Endovascular single-branched stent graft to treat complicated type B aortic dissection involving aortic arch anomalies

Abstract

Background

The optimal treatment of complicated type B aortic dissection (cTBAD) involving arch anomalies remain unclear.

Methods

We consecutively enrolled patients with cTBAD involving arch anomalies who underwent endovascular repair using a single-branched stent graft (SBSG) at our medical center between January 2020 and January 2023. The demographics, clinical manifestation, operation detail, and follow-up outcomes of these patients were retrospectively collected and analyzed.

Results

A total of 16 patients (14 men; 55.8 ± 11.7 years) were enrolled, including isolated left vertebral artery (ILVA) (n = 6), aberrant right subclavian artery (ARSA) (n = 7), and right aortic arch and aberrant left subclavian artery (ALSA) with Kommerell’s diverticulum (KD) (n = 3). Among them, six patients with multi-branched arch anomalies. The endovascular management strategies of patients were diverse based on their aortic morphology. The early outcome demonstrated that one patient experienced an immediate intraoperative type I_a endoleak, which was resolved by balloon dilation, and two patients exhibited bird-beak configuration. After a median of follow-up of 910 (743–1023) days, the long-term outcome revealed that two patients developed endoleak. No death, retrograde type A aortic dissection (RTAD), paraplegia, stent graft-induced new entry tear (SINE), or branch section stenosis of SBSG were observed during the follow-up.

Conclusion

Our limited experience suggests that endovascular repair with a SBSG appears to be a relatively safe, feasible, and effective treatment option for patients with cTBAD and arch anomalies.

Introduction

The main treatment for type B aortic dissection (TBAD) is optimal medical therapy. However, in the event of clinical complexity, such as aortic rupture or malperfusion, emergency intervention should be necessary [1]. In the past decade, advancement in endovascular interventional techniques have revolutionized the management of complicated TBAD (cTBAD), shifting the treatment pattern from open surgical repair to endovascular repair [2]. The presence of arch anomalies poses challenges in the management of cTBAD. Limited studies and case series have been reported, most of such patients were treated by open surgical repair or hybrid technique [3,4,5,6]. To date, the standard treatment for these patients remains uncertain.

The efficacy and safety of the single-branched stent graft (SBSG) in treating patients with TBAD involving the left subclavian artery (LSA) [7] have been evaluated. However, its application in cTBAD involving arch anomalies remains unclear. Therefore, this retrospective study aims to present the clinical characteristics and long-term outcome of these patients who underwent the endovascular repair using a SBSG at a single center.

Methods

Study design and patient enrollment

Consecutive patients with cTBAD involving arch anomalies underwent thoracic endovascular aortic repair (TEVAR) using a SBSG, were enrolled between January 2020 and January 2023 (Fig. 1). The written informed consent was obtained from the patient(s) to publish their anonymized information in this article. This retrospective study adhered to the principles of the Helsinki Declaration and received approval from the Ethics Committee of The First Affiliated Hospital of Xi’an Jiaotong University (No. XJTU1AF2023LSK- 148).

Fig. 1

A consort diagram of the study population. TBAD: type B aortic dissection; TEVAR: thoracic endovascular aortic dissection; cTBAD: complicated type B aortic dissection; PLZ: proximal landing zone; SBSG: single-branched stent graft; BA: “Bovine” arch

Definitions

Isolated left vertebral artery (ILVA) refers to the direct origin of the left vertebral artery from the aortic arch. Aberrant right subclavian artery (ARSA) is a right subclavian artery originates as the fourth branch from the aorta; Kommerell’s diverticulum (KD) represents a persistent remnant resulting from the failed retraction of the fourth primitive dorsal aortic arch, which may be manifest in patients with an ARSA. The “bovine” arch (BA) is an aortic arch that shares a common origin with the innominate artery (IA) and left common carotid artery (LCCA), or the LCCA originating directly from the IA. Right side of aortic arch (RAA) with aberrant left subclavian artery (ALSA) with KD: a four-vessel aortic arch is situated to the right of the main trachea, and the ALSA originates from either the distal arch or proximal descending aorta, mirroring the ARSA. While a KD can be observed at the origin of the ALSA. Technical success was defined as the accurate delivery and positioning of the main trunk and branch section of the SBSG to the predetermined location, followed by successful deployment of the stent graft, safe removal of the delivery device from the body, and postoperative angiographic imaging demonstrating no type I or III endoleaks and patency of the stent grafts.

