Type I endoleak

Type I endoleaks are a subgroup of endoleaks which occur at graft ends, often due to an inadequate seal. 

Pathology

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 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.

Associations

• can be most common after repair of thoracic aortic aneurysms ⁴

Subtypes

TheyType I endoleaks can be subgroupedsubdivided into three further categories

• Ia: proximal
• Ib: distal
• Ic: iliac occluder

Radiographic features

Type I endoleaks are can be associated with measurable increases in aneurysm sac size.

CT angiography

Usually preferredPreferred imaging modality of choice. Multiphased scanning is helpful. Unenhanced CT may show hyperattenuating acute haemorrhage 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.

Ultrasound

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 poorly deployed endograftendografts, covered extension cuffs, which can usuallybe used. These can 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 leaks, 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.