Clinical Outcomes After Crossed-Limb vs. Conventional Endograft Configuration in Endovascular AAA Repair

Unintended Exchange of Target Vessels for Celiac Trunk and Superior Mesenteric Artery Branches in Complex Endovascular Aortic Repair

PURPOSE

The treatment of thoracoabdominal aortic aneurysms (TAAAs) using branched endovascular aortic repair (BEVAR) is safe and effective. During deployment, the superior mesenteric artery (SMA) branch can unintentionally open into the celiac trunk (CT) ostium and switched catheterization of the SMA from the CT branch and the CT from the SMA branch can be used as an alternative technique in these cases. This study aimed to investigate the outcome of exchanging the intended target vessels (TVs) for the CT and SMA branches during BEVAR.

MATERIALS AND METHODS

A single-center retrospective analysis of patients with TAAAs who underwent BEVAR, using off-the-shelf or custom-made devices (CMDs), with an unintended exchange of TVs for the CT and SMA branches was performed.

RESULTS

Between 2014 and 2023, 397 patients were treated with BEVAR for TAAA. Eighteen (4.5%) of those patients were treated with an exchange of TVs for the CT and SMA branches. T-branch was used in 9 cases (50%) and the remaining patients were treated with CMDs. Twelve patients were treated electively, 3 were symptomatic and 3 presented with rupture. Of 36 mesenteric TVs in those 18 patients, 34 (94%) were catheterized successfully, including all 18 SMAs and 16 of the 18 CTs. No branch stenosis or occlusion of the switched mesenteric TVs was detected during follow-up. During 30-day follow-up, 3 patients died and during a median follow-up of 3 (interquartile range [IQR]: 1-15) months 3 more patients died. None of the deaths or the 2 unintended reinterventions was induced by the mesenteric TV exchange. The median hospital stay was 14 (IQR: 9-22) days with a median of 4 (IQR: 2-11) days at the intensive care unit.

CONCLUSION

The exchange of the mesenteric TVs for the CT and SMA branches during BEVAR with off-the-shelf and CMD endografts is feasible with good TV patency and freedom from TV-related reinterventions. This alternative technique should be considered in selected cases when direct catheterization via the intended branch is deemed more time-consuming or not feasible.

CLINICAL IMPACT

This is the first description of using an exchange of target vessels for the celiac trunk and the superior mesenteric artery branches in patients with thoracoabdominal aortic aneurysms undergoing BEVAR, using off-the-shelf or custom-made devices. The high success rate as well as the good clinical results without any branch stenosis or occlusion during follow-up highlight the feasibility of this alternative technique. It could help in challenging cases when catheterization of the intended target vessels is not possible or too time consuming, resulting in higher success rates of BEVAR and better clinical results.

Impact of Cross-Limb Stent-Graft Configuration on Hemodynamics in Abdominal Aortic Aneurysm Interventional Therapy

PURPOSE

The cross-limb (CL) technique is a commonly used endovascular treatment for addressing unfavorable anatomical features in patients with abdominal aortic aneurysm (AAA). The configuration of CL stent-graft plays a critical role in determining the postoperative hemodynamic properties and physiological behaviors, which ultimately impact the efficacy and safety of endovascular AAA treatment. This study aims to investigate the relationship between hemodynamics and CL stent-graft configuration from a hemodynamic perspective.

METHODS

Five distinct geometric models of cross-limb (CL) stent-graft configurations were constructed by optimizing the real clinical computed tomography angiography (CTA) data. These models varied in main body lengths and cross angles and were used to perform numerical simulations to analyze various hemodynamic parameters. Flow pattern, distribution of wall shear stress (WSS)-related parameters, localized normalized helicity (LNH), pressure drop, and the displacement force of all models were examined in this paper.