Operative technique

The SBSG (MicroPort Endovastec, Shanghai, China) was made of nitinol and polyester and was composed of a main trunk and the side branched stent graft. All operations are independently performed by interventional surgeons with more than 5 years of operative experience. The procedural details of TEVAR have been described in previous study [8].

The principles of procedure: (i) assuring complete exclusion of the primary entry tear by the main trunk of the SBSG, the branch section was positioned in the supra-arch branch closet to the primary entry tear; (ii) under the premise of adhering to principle (i), the parallel-stent techniques (chimney/periscope) is employed for the revascularization of additional aortic branches covered by the main trunk of the SBSG, and the fenestration is utilized for revascularizing the dominant vertebral artery originating from the aortic arch, which is covered by the main trunk of the SBSG.

The methods of ILVA reconstruction: (i) assessing the cerebral blood supply, and the patients with acute stroke, incomplete Willis’s ring, or dominant left vertebral artery require ILVA reconstruction; (ii) we employed the customized fenestration to reconstruct the ILVA. For patients presenting with clinical urgent conditions such as aortic rupture or acute stroke, emergency preoperative-customized fenestration should be promptly conducted based on the assessment and measurement results of computed tomography angiography (CTA). First, measure the distance and angle between the origin of the ILVA and the aortic branch artery requiring reconstructed with the branch section of SBSG, as well as the size of the origin of ILVA. Second, partially open the SBSG in vitro and position the location of ILVA on the SBSG based on the above measurement results. Finally, use a heated needle ablation method to preform precise-customized fenestration. For the rest of patients, a 3D printing model is utilized to depict their individualized aortic morphology, and simulate the release of SBSG within the model. Then, the precise fenestration of ILVA on the model is achieved through heated needle ablation technique for in vitro (the size of fenestration should be slightly or equal the origin of ILVA); (iii) after the customized fenestration, the SBSG should be retracted, and then advanced along the delivery system into the aorta of patients.

Follow-up and end points

Survival was assessed by outpatient clinic visit and/or telephone interview. The standard follow-up schedule, conducted by postoperative CTA at the 1, 3, 6 and 12 months of post-operation, and annually thereafter, was performed to assess the major devices-related adverse events (MDAEs), including aortic rupture, retrograde type A aortic dissection (RTAD), paraplegia, stent graft-induced new entry tear (SINE), endoleaks, the branch section stenosis of the SBSG.

Statistical analysis

The continuous variables were presented as means and standard deviations, while the skewed variables were reported using median and quartiles. Additionally, a description of the range was provided. The categorical variables were expressed as frequencies and percentages. All statistical analyses were performed using IBM SPSS Statistics software version 26 (IBM Corp., Armonk, NY, USA).

Results

From January 2020 to January 2023, 16 patients (14 men) with cTBAD involving arch anomalies were confirmed by preoperative imaging examinations. The mean age was 55.8 ± 11.7 years (range from 28 to 73 years). The baseline characteristics are shown in Table 1, and the clinical characteristics of the patients are summarized in Table S1.

Table 1 Baseline characteristics

The preoperative CTA images showed that the location of primary entry tear (LPT) of 11 patients (68.8%) was at the Z₃, the mean distance from the primary entry tear to the distal end of the LSA was 14.2 ± 7.2 mm, and the median distance from the proximal end of the dissected aorta to the distal end of the LSA was 1.9 (− 5.8 to 7.8) mm (Table S2).

All patients underwent TEVAR, with indications primarily including aortic rupture (n=3), cerebral malperfusion (n=5), distal extremity malperfusion (n=3), renal malperfusion (n=2), visceral malperfusion (n=2) and spinal cord injury (n=1). To completely exclude the primary entry tear and achieve revascularization of the aortic branches, the branch section of SBSG was positioned to aortic branches (n = 10), RSA (n = 5), or LCCA (n = 1) depending on the specific morphology of the aortic lesion. More detailed information about the endovascular repair is presented in Table 2.

Table 2 Procedure management and follow-up outcome of enrolled patients

Follow-up and long-term outcome

The primary technical success was 100%. All patients survived the operation and followed for a median of 910 (743–1023) days. In patient 9, an immediate intraoperative type I_a endoleak was observed by angiography following stent implantation and successful managed through balloon dilation. The long-term outcome of this patient is favorable as observed in the CTA image of follow-up (Fig. 2). All patients had routine CTA follow-up at our medical center, and 1-year follow-up showed the patency of SBSG, shrinking of the false lumen, and enlargement of the true lumen.

