Surgical management of acute type A aortic dissection: branch-first arch replacement with total aortic repair

Abstract

Acute type A dissection (ATAAD) remains a morbid condition with reported surgical mortality as high as 25%. We describe our surgical approach to ATAAD and discuss the indications for adjunct techniques such as the frozen elephant trunk or complete aortic repair with endovascular methods. Arch replacement using the "branch-first technique" allows for complete root, ascending aorta, and arch replacement. A long landing zone is created for proximal endografting with a covered stent. Balloon-assisted intimal disruption and bare metal stenting of all residual dissected aorta to the level of the aortic bifurcation is then performed to obliterate the false lumen (FL) and achieve single true lumen (TL) flow. Additional branch vessel stenting is performed as required.

Keywords: Aorta; dissection; endovascular techniques.

Figure 1

Stanford type A aortic dissection. Note the entry and re-entry tears in the ascending, descending thoracic and abdominal aorta. The left renal artery arises from the false lumen, the dissection extend into the left common iliac artery.

Figure 2

Following establishment of cardiopulmonary bypass, the “branch-first” aortic arch reconstruction proceeds as follows: (A) the innominate artery is clamped proximal to its bifurcation and distal to its origin from the arch. Right hemispheric cerebral perfusion is maintained through the left common carotid and subclavian arteries via collateral channels. Apart from the circle of Willis, there is a plethora of extra-cranial collateral channels that augment cerebral perfusion during individual clamping of branch vessels. These include collateral channels between; the external and internal carotid arteries; the right and the left carotid arteries; the upper and lower body; and the subclavian and carotid arteries (4); (B) the innominate stump is ligated and the anastomosis to the first limb of the branched graft completed; (C) antegrade right hemispheric cerebral perfusion is resumed via the perfusion side arm. Left hemispheric cerebral perfusion during construction of the left common carotid anastomosis is maintained via the same collaterals described above; (D) subclavian anastomosis is completed and all three arch branches are perfused; (E) anastomosis of the arch graft to the distal arch. Note that the distal anastomoses can be performed in Zone 2 which is usually better quality tissues, allows improved access to the anastomoses and reduces the risk of recurrent laryngeal nerve injury. Antegrade flow is recommended via the “ante flow” side arm of the graft. After completion of the root anastomosis, connection of the TAPP graft to the ascending graft proceeds without interruption of cerebral perfusion.

Figure 3

(A) When a FET is used, the “branch first” arch reconstruction proceeds as described above. Under moderate hypothermic arrest, the FET is positioned and deployed in the true lumen in the descending thoracic aorta. The distal anastomosis is again constructed, usually in Zone 2, and antegrade systemic perfusion recommenced; (B) after completion of the root reconstruction, the TAPP graft is then connected proximally. Depending on the lie of the TAPP graft, it may either be connected to the first limb of the FET graft or the anastomosis can be constructed in a similar fashion to Figure 2. FET, frozen elephant trunk.

Figure 4

In the case of ongoing or recurrent branch vessel ischemia or malperfusion, radiological TL collapse, rapid dilatation of the FL, or other markers of compromised TL perfusion, we proceed to completion thoracoabdominal stenting. TL, true lumen, FL, false lumen.

Figure 5

(A) A covered stent graft (Zenith TX2 TAA 112 Endovascular Graft, Cook Medical, Bloomington, IN, USA) is introduced and positioned within the predesigned dacron proximal landing zone; (B) the first stent is deployed so that the distal end is positioned at the junction of middle and upper third of the descending thoracic aorta. Further covered stent grafts can be deployed down to the diaphragm/celiac trunk if required but increased coverage is associated with increased risk of spinal cord injury.

Figure 6

The remaining thoracic (A) and abdominal (B) aorta down to the aortic bifurcation is then lined with bare metal uncovered stent grafts (Zenith Dissection endovascular stent, Cook Medical Inc., Bloomington, IN, USA).

Figure 7

An angioplasty balloon (Coda Balloon Catheter, Cook Medical Inc., Bloomington, IN, USA) is then used to sequentially expand the bare metal stents and rupture the septum between the TL and FL to create a single aortic channel.

Figure 8

This patient also required stent grafting to the left renal artery and left common iliac artery. At the conclusion of the procedure, aortography is performed and the patency of the aortic lumen and the visceral and other branch vessels are confirmed.