RESULTS

In patient-specific cases, helical flow and WSS increase with the main body. However, it also generated secondary flow in localized areas, leading to increased oscillation in the WSS direction. Notably, increasing the stent graft's main body length or decreasing the cross angle reduced the displacement force exerted on the stent-graft. Reducing the cross angle did not significantly alter the hemodynamic characteristics.

CONCLUSION

In the clinical practice of CL deployment, it is crucial to carefully consider the stent-graft configuration and the patient specific to achieve optimal postoperative outcomes. This study provides valuable insights for guiding stent selection and treatment planning in patients with abdominal aortic aneurysm undergoing CL techniques, from a hemodynamic perspective.

A hemodynamic study of blood flow models on various stent graft configurations during aorto-iliac reconstruction

PURPOSE

To compare the hemodynamic performance of three (Bottom Up non-ballet, Top-Down non-ballet, Top Down ballet) idealized stent graft configurations used during endovascular repair of abdominal aortic aneurysms, under the influence of various rheological models.

METHODS

Ten rheological models are assumed and a commercial finite volume solver is employed for the simulation of blood flow under realistic boundary conditions. An appropriate mesh convergence study is performed and five hemodynamic variables are computed: the time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), endothelial cell activation potential (ECAP) and displacement force (DF) for all three configurations.

RESULTS

The choice of blood flow model may affect results, but does not constitute a significant determinant on the overall performance of the assumed stent grafts. On the contrary, stent graft geometry has a major effect. Specifically, the Bottom Up non-ballet type is characterized by the least favorable performance presenting the lowest TAWSS and the highest OSI, RRT and ECAP values. On the other hand, the Top Down ballet type presents hemodynamic advantages yielding the highest TAWSS and lowest OSI, RRT and ECAP average values. Furthermore, the ballet type is characterized by the lowest DF, although differences observed are small and their clinical relevance uncertain.

CONCLUSIONS

The effect of the assumed rheological model on the overall performance of the grafts is not significant. It is thus relatively safe to claim that it is the type of stent graft that determines its overall performance rather than the adopted blood flow model.

DANCER: Study protocol of a prospective, non-randomized controlled trial for crossed limb versus standard limb configuration in endovascular abdominal aortic aneurysm repair

Background

Hostile anatomy, especially severely angulated neck and tortuous iliac arteries, has always been a conundrum in endovascular aneurysm repair (EVAR). Crossed limb (CL) graft, also called the “ballerina technique,” has been utilized to address this problem by facilitating gate cannulation. In terms of short and long-term outcomes, correlated studies have made inconsistent conclusions and this issue remains controversial. Based on a previous cohort study conducted in our center, we aim to prospectively compare the safety and efficacy between CL and standard limb (SL) configuration in patients receiving EVAR.

Methods

This is a prospective, single-center, non-randomized controlled trial. A total of 275 patients who meet the inclusion criteria will be enrolled and allocated with a 4:11 ratio of CL to SL, which is based on results of our previous study. All patients will receive same perioperative management and postoperative medications. All EVAR procedures will be performed under standard protocol, utilizing Endurant II or IIs Stent Graft. The configuration of the graft stent will be decided by surgeons and confirmed by final angiography. The primary outcome is 3-year freedom from major adverse limb-graft events (MALEs). Endpoints will be assessed at the following time points: 1, 6, 12, 24, and 36 months.

Discussion

To our best knowledge, this crosseD vs. stANdard Configuration in Endovascular Repair (DANCER) trial is the first non-randomized controlled trial to compare these two graft configurations in EVAR. The main aim is to compare the MALEs between two groups at 3 years postoperatively. This trial will hopefully provide high-level evidence for employing CL in EVAR.

Clinical trial registration

[www.chictr.org.cn], identifier [ChiCTR2100053055].

Meta-Analysis of the Crossed Versus Standard Limb Configuration in Endovascular Aneurysm Repair

OBJECTIVE

To investigate whether the crossed-limb technique confers better or worse clinical outcomes compared to the standard straight limb configuration in standard endovascular aneurysm repair (EVAR).

