, and bCardiovascular Centre, Lake Macquarie Private Hospital, Newcastle, NSW, Australia

Introduction. The aim of this study was to review our experience of popliteal aneurysms using endovascular techniques. Methods. Thirty popliteal aneurysms in 25 patients were treated over an 11-year period. Median aneurysm diameter was 26 (16–48) mm. Five were symptomatic and 25 asymptomatic. Patients were treated with the Haemobahn/Viabahn stent-graft (26), Passager (two), Aneurx (one), and PTFE homemade device (one). Data were assessed using life table analysis, and expressed as cumulative patency rates and standard error (SE). Results. Median follow-up was 24 (range 1–95) months. Primary patency was 92.9% (SE 4.5%), 84.7% (SE 6.8%), 80% (SE 8.2%), 74.5% (SE 9.4%) and 74.5% (11.3%) at 1, 6, 12, 24 and 36 months, respectively. Cumulative secondary patency was 96.5% (SE 3.3%), 88.7% (SE 6.0%), 88.7% (SE 8.6%), 83.2% (SE 8.0%) and 83.2% (SE 9.8%) at 1, 6, 12, 24 and 36 months, respectively. Conclusion. Endovascular treatment of popliteal aneurysms in this series achieved patency rates similar to open surgery. Aneurysm repair was performed without peroperative deaths and the risks associated with open surgery. Keywords: Popliteal aneurysms; Limb loss; Flexible stent grafts; Thrombolysis; Patency rates; Antiplatelet agents; Endoleak.

Introduction Popliteal aneurysms (PA) may cause serious ischaemic complications, associated with thrombosis or embolisation, resulting in limb loss. Popliteal aneurysms are associated with nerve and vein compression and also rupture and death. Guvendik et al. described PA as the ‘sinister harbinger of sudden catastrophe’.1 PA has a prevalence of 1% in the general population, is often bilateral, and associated with abdominal aortic aneurysms.2,3 It is estimated that the likelihood of an asymptomatic popliteal aneurysm becoming symptomatic is around 14–24% per year.2,4 Untreated PA will progress to complications in almost 70% of cases in 5 years and has a strong association with limb loss in up to 30–40% of patients.2,4 Antyllus in 200 BC first described ligation and packing as the treatment of popliteal aneurysm.5 Since then, the traditional method of treating PA has been *

Presented at the European Society for Vascular Surgery, XIX Annual Meeting, September 2005 Helsinki, Finland. *Corresponding author. I.V. Mohan, FRCS, Consultant Vascular Surgeon, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK. E-mail address: [email protected]

ligation and bypass using long saphenous vein, or polytetrafluoroethylene (PTFE) as the conduit, from a medial or posterior surgical approach. These procedures have patency rates of 70–80% at 5 years for vein grafts and much less for prosthetics.4,6,7 Saphenous vein has, therefore, remained the conduit of choice. There is some controversy as to what constitutes the threshold size for intervention for asymptomatic PAs. Lowell and colleagues, recommended surgery for PAs greater than 2 cm, but Galland recommended 3 cm as a cut-off. 8,9 All, however, agree that PAs more than 3 cm require intervention, and many authors have noted that outcome is better with elective intervention before loss of distal runoff vessels from embolisation.8,10 The advent of endovascular technology and its application in the treatment of aortic aneurysms, have led to the adaptation of these techniques for the treatment of peripheral aneurysms. The first case was reported by Marin et al. using a home made device.11 Since then, there have been many advances in the design and types of stent grafts, including the highly flexible PTFE lined nitinol stents (W.L. Gore and Associates, Inc., Flagstaff, AZ, USA). These stents are

1078–5884/000149 + 06 $35.00/0 q 2006 Elsevier Ltd. All rights reserved.

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more compliant to the movement and the unique mechanical stresses that are observed in the popliteal artery. This retrospective study reviewed our experience of treating popliteal aneurysms using endovascular techniques.