Fig. 2

Preoperative and postoperative CTA image of patient 9. The frontal (A) and posterior (B) perspectives of the perioperative CTA image were utilized for three-dimension reconstruction, and the white arrow indicated the location of the ARSA. C The preoperative CTA image of the patient with TBAD involving ARSA (white arrow). The frontal (D) and posterior (E) perspectives of the postoperative CTA image were utilized for three-dimension reconstruction. F The ARSA was reconstructed using branch section of the SBSG (red arrow), and the LSA was reconstructed using a chimney stent (green arrow). The 1-year postoperative follow-up revealed that the stent-grafts were patency

During the follow-up, Patient 6 developed a type II endoleak caused by blood reflux from the intercostal arteries. Given the minimal amount of reflux observed, we opted for conservative management and continued with close follow-up (Fig. 3). Patient 14 developed type I_b endoleak originating from the gap between the periscope graft and the main trunk of the SBSG, since this leak was asymptomatic and the size of the false lumen and KD remained unchanged, conservative therapy and close follow-up were considered (Fig. 4). None of patients had RTAD, paraplegia, or other MDAEs.

Fig. 3

Preoperative and postoperative CTA image of patient 6. The frontal (A) and posterior (B) perspectives of the perioperative CTA image were utilized for three-dimension reconstruction, and the white arrow indicated the origin of the ILVA. C The preoperative CTA image of the patient, and the yellow arrow indicates the location of the primary entry tear. The frontal (D) and posterior (E) perspectives of the postoperative CTA image were utilized for three-dimension reconstruction, and the white arrow indicated the origin of the ILVA. The LCCA was reconstructed using branch section of the SBSG, and the LSA was reconstructed using a periscope graft. F The 1-year postoperative follow-up revealed the presence of a type II endoleak caused by blood reflux from the intercostal arteries (the red arrow)

Fig. 4

Preoperative and postoperative CTA image of patient 14. The frontal (A) and posterior (B) perspectives of the perioperative CTA image were utilized for three-dimension reconstruction. The branches of the aortic arch are as following: a the RSA, b the right common carotid artery (RCCA), c LCCA, d ALSA. C The preoperative CTA image revealed signs of aortic rupture in the cross-sectional of the aortic arch, accompanied by bilateral pleural effusion, and the yellow arrow indicates the location of the primary entry tear. The frontal (D) and posterior (E) perspectives of the postoperative CTA image were utilized for three-dimension reconstruction. The RSA was reconstructed using branch section of the SBSG, and the ALSA was reconstructed using a periscope graft. F The 1-year postoperative follow-up revealed the presence of a type I_b endoleak originating from the distal end of the periscope graft (the white arrow)

Discussion

Our current study demonstrated that the endovascular repair using a SBSG represents a safe and efficacious treatment option in select patients with cTBAD involving arch anomalies, exhibiting a high technical success rate and minimal incidence of postoperative complications.

The incidence of aortic arch anomalies, as detected by imaging examinations, ranges from 0.7% to 38.8% [8, 9], but the coexistence of TBAD and arch anomalies remains relatively uncommon. The rare condition may be attributed to the hemodynamic alterations associated with abnormal arch patterns [10], which render such patients more susceptible to dissection formation, thereby presenting significant challenges in aortic repair. So far, no standard therapy has been established for these patients. Previously, these patients were frequently managed by open surgical repair or hybrid techniques, which had a higher postoperative mortality and complications, including significant blood loss and more invasive injury [11,12,13]. Several studies have reported the endovascular repair for treating patients with TBAD involving a solitary branched vascular anomaly [14, 15], whereas limited research exists regarding patients exhibiting multi-branched anomalies of aortic arch. Our study presents, for the first time, the utilization of SBSG in endovascular repair in patients with cTBAD involving arch anomalies, especially when multi-branched variations are involved.

Suzuki et al. [16] emphasized the necessity for reconstructing the ILVA to mitigate the risk of neurological deficits resulting from malperfusion of brainstem and cerebellum caused by an inadequate circle of Willis. In our study, customized fenestration technique was employed to revascularize the ILVA in five patients with cTBAD. Additionally, in Patient 2, given the presence of a dominant right vertebral artery and a complete circle of Willis observed on the intracranial vascular angiography, we opted to directly occlude the ILVA using the main trunk of the SBSG. During the follow-up, Patient 6, who diagnosed with ILVA and BA, developed a type II endoleak attributed to reflux from the intercostal artery, while no paraplegia, posterior cerebral ischemia, or infarction was observed in the remaining patients (Fig. 3).