METHODS

We conducted a systematic review to identify studies comparing outcomes of EVAR with the crossed versus standard limb configuration. MEDLINE, EMBASE, CINAHL, and CENTRAL were searched in March 2021 using the Healthcare Databases Advanced Search interface developed by the National Institute for Heath and Care Excellence. The risk of bias was assessed with the Newcastle-Ottawa scale (NOS) and the Risk Of Bias In Non-randomized Studies - of Interventions (ROBINS-I) tool. Summary estimates were calculated using the odds ratio (OR), risk difference (RD), or mean difference (MD) and 95% confidence interval (CI), applying the Mantel-Haenszel or inverse variance statistical method. Random-effects models were employed.

RESULTS

Four observational studies qualified for inclusion, reporting a total of 1132 patients. All presented contemporary experiences. Baseline clinical characteristics were largely similar between patients with and without the crossed-limb configuration, but the anatomy tended to be less favourable in patients treated with the crossed-limb technique. No statistically significant difference was found in the primary outcomes: limb occlusion (OR 1.44, 95% CI 0.65 - 3.19), type Ib endoleak (RD 0.01, 95% CI -0.03 - 0.04), type III endoleak (RD 0.01, 95% CI -0.01 - 0.03); or secondary outcomes: perioperative mortality (RD 0.00, 95% CI -0.03 - 0.03), type Ia endoleak (RD 0.00, 95% CI -0.03 - 0.02), type II endoleak (OR 1.38, 95% CI 0.51 - 3.74), procedure duration (MD 18.07 min, 95% CI -1.14-37.29). Inconsistency across studies was low for all outcomes. The studies were judged to be of high quality on the NOS. The main bias identified using the ROBINS-I tool was due to confounding.

CONCLUSIONS

The crossed-limb technique was not found to confer inferior clinical outcomes in the medium term compared to the standard limb configuration in patients who undergo standard EVAR.

Comparative evaluation of ballet-type and conventional stent graft configurations for endovascular aneurysm repair: A CFD analysis

PURPOSE:

Cross limb stent graft (SG) configuration technique for endovascular aneurysm repair (EVAR) is employed for splayed aortic bifurcations to avoid device kinking and smoothen cannulation. The present study investigates three types of stent graft (SG) configurations for endovascular aneurysm repair (EVAR) in abdominal aortic aneurysm. A computational fluid dynamic analysis was performed on the pulsatile non-Newtonian flow characteristics in three ideally modeled geometries of abdominal aortic (AA) SG configurations.

METHODS:

The three planar and crosslimb SG configurations were ideally modeled, namely, top-down nonballet-type, top-down ballet-type, and bottom-up nonballet-type configurations. In top-down SG configuration, most of the device is deployed in the main body in the vicinity of renal artery and the limbs are extended to the iliac artery. While in the bottom-up configuration, some of the SG device is deployed in the main body, the limbs are deployed in aortic bifurcation, and the extra stent graft of the main body is extended to the proximal aorta until the below of the renal artery. The effects of non-Newtonian pulsatile flow on the wall stresses and flow patterns of the three models were investigated and compared. Moreover, the average wall shear stress (AWSS), oscillatory shear stress index (OSI), absolute helicity, pressure distribution, graft displacement and flow visualization plots were analyzed.

RESULTS:

The top-down ballet-type showed less branch blockage effect than the top-down nonballet-type models. Furthermore, the top-down ballet-type configuration showed an increased tendency to sustain high WSS and higher helicity characteristics than that of the bottom-up and top-down non-ballet type configurations. However, displacement forces of the top-down ballet-type configuration were 40% and 9.6% higher than those of the bottom-up and top-down nonballet-type configurations, respectively.

CONCLUSIONS:

Some complications such as graft tearing, thrombus formation, limb disconnection during long term follow up periods might be relevant to hemodynamic characteristics according to the configurations of EVAR. Hence, the reported data required to be validated with the clinical results.

