The proximalization of arch repair to zone 0 with a frozen elephant trunk (FET) improves mortality and reduces the incidence of spinal cord injury, stroke, renal injury, and visceral ischemia [1]. It is challenging to reoperate a residual dissecting type B aneurysm after ascending aorta replacement for type A dissection [2]. To simplify this procedure, we employed a straightforward hybrid approach using a FET straight vascular prosthesis. This method involves cutting and sewing the previous ascending graft, inserting the FET, and debranching the arch vessels with a trifurcated graft. Consequently, aortic proximalization to zone 0 is achieved through this debranch-first technique. This approach can streamline the reoperation, as it eliminates the need for incision or resection of the residual aneurysm or the fragile distal aorta.

We performed zone 0 arch-first rerouting FET in 3 patients with residual dissecting aneurysms after ascending aorta replacement for type A acute aortic dissection, regardless of the entry tear location (2017–2019; 1 man and 2 women; age range, 67–83 years). These patients presented dilatation of the residual type B aneurysm and required surgery (Fig. 1).

Figure 1. Preoperative (A) and postoperative (B) computed tomography.

The institutional ethics committee granted approval for this study (no., 02-010) and waived the requirement for patient consent.

Median sternotomy was performed, followed by minimal dissection of the mediastinum. Cardiopulmonary bypass was then established, with inflow through the ascending aorta via a branch of the prosthetic graft (1-branched J-graft; Japan Lifeline, Tokyo, Japan) equipped with a 9-mm side-arm (Fig. 2A), and outflow through the right atrium. The femoral artery was prepared for temporary distal perfusion.

Figure 2. (A) Scheme of ascending aorta inflow through the side branch of the prosthetic graft (red arrow). A new prosthetic graft for inflow was sewn to the side branch of the existing graft (prosthetic graft shown in gray). Systemic perfusion started from the side branch (red arrow). (B) Arch vessels were anastomosed to trifurcate the graft in end-to-end fashion (black arrows). Cerebral perfusion started from the side branch (red arrow). (C) Frozen elephant trunk (FET; yellow) insertion from zone 0 (black arrow), and systemic perfusion from the femoral artery (red arrow with black borders) with FET balloon occlusion (green). (D. Single-layer anastomosis of the graft and frozen elephant trunk (black arrow). (E) Completion of the hybrid arch by anastomosis of the arch graft to the ascending graft (black arrow).

We utilized a FET straight vascular graft (FROZENIX; Japan Lifeline, Tokyo, Japan) [3]. The size of the FET was determined by preoperative computed tomography, and was set to be 1.15 times larger than the true lumen size of the distal landing zone. The graft length was consistently 120 mm in all cases, which is equivalent to the length from zone 0 to the T6–7 level at the descending aorta. This is because an excessively long prosthesis can increase the risk of paraplegia [4].

An additional 9-mm side branch was anastomosed to the trifurcated graft (Vascutec Gelweave Trifurcate Arch Graft; Terumo Co., Tokyo, Japan) to facilitate cerebral perfusion (Fig. 2A). The surgical procedure consisted of three steps, as shown in Supplementary Video 1. The first step involved debranching the arch using a trifurcated graft under deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion. This is followed by antegrade selective cerebral perfusion from the side branch, and the proximal stump closure of the arch vessels (Fig. 2B). The second step involved making an incision in the ascending aorta graft between the previous distal anastomosis and the existing side branch. This was followed by FET insertion from zone 0 to the T7 level of the descending aorta under the guidance of transesophageal echocardiography. The graft-FET was then sutured in a single layer under femoral artery systemic perfusion with balloon occlusion of the FET (Fig. 2C). Subsequent antegrade systemic perfusion from the side branch of the ascending aorta graft was performed after the completion of the anastomosis (Fig. 2D). The third and final step involved the anastomosis of the arch graft to the side branch of the ascending graft (Fig. 2E), followed by weaning from cardiopulmonary bypass.

All patients were treated successfully. There were no instances of in-hospital death, stroke, or paraplegia. In one case, an additional endovascular stent graft was performed as planned. The durations of circulatory arrest, aortic cross-clamping, and cardiopulmonary bypass were 21.6±2.3 minutes, 90.0±27.1 minutes, and 220.0±7.0 minutes, respectively. All patients were monitored for a period of 8 to 22 months without any complications.

The mortality rate associated with redo surgery for residual dissecting type B aneurysms following type A repair remains high [2]. The debranch-first technique, utilizing zone 0 FET, presents a simpler and less invasive alternative for treating residual dissecting type B aneurysms compared to the conventional total arch replacement. This is because it negates the need for dissection of periaortic tissues and resection of the aortic arch wall.

Consequently, debranching in zone 0 allows for the proximalization of the distal anastomosis to zone 0. This provides surgeons with a close view and the ability to manipulate the aorta in the shallow surgical field, thereby facilitating safe and simple anastomosis, as well as hemostatic stitches [5]. This process involves only cutting and sewing the previous ascending prosthetic graft, in conjunction with healthy arch vessel anastomosis. Moreover, aortic proximalization provides a sufficient proximal landing zone, which facilitates additional treatment for descending aortic lesions with an endovascular stent graft. It also enables effective thrombo-occlusion of the distal false lumen.

The arch-first strategy under DHCA is our preferred strategy for arch repair. This strategy is favored because it eliminates the need to spend time establishing selective cerebral perfusion, and it avoids cluttering the surgical field with numerous cerebral perfusion catheters. Given that the duration of circulatory arrest was a mere 21.6 minutes, there was no need for selective cerebral perfusion via catheter. Furthermore, the aortic arch’s shrinkage during DHCA simplifies the process of arch vessel anastomosis.

The arch graft utilized in this procedure must be small. Given that the dissection of the anterior mediastinum is minimal, there is limited space for quadrifurcated arch grafts. The size of a trifurcated graft is ideally suited to fit the narrow space between the sternum and the ascending graft without causing any kinking.

The adequacy of blood flow to the entire brachiocephalic system provided by a relatively small debranch graft is a matter of debate. Shimizu et al. [6] conducted a study on the cerebral blood flow in 16 hybrid arch cases, which involved right subclavian artery to left carotid and subclavian artery bypass, using single-photon emission computed tomography. Their conclusion was that the postoperative total cerebral blood flow was similar to the preoperative flow [6]. Similarly, Goto et al. [7] reported that zone 1-2 debranching thoracic endovascular aortic repair with an extra-anatomical bypass did not affect the total intracranial blood flow. These findings suggest that a trifurcated graft can supply sufficient cerebral blood flow in a debranch-first zone 0 FET procedure.

In conclusion, the debranch-first technique, used in conjunction with zone 0 FET, effectively completes aortic proximalization. This process aids in the reoperation of residual type B dissecting aneurysms. Furthermore, aortic proximalization creates an ample proximal landing zone, which simplifies the additional treatment of descending aortic lesions with endovascular stent grafts.

Authors contributions

All the work was done by Yoshito Inoue.

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Supplementary materials

Supplementary materials can be found via https://doi.org/10.5090/jcs.23.084. Supplementary Video 1. Video of the arch-first rerouting and zone 0 frozen elephant trunk technique.