Endovascular management of acute aortic dissection

Abstract

Acute dissection of the thoracic aorta is a potentially life-threatening condition which requires collaborative treatment from multiple specialties for optimal patient outcomes. Dissections involving the ascending aorta and aortic arch have traditionally been managed entirely by surgery, while dissections beyond the arch vessels have most commonly been relegated to medical management. This algorithm has been undergoing a paradigm shift over the past two decades due to improvements in stent graft technology, better understanding of the hemodynamic interactions of the true and false lumen and their influence on organ and limb perfusion, and improvements in medical management and long term surveillance for dissection-related complications. This manuscript includes a brief discussion of the pathogenesis and etiology of dissection, followed by an in-depth review of the medical and endovascular techniques utilized to treat patients afflicted by this condition.

Keywords: Aorta; dissection; fenestration; malperfusion; stent graft.

Figure 1

Contrast-enhanced CT angiography (CTA) of a 29-year-old man with history of Marfan syndrome and hypertension, presenting with severe chest pain radiating to his abdomen with transient paresthesia of left lower extremity. (A) Thoracic imaging confirms an aneurysmal type A aortic dissection originating at the aortic root (arrowhead) and true lumen collapse in descending thoracic aorta (arrow); (B) at the level of the pelvis, note is made of a patent right common femoral artery (arrow) and an occluded left common femoral artery.

Figure 2

A schematic diagram of type B aortic dissection is depicted. The primary entry tear is localized to the proximal descending thoracic aorta. The dissection flap distal to this shows evidence of collapse of the true lumen, resulting in dynamic obstruction of the celiac and superior mesenteric arteries. In dynamic obstruction, the dissection does not extend into the branch vessels but rather occludes them by intermittent obstruction of the flap during the cardiac cycle. In contrast, the left renal artery shows evidence of dissection without reentry in the course of the branch vessel. In this branch, there is formation of thrombus in the left renal artery false lumen, which in turn causes a static obstruction and resultant renal malperfusion. F, false lumen; SMA, superior mesenteric artery; T, true lumen.

Figure 3

Intravascular ultrasound (IVUS) allows delineation of both the true (arrowhead) and false lumen (arrow). IVUS assessment for complete true lumen placement of the wires from each access site is critical for treatment of dissection. Additionally, true lumen thrombus may occasionally develop in these patients, which may be identified using IVUS and treated accordingly to prevent distal limb embolization when true lumen flow is restored.

Figure 4

Image depiction of a Rosch-Uchida needle used to traverse the dissection flap from the true to the false lumen with IVUS. The direction of the needle puncture is determined using real time IVUS guidance at the level of the needle tip, which is directed through the dissection flap, generally from the smaller true to the larger false lumen (A). After advancing the catheter over the stylet into the false lumen, the stylet is removed and a wire is placed into the false lumen (B). A 16 mm angioplasty balloon is centered across the flap and inflated to widen the fenestration and promote flow from false-to-true lumen (C), thus creating a fenestration (D). IVUS, intravascular ultrasound; SMA, superior mesenteric artery.

Figure 5

Although fenestration can equalize pressures across the dissection flap, self-expanding 16- to 18-mm-diameter Wallstents (Boston Scientific—Marlborough, MA) are usually placed to buttress open the aortic true lumen and are typically placed near the compromised branch vessel (A). These are usually inserted via the already obtained percutaneous access sheaths and deployed by IVUS guidance. Care is taken to withdraw the guidewire from across the fenestration tear and re-advance it within the aortic true lumen, so as to deploy the stents exclusively within the aortic true lumen, rather than straddle the tear from true to false lumen. Fenestration and stenting of the aortic true lumen treats the dynamic obstruction of the depicted mesenteric vessels, but not the static obstruction seen in the depicted left renal artery. In this branch, pressure measurements confirm a significant (>20 mmHg) systolic gradient requiring additional treatment (B). SMA, superior mesenteric artery.

Figure 6

Intra-procedural fluoroscopy images of a type B aortic dissection. (A) An IVUS catheter can be seen in the true lumen, which helped ascertain directionality of the needle puncture during fenestration. An angioplasty balloon is centered across the flap and inflated to widen the fenestration and promote flow from false-to-true lumen. A subtle waist can be identified at the site of puncture. (B) A supra-celiac Wallstent is deployed to maintain patency of the previously collapsed true lumen. Pre-deployment IVUS can help with stent positioning. (C) The caudal aspect of the supra-celiac true stent can be seen at the top of the image (arrow). This patient also underwent a second infrarenal fenestration (not shown), and is now being treated with true lumen aortoiliac stenting (arrowhead). IVUS, intravascular ultrasound.

Figure 7

A 67-year-old man presents with acute onset of sharp chest pain radiating to back. (A) Contrast enhanced CT angiography (CTA) confirms an aneurysmal type B aortic dissection with true lumen (TL) and false lumen (FL) delineated. There is evidence of acute aortic rupture with mediastinal hematoma (arrow). (B) 3D CTA reconstruction demarcating the extent of aortic dissection lateral to the left subclavian artery origin (black arrow) with extension to the supra-celiac descending thoracic aorta. The left subclavian artery is denoted by the white arrowhead.(C) Intra-procedural fluoroscopy images demonstrating an Omni Flush catheter with radiopaque markers and an aortic stent graft (black arrowheads), not yet deployed. The device delivery system is advanced over a stiff wire and properly positioned. The fluoroscopic detector is positioned in the left anterior oblique position to better profile the aortic arch and landing zones, which are delineated angiographically and with IVUS at our institution. The black arrow denotes the false lumen. (D) Post-TEVAR 3D CTA reconstruction demonstrates a deployed aortic stent graft maintaining patency of the true lumen. TEVAR, thoracic endovascular aortic repair; IVUS, intravascular ultrasound.