Editor's Choice - Mid Term Outcomes of Crossed Limb vs. Standard Limb Configuration in Endovascular Abdominal Aortic Aneurysm Repair: A Propensity Score Analysis

OBJECTIVE

The aim was to compare mid term outcomes between crossed limb (CL) and standard limb (SL) configuration in patients who underwent endovascular aortic aneurysm repair (EVAR).

METHODS

This was a comparative cohort study. Eligible patients who underwent EVAR between September 2011 and March 2019 in a tertiary academic centre were included. Inverse probability of treatment weighting (IPTW) was used to balance the demographic, anatomical and operative baseline characteristics between the two groups. The primary outcome was adverse limb events including type IB endoleak (T1BEL), type III endoleak, and limb occlusion. Cox proportional hazards regression and marginal structural model were performed to compare time to event outcomes.

RESULTS

The study included 729 patients (194 CL and 535 SL) with a median follow up of 34 months (interquartile range 16 - 62 months). The weighted analyses revealed no significant difference between CL and SL EVAR in terms of adverse limb events, type IA endoleak (T1AEL), type II endoleak (T2EL), re-intervention, and overall survival. In the subgroup analysis of large aneurysm sac, the CL configuration was associated with a significantly decreased risk of T1BEL (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.12 - 0.78, p = .014). Similar results were also observed in the subgroup of tortuous iliac arteries (HR 0.30, 95% CI 0.11 - 0.81, p = .017). After stratification by severe neck angulation, no significant difference was found between CL and SL EVAR for T1AEL, but the CL configuration was associated with a significantly increased risk of re-intervention (HR 2.69, 95% CI 1.31 - 5.51, p = .007). In addition, a trend towards a higher risk of adverse limb events in the CL group with severely angulated proximal neck was observed.

CONCLUSION

CL configuration in EVAR is safe and may be associated with a lower risk of T1BEL in patients with a large aneurysm sac or tortuous iliac arteries. However, it should be applied cautiously to aneurysms with a severely angulated neck due to the potentially higher risk of re-intervention.

Emergent Triple-Branched TEVAR and Redistribution of the Branches to the Supra-Aortic Target Vessels for Treatment of a Contained Ruptured Descending Aortic Aneurysm Associated With a Chronic Type A Aortic Dissection

PURPOSE

To demonstrate the feasibility of urgent endovascular treatment of a chronic type A dissection and contained rupture of the false lumen using a noncustomized triple-branched arch endograft, which necessitated reassignment of the branches to the supra-aortic vessels.

CASE REPORT:

A 57-year-old patient with a contained rupture of the descending thoracic aorta, in the setting of a chronic type A dissection and a maximum aortic diameter of 85 mm, was converted to endovascular repair after failure of an open surgical approach. A custom-made triple-branched arch endograft designed for another patient was employed, with concomitant occlusion of the false lumen using a Candy Plug occluder. To adjust the graft's configuration to the patient's anatomy, the supra-aortic vessels were not assigned to the originally planned branches. The 12-month follow-up angiography demonstrated a satisfactory result.

CONCLUSION

A noncustomized triple-branched arch endograft can be used in an emergency setting to treat chronic type A dissection, reassigning the branches to the supra-aortic vessels as needed.

Patient-specific 3D Printing: A Novel Technique for Complex Pediatric Renal Transplantation

OBJECTIVE

The authors investigated a novel application of patient-specific three-dimensional (3D) printing, to enhance preoperative, multidisciplinary planning in complex, living-donor pediatric renal transplantation.

SUMMARY BACKGROUND DATA

For children with end-stage kidney disease, the transplantation of adult-sized, living-donor kidneys into small recipients (<20 kg) with increasingly complex structural anomalies can be difficult. Establishing the operative feasibility in such cases demands a surgical understanding of anatomy to be derived from medical imaging. However, this is hampered by the representation of complex structures in 2D, the inherent interpretive expertise this demands, and the challenge of conveying this appreciation to others.