Methods Thirty PA in 25 patients were treated over an 11-year period (1994–2005) at two centres. All patients were male and the median age was 74 (range 56–83) years. Patient risk factors are shown in Table 1. All patients had colour flow duplex and angiography, and ankle brachial pressure index (ABPI) measured pre-operatively, 18 limbs were also investigated with spiral CT (computerized tomography) scans. The popliteal artery was considered aneurysmal if it was more than 2.0 cm in diameter, or was 1.5 times the diameter of the adjacent normal popliteal artery. The smallest aneurysms treated were 16 mm diameter (in two patients); one was symptomatic and the other patient had had his contralateral PA previously treated, and requested intervention. Five limbs were symptomatic, one with acute ischaemia, treated with thrombolysis prior to stenting of the popliteal aneurysm. One patient had limiting claudication, one presented with venous compression, and one had symptoms of embolisation. A further nine patients had mild to moderate claudication reflecting the number of run-off vessels (ABPI!0.8). All but one patient in this series had atherosclerotic popliteal aneurysms: this patient had a false aneurysm, following a knee injury 12 months previously. One patient developed true aneurysms in the popliteal arteries bilaterally, after femoro-popliteal bypass surgery for claudication (22 and 28 years previously). Aneurysm characteristics are shown in Table 2. All procedures were performed in the main operating theatre. Interventions were carried out under local anaesthesia in 22 limbs, regional anaesthesia in four, and general anaesthesia in four. Two patients had bilateral procedures at the same sitting. Heparin and an antiplatelet agents were given in all cases. All cases were approached from an ipsilateral Table 1. Vascular risk factors for patients with popliteal aneurysms Risk factors

n

Percentage

Hypertension Hypercholesterolaemia History of smoking Ischaemic heart disease Diabetes Chronic bronchitis

22 10 21 10 2 8

88 40 84 40 8 32

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antegrade common femoral artery puncture with an 8– 14 Fr sheath. Twenty-six limbs were treated with the Haemobahn/Viabahn stent graft (W.L. Gore and Associates, Inc., Flagstaff, AZ, USA). We also used Passager (two) (Boston Scientific, Waterdown, MA, USA); Aneurx (one) (Medtronic, Inc., Minneapolis, MN, USA); and a PTFE homemade device (one). One patient who developed popliteal aneurysms following femoro-popliteal bypass grafts in the 1970s for claudication, had cut-down procedures to the vein grafts through which the stent grafts were deployed, the first was repaired in 1996 with a Passager stent graft (Boston Scientific, Waterdown, MA, USA), and the contralateral side in 2002 with an Aneurx stent graft (Medtronic, Inc., Minneapolis, MN, USA). One further Passager graft was deployed in 1998, all other patients had Haemobahn/Viabahn stent grafts (W.L. Gore and Associates, Inc., Flagstaff, AZ, USA) (Fig. 1(a)–(d)). Inclusion criteria used in patient selection for endovascular treatment of PA were anatomical suitability for use of an endovascular device, including non-aneurysmal or stenotic access vessels; suitable healthy vessels (at least 2.0 cm in length) for proximal and distal fixation of the endovascular device, in addition we were very cautious with extensive tortuous aneurysms and the possible need for numerous stents. Overall 50% of popliteal aneurysms treated at our two centres during this time period were treated with stent grafts; all others had open surgery for symptoms or unsuitable anatomy. Stent-graft sizing was determined by duplex and calibrated angiography with at least 1 mm oversize. Completion angiogram and post-operative Duplex Table 2. Vascular characteristics of patients and limbs treated with popliteal endografts Popliteal aneurysms Median popliteal aneurysm diameters Symptomatic Asymptomatic

26 (range 16–48) mm 5 25 n

Runoff vessels 0 1 2 3 Contralateral popliteal artery Normal Aneurysmal Occluded Previous bypass Ectatic Abdominal aorta Aneurysmal Non-aneurysmal

1 8 14 7 9 13 3 2 3 11 14

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Fig. 1. (a) Preliminary arteriogram for calibration and sizing a popliteal aneurysm for stenting. (b) Radiograph demonstrating positioning of the stent graft device for popliteal aneurysm stenting. (c) Angiogram after deployment of Haemobahn stent graft excluding the popliteal aneurysm. (d) Lateral view angiogram of the popliteal artery aneurysm after deployment of the stent graft with the knee in the 908-flexed position.

was performed in all cases, together with a lateral view with the knee in the flexed position. All patients had duplex scans at 1 month, 3 months and then at 6-monthly intervals. All patients were given antiplatelet agents in the long term, this was initially aspirin and more recently some patients were prescribed clopidogrel. Descriptive statistics were used and data were assessed using Kaplan–Meier life table analysis, and expressed as cumulative patency rates and standard error (SE).12

Results Deployment was successful in all 30 cases and there were no early mortality. Median follow up was 24 (range 1–95) months, and there was no limb loss. Median number of stents used was 2 (range 1–3). Where multiple stents were used, we aimed for at least

