Comparison of the Proximalized Distal Aortic Arch Anastomosis Site

Summary

Here, we present a protocol for two approaches to total arch replacement with a proximal anastomosis in zones 0/1 or zone 2 for aortic arch replacement, along with differences in outcomes reported in the literature.

Abstract

Total arch repair (TAR) has traditionally been performed with a zone 3 distal anastomosis. In recent years, proximalization of the distal anastomosis has been utilized with proposed benefits including an easier distal anastomosis, reduced risk of bleeding, and lower rates of recurrent laryngeal nerve injury. While there have been several comparisons between more proximal distal anastomoses and the traditional zone 3 anastomosis, there have been limited comparisons between proximal anastomoses in zones 0-2.

TAR with a frozen elephant trunk (FET) in zone 0 or 1 generally requires debranching of the head vessels proximally or a combination of head vessel bypasses with deployment of the FET across the aortic arch. Select hybrid arch FET devices are available in trifurcated configurations specifically made for a zone 0 distal anastomosis. A zone 2 arch can often be performed with a branched or straight graft and with head vessel anastomoses in the aortic arch.

In four studies published to date comparing outcomes following proximal (zone 0/1) or more distal (zone 2) anastomoses, the majority of outcomes, including mortality, stroke, and aortic remodeling, were not significantly different. Rates of major bleeding were more common with a zone 2 distal anastomosis.

Proximalization of the distal anastomosis at the time of TAR carries several benefits. Rates of bleeding were lower with a more proximal anastomosis, suggesting improved safety with a zone 0 or 1 anastomosis, without added risk in other metrics.

Introduction

Acute type A aortic dissection (ATAAD) necessitates emergent surgical intervention to reduce the risk of morbidity and mortality¹. The hemiarch repair has long been the minimum intervention for ATAAD, resecting the primary entry tear and stabilizing the aortic arch. Extended arch or total arch repairs (TAR) have been utilized for specific indications such as arch tears, aneurysmal arches, or in patients with known connective tissue disease. Aortic arch interventions may be required in other settings as well, including aortic arch aneurysms, chronic dissections, and penetrating aortic ulcers. While more extensive interventions, extended arch repairs have been associated with similar or even improved outcomes compared to the hemiarch repair in recent years^2,3,4. The advent of the frozen elephant trunk (FET) has facilitated more extensive single-stage repairs and proximalization of the distal anastomosis, between zones 0-2, while still treating the entire aortic arch, reducing the difficulty of the distal anastomosis, and lowering the risk of recurrent laryngeal nerve injury^{4,5,6,7,8,9,10}.

With several potential options for the distal anastomosis site, the optimal location of the distal anastomosis has not been determined, and currently, zone selection depends on patient anatomy and surgeon preference. Herein, we provide a protocol describing the key technical aspects and differences between the selection of the distal anastomosis proximally (zone 0-1) and distally (zones 2) and the influence of these approaches on outcomes following TAR + FET. We also illustrate the differences in outcomes by performing a narrative review of the literature comparing the outcomes following aortic arch repair with a proximal anastomosis.

Protocol

The protocol should be approved and performed following the institutional review board guidelines. Written consent must also be obtained from the patients prior to the surgical procedure. For this study, an ethical statement is not applicable to this article. No patient data has been utilized, and all references to the literature have been cited.

1. Zone 0 and 1 arch

NOTE: Proximalization of the TAR with FET requires anastomosis of the ascending aortic graft in either zone 0 or zone 1 (Figure 1, Figure 2A).

1. Cardiopulmonary bypass
   1. Begin the procedure with the initiation of cardiopulmonary bypass and hypothermic circulatory arrest.
   2. Perform cardiopulmonary bypass either centrally or peripherally and accomplish it by aortic and venous cannulation.
   3. Perform central aortic cannulation by placing purse strings in the ascending aorta and placing an aortic cannula into the ascending aorta, securing it with the pursestring, and connecting it to the cardiopulmonary bypass circuit.
   4. Perform peripheral cannulation by an end-to-side anastomosis of a graft to the axillary or femoral artery with a prolene suture, which is then cannulated with the aortic cannula by placing the cannula into the graft and securing it with a silk tie around the graft and cannula, or percutaneously, where arterial access is gained via needle puncture, place a wire in the artery, and place the cannula over the wire into the peripheral artery.
   5. Perform venous cannulation similarly, either centrally by cannulation of the right atrium by the placement of a pursestring in the right atrium and direct cannulation, or peripherally via percutaneous access of the femoral vein, which includes gaining access to the vein with a needle puncture, placing a wire into the femoral vein, and advancing a cannula over the wire.
2. Resection of the ascending aorta
   1. Resect the ascending aorta and proximal aortic arch to zone 0 or 1. Debranch the head vessel in these cases where the head vessels are anastomosed proximally on the aortic graft and deploy a FET to treat the disease arch. Accomplish this by ligating and dividing the head vessels and anastomosing them proximally on the ascending aorta using a running 4-0 synthetic polypropylene suture.
3. Deploy the FET.
   1. Place the selected device into the aortic arch until the sewing cuff is in contact with the distal anastomosis site, deploy the device, and secure the FET at the distal site using a running 3-0 synthetic polypropylene suture where the aorta was resected.
   2. In cases of an off-the-shelf device, use existing options made in a trifurcated configuration, allowing for a single branch off of the proximal ascending aorta to revascularize all three head vessels with end-to-end anastomoses.
   3. Where an off-the-shelf device is not used, deploy an antegrade thoracic endovascular aortic repair (TEVAR) stent into the arch from zone 0 or 1 with the ascending aortic graft anastomosed to the proximal end of the TEVAR graft.
4. Head vessel revascularization
   1. Then, revascularize the head vessels, either by end-to-end anastomoses of grafts to the ascending aortic graft, or by debranching and reimplanting the innominate artery, followed by a carotid-carotid-subclavian bypass and tying off the head vessels at their proximal ends.
      ​NOTE: Benefits of this approach include an easier distal anastomosis, easier delivery of antegrade cerebral perfusion, and a potentially reduced risk of stroke by minimizing manipulation of the carotid arteries in cases where carotid-carotid-subclavian bypasses are utilized.

