Dissecting Pseudoaneurysms and Blister Aneurysms

In contrast to “true” aneurysms, which have walls that contain intima, media, and adventitia, “false” or pseudoaneurysms no longer have all layers of the normal mural components. The precise mechanisms of pseudoaneurysm formation remain unclear but are believed to result either from a tear of the intima with blood dissecting into the wall or rupture of vasa vasorum. The classic angiographic appearance of a dissecting pseudoaneurysm is a fusiform dilatation with or without adjacent stenosis. Once ruptured there is a high rate of re-rupture during the first week. Symptomatic, ruptured or large pseudoaneurysms warrant treatment. Depending on the location of the pseudoaneurysm and clinical scenario, deconstructive or reconstructive approaches can be utilized, while endovascular reconstructive techniques are more commonly employed for intracranial lesions. “Blister” aneurysms are rare, fragile pseudoaneurysms with a high risk of re-rupture as well as rupture during treatment. Flow diversion appears to be emerging as a preferred method for treatment of these aneurysms, offering a higher rate of occlusion with decreased risk of iatrogenic rupture.