Geometric and hemodynamic analysis of fenestrated and multibranched aortic endografts

Outcomes of Zone 1 Thoracic Endovascular Aortic Repair With Fenestrated Surgeon-Modified Stent-Graft for Aortic Arch Pathologies

OBJECTIVES

This study evaluated the feasibility and safety of zone 1 thoracic endovascular aortic repair (TEVAR) with fenestrated surgeon-modified stent-graft (SMSG) for aortic arch pathologies.

METHODS

Between March 2016 and November 2020, 34 consecutive patients underwent zone 1 TEVAR with fenestrated SMSG for aortic arch pathologies. Outcomes included technical success, perioperative, and follow-up morbidity and mortality.

RESULTS

During the study period, 34 patients were treated with zone 1 TEVAR with fenestrated SMSG. Twenty-four (70.6%) patients presented with type B aortic dissections, 9 (26.5%) patients presented with aneurysms (7 located on the lesser curvature side of aortic arch), 1 (2.9%) patient presented with type Ia endoleak after previous TEVAR owing to traumatic aortic dissection. The proximal landing zone for all patients were in zone 1, and all supra-aortic trunks were reconstructed, except for one left subclavian artery. Technical success was achieved in all cases. The 30-day estimated survival (±SE) was 90.9% ± 5.0% [95% confidence interval (CI): 77.0%-97.0%]. The 30-day estimated freedom from reintervention (±SE) was 87.9% ± 5.7% (95% CI: 73.4%-95.3%). At a median follow-up of 48 months (range, 12-68 months), 2 patients died, including 1 aortic-related death and 1 non-aortic-related death. One patient had reintervention 13 months after the operation owing to type Ia endoleak. All supra-aortic trunks were patent. The estimated survival (±SE) during follow-up was 85.1% ± 6.2% (95% CI: 69.9%-93.6%). One (2.7%) patient had stroke. The estimated freedom from reintervention (±SE) during follow-up was 84.2% ± 6.5% (95% CI: 69.9%-93.5%).

CONCLUSIONS

Zone 1 TEVAR with fenestrated SMSG is an alternate option for treatment of aortic arch pathologies in experienced centers.

Fate of target visceral vessels in fenestrated and branched complex endovascular aortic repair

OBJECTIVE

To assess branch vessel outcomes after endovascular repair of complex aortic aneurysms analyzing possible factors influencing early and long-term results.

METHODS

The Italian Multicentre Fenestrated and Branched registry enrolled 596 consecutive patients treated with fenestrated and branched endografts for complex aortic disease from January 2008 to December 2019 by four Italian academic centers. The primary end points of the study were technical success (defined as target visceral vessel [TVV] patency and absence of bridging device-related endoleak at final intraoperative control), and freedom from TVV instability (defined as the combined results of type IC/IIIC endoleaks and patency loss) during follow-up. Secondary end points were overall survival and TVV-related reinterventions.

RESULTS

We excluded 591 patients (3 patients with a surgical debranching and 2 patients who died before completion from the study cohort) were treated for a total of 1991 visceral vessels targeted by either a directional branch or a fenestration. The overall technical success rate was 98.4%. Failure was related to the use of an off-the-shelf (OTS) device (custom-made device vs OTS, HR, 0.220; P = .007) and a preoperative TVV stenosis of >50% (HR, 12.460; P < .001). The mean follow-up time was 25.1 months (interquartile range, 3-39 months). The overall estimated survival rates were 87%, 77.4%, and 67.8% at 1, 3, and 5 years, respectively (standard error [SE], 0.015, 0.022, and 0.032). During follow-up, TVV branch instability was observed in 91 vessels (5%): 48 type IC/IIIC endoleaks (2.6%) and 43 stenoses-thromboses (2.4%). The extent of aneurysm disease (thoracoabdominal aortic aneurysm [TAAA] types I-III vs TAAA type IV/juxtarenal aortic aneurysm/pararenal aortic aneurysm) was the only independent predictor for developing a TVV-related type IC/IIIC endoleak (HR, 3.899; 95% confidence interval [CI]:, 1.924-7.900; P < .001). Risk of patency loss was independently associated with branch configuration (HR, 8.883; P < .001; 95% CI, 3.750-21.043) and renal arteries (HR, 2.848; P = .030; 95% CI, 1.108-7.319). Estimated rates at 1, 3, and 5 years of freedom from TVV instability and freedom from TVV-related reintervention were 96.6%, 93.8%, and 90% (SE, 0.005, 0.007, and 0.014) and 97.4%, 95.0%, and 91.6% (SE, 0.004, 0.007, and 0.013), respectively.