METHODS

We report the novel use of patient-specific 3D printed models to achieve personalized management for 3 children who underwent living-donor renal transplantation. Each presented a unique surgical challenge that would otherwise prevent preoperative determination of transplantation feasibility. Patient-specific geometries were segmented from imaging data and fabricated using polyjet, 3D printing technology. Models were verified by an expert radiologist and presented during multidisciplinary discussion and surgical simulation.

RESULTS

3D printed models enhanced preoperative deliberation and surgical simulation and allowed on-table exploration of a small child to be avoided. We have critically determined specific clinical indications, technical insights, limitations, and outcomes of this approach. At latest follow-up (>16 mo) all patients remain well with functioning renal allografts.

CONCLUSIONS

We report the new and safe integration of patient-specific 3D printing into complex pediatric renal transplantation. This technique enhances surgical planning and can inform operative feasibility in those cases which would otherwise be uncertain.

One Technique to Modulate a Device Implantation Path in a Short Treatment Length Using the Gore IBE Device

The GORE EXCLUDER Iliac Branch Endoprosthesis (IBE; W. L. Gore and Associates, Flagstaff, AZ, USA) applicability is limited by the aorto-iliac length (AOL). The shortage may be a major exclusion criterion. An 85-year-old male presented with an abdominal aortic and left common iliac arterial aneurysm. The left-side AOL was 146-mm, which was deemed 19-mm too short for IBE usage. To increase implantation length, the contra-lateral connection stent graft was deployed along the implantation line, wound half-circumferentially around the ipsilateral limb. Any form of endoleak, limb occlusion, and device migration has not been observed for twelve months.

Positional Changes of an Endurant Endograft Leading to Simultaneous Ipsilateral Iliac Limb Obstruction and Contralateral Type IIIa Endoleak

We report the case of a 79-year-old man who was admitted to our department with acute limb ischemia due to the occlusion of the left iliac limb of an Endurant endograft. The admission computed tomography angiography revealed also a type IIIa endoleak due to modular disconnection of the iliac extensions from the right iliac limb of the endograft main body. Interestingly, during the 4-year post-endovascular aneurysm repair period, an increased kinking of the right limb has been observed leading to an almost cross-limb configuration of the limbs at the time of complications. To our knowledge, this is the first case in the literature of the simultaneous presence of limb thrombosis and late type IIIa endoleak with this particular device. The ischemia was treated with a femoro-femoral cross-over bypass, and the endoleak was corrected with the position of 2 Endurant iliac limb extensions bridging the dislocated endograft pieces.

Early and Mid-Term Results of Endovascular Aortic Repair Using a Crossed-Limb Technique for Patients with Severely Splayed Iliac Angulation

Objective: We evaluated early and mid-term results of endovascular aortic repair (EVAR) using crossed-limb and non-crossed-limb techniques.

Material and Methods: From December 2011 to October 2013, 37 patients (31 men; mean age 75.4 years) were treated with EVAR (crossed-limb, 21 and non-crossed-limb, 16). We compared technical success, maximum short-axis diameter of abdominal aortic aneurysm, iliac angulation, time for catheterization of the short contralateral limb gate of the main body (SCT), and complications between the groups.

Results: The mean follow-up period was 810±230 days. The technical success rate was 100%. There was no significant difference between the groups in terms of mean short-axis diameter. Iliac angulation was significantly wider in the crossed-limb group (53.3±14.6 vs. 39.4±13.0, p=0.0049). There was no significant difference between the groups in terms of SCT. Limb occlusion occurred in two cases (one crossed-limb and one non-crossed-limb). There were no aneurysm-related deaths.

Conclusion: There were no differences between the crossed-limb and non-crossed-limb techniques in terms of early and mid-term results of EVAR. A crossed-limb technique can be performed safely without prolonged SCT even in severely splayed iliac angulation cases.