Commentary: Global differences in endovascular treatment of chronic aortic dissections: a comparison of physicians in the United States, Europe, and Asia

The entire concept of treating “acute” aortic dissections endovascularly makes good sense to me because the intimal flap is extremely mobile and flexible. It is a very dynamic situation, with extremely fragile and diseased aortic wall that makes it almost impossible to treat this pathology via an open approach. Closing of the entry tear with an endograft has a reasonable chance of resulting in thrombosis of the false lumen, which will likely prevent further acute complications (rapid dilatation, rupture, organ ischemia) and aneurysm formation in the long run.
This is all completely different in the case of a “chronic” dissection, in which a firm intimal flap (lamella) is present, and the aortic wall is relatively firm, making open repair a lot easier than in the case of acute dissection. Studies with dynamic cine computed tomographic angiography on patients with chronic dissections clearly show the immobility and stiffness of the lamella. All surgeons with experience in treating chronic dissections by open graft implantation realize this quality of the lamella: it is so robust that it is very unlikely (impossible?) that any stent-graft will ever be capable of pushing it toward the false lumen to close it off.
In my mind, chronic dissections can be treated via an endovascular approach only when there are normal, good-quality sealing zones proximally and distally, basically treating it like a normal aortic aneurysm. This is usually not the case in chronic dissections; often, an adequate proximal landing zone is present, but distally, the stent-graft must land in the true lumen. This leaves open a giant fenestration distally, which results in continuous flow in the false lumen originating from the distal attachment, making it extremely unlikely that the pressure on the still perfused false lumen will be any different than before stent-grafting. Basically, even though the stent-graft has been implanted, there is continued pressurization of the outside aortic wall, with all the associated potential for complications remaining.
Some investigators explain the concept of stent-grafting for chronic dissections with the distal end landing in a dissected area by hypothesizing that it may work exactly the same as with acute dissections: by closing of the entry tear, the flow in the still perfused false lumen may change as a result of different pressure gradients. In my mind, this is very unlikely and will be difficult to prove without the use of large, randomized studies.