Clinical Significance of Type II Endoleak after Endovascular Repair of Abdominal Aortic Aneurysm

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Type II endoleaks after endovascular repair of abdominal aortic aneurysm (EVAR) are a result of retrograde flow from arterial branches (e.g., lumbar and inferior mesenteric) refilling the aneurysm sac, which has been excluded by the stent graft. Controversy continues with regard to the clinical significance and treatment of type II endoleaks. To develop recommendations for management, we analyzed outcome data from 10 EVAR trials completed over the last 5 years involving a total of 2,617 cases. The incidence of type II endoleak at discharge or 30 days was 6–17%, at 6 months 4.5–8%, and at 1 year 1–5%. Successful resolution of endoleak following secondary interventions was observed in 11–100% of cases. There were 10 conversions to open repair and no ruptures related to type II endoleak. In patients observed for 12 months with computed tomography and/or ultrasound, approximately one-half of type II endoleaks disappeared spontaneously. In the absence of a type I endoleak, our analysis of the current literature suggests that intervention for type II endoleak should be undertaken for abdominal aortic aneurysm sac enlargement occurring after 6 months, persistence for >12 months without abdominal aortic aneurysm sac enlargement, or an aneurysm sac pressure >20% of systolic blood pressure; translumbar aneurysm sac thrombosis and intra-arterial feeding vessel occlusion appear to be prudent management options.

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INTRODUCTION

In the 14 years since Parodi et al. reported the first successful endovascular repair of an abdominal aortic aneurysm (EVAR) by transfemoral implantation of a tube graft, endoleak has become the Achilles' heel of this major advance in vascular surgery.1 Defined as arterial perfusion outside the stent graft lumen and within the aneurysmal sac, endoleaks are divided into four commonly recognized types (types I-IV).

Type II endoleaks arise as a result of retrograde flow from aortic arterial

MATERIALS AND METHODS

To develop recommendations for type II endoleak management, we analyzed reported outcome data from 10 EVAR trials published between 2000 and 2004, consisting of a total of 2,617 patients. The studies we selected had similar entry criteria, methods, adequacy of outcome reporting, and duration and intensity of follow-up. The endovascular grafts used for EVAR in the reviewed trials included AneuRx® (Medtronic, Santa Rosa, CA), Talent® (Medtronic World Medical, Sunrise, FL), Vanguard®

RESULTS

Analysis of data accumulated from multiple clinical trials requires a certain similarity in entry criteria, study methods, and follow-up in order to make reliable conclusions. We reviewed data from 10 recent trials that showed corresponding study design in terms of selection criteria, patient demographics, and follow-up protocol after EVAR (Table I. We recognized that reporting of type II endoleak rates at intervals reflects the incidence of secondary interventions as well as natural history.

DISCUSSION

A complex array of factors, including device construction, collateral pattern, amount of aneurysmal clot, spontaneous thrombosis, and secondary interventions, influence the incidence of early and late endoleaks, which we found to vary 10-fold from 3% to 30% at the same postinterventional interval (Table II). If the patency of collaterals were the sole factor determining type II endoleaks, it would seem reasonable that, given case series as large as these reports, the incidence would not vary so

CONCLUSIONS

A review of 2,617 patients reported in 10 trials published within last 5 years showed that the reported incidence of type II endoleak ranges 6–17% upon discharge or 30 days post-EVAR but decreases to 1–8% at 6-month follow-up. There were no aneurysmal ruptures related to type II endoleak in the studies reviewed, supporting the concept that type II endoleaks may be managed more conservatively than type I endoleaks. We conclude that type II endoleaks may be followed carefully up to 12 months,

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Presented at the Twenty-second Annual Meeting of the Southern California Vascular Surgery Society, San Diego, CA, May 1, 2004.

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