CONCLUSIONS

Intraoperative failure to bridge a TVV was associated with a preoperative TVV stenosis of >50% and the use of OTS devices. Midterm outcomes were satisfying, with an estimated 5-year freedom from TVV instability and reintervention of 90.0% and 91.6%, respectively. During follow-up, the larger extent of aneurysm disease was associated with an increased risk of TVV-related endoleaks, whereas a branch configuration and renal arteries were more prone to patency loss.

Analysis of predisposing factors for type III endoleaks from directional branches after branched endovascular repair for thoracoabdominal aortic aneurysms

BACKGROUND

Mid-term durability of branches has already been established, and BF-branched and fenestrated endovascular repair has shown comparable results with open repair in the treatment of thoracoabdominal aortic aneurysms (TAAAs). Nevertheless, target vessel instability remains the most frequent adverse event after complex endovascular aortic repair. Type III endoleaks from directional branches have been reported with a low incidence, but risk factors for this complication have not been investigated yet.

METHODS

This was a dual-center observational retrospective cohort study. Data were collected prospectively for each patient treated with branched endovascular repair between April 2008 and December 2019. The primary outcome was to assess potential risk factors for branch disconnection and fracture. A logistic regression analysis was performed, including preoperative and postoperative measurements as well as intraoperative details. A Cox regression hazard analysis was performed to evaluate the influence of preoperative aneurysm diameter and target vessel angulation on the outcome during follow-up.

RESULTS

Two hundred ninety-five target visceral vessels (TVVs) in 91 patients were considered suitable for cannulation. Technical success was 96.9% (286/295 TVVs). The median follow-up was 32.5 months (interquartile range, 14.2-50.1 months). Twelve type III endoleaks from directional branches were detected (4.2%; 5 bridging stent graft fractures and 7 disconnections). Five type III endoleaks involved the celiac trunk (one fracture and four disconnections), five the superior mesenteric artery (four fractures and one disconnection), and two the renal arteries (both disconnections). The median time to type III endoleak was 22.2 months (interquartile range, 10.9-37.6 months). Preoperative TAAA diameter (P = .028), preoperative TVV angulation (P = .037), the use of a BeGraft stent graft as bridging stent graft (P = .001), and different stent types on the same vessel (P = .048) were associated with type III endoleak at univariable analysis. Using a BeGraft stent graft (P = .010) was the only significant factor predisposing to type III endoleak at multiple logistic regression. The Cox regression analysis showed a two-fold increased risk for type III endoleak for every 10-mm increase in preoperative TAAA diameter (hazard ratio, 2.00; 95% confidence interval, 1.08-3.72; P = .028) and a 1.5 increased risk every 12° increase of preoperative TVV angulation (hazard ratio, 1.47; 95% confidence interval, 1.02-2.10; P = .037).

CONCLUSIONS

Type III endoleaks from directional branches are a non-negligible complication after branched endovascular repair, with a relevant incidence. They tended to be clustered on specific patients, and aneurysm diameter and TVV angulation are strictly associated with the outcome. Different stent types on the same vessel should be avoided whenever possible. An intensified follow-up should be adopted for patients with large aneurysms, implanted with first-generation BeGraft, or who have been already diagnosed with type III endoleaks.

Three-Dimensional Geometric Analysis of Balloon-Expandable Covered Stents Improves Classification of Complications after Fenestrated Endovascular Aneurysm Repair

In balloon-expandable covered stent (BECS) associated complications after fenestrated endovascular aneurysm repair (FEVAR), geometric analysis may determine the cause of failure and influence reintervention strategies. This study retrospectively classifies BECS-associated complications based on computed tomographic angiography (CTA) applied geometric analysis. BECS-associated complications of FEVAR-patients treated in two large vascular centers between 2012 and 2021 were included. The post-FEVAR CTA scans of complicated Advanta V12 BECSs were analyzed geometrically and complications were classified according to its location in the BECS. BECS fractures were classified according to an existing classification system. In 279 FEVAR-patients, 34 out of the 683 included Advanta V12 BECS (5%) presented with a complication. Two Advanta V12 complications occurred during the FEVAR procedure and 32 occurred during follow-up of which five post-FEVAR CTA scans were missing or not suitable for analysis. In the remaining 27 BECSs complications were classified as (endoleaks (n = 8), stenoses (n = 4), occlusions (n = 6), fractures (n = 3), and a combination of complications (n = 6)). All BECSs associated complications after FEVAR with available follow up CTA scans could be classified. Geometric analysis of BECS failure post-FEVAR can help to plan the reintervention strategy.

