What is an endoleak?

So an endoleak is basically the finding of blood flow within the aneurysm after a stent graft has been placed. So the whole purpose of these stent grafts is to exclude blood flow from the aneurysm so the aneurysm is not under any blood pressure and therefore can't rupture and ideally all the blood that's within the aneurysm sac will thrombose and block off once the stent graft has been put in. What we sometimes find on post-procedural CT scanning or ultrasound scanning is that there is still some blood flow in the aneurysm sac. And then it gets a bit more difficult. Sometimes the blood flow is slipping around the seal zones of the stent graft, either above or below, and and that's called a type 1a or 1b endoleak. And that tends to be very high pressure and therefore has to be treated with a degree of urgency. Similarly, if there's a disconnect between the modular components of stem grafts or if there's a hole in the stem graft, that leads to what's called a type 3 endoleak, which is also very high pressure and could lead to aneurysmal sac rupture. So it has to be dealt with quickly. The majority of endoleaks, though, we see blood within the aneurysm sac that actually come in from back bleeding from these tiny little arteries that come off the back of the aorta and run towards the spine, or the lumbar arteries, or the inferior mesenteric artery. And these are much lower pressure and probably don't need any treatment. And what we do do is keep an eye on the endosac, which is one of the reasons we keep patients under surveillance. And if that's staying static or shrinking, even in the presence of a type 2 endomeg or a low pressure endomeg, there's no need to do anything. But if the aortic sac starts to get bigger and bigger, then we do need to perform some minimally invasive interventional treatment to stop that bad flow.