Type II endoleaks
A type II endoleak is a commonest form of endoleak are after an abdominal aortic repair.
Epidemiology
They are the most common types of endoleaks and may occur in 10-44% of patients having repairs and can comprise around half of all endoleaks.
Pathology
They may be simple or complex. Simple leak usually occur secondary to backflow (retrograde) from collateral arteries, most notably from the inferior mesenteric and lumbar vasculature. They may also occur from other aortic collaterals such as the internal iliac, median sacral or accessory renal arteries.
Radiographic features
CT
CT has the advantage of having the ability to acquire seqeuntial images from a number of different “phases”.
- non-contrast phase: acquired first to detect high attenuating structures such as calcium or mural thrombus.
- arterial and delayed phases: used to visualize arterial structures and “late” events such as endoleaks, which are not necessarily visible during the arterial phase
Dual energy CT
Dual-energy CT acquires datasets at two different photon spectra in a single acquisition, and have give both enhanced and nonenhanced data. It can be used to detect endoleaks with good accuracy and at a reduced radiation exposure
Complications
- aortic aneurysm rupture: a rupture after EVAR secondary to an isolated type II endoleak is rare (less than 1 %, but over a third are thought to occur in the absence of sac expansion
Treatment and prognosis
It usually resolves spontaneously over time and requires no treatment. Some recommend intervention in patients with type II endoleak when the sac diameter is more than 10 mm . Embolization of the branch vessel is indicated if the aneurysm sac continues to expand in size. Such options include
- transarterial embolotherapy
- translumbar and direct sac embolotherapy
- percutaneous transcaval embolization
Endoleaks with a stable or decreased aneurysmal sac size may be followed up with CT given the generally high rates of spontaneous resolution and a low risk of rupture in published literature .