Insights on Bridging Stent Grafts in Fenestrated and Branched Aortic Endografting

Indications, technical aspects, and outcomes of stent placement in chronic iliofemoral venous obstruction

BACKGROUND

Iliofemoral Venous Stent Placement (IVS) has evolved to a well-established endovascular treatment modality for chronic iliofemoral venous obstruction (CIVO). Dedicated venous stents gained FDA approval in 2019 and solidified IVS as a defined intervention with clear indications, contraindications, risks, benefits, and procedural management principles. This review focuses on the indications, technical aspects and outcomes of stenting for CIVO. Other aspects pertaining to IVS are covered in manuscripts that are part of this series.

METHODS

This study conducted a literature search limited to English articles. Three search strategies were employed, and references were managed in Covidence software. Four investigators independently screened and evaluated articles, excluding meta-analyses, clinical trial protocols, and non-relevant studies. Eligible studies, focused on clinical outcomes and stent patencies, underwent thorough review.

RESULTS

The literature search yielded 1,704 studies, with 147 meeting eligibility criteria after screening and evaluation. Exclusions were based on duplicates, irrelevant content, and non-iliac vein stent placement.

CONCLUSION

Successful IVS for CIVO relies on meticulous patient selection, consistent use of IVUS during procedures, and attention to the technical details of IVS.

Case Series on Double-Barrel Stenting for the Renal Arteries Associated With Fenestrated Repair (FEVAR) of Complex Anatomy Aortic Aneurysms

The double-barrel stenting (DBS) is a technique in which 2 parallel stents are simultaneously deployed through the same reinforced fenestration, into 2 adjacent target vessels. Prior reports describe the application of this technique for the treatment of superior mesenteric artery dissection with aneurysmal degeneration, coronary artery bifurcations, aortic arch branches, and intracranial aneurysms. The DBS technique is particularly useful in the context of fenestrated repair (FEVAR) of complex anatomy aortic aneurysms when the origin of visceral arteries branch off the aorta very close to each other or present early branches. We herein describe a case series including 7 patients who underwent a FEVAR procedure for thoracoabdominal and juxtarenal aortic aneurysms in which the presence of accessory renal arteries (ARA) or early renal branches was the reason for the application of this technique. Technical success was 100% and all stents were patent in the last follow-up CT scan (follow-up range: 1.8-62.8 months). There was only 1 small endoleak from indetermined source potentially related to the DBS, but the aneurysm sac decreased in size during follow-up and no secondary intervention was needed. Therefore, the DBS technique is a viable option for the incorporation of ARA or early renal branches to a fenestrated repair of aortic aneurysms with complex anatomy.

Endovascular reconstruction of the aortic arch with new-generation dual-branch and triple-branch endograft: design, applicability, indications, outcomes, and future directions

INTRODUCTION

Repair of aortic arch pathologies such as degenerative aneurysms and dissections still represents a significant challenge for vascular and cardiac surgeons. We focused on the design, evolution, implementation, and prospects of endovascular dual branch technology for treatment of pathologies in the aortic arch.

AREAS COVERED

The literature search was conducted in a non-systematic fashion through the PubMed and Scopus databases; articles deemed relevant to the scope of the work and fully published in English language from January 12,000 until December 2023 were considered for inclusion. Two companies so far have developed and launched in market a dedicated arch dual branch platform: Terumo Aortic and Cook Medical.

EXPERT OPINION

A common limitation to the available technology is represented by the fact that urgent cases (i.e. large or rapidly growing aneurysms, symptomatic patients) cannot be treated because the customization process generally takes between 6 and 8 weeks, and there is an inherent risk for aorta-related adverse events to happen during the waiting time. While the future holds much promise, several technical hurdles still exist and further developments (in device design, operators' skills, patients' selection, and outcomes assessment) are needed to establish the safety and effectiveness of treatment particularly over the long-run.