2. Zone 2 arch

NOTE: A zone 2 arch utilizes the same initial principles as the proximal approaches (Figure 2B).

1. Establish cardiopulmonary bypass
   1. Establish cardiopulmonary bypass and hypothermic circulatory arrest with cerebral perfusion.
2. Resection of the ascending aorta
   1. Resect the ascending aorta and proximal arch. In this case, reimplant the innominate artery and left common carotid, and leave the left subclavian artery in place or reimplant it more proximally.
3. Head vessel revascularization
   1. With respect to head vessel revascularization, use branched devices that allow for direct end-to-end anastomoses of the innominate artery and left common carotid, or anastomose them directly to a tubular arch graft without dedicated branches. If the left subclavian artery is covered by the FET and is not reimplanted proximally, revascularize it. This is most commonly done with a carotid-subclavian bypass.
4. Arch first approach
   1. Complete this approach with a proximal-first or arch-first approach.
      1. For the arch-first approach, complete the head vessel anastomoses first. This allows for improved cerebral perfusion by allowing bilateral antegrade cerebral perfusion via the carotid arteries once they are revascularized.
      2. Then, complete the distal aortic anastomosis to restore perfusion to the body. Once this is complete, commence systematic perfusion and rewarming. Then, perform the proximal aortic anastomosis during rewarming.
5. Proximal first approach
   1. For the proximal-first approach, complete the aortic root and ascending aortic repair prior to circulatory arrest in order to reduce hypothermic circulatory arrest times¹¹. Once the target temperature has been reached, perform the distal and head vessel anastomoses.
      ​NOTE: Benefits of this approach include more complete resection of the diseased aortic arch tissue, fewer required bypasses, and less mobilization of the head vessels.

Results

This section reports outcomes from select studies in the literature comparing outcomes of TAR using a more proximal (zone 0/1) distal anastomosis or more distal (zone 2) anastomosis, often based on the Ishimura Zones. Studies were included if they were retrospective, prospective, or randomized controlled trial studies comparing outcomes of TAR. Case reports, previous reviews, or studies reporting outcomes on a single surgical approach were excluded. Characteristics of the included studies...

Discussion

Extended arch repairs have become more frequently utilized for ATAAD, and the FET has allowed flexibility in the location of the distal anastomosis. The TAR FET procedure has expanded the versatility of the TAR procedure, allowing for proximalization of the distal anastomosis while still treating the entire aortic arch. Proximalization of the distal anastomosis to zones 0-2 are proposed to have several advantages, including an easier distal anastomosis, a more accessible anastomosis to address bleeding, and reduced risk ...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3-0 Prolene sutures	Ethicon, New Jersey, USA	https://www.jnjmedtech.com/en-US/product/prolene-polypropylene-suture	This is just one example
4-0 Prolene sutures	Ethicon, New Jersey, USA	https://www.jnjmedtech.com/en-US/product/prolene-polypropylene-suture	This is just one example
Aortic cannula	Medtronic	https://www.medtronic.com/me-en/healthcare-professionals/products/cardiovascular/cannulae.html	This is just one example
E-vita Open Neo	Artivion, Georgia, United States	https://artivion.com/product/e-vita-open-neo/	Frozen elephant trunk device
Frozenix J Graft	Japan Lifeline, Tokyo, Japan.	https://www.j-graft.com/frozenix/	Frozen elephant trunk device
Silk tie	Ethicon, New Jersey, USA)	https://www.jnjmedtech.com/en-US/product/perma-hand-silk-suture	This is just one example
Thoraflex	Terumo Corporation, Tokyo, Japan.	https://terumoaortic.com/products/thoraflex-hybrid/	Frozen elephant trunk device
Venous Cannula	Medtronic	https://www.medtronic.com/me-en/healthcare-professionals/products/cardiovascular/cannulae.html	This is just one example