Aortic dissection: Perspectives in the era of stent-graft repair

DeBakey and Stanford classification schemes for acute aortic dissection. The principle distinction between proximal and distal dissections is the involvement of the ascending aorta.

Demographic and clinical features of 512 patients with acute aortic dissection classified by the DeBakey system. The distribution of dissection extent, demographic features, and incidence of peripheral vascular complications were similar over the 35-year period (1965 to 1999) in which these patients were treated. Patients with type III dissections tend to be older and almost universally hypertensive. As anticipated, vascular complications tend to cluster among the more extensive type I and IIIb dissections. HBP, High blood pressure; VC, vascular complications. (Adapted from Lauterbach SR, Cambria RP, Brewster DC, et al: Contemporary management of aortic branch compromise resulting from acute aortic dissection. J Vasc Surg 2001;33:1185-92 and Cambria RP, Brewster DC, Gertler J, et al: Vascular complications associated with spontaneous aortic dissection. J Vasc Surg 1988;7:199-209.)

Stent-graft treatment (white arrow) of a mid descending thoracic aorta penetrating atheromatous ulcer (black arrows).

Distribution of peripheral vascular complications in 512 patients over a 35-year period (1965 to 1999) treated at the Massachusetts General Hospital. Peripheral vascular complications are classified by aortic branch site. Differences between site occlusions and clinical events represent asymptomatic occlusions. HBP, high blood pressure.

Mechanisms of aortic branch obstruction in acute dissection. A, In dynamic obstruction, the septum may prolapse into the vessel ostium during the cardiac cycle, and the compressed true lumen flow is inadequate to perfuse branch vessel ostia, which remain anatomically intact. B, Near complete circumferential dissection with static obstruction. The cleavage plane of the dissection extends into the ostium and compromises inflow. Thrombosis beyond the compromised ostia may further worsen perfusion. C, Spontaneous perfusion of aortic branches perfused from the false lumen occurs if the dissecting process tears the ostia away from the true lumen. Such spontaneous “fenestrations” often account for persistent false lumen flow. F, false lumen; T, true lumen.

Sagittal computed tomography view of aortic dissection.

Surgical fenestration of the infrarenal aorta. The septum is excised up to the clamp (dashed line), and proximal anastomosis to a short tube graft is carried out with interrupted pledgetted fine sutures (because part of the anastomosis circumference is carried out to the adventitial layer alone). The distal aortic suture line (inset) is carried out to an aorta-felt composite after aortic layers have been approximated.

Stent-graft deployment to cover the proximal entry tear in the hopes of inducing false lumen thrombosis and true lumen re-expansion. The latter should also alleviate “downstream” branch compromise caused by dynamic obstruction mechanisms. False lumen thrombosis in the thoracic aorta should, in theory, minimize subsequent aneurysmal expansion of the outer wall of the false lumen.

Thoracic aortic stent-graft designed specifically for treatment of dissection. This particular polyester-over-Z-stent construct has bare metal proximal fixation stents (desirable to minimize risk of retrograde dissection) but is augmented with multiple uncovered distal stents to insure true lumen expansion.

Anatomic requirements for stent-graft repair of acute aortic dissection.

Endovascular balloon fenestration from the true to the false lumen. This causes decompression of the false lumen and allows perfusion of side branches originating from the true lumen and compromised by dynamic obstruction (see text). In this particular example, note also static obstruction of the left renal artery, which will require stenting from the true lumen.

Thoracoabdominal aneurysm of chronic dissection etiology 22 years after short graft repair of type B dissection entry tear (large arrow). Note large aneurysmal dilatation of the outer wall false lumen and narrowed compressed true lumen (3 arrows), from which multiple patent intercostals vessels emanate. Open surgical thoracoabdominal resection was curative.