Minimally invasive versus surgical treatment of an aneurysm of the popliteal artery

The popliteal artery is a blood vessel situated behind the knee joint. Sometimes it weakens and expands like a balloon, known as an aneurysm. If left untreated, the blood clot within the aneurysm may embolise or the aneurysm may rupture or get blocked. Any of these complications can lead to limb loss or even death. Traditionally, popliteal artery aneurysm (PAA) has been treated surgically. However, it is also possible to treat the condition by deploying an endovascular stent graft through a small puncture in the groin. An endovascular stent graft is a fabric tube supported by a metal mesh which sits snugly and forms a seal within the artery. The success of the procedure is determined by the ability of the surgically applied graft or the stent graft to remain unblocked. Blockage of the graft decreases the leg circulation, which may require emergency surgery. Some consider the surgical technique to be the gold standard, although the feasibility of the endovascular technique has been well documented in many retrospective studies. Level-1 evidence is only obtained however when two techniques are pitted against each other in a prospective randomised controlled trial (RCT).

The purpose of this review was to combine the data from all the RCTs performed to date comparing the surgical technique versus the endovascular technique for the treatment of non-emergency PAA. An extensive search of the medical literature databases was performed. One completed RCT and another ongoing RCT were found. In the published RCT, 30 PAAs were treated (15 by the endovascular technique and 15 by the surgical technique). Each case was followed up for a minimum of four years. In the group of patients treated using the endovascular technique there were two blockages. One case was re-stented and the other case required a surgical bypass. In the surgical group there were also two blockages, which did not require any treatment. There were no limb losses. The time taken to complete the procedure and the length of hospital stay were shorter in the endovascular group. The major limitation of this study was that there were only 15 PAAs in each group. Due to the limitations of the current evidence, we are unable to determine the effects of an endovascular stent graft versus conventional open surgery for the treatment of asymptomatic PAAs. The larger ongoing multicentre RCT should provide more information in the future. In the meantime, based on the current evidence, it is reasonable to suggest that a favourable operating time and length of hospital stay for the endovascular method may make it a slightly more acceptable option for the first line treatment of non-emergency PAA.

Authors' conclusions: 

Due to the limitations of the current evidence from one small underpowered study, we are unable to determine the effectiveness of endovascular stent graft versus conventional open surgery for the treatment of asymptomatic PAAs. A larger ongoing multicentre RCT should provide more information in the future. However, it seems reasonable to suggest that endovascular repair should be considered as a viable alternative to open repair of PAA on a case by case basis.

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Background: 

Popliteal artery aneurysm (PAA) is a focal dilatation and weakening of the popliteal artery. If left untreated, the aneurysm may thrombose, rupture or the clot within the aneurysm may embolise causing severe morbidity. PAA may be treated surgically by performing a bypass from the arterial segment proximal to the aneurysm to the arterial segment below the aneurysm, which excludes the aneurysm from the circulation. It may also be treated by a stent graft that is inserted percutaneously or through a small cut in the groin. The success of the procedure is gauged by the ability of the graft to stay patent over an extended duration. While surgical treatment is usually preferred in an emergency, the evidence on first line treatment in a non-emergency setting is unclear.

Objectives: 

To assess the effectiveness of an endovascular stent graft versus conventional open surgery for the treatment of asymptomatic popliteal artery aneurysms (PAA) on primary and assisted patency rates, hospital stay, length of the procedure and local complications.

Search strategy: 

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched June 2014) and CENTRAL (2014, Issue 5). Clinical trials databases were searched for any ongoing or unpublished studies.

Selection criteria: 

All randomised controlled trials (RCTs) comparing endovascular stent grafting versus conventional open surgical repair in patients undergoing unilateral or bilateral prophylactic repair of asymptomatic PAAs were included.

Data collection and analysis: 

Data were collected on primary and secondary patency rates (primary endpoints) as well as operating time, the length of hospital stay, limb salvage and local wound complications (secondary endpoints).

Main results: 

A single RCT was identified that conformed to the inclusion criteria. There was a low risk of selection bias and detection bias. However, the risks of performance bias, attrition bias and reporting bias were unclear from the study. Despite being an RCT, the level of evidence was downgraded to moderate due to the small sample size, resulting in wide confidence intervals (CIs); only 30 PAAs were randomised over a period of five years (15 PAAs each in the groups receiving endovascular stent graft and undergoing conventional open surgery). The primary patency rate at one year was 100% in the surgery group and 93.3% in the endovascular group (P = 0.49). However, the assisted patency rate at one year was similar in both groups (100% patency). There was no clear evidence of a difference between the two groups in the primary or secondary patency rates at four years (13 grafts were patent from 15 PAA treatments in each group). However, the effects were imprecise and compatible with the benefit of either endovascular stent graft or surgery or no difference. Mean hospital stay was shorter in the endovascular group (4.3 days for the endovascular group versus 7.7 days for the surgical group; mean difference (MD) -3.40 days, 95% CI -4.42 to -2.38; P < 0.001). Mean operating time was also reduced in the endovascular group (75.4 minutes in the endovascular group versus 195.3 minutes in the surgical group; MD -119.20 minutes, 95% CI -137.71 to -102.09; P < 0.001). Limb salvage was 100% in both groups. Data on local wound complications were not published in the trial report.

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