2 cm overlap or more. Median aneurysm length was 10 (range 6–24) cm and median covered length with the endograft was 15 (range 10–30) cm, the distal popliteal artery was the landing site in all cases apart from two; in these the landing zone was in the tibio-peroneal trunk. In only one of these two were the anterior tibial artery sacrificed, as it was previously occluded in the other. Our earliest popliteal aneurysm was repaired in 1994 with a homemade PTFE device (similar to that used by Marin),11 this graft occluded after 4 months; but the limb was salvaged with an in situ femoroperoneal vein graft. Another graft occlusion occurred at 10 months, which was successfully thrombolysed, proximal extension of the aneurysm was noted and restented, the graft itself had not migrated. One graft failure occurred at 2 months following a period of prolonged knee flexion (thrombolysis was unsuccessful), and another after 19 months when the patients Eur J Vasc Endovasc Surg Vol 32, August 2006

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Table 3. Summary of outcome for failed popliteal endografts Age (years)

Time to occlusion

Graft type

Treatment

Secondary patency

Outcome

68 83 73 59 70 82

10 days 1 month 2 months 4 months 10 months 19 months

Haemobahn Haemobahn Haemobahn PTFE Haemobahn Haemobahn

Femoro-peroneal bypass Successful thrombolysis Failed thrombolysis Femoro-peroneal bypass Successful thrombolysis None

No 20 months No No 47 months No

Limb salvage Limb salvage Claudication Limb salvage Limb salvage Claudication

developed cardiac failure. Two further graft failures are described in Table 3. None of our patients with failed grafts had amputations, two had successful thrombolysis, two had successful limb salvage surgery (femoro-peroneal bypass grafts) and two became claudicants (ABPI 0.5–0.6) and declined further intervention (Table 3). Three endoleaks were noted altogether; two type II endoleaks, one observed early and resolved spontaneously, and the other a late observation that is still being monitored. There was a small distal type I endoleak which resolved spontaneously after 1 month. Two patients in this series died during follow-up, one at 6 months from a myocardial infarction and the other from heart failure at 20 months. The second patient occluded his endograft 1 month prior to his death (after 19 months). Overall mean aneurysm diameter decreased by 0.4 (range 0–1.2) cm and no sac

enlargement was noted, even in the patients with endoleak. Stent graft migration was not observed in this study. Overall 1-month cumulative primary patency was 92.9% (SE 4.5%). Six-month primary cumulative patency was 84.7% (SE 6.8%), and 12-month patency was 80% (SE 8.2%). Cumulative primary patency remains at 74.5% at 24 and 36 months (SE 9.4 and 11.3%, respectively). Cumulative one-month secondary patency was 96.9% (SE 3.3%), 88.7% at 6 and 12 months (SE 6.0 and 6.7%), and 83.2% at 24 and 36 months (SE 8.0 and 9.8%) (Fig. 2).

Discussion This study is the second largest series of endovascular treated popliteal aneurysms to date; and our results

Popliteal Aneurysm Stent Grafts Patency Rates Secondary patency Primary patency

Cummulative Patency

100% 80% 60% 40% 20% 0% 0 - 1 1 to 3

3 to 6

6 to 12 to 18 to 24 to 30 to 36 to 42 to 48 to 54 to 60 to 66 to >72 12 18 24 30 36 42 48 54 60 66 72

Interval (months)

Fig. 2. Graph comparing primary and secondary stent graft patency rates for popliteal aneurysm stent-grafts. Broken line indicates when standard error exceeds 10%. Eur J Vasc Endovasc Surg Vol 32, August 2006

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are consistent with the experience of the Groningen group who presented data on 57 unselected patients treated with the Haemobahn/Viabahn stent graft alone.13 Two of our six occlusions (33%) occurred within the 1st month, and four (66%) occurred within the first 4 months; and there were two late occlusions (at 10 and 19 months). Primary cumulative patency rates were 80% at 12 months, and 74.5% at 24 and 36 months; cumulative secondary patency rates were 88.7% at 12 months, and 83.2% at 24 and 36 months. Conventional bypass grafting has achieved average 5-year graft patency of between 70 and 80%.3,4,7 The outcome for symptomatic patients is worse than that for asymptomatic patients and also for patients with fewer runoff vessels, and early intervention in popliteal aneurysms may avoid the degradation of runoff vessels.10,14 Because of small numbers in currently published series, we cannot yet show that the same result, for graft patency, will hold true for endovascularly treated popliteal aneurysms in the long term. However, significant progress has been made since our first endograft repair of a popliteal aneurysm was attempted in 1994, with a polytetrafluoroethylene (PTFE) graft, similar to that described by Marin and colleagues.11 We used the Passager stent graft in two patients (Boston Scientific, Waterdown, MA, USA), and the limb of an Aneurx (Medtronic, Inc., Minneapolis, MN, USA) aortic stent graft in another. These grafts were not very compliant or flexible, and probably not well suited for use in the highly mobile popliteal vessels, but remained patent at more than 30 months of follow-up. Since then, there has been increasing availability and refinement of commercially available stent grafts, especially the highly flexible, Haemobahn/Viabahn nitinol stent graft (W.L. Gore and Associates, Inc., Flagstaff, AZ, USA). The biomechanical forces that influence the popliteal artery during movement appear to be unique in the human body. Wensing and colleagues described dynamic changes in curvature of the femoro-popliteal segment corresponding to the patient’s age.15 They concluded that in the flexed position in patients under 30 years of age, minor arterial curves were noted proximal to the adductor hiatus. In patients over 45 years one or more curves were located distal to the adductor hiatus (in the popliteal fossa). And in patients over the age of 60 years, the curves did not disappear during knee extension. For this and other reasons, all of our recent experience has been with the Haemobahn/Viabahn stent graft; this self-expanding graft (sinusoidally shaped, helically wrapped) with ultrathin (100 mm) ePTFE coating luminal surface is flexible, relatively kink resistant and seems best for placement in the popliteal artery. Haemobahn

