Total aortic repair for acute type A aortic dissection: a new paradigm

Abstract

The currently accepted guidelines of open surgical repair for acute type A aortic dissection (ATAAD) include the resection of the primary entry tear, replacement of the ascending aorta and "hemi-arch" with an open distal anastomosis, and aortic valve resuspension and some form of obliteration of the aortic root false lumen. The principal aim being protection against aortic rupture, aortic regurgitation, and coronary ischemia and restoration of antegrade preferential true lumen perfusion. Proponents argue that this operation is tailored to be in the armamentarium of most cardiac surgeons and deliver the lowest early operative risk, while leaving the infrequent long-term sequelae to be dealt with electively by experienced aortic centres. While a superficially compelling argument, the actual outcomes suggest that it falls significantly short of achieving its noble goals on both acute and chronic counts. This led us to develop a seemingly more radical but in practise safe paradigm, which aims to achieve total aortic healing in the acute phase.

Keywords: Aorta; dissection; endovascular stenting.

Figure 1

Modes of failure in endovascular stenting after ascending aorta or “hemi-arch” repair for ATAAD.

Figure 2

Reproduced with permission (26). Copyright 2016, AME Publishing Company. 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 tissue, allows improved access to the anastomoses and reduces the risk of recurrent laryngeal nerve injury. Antegrade flow is recommenced 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

Reproduced with permission (26). Copyright 2016, AME Publishing Company. (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; (C) digital subtraction angiography demonstrating the covered stent extending from the Dacron landing zone into the upper descending aorta.

Figure 4

Reproduced with permission (26). Copyright 2016, AME Publishing Company. 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); (C) deployment of the uncovered stent graft with small overlap of previous stent.

Figure 5

Reproduced with permission (26). Copyright 2016, AME Publishing Company. 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 6

Balloon dilation of bare metal stent demonstrating rupture of septum (27). Available online: http://www.asvide.com/article/view/24377

Figure 7

Reproduced with permission (26). Copyright 2016, AME Publishing Company. (A) 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; (B) digital subtraction angiography demonstrating restoration of flow to left renal artery after visceral branch stenting.

Figure 8

Final angiography demonstrating true lumen flow with no filling of false lumen (28). Available online: http://www.asvide.com/article/view/24378

Figure 9

CT Aortogram at 4 years post total aortic repair for ATAAD. (A) 3D reconstruction demonstrating a stable aorta with no false lumen patency; (B) 3D reconstruction of visceral branches including left renal artery stent.