Anatomical Feasibility Study on Novel Ascending Aortic Endograft With More Proximal Landing Zone for Treatment of Type A Aortic Dissection

Objective

Type A aortic dissection (TAAD) is associated with high morbidity and mortality, and open surgery is the best treatment option. Development of endovascular repair devices for TAAD will benefit patients deemed unfit for open surgery. In this study, we performed a thorough investigation of anatomical features in Asian patients with TAAD to learn about the patient eligibility of a novel ascending aortic endograft technique.

Methods

Computed tomography angiography (CTA) images of TAAD cases in our institution from January 2015 to November 2021 were reviewed, and three-dimensional reconstructions were performed with the Endosize software (Therenva, Rennes, France). Anatomic structures including length measured along centerline and greater/lesser curvature, ascending aorta/aortic root dimensions, as well as location of entry tear and extent of dissection were analyzed.

Results

A total of 158 patients were included [median age 58 years, interquartile range (IQR), 30–76 years; 115 males, 72.8%]. In 99 (62.7%) of the cases, entry tear was distal to the sinotubular junction (STJ). In 106 (67.1%) of the cases, the pathology proximally extended into the aortic root, which was intramural hematoma in 37 (23.4%) of the cases, and the aortic root was free from the pathology in 52 (32.9%) of the cases. The median distance from the STJ to the proximal edge of the ostium of the innominate artery (IA) measured along the centerline was 65 mm (IQR 58–74 mm). The median distance from the distal edge of the higher coronary ostium to the STJ was 7.95 mm (IQR 5.625–10.9 mm). The bare metal stent part was set between the edge of the higher coronary ostium and the STJ. In our series, 63 (39.9%) of the cases had this distance >10 mm. The relative difference was <20% between the STJ and the proximal edge of the ostium of the IA in 92 (58.2%) of the cases. Ascending aorta radius of curvature was 52.2 mm (IQR 43.7–63.7 mm).

Conclusions

Our study demonstrates that 56.3% of the TAAD cases would be amenable to endovascular repair by the novel ascending aortic endograft, with sufficient landing zone free of the dissected aorta.

In Vitro Geometry Analysis of Fenestrations in Endovascular Aneurysm Repair

PURPOSE

Changes in the flared end of balloon-expandable covered stent (BECS) may precede BECS-associated complications but are not regularly assessed with computed tomographic angiography (CTA) after fenestrated endovascular aneurysm repair (FEVAR). Validation of the flare geometric analysis (FGA) and assessment of intraobserver and interobserver variability are investigated in this study.

METHODS

Two series of 3 BeGraft BECSs (Bentley InnoMed GmbH, Hechingen, Germany) and 1 series of 3 Advanta V12 BECSs (Getinge AB, Göteborg, Sweden) were deployed in 3 side branches (45°, 60°, and 90° aortic branch angles) of an aorta phantom model. A standard post-FEVAR CTA scan was acquired. Computed tomographic angiography-derived measurements consisted of centerline reconstructions and placement of 3-dimensional coordinate markers by 2 observers in a vascular workstation. Flare geometric analysis calculates 3 BECS parameters: the circumferential flare-to-fenestration distance (FFD), which is the distance from the proximal end of the flare to fenestration, and diameters at the proximal end of the flare (Dflare) and at the fenestration (Dfenestration). Computed tomographic angiography-derived measurements were validated against microscopy measurements. Bland-Altman plots were used to determine the intraobserver and interobserver variability of the BECS parameters and intraclass correlation coefficient (ICC).

RESULTS

For each BECS, the FFD at 4 equidistant quadrants of the circumference, Dflare, and Dfenestration were calculated. The mean difference and repeatability coefficient (RC) of the validation were 0.8 (2.1) mm for FFD, 0.4 (1.0) mm for Dflare, and -0.2 (1.2) mm for Dfenestration. The mean intraobserver and interobserver difference (RC) was 0.5 (1.6) mm and 0.7 (2.6) mm for FFD, 0.1 (0.6) mm and 0.1 (0.7) mm for Dflare, and -0.1 (0.8) mm and -0.8 (1.0) mm for Dfenestration. The mean ICC of intraobserver variability was 0.86 for FFD, 0.94 for Dflare, and 0.78 for Dfenestration. The mean ICC of interobserver variability was 0.77 for FFD, 0.92 for Dflare, and 0.48 for Dfenestration.

CONCLUSION

This study showed that FGA of the flared ends of BECS can be performed with high accuracy in a phantom model, with good intraobserver and interobserver variability. Flare geometric analysis can be used to determine flare geometry of the BECS on standard post-FEVAR CTA scans.

