Type I endoleaks are a sub group of endoleaks which occur at graft ends, often due to inadequate seal.
They occur as a result of poor apposition between one of the attachment sites of a stent-graft and the native aortic or iliac artery wall. Blood can leak can occur through this defect into the aneurysm sac.
They can be seen immediately after stent-graft deployment due to several reasons including
- incomplete dilation of the stent-graft, aortic tortuosity
- steep aortic angulation.
Delayed-type I endoleaks may be related to changes in the configuration of the aorta as the aneurysm sac shrinks. These are considered high-pressure endoleaks, and there is a high risk of aneurysm sac rupture because of direct exposure of the aneurysm wall to aortic pressure.
- can be most common after repair of thoracic aortic aneurysms 4
They can be subgrouped into three further categories
- Ia: proximal
- Ib: distal
- Ic: iliac occluder
Type I endoleaks are can be associated with measurable increases in aneurysm sac size.
Usually preferred imaging modality of choice. Multiphased scanning is helpful. Unenhanced CT may show hyperattenuating acute hemorrhage within the aneurysm sac.
After contrast administration, a dense contrast collection is usually seen centrally within the sac and is often continuous with one of the attachment sites.
On Doppler sonography, a jet of flow may be seen originating from one of the attachment sites.
Treatment and prognosis
Type Ia leaks
Initial treatment can include balloon angioplasty of the proximal attachment site, aimed at remodelling the stent graft to achieve an adequate seal. If angioplasty is unsuccessful, balloon expandable bare metal stents such as Palmaz stents can be deployed over the affected attachment site to promote apposition of the proximal stent graft with the aortic wall.
In cases of undersized or maldeployed endografts, covered extension cuffs, which can usually be matched in size and material to the native endograft.
Some newer devices include EndoStaples and EndoAnchors which mechanically attach the proximal endograft with the aortic wall.
Type Ib leaks
Are usually considered easier to manage than IA, with numerous available iliac extender limbs, covered stents, and bare metal stents to close the endoleak defect.
Despite these advances in endovascular techniques, there are still cases that require surgical repair for definitive treatment.
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