2 The procedure
2.1.1 Popliteal artery aneurysms are the most common peripheral aneurysms. They can cause leg ischaemia by embolism or thrombosis and may rupture. Current treatment is usually by open surgical bypass grafting. Postoperative antiplatelet therapy is generally given.
2.2.1 Endovascular repair stent-grafting of popliteal aneurysms is carried out with the patient under local or general anaesthesia. Under fluoroscopic guidance, a stent-graft device is inserted into the femoral artery using standard catheter and guidewire techniques. Care is taken to ensure adequate length of anchoring stent in the normal vessel, both proximally and distally, to bridge the popliteal aneurysm and fully exclude the aneurysm from the circulation.
2.2.2 A range of different stents are available for this procedure.
Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/guidance/IP/817/overview
2.3.1 A meta-analysis of 320 patients treated by endovascular repair reported primary and secondary patency rates at 1 year of 83% (95% CI 79% to 88%) and 86% (95% CI 82% to 91%) respectively. In the same meta-analysis, comparative data were available for 159 patients: the primary patency rate at 1 year for endovascular repair was 84% (36/43), compared with 85%) 99/116) for open repair (p = 0.46). Secondary patency rates at 1 year were 86% (37/43) for endovascular repair and 95% (110/116) for open repair (p = 0.07). A non-randomised comparative study of 43 patients (56 limbs; 15 endovascular and 41 open repair) reported primary patency rates of 83% and 88% respectively at 24-month follow-up (p = not significant). A case series of 60 patients at 24 months were 100% and 92% for endovascular and open repair respectively (p = not significant). A case series of 60 patients reported that the primary patency rate was 77% at 3 years and 70% at 5 years. Primary patency is defined as uninterrupted patency following revascularisation. Secondary patency implies that re-intervention has been required to restore patency.
2.3.2 A case series of 50 patients reported that 98% (56/57) of aneurysms were completely excluded after endovascular repair.
2.3.3 The case series of 50 patients reported a limb salvage rate of 97% (55/57).
2.3.4 A randomised controlled trial (RCT) of 42 patients treated by endovascular or open repair reported that 14% (3/21) of patients in the endovascular group required open repair because of endograft occlusion during a mean follow-up of 47 months. In the case series of 50 patients, stent-graft occlusion occurred in 16% (9.57) of aneurysms (2 were successfully treated by thrombolysis, 5 were treated by femoropopliteal bypass, 1 patient was asymptomatic and was not treated, and in the remaining patient, treatment of the occlusion was delayed leading to severe limb ischaemia requiring amputation).
2.3.5 The Specialist Advisers listed key efficacy outcomes as successful exclusion of the aneurysm, long-term prevention of thrombosis and distal emoblisation, prevention of rupture, and limb salvage.
2.4.1 Endograft thrombosis occurred in 10% (2/21) of patients treated by endovascular repair the day after the procedure in the RCT of 42 patients. In 1 patient, intra-arterial thombolytic therapy followed by an additional endovascular procedure was successful. The other patient required open repair after 72 hours. Acute thrombosis was reported in 6% (2/23) of aneurysms within 24 hours of the procedure in the case series of 29 patients; both aneurysms were successfully recanalised with catheter-directed thrombolysis and balloon angioplasty or rheolytic thrombectomy. In this study, a further 4 patients were diagnosed with thrombosis during follow-up (1 was described as acute and 3 as subacute).
2.4.2 Stent fracture in 4% (3/73) of aneurysms (2 leading to occlusion) and stent migration in 12% (9/73) of aneurysms were reported in the case series of 60 patients. Stent migration was reported in 7% (4/57) of procedures in the case series of 50 patients.
2.4.3 Stenosis was reported in 3% (2/73) of procedures (timing of events not stated) in the case series of 60 patients. These were treated by percutaneous transluminal angioplasty.
2.4.4 There was 1 report of distal embolsiation necessitating amputation in the case series of 50 patients.
2.4.5 The Specialist Advisers listed anecdotal adverse events as stent occlusion leading to acute limb ischaemia, stent-graft thrombosis, graft failure due to repeated mechanical stress, endoleak and puncture-site arterial bleeding. They considered theoretical adverse events to include stent-graft infection and loss of aneurysm control.