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deployment is different from Viabahn, Haemobahn unfolds from a rolled/furled configuration and may not open fully if there is significant oversizing. This can be difficult to detect since balloon dilatation inside the graft does not necessarily show the infolding, which is dependent on angle of the image intensifier tube. Viabahn is packed in a more favorable way, with concentric multiple minor folds. There are some limitations with the Haemobahn/Viabahn stent graft. It can shorten significantly, and may also ‘bow’ into a larger sac, causing uncertainty of position, and sometimes make it necessary to use several grafts overlapped. It may be difficult to use if there is not a good ‘neck’ or cuff of relatively normal popliteal artery distally (especially if it shortens). Extensive, tortuous popliteal aneurysms are probably not good candidates for endovascular repair due to tortuosity and compression of the grafts and the requirement for multiple overlapping segments. Diaz and colleagues further investigated the morphological changes in the popliteal artery during knee flexion and described the presence of ‘hinge points’ in this vessel segment.16 Biomechanical stresses between the host artery and the implanted stent as a result of this mobility may be responsible for stent fractures. The debate regarding stent fractures has significant implications after the insertion of a stent graft in relation to occlusion. The SIROCCO I trial was designed to investigate the effectiveness of self expanding, drug-eluting stents in the treatment of femoro-popliteal occlusive disease; this study demonstrated a stent fracture rate of 18.2% in patients with multiple stents in the femoro-popliteal segment, but did not find any correlation with graft occlusion.17 Scheinert and colleagues, however, reported a stent fracture rate of 37.2% in the femoro-popliteal segment and demonstrated a reocclusion rate of 34.4% in limbs with fractured stents.18 Tielliu, reporting the largest series of endograft repair of popliteal aneurysms, found two stent fractures in the Haemobahn device that ultimately resulted in graft occlusions.13 One of the limitations of this series is that our cohort did not all have plain radiographs in follow-up and we cannot comment on stent fractures. All of our patients were placed on antiplatelet therapy, aspirin (75–325 mg) and more recently we have used clopidogrel (75 mg); two of our patients were also on warfarin for atrial fibrillation. This rationale is based on the Antiplatelet Trialists’ Collaboration that demonstrated a 32% reduction in graft occlusion in patients who received antiplatelet agents.19 The CAPRIE Trial subsequently demonstrated an increased benefit of clopidogrel over aspirin.20 The CREDO trial found that a loading Eur J Vasc Endovasc Surg Vol 32, August 2006

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strategy and long term clopidogrel therapy significantly reduced death and vascular events for coronary stents.21 Although the benefits of antiplatelet agents are well established, there are no specific data supporting the use of antiplatelet agents in the lower limbs, either as monotherapy or as combination therapy. However, in a univariate analysis, the Groningen group found that the additional use of clopidogrel was the only factor that predicted success of a popliteal stent graft.13 Endovascular repair of abdominal aortic aneurysm is associated with types I and II endoleaks, and we have described similar findings after endovascular repair of the popliteal artery. Thus far, we have noted no evidence of enlargement of the aneurysm sac. Whether or not this will feature in the long term is yet to be determined, but we do know that popliteal aneurysms treated by exclusion and bypass may demonstrate persistent blood flow and even enlargement of the aneurysm sac.22,23 The advent of flexible and versatile new stent grafts marks a major step forward in the treatment of popliteal (and perhaps other peripheral) aneurysms with results comparable to conventional surgery.13,24 Endovascular repair of popliteal aneurysms is a promising technique with good short and intermediate term results. However, long term surveillance of these procedures in essential to monitor the function and durability of the stent grafts. Antiplatelet therapy in the form of clopidogrel as monotherapy or combination therapy is essential.13,25 In conclusion, endovascular treatment of popliteal aneurysms in this selected series of patients with suitable anatomy achieved patency rates similar to that of open surgery. Aneurysm repair was performed without peroperative deaths, and endograft failure in this series was not associated with limb loss.