Cleaning Up the Chimney: Early Renal Stent Graft Thrombosis Following Endovascular Treatment of a Juxtarenal Aortic Aneurysm With the Chimney Technique

The endovascular management of juxtarenal aortic aneurysms with the chimney technique (ch-EVAR) has gained popularity in recent years. It provides an alternative to open repair, allowing treatment of challenging anatomies with devices readily available in any vascular suite. The primary drawback persists as the occurrence of type-Ia endoleak from gutters and renal stent thrombosis. We present two cases of early renal stent graft thrombosis following chimney endovascular aneurysm repair. The first patient was an 80-year-old man who underwent single ch-EVAR and came back on the fifth post-op day with renal stent graft thrombosis. He was re-operated for recanalization and additional stenting of his chimney graft. The patient recovered well with no complications. The second case involved a 72-year-old man with a juxtarenal aneurysm, treated with ch-EVAR on both renal arteries. Unfortunately, on the 10th post-op day, he was referred to our department due to lumbar pain and acute renal failure due to chimney graft thrombosis bilaterally. The left renal chimney graft was recanalized by endovascular means. On the contrary, despite efforts of the endovascular and open approach, the right chimney graft and the right renal artery remained occluded. While ch-EVAR is a viable and off-the-shelf solution for urgent and complex juxtarenal aortic aneurysms, it should be performed with awareness of the potential for graft thrombosis and persistent endoleaks. Despite these complications, the chimney technique can still be a viable treatment option. A better understanding of the indications and advancements in the devices used can lead to better long-term results.

A Systematic Review and an Updated Meta-Analysis of Fenestrated/Branched Endovascular Aortic Repair of Chronic Post-Dissection Thoracoabdominal Aortic Aneurysms

The objective of this study is to present the current outcomes of fenestrated/branched endovascular repair (F/BEVAR) for post-dissection thoracoabdominal aortic aneurysms (PDTAAAs). A systematic review of the literature according to PRISMA guidelines up to October 2023 was conducted (protocol CRD42023473403). Studies were included if ≥10 patients were reported and at least one of the major outcomes was stated. A total of 10 studies with 585 patients overall were included. The pooled estimate for technical success was 94.3% (95% CI 91.4% to 96.2%). Permanent paraplegia developed with a pooled rate of 2.5% (95% CI 1.5% to 4.3%), whereas a cerebrovascular event developed with a pooled rate of 1.6% (95% CI 0.8% to 3.0%). An acute renal function impairment requiring new-onset dialysis occurred with a pooled rate of 2.0% (95% CI 1.0% to 3.8%). Postoperative respiratory failure was observed with a pooled estimate of 5.5% (95% CI 3.8% to 8.1%). The pooled estimate for 12-month overall survival was 90% (95% CI 85% to 93.5%), and the pooled estimates for 24-month and 36-month survival were 87.8% (95% CI 80.9% to 92.5%) and 85.5% (95% CI 76.5% to 91.5%), respectively. Freedom from reintervention was estimated at 83.9% (95% CI 75.9% to 89.6%) for 12 months, 82.8% (95% CI 68.7% to 91.4%) for 24 months and 76.1% (95% CI 60.6% to 86.8%) for 36 months. According to the present findings, F/BEVAR can be performed in PD-TAAAs with high rates of technical success and good mid-term results.

Renovisceral artery alterations due to branched endovascular aortic repair and respiratory-induced deformations

OBJECTIVE

This study quantified respiratory-induced dynamics of branch vessels before and after thoracoabdominal aortic aneurysm (TAAA) branched endovascular aneurysm repair (bEVAR).

METHODS

Patients with TAAA were recruited prospectively and treated with bEVAR, predominantly with Zenith t-Branch and BeGraft Peripheral PLUS bridging stents. Using SimVascular software, three-dimensional geometric models of the vessels and implants were constructed from computed tomography angiograms during both inspiratory and expiratory breath-holds, preoperatively and postoperatively. From these models, branch take-off angles, end-stent angles (transition from distal end of stent to native artery), and curvatures were computed. Paired, two-tailed t tests were performed to compare inspiratory vs expiratory geometry and pre- vs postoperative deformations.

RESULTS

We evaluated 52 (12 celiac arteries [CA], 15 superior mesenteric arteries [SMA], and 25 renal arteries [RA]) branched renovisceral vessels with bridging stents in 15 patients. Implantation of bridging stents caused branch take-off angle to shift inferiorly in the SMA (P = .015) and RA (P = .014) and decreased the respiratory-induced branch angle motion in the CA and SMA by approximately 50%. End-stent angle increased from before to after bEVAR for the CA (P = .005), SMA (P = .020), and RA (P < .001); however, respiratory-induced deformation was unchanged. Bridging stents did not experience significant bending owing to respiration.