Impact of target visceral vessel anatomical configuration on early complications following endovascular repair of thoracoabdominal aortic aneurysms

Impact of target visceral vessel anatomical configuration on early complicatins following endovascular repair of thoracoabdominal aortic aneurysms Objectives: Fenestrated and branched endovascular aortic repair (fEVAR-bEVAR) is a viable treatment option for thoracoabdominal aortic aneurysms but target visceral stent (TVS) endoleak and thrombosis remain a limiting factor. This study aims to evaluate TVS anatomy impact on one-year risk of thrombosis and endoleak.

METHODS

Patients treated with fEVAR-bEVAR for thoracoabdominal aneurysms between 2008-2020 in our centre were enrolled. We recorded comorbidities, operative details, one-month postoperative CT scan (anatomical reference), and TVS behaviour: thrombosis and endoleak at one-year follow-up. For each TVS, different points were identified using a centre-lumen-line: (A) TVS origin, (B) end of branch/fenestration, (C) visceral vessel entry, (D) end of TVS, (E) 1-cm distally. We analyzed TVS tortuosity ((centre-lumen-line/straight distance)-1, in %), image vector analysis of each segment in 2D (antero-posterior, left-right) and 3D (craneo-caudal displacement), and centre-lumen-line analysis (bending in ABC and CDE). Three independent observers performed a blind analysis, and anatomical differences between bEVAR/fEVAR, and cases with/without 1-year thrombosis and TVS endoleak, were compared using Kaplan-Meier curves (Log-Rank test), and T-Test/Wilcoxon signed-ranks test respectively.

RESULTS

54 patients (72±713 years mean age; 182 TVS: 50 branches, 132 fenestrations) met the inclusion criteria. bEVAR cases had longer stents, with more caudal 3D angulation and greater ABC angulated segment. After excluding bEVAR cases (low case number), 97 fEVAR TVS were analyzed. Five thrombosis and seven endoleaks were observed. While anatomical configuration showed no association to thrombosis, it was related to endoleak: these cases presented more tortuous stents (5.97%±0.10, 21.40%±0,22, P=.011), with more angulated centre-lumen-line at ABC segment (5.69°±15.77°, 7.18°±7.77°, P=.012), and more upward-pointing stents in the origin of the stent (AB: 89.07°±24.46°, 109.09°±16.56°, P=.012; BC: 87.86°±21.10°, 113.11°±22.23°, P=.026).

CONCLUSIONS

Anatomical configuration of the TVS is associated with stent type I-III endoleak, but not thrombosis, at one-year following fEVAR. Cases with endoleak presented more tortuous stents, with a more angulated exit from the endograft and upward-pointing of the origin of the stent.

Mechanical Behaviour of Fenestrations in Current Aortic Endografts

OBJECTIVE

The aim of this study was to assess the mechanical characteristics of current commercially available fenestrated endografts (FE). The performance of the fenestrations according to the design were compared as the relationship between a bridging covered stent graft (CSG) and the fenestration.

METHODS

A total of 21 Zenith (Cook Medical, Bloomington, IN, USA) and 17 Anaconda (Terumo Company, Inchinnan, UK) fenestrations were studied. Radial extension tests were performed, inserting two half cylinders spaced up to 2 mm in a 7 mm diameter fenestration from each device. Branch pull out force was measured to test the stability of the assembly with a calibrated 8 mm branch and two CSGs: Advanta V12 (Atrium Medical; Hudson, NH, USA) and BeGraft Peripheral Stent Graft (Bentley InnoMed GmbH, Hechingen, Germany). A branch was inserted in both the 7 mm diameter fenestrations and in a control 7 mm fenestration. Fatigue tests were performed on the devices to assess long term outcomes of the endograft.

RESULTS

Over a 2 mm vertical displacement, the resulting loading curves look similar for both devices. The force value level was 33.4 ± 6.9 N for the Cook fenestration and 54.45 ± 18 N for the Anaconda fenestration (p = .001). With respect to an 8 mm calibrated branch, the required extraction strength from the fenestration was statistically significantly greater with the Anaconda device (9.5 ± 4.7 N vs. 4.49 ± 0.28 N; p = .001). The required strength to extract the V12 CSG from a control cylindered shape was statistically significantly higher than for the BeGraft CSG (6.75 ± 2.86 N vs. 1.83 ± 0.67 N; p = .003). The surface area of the fenestration of the Cook device was increased with cycling (7 200 cycles) compared with the Anaconda device (15.5% vs. 6.5% hole surface area increase).

CONCLUSION

The mechanical performance of the fenestration can be fine tuned by considering its design. A CSG optimising the performance of the fenestration and the CGS-fenestration interface could reduce the risk of leakage in clinical practice.