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7 Reilly MK, Abbott WM, Darling RC. Aggressive surgical management of popliteal artery aneurysms. Am J Surg 1983; 145:498–502. 8 Lowell RC, Gloviczki P, Hallett Jr JW, Naessens JM, Maus TP, Cherry Jr KJ et al. Popliteal artery aneurysms: the risk of nonoperative management. Ann Vasc Surg 1994;8:14–23. 9 Galland RB, Magee TR. Management of popliteal aneurysm. Br J Surg 2002;89:1382–1385. 10 Halliday AW, Taylor PR, Wolfe JH, Mansfield AO. The management of popliteal aneurysm: the importance of early surgical repair. Ann R Coll Surg Engl 1991;73:253–257. 11 Marin ML, Veith FJ, Panetta TF, Cynamon J, Sanchez LA, Schwartz ML et al. Transluminally placed endovascular stented graft repair for arterial trauma. J Vasc Surg 1994;20:466–472. 12 Rutherford RB, Baker JD, Ernst C, Johnston KW, Porter JM, Ahn S et al. Recommended standards for reports dealing with lower extremity ischaemia: revised version. J Vasc Surg 2001; 26:517–538 [erratum in J Vasc Surg 2001;33:805]. 13 Tielliu I, Verhoeven ELG, Zeebregts CJ, Prins TR, Span MM, van den Dungen JJ. Endovascular treatment of popliteal artery aneurysms: results of a prospective cohort study. J Vasc Surg 2005; 41:561–567. 14 Carpenter JP, Barker CF, Roberts B, Berkowitz HD, Lusk EJ, Perloff LJ. Popliteal artery aneurysms: current management and outcome. J Vasc Surg 1994;19:65–72. 15 Wensing PJ, Scholten FG, Buijs PC, Hartkamp MJ, Mali WP, Hillen B. Arterial tortuosity in the femoropopliteal region during knee flexion: a magnetic resonance angiography study. J Anat 1995;187:133–139. 16 Diaz JA, Villegas M, Tamashiro G, Micelli MH, Enterrios D, Balestrini A et al. Flexion of the popliteal artery: dynamic angiography. J Invasive Cardiol 2004;16:712–715. 17 Duda SH, Pusich B, Richter G, Landwehr P, Oliva VL, Tielbeek A et al. Sirolimus-eluting stent for the treatment of obstructive superficial femoral artery disease. Six month results. Circulation 2002;106:1505–1509. 18 Scheinert D, Scheinert S, Sax J, Piorkowski C, Braunlich S, Ulrich M et al. Prevalence and clinical impact of stent fractures after femoropopliteal stenting. J Am Coll Cardiol 2005;45:312–315. 19 Antiplatelet Trialists’ Collaboration. Collaborative overview of randomized trials of antiplatelet therapy. Part II. Maintenance of vascular graft or arterial patency by antiplatelet therapy. BMJ 1994;308:159–168. 20 CAPRIE Steering Committee. A randomized, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet 1996;348:1329–1339. 21 Steinhubl SR, Berger PB, Mann JT, Fry ET, DeLago A, Wilmer C et al. Early and sustained dual oral antiplatelettherapy following percutaneous coronary intervention. A randomized controlled trial. JAMA 2002;288:2411–2420. 22 Jones WT, Hagino RT, Chiou AC, Decaprio JD, Franklin KS, Kashyap KS. Graft patency is not the only clinical predictor of success, after exclusion and bypass of popliteal artery aneurysm. J Vasc Surg 2003;37:392–398. 23 Kirkpatrick UJ, McWilliams RG, Martin J, Brennan JA, Gilling-Smith GL, Harris PL. Late complications after ligation and bypass for popliteal aneurysm. Br J Surg 2004;91:174–177. 24 Antonello M, Frigatti P, Battochio P, Lepidi S, Cognolato D, Dall’Antonia A et al. Open repair versus endovascular treatment for asymptomatic popliteal artery aneurysm: results of a prospective randomised study. J Vasc Surg 2005;42:185–193. 25 Aulivola B, Hamdan AD, Hile CN, Sheahan MG, Skillman JJ, Cambell DR et al. Popliteal artery aneurysms: A comparison of outcomes in elective versus emergent repair. J Vasc Surg 2004;39:1171–1177. Accepted 12 January 2006 Available online 20 March 2006