Interventional procedure consultation document

Endovascular repair of popliteal aneurysms

Treating popliteal aneurysms by inserting a mesh tube

The popliteal artery is situated behind the knee and conveys blood to the lower leg and foot. An aneurysm is an abnormal swelling in the wall of an artery. Endovascular repair of popliteal aneurysm involves inserting a ‘stent-graft’ device through the femoral artery (in the groin) and lining the inside of the aneurysm. The aim is for the stent-graft to bridge the weak spot within the artery and exclude the aneurysm, to reduce its risk of clotting or rupture.

The National Institute for Health and Clinical Excellence (NICE) is examining endovascular repair of popliteal aneurysms and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about endovascular repair of popliteal aneurysms.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

• comments on the provisional recommendations
• the identification of factual inaccuracies
• additional relevant evidence, with bibliographic references where possible.

Note that this document is not NICE’s formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that NICE will follow after the consultation period ends is as follows.

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved. NICE reserves the right to summarise and edit comments received during consultations, or not to publish them at all, where in the reasonable opinion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 21 January

Target date for publication of guidance: April 2011

1   Provisional recommendations

1.1  Current evidence on endovascular repair of popliteal aneurysms is limited in quantity but shows no major safety concerns. Evidence on efficacy is limited to the short-term and therefore inadequate. This procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2  Clinicians wishing to undertake endovascular repair of popliteal aneurysms should take the following actions.

• Inform the clinical governance leads in their Trusts.
• Ensure that patients and their carers understand the uncertainty about the procedure’s long-term efficacy and provide them with clear written information. In addition, the use of NICE’s information for patients (‘Understanding NICE guidance’) is recommended (available from www.nice.org.uk/IPGXXXpublicinfo). [[details to be completed at publication]]
• Audit and review clinical outcomes of all patients having endovascular repair of popliteal aneurysms (see section 3.1).

1.3  Patient selection for this procedure should be carried out by a multidisciplinary team which should include a vascular surgeon and an interventional radiologist with specific training and experience in the technique.

1.4  NICE encourages research into endovascular repair of popliteal aneurysms and may review this procedure on publication of further evidence.

2  The procedure

2.1  Indications and current treatments

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 by open surgical bypass grafting. 

2.2  Outline of the procedure

2.2.1  Endovascular repair of popliteal aneurysms is carried out with the patient under local or general anaesthesia. After surgical exposure or percutaneous puncture of the femoral artery, a stent-graft device is inserted under fluoroscopic guidance using standard catheter and guidewire techniques. Care is taken to position the stent-graft to bridge the popliteal aneurysm, with an adequate length of anchoring stent in the normal vessel both proximally and distally, to 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   Efficacy

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). Secondary patency rates 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. The secondary patency rate was 86% at 3 years and 76% 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 and a case series of 29 patients reported that 100% (33/33) of aneurysms were successfully excluded from the circulation. 

2.3.3  The case series of 50 patients reported a limb salvage rate of 96% (55/57).

2.3.4  An 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 embolisation, prevention of rupture, and limb salvage.

2.4   Safety

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 thrombolytic therapy followed by an additional endovascular procedure was successful. The other patient required open repair after 72 hours. Acute thrombosis was reported in 6% (2/33) 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 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 embolisation 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.

3   Further information

3.1  This guidance requires that clinicians undertaking the procedure make special arrangements for audit. NICE has identified relevant audit criteria and is developing an audit tool (which is for use at local discretion), which will be available when the guidance is published.

Barrie White

Vice-Chairman, Interventional Procedures Advisory Committee

December 2010

_{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

 _{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}