Current state of hybrid solutions for aortic arch aneurysms

Abstract

Since its inception in the early 2000s, hybrid arch repair (HAR) has evolved from a novel approach to a well-established treatment modality for aortic arch pathology in appropriately selected patients. HAR procedures have been proposed as a means to circumvent the perioperative morbidity and mortality associated with open total arch replacement. These procedures, all of which remain off-label applications of approved endograft technology, combine more conventional open surgical techniques, to create endograft landing zones, with thoracic endovascular aortic repair to exclude the aortic pathology from the circulation. The current classification system for HAR was proposed in 2013 and consists of three types, designated by the Roman numerals I, II and III. The current system has become outdated, however, with the advent of newer technologies, and herein we propose a new, updated classification system that is more encompassing with regards to the broad array of options available to treat aortic arch disease. Likewise, an institutional algorithm to guide patient and operative selection for HAR is presented. Patients are considered for HAR if they have either high-risk comorbidities or high-risk anatomy, with an important feature of the algorithm being that any decisions about repair strategy should be made by a surgical team with expertise in both open and endovascular techniques. Despite being performed for nearly two decades, the evidence around HAR consists mainly of single center series (level B-C evidence) with no randomized controlled trials. The data suggest HAR to be a safe alternative to open repair with acceptable short and mid-term results. As we as aortic surgeons continue to move towards less invasive approaches, both conventional open and hybrid techniques will remain important tools in the toolbox for arch repair, although the advent of multi-branched arch endografts will almost certainly reduce the extent of open or hybrid repair in many patients and eliminate it altogether in others.

Keywords: Hybrid; aneurysm; aortic arch; dissection; endovascular.

Figure 1

Original HAR classification system proposed in 2013. Reproduced with permission from reference (6). HAR, hybrid arch repair.

Figure 2

Type I HAR with LSA revascularized via carotid-subclavian bypass. Although not shown in the drawing, the LSA would typically be occluded proximally using endovascular techniques as part of the procedure. HAR, hybrid arch repair; LSA, left subclavian artery.

Figure 3

Postoperative CTA 3D-reconstruction images demonstrating examples of type I (left) and type II (right) HAR with transthoracic aorta-axillary bypass, which is performed at the time of the first stage debranching procedure. The type II HAR patient in the right panel also had a right to left carotid-carotid bypass (performed at time of 2^nd stage TEVAR), as only the innominate artery was accessible via sternotomy for debranching at the time of the first stage procedure. HAR, hybrid arch repair; TEVAR, thoracic endovascular aortic repair.

Figure 4

Type I HAR with antegrade stent graft deployment. We reserve the use of this approach to those situations in which the patient has inadequate iliofemoral access for retrograde delivery. HAR, hybrid arch repair.

Figure 5

Type III HAR utilizing a frozen elephant trunk. Reproduced with permission from reference (14). HAR, hybrid arch repair.

Figure 6

Zone 1 HAR (left panel) with cervical arch debranching (right common carotid-left common carotid-left subclavian artery bypass via neck incisions) with PLZ in zone 1 just distal to the innominate artery. Zone 0 HAR (right panel) involves cervical arch debranching similar to the zone 1 HAR procedure, but with PLZ in zone 0. Perfusion of the innominate artery and cervical debranching bypass graft is maintained via either an off-label “snorkel” endograft, as shown in the figure, or an investigational branched endograft. Right image reproduced with permission from reference (15). HAR, hybrid arch repair; PLZ, proximal landing zone.

Figure 7

Proposed new and expanded classification system of hybrid arch repair.

Figure 8

Algorithm for selecting surgical approach to the patient with an aortic arch aneurysm.

Figure 9

Type I_D HAR drawing (left) and intra-op photograph (right) demonstrating the 4+ cm PLZ in the existing ascending Dacron graft distal to the arch debranching graft. Illustrated by Megan Llewellyn, MSMI, CMI; copyright Duke University; with permission under a CC BY-ND 4.0 license. HAR, hybrid arch repair; PLZ, proximal landing zone.

Figure 10

Intraoperative pre- (left) and post- (right) angiograms demonstrating endovascular exclusion of a large saccular mid arch aneurysm in a high-risk patient using an investigational dual branch device. The left subclavian artery has been covered and revascularized via carotid-subclavian bypass.

Video

Current state of hybrid solutions for aortic arch aneurysms.