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BACKGROUND: Type III endoleak caused by aortic endograft component uncoupling is an uncommon complication of endovascular aortic aneurysm repair (EVAR). Despite the advantages of anatomic fixation and extended seal zone technology, late uncoupling can be uniquely associated with main-body type modular endograft components.
METHODS: Since 2006, 605 patients have been treated using the Endologix (Irvine, California) Intuitrack and AFX EVAR systems at three affiliated hospitals. Fifteen (2.5%) patients requiring secondary interventions for main-body aortic endograft component uncoupling and Type III endoleak were identified. All available pre- and post-operative CT scans, operative reports, and medical records were reviewed for retrospective analysis under IRB approval.
RESULTS: There were 14 men and one woman with a mean age of 72 years. The initial mean maximum AAA diameter was 7.3 cm (range 4.7 - 12.48cm) and the final AAA diameter before secondary intervention was 7.29 cm (range 5.31 - 12.54cm). In 5 cases under the original Indications for Use (IFU), there was no oversizing of the proximal cuff. Eleven cases were performed with the Intuitrack system and 4 with AFX. The mean time from the original EVAR procedure to secondary intervention was 27 months (range 4 - 47 months). Prior to the diagnosis of main-body endograft uncoupling, there was no indication of AAA enlargement and only 5 patients ever demonstrated Type III contrast endoleak. The initial mean renal artery to aortic bifurcation distance was 12.08cm and at the time of secondary intervention was 12.18cm. In contrast, the mean secondary AAA centerline distance increased from 12.19cm to 14.63cm (12%) consistent with significant buckling of the endograft in the central main-body overlap zone. Three patients returned with ruptured AAA and despite timely and successful endovascular relining of the endoleak, two died of myocardial infarction. Two patients developed AAA thrombosis requiring endograft explant, one of which died.
CONCLUSION: It has been proposed that stable or shrinking AAA post EVAR without evidence of endoleak at two years can be followed without CT scans. Until more data are forthcoming with respect to the revised IFU for the Endologix AFX system, the current study strongly indicates that at least annual CT scans should be continued indefinitely. Past cases treated and followed under the older IFU should be recalled and restudied. The usually expected indicators of endograft failure such as increasing AAA diameter, and contrast enhancement (endoleak) may be absent in this situation. Indicators associated with endograft main-body uncoupling include: a large initial AAA sac, angulation or buckling of the endograft, increasing centerline renal to bifurcation distance, migration of the endograft within the sac, increasing AAA eccentricity, and loss of component overlap. Endograft uncoupling and suspicious angulation should be treated by relining and stabilizing the endograft with one or more oversized “bridging” components. Prevention is best achieved by careful pre-operative planning with the use of oversized proximal aortic cuffs and the maximum allowable component overlap according to current IFU. In cases where the component overlap appears to be inadequate, bridging cuffs should be placed even without signs of endoleak.