Several studies have endeavored to manage patients with ARSA using TEVAR with the chimney technique, but there are still challenges concerning technical success rate [14] and incidence of postoperative endoleak [15]. In this study, we opted to reconstruct ARSA using the branch section of the SBSG and employ the chimney technique for LSA reconstruction in patients with cTBAD involving both ARSA and LSA. Meanwhile, a KD was founded in the origin of ARSA in one of the patients with cTBAD. The treatment of KD remains controversial. Some case reports [17] demonstrated that the main aim of the TEVAR procedure in KD was to occlude the diverticulum with coils or plugs and reconstruct the ARSA. We strategically positioned the branch section of SBSG within the ARSA of a patient with cTBAD involving ARSA with KD to achieve simultaneously coverage of primary entry tear, exclusion of the KD, and reconstruction of the ARSA in a more physiologically appropriate manner for the aortic arch. The routine follow-up with CTA revealed spontaneous thrombosis of the KD, without detection of any abnormal blood flow and endoleaks.

The RAA and ALSA with KD represents a complicated and rare arch anomaly, often needing surgical or hybrid management [18]. In the study, the complicated arch anomalies were observed in three patients. Patient 14 presented with signs of aortic rupture, requiring emergency endovascular repair. Given that the primary entry tear located in the aortic arch and the dissection lesion involved the RSA and ALSA, we employed a SBSG to exclude the primary entry tear and revascularize the RSA, and a periscope graft was employed to reconstruct the ALSA and close the KD. 1 year of follow-up CTA demonstrated that a type I_b endoleak originating from the distal end of the periscope graft, allowing blood to flow into the KD through the main trunk of the SBSG and the periscope graft. However, considering the minimal changes observed in both false lumen size and KD dimensions, we have chosen to continue with close follow-up observation (Fig. 4). If subsequent evaluations reveal an enlargement of either the false lumen or KD, coiling embolization will be considered as a potential treatment option. Another 2 patients presented with signs of distal extremity malperfusion, to reconstruct the branch arteries, occlude the KD, and recover the physiological hemodynamic state, we deployed the branched-covered stent at the distal end of the branch section of the SBSG with in the ALSA, which demonstrated the robust long-term outcome.

We observed the bird-beak configuration in two patients with cTBAD and ARSA during digital subtraction angiography performed following the SBSG implantation. The phenomenon may be attributed to the significantly smaller angle of the aortic arch in patients with ARSA [14], as Boufi et al. [19] have confirmed that a steep aorta is a risk factor for bird-beak configuration after TEVAR. However, the incidence of bird-beak configuration after TEVAR in our study was comparatively lower than that reported in previous studies [20], potentially attributed to a strategy employed during the procedure. Before the release of the SBSG, we tried to ensure the super stiff guidewire and delivery system along the outer curve of the aortic arch, and fix it by pulling the branch traction guidewire situated in the branch artery. During the release of the main trunk of the SBSG, its proximal end was expanded from the outer curve towards the inner curve of the aortic arch, rather than from center to periphery within the aortic lumen. This approach facilitates complete apposition between the covered stent and inner curve of the aortic arch, thereby reducing the occurrence of bird-beak configuration following TEVAR. However, expediting release process for the main trunk of the SBSG is imperative to avoid distal displacement of the stent graft caused by hemodynamic forces.

In addition to employing the SBSG for endovascular repair, our study has also utilized alternative revascularization techniques, including fenestration and parallel-stent technique. Although these revascularization procedures could be avoided using multi-branched stent graft, the anatomical suitability of patients for this type of intervention remains limited [21].

Limitation

Firstly, the small sample size and retrospective observational design in a single medical center inherently limit its extensibility. Secondly, long-term aortic remodeling following operation was not assessed. Thirdly, we did not compare outcomes between endovascular repair with a SBSG and surgical repair or hybrid technique, nor did we evaluate the impact of alternative revascularization techniques on outcomes.

Conclusion

The successful endovascular repair of cTBAD involving arch anomalies can be achieved using the SBSG, resulting in a robust long-term outcome. The combination of the SBSG and other revascularization technique offers a viable option for managing cTBAD involving multi-branched arch anomalies.