Proximalization to zone 0/1- The further we advance
Though the FET has recently been implanted in zone 2, it is not without challenges and complications. These challenges and complications may be less as compared to implantation in zone3, but they still persists - recurrent laryngeal nerve palsy (2.8% vs 5.2%, p=0.526), permanent neurological defect (5.8% vs 9.9%, p=0.431), paraplegia (0 vs 4.7%, p=0.191), bleeding (15.9% vs 12.2%,p=0.553) [9]. In the quest to reduce the complication, newer technical devices are being introduced. This necessitates the debranching of the supra-aortic arch vessels to zone 0 and later implant the hybrid prosthesis in zone 0/1. Different techniques to debranch the three supra-aortic vessels in the mediastinum to Zone 0 are described - trifurcation arch graft with a perfusion side arm port (TAPP graft, Vascutek Ltd., Renfrewshire, Scotland [10], 4-branched Dacron graft [11], Lupiae prosthesis (Vascutek Terumo Inc, Scotland, UK) [12] or individual branch graft to each branch vessel [13]. Among these ‘branch first’ techniques popularized by Matalanis has a minimum DHCA time and reduced cardiopulmonary bypass time [10]. With the advent of the neo E-vita and E-novia, the hybrid prosthesis can be implanted in zone 0 to 3, and the supra aortic arch vessels can be reimplanted individually, en bloc or just left in situ with an uncovered stent graft
The advantages to implant the graft in zone 0/1 include (a) proximalization of aortic arch to zone 0 (b) surgeons not familiar with aortic arch and antegrade circulation can as well perform the procedure with a brief period of DHCA after initial debranching (c) Can eliminate the incidence of recurrent laryngeal nerve palsy and significantly decrease paraplegia (d) The techniques allow a systematic interrogation of each branch anastomosis ensuring secure hemostatic anastomosis (e) Distal anastomosis is more proximal, enabling an easier hemostatic check after the release of cross clamp.
Patients, who are sick with complex and very acute aortic dissection including distal arch/proximal descending aorta re-entry tears, are not suitable for total arch replacement or any complex surgery like FET as a prolonged cardiopulmonary bypass time may be deleterious. These patients may benefit from E-novia. The hybrid prosthesis consists of a distal covered and proximal non-covered stent-graft portion. The covered stent-graft is placed in the descending thoracic aorta while the non-covered stent-graft is accommodated in the aortic arch. The proximal anastomosis would be performed in Zone 0, eventually reducing the ischemic time and hypothermic circulatory arrest time. This combines the classic fast proximal aortic repair with the proposed downstream benefit of the descending aorta in FET. The concept is similar to the PETTICOAT experience in acute type B dissection where the branch vessel stays open when there is adequate run off in the target vessel. The early result in 6 patients has been published recently [14], and discussed by Roselli [15]. These are at present reserved for acute type I aortic dissection, Penn B, C, BC, and patients with severe concomitant disease [5].