CONCLUSIONS

The decrease in respiratory-induced deformation of branch take-off angle from before to after bEVAR should decrease the risk of device disengagement and endoleak. The unchanging respiratory-induced end-stent bending, from before to after bEVAR, means that bEVAR maintains native vessel dynamics distal to the bridging stents. This factor minimizes the risk of tissue irritation owing to respiratory cycles, boding well for branch vessel patency. The longer bridging stent paths associated with bEVAR may enable smoother paths subject to less dynamic bending, and potentially lower fatigue risk, compared with fenestrated EVAR.

Stent-Graft Fabrics Incorporating a Specific Corona Ready to Fenestrate

In situ fenestration of endovascular stent-grafts has become a mainstream bailout technique to treat complex emergent aneurysms while maintaining native anatomical visceral and aortic arch blood supplies. Fabric tearing from creating the in situ fenestration using balloon angioplasty may extend beyond the intended diameter over time. Further tearing may result from the physiologic pulsatile motion at the branching site. A resultant endoleak at the fenestrated sites in stent-grafts could ultimately lead to re-pressurization of the aortic sac and, eventually, rupture. In an attempt to address this challenge, plain woven fabrics were designed. They hold a specific corona surrounding a square-shaped cluster with a plain weave fabric structure, a 2/2 twill, or a honeycomb. The corona was designed to stop potential further tearing of the fabric caused by the initial balloon angioplasty and stent or later post-implantation motion. The cluster within the corona was designed with relatively loose fabric structures (plain weave, 2/2 twill weave, and honeycomb) to facilitate the laser fenestration. Two commercial devices, Anaconda (Vascutek, Terumo Aortic) and Zenith TX2 (Cook), were selected as controls for comparison against this new design. All the specimens were characterized by morphology, thickness, and water permeability. The results demonstrated that all specimens with a low thickness and water permeability satisfied the requirements for a stent graft material that would be low profile and resistant to endoleaks. The in situ fenestrations were performed on all fabrics utilizing an Excimer laser followed by balloon angioplasty. The fabrics were further observed by light microscopy and scanning electron microscopy. The dimension of the fenestrated apertures was smaller than the balloon's diameter. The tearing was effectively confined within the corona. The clinical acceptability of this concept deserves additional bench testing and animal experimentation.

Meta-analysis of Comparative Studies Between Self- and Balloon-Expandable Bridging Stent Grafts in Branched Endovascular Aneurysm Repair

PURPOSE

Currently there is no robust evidence which type of bridging stent graft provides better outcomes after branched endovascular aortic repair (BEVAR). Self-expanding (SESG) and balloon-expandable (BESG) stent grafts are both commonly used to connect branches to their respective target vessels (TV). The aim of the current review was to evaluate the impact of the type of bridging stent grafts on TV outcomes during the mid-term follow-up after BEVAR.

MATERIALS AND METHODS

The study protocol was registered to the PROSPERO (CRD42021274766). A search of the English literature was conducted, using PubMed and EMBASE databases via Ovid and Cochrane database via CENTRAL, from inception to June 30, 2021, using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Only comparative studies on BEVAR reporting TV outcomes related to BESG vs SESG were considered eligible. Individual studies were assessed for risk of bias using the Newcastle Ottawa Scale. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach was used to evaluate the quality of evidence. The primary outcomes were primary patency, freedom from endoleak, TV instability, and re-intervention between BESG and SESG, used as bridging stents in branches. The outcomes were summarized as odds ratio along with their 95% confidence intervals (CI), through a paired meta-analysis.

RESULTS

Five out of 609 articles published from 2016 to 2020 were included in the analysis. In total, 1406 TV were revascularized, 547 (38.9 %) with BESGs and 859 with SESGs. The overall pooled primary patency (odds ratio [OR], 0.40; 95% confidence interval [CI], 0.29-1.09; p=.256, I²=4.24%) and freedom from branch-related endoleak (OR, 0.65; 95% CI, 0.17-1.48; p<.122, I²=0.18%) did not differ between the stent types during the available follow-up (17 months, range = 12-35 months). In 4 studies (619 TV), SESG required fewer secondary interventions (OR, 1.04; 95% CI, 0.23-1.83; p=.009, I²=0%) and TV instability rate was lower (OR, 0.99; 95% CI, 0.33-1.65; p=.003, I²=0%) compared with BESG during the available follow-up.

CONCLUSION

BESG and SESG seem to perform similarly in terms of primary patency and branch-related endoleak during the mid-term follow-up. Current data from retrospective studies suggest that overall TV instability and re-intervention rates are favorable for SESG as bridging stent grafts in BEVAR.