Type III Endoleak Incidence and Outcomes in Endovascular Aortic Repair: Comparison of Anatomical and Proximal Fixation Devices

PURPOSE

To evaluate the influence of endograft fixation type on the incidence, treatment, and outcomes of type III endoleaks (TIIIELs).

MATERIALS AND METHODS

Abdominal aortic aneurysms (AAAs) treated with bifurcated endografts between 1994 and 2020 were prospectively collected and reviewed. The endograft included were classified as "Anatomical Fixation" (AF) (Powerlink [Endologix] and AFX [Endologix]) or "Proximal Fixation" (PF). The primary outcome was the incidence of TIIIEL over time, stratified by fixation type. Secondary outcomes included between-group comparisons of baseline characteristics, intraoperative details during TIIIEL correction, and survival analysis after TIIIEL diagnosis.

RESULTS

A total of 2065 endovascular aneurysm repairs were performed: 872 (42.2%) with AF and 1193 (57.8%) with PF devices. The estimated incidence of TIIIEL at 1, 5, and 10 years was 0.4%, 4.2%, and 7.3%, and 0.5%, 3.2%, and 4.6% for AF and PF, respectively (p=0.157), and fixation type was not associated with TIIIEL development in the competing risk regression model (p=0.101). The cumulative overall survival rate in patients diagnosed with TIIIEL did not differ significantly between the groups (p=0.077). The rate of recurrent TIIIELs was significantly lower in the AF group (7.1% vs 22.7%; p=0.044); however, no significant difference was found in secondary reintervention between the two groups (11.9% vs 27.3%, p=0.074). Patients with angulated and calcified aortic neck (SHR 3.4, 95% CI 1.2-9.6, p=0.022) and larger aneurysms (SHR 1.2; 95% CI 1.1-1.3; p<0.001) had a higher risk of TIIIEL. Likewise, the use of three or more endograft components increased the risk of TIIIEL by 3.1 times (SHR 3.1; 95% CI 1.7-5.4; p<0.001).

CONCLUSIONS

The occurrence of TIIIELs was not affected by the type of endograft fixation. For larger abdominal aortic aneurysms (AAAs) and aneurysms with angulated and calcified aortic necks, there is a higher likelihood of developing TIIIELs during follow-up, regardless of the endograft type used.

CLINICAL IMPACT

The type of fixation does not influence the incidence of TIII ELs. EVAR in larger AAAs and aneurysms with angulated and calcified aortic necks have a higher risk of developing TIII EL. Moreover, the risk of TIII EL is considerably increased by the use of three or more modular components.

Delayed migration due to shortening of the lower part of AFX endograft's main body in angled fusiform abdominal aortic aneurysm

We encountered two fusiform abdominal aortic aneurysm cases with delayed AFX endograft (Endologix Inc) migration >4 years after placement. These cases showed shortening and slight angulation of the main body in the anteroposterior direction. We speculate that the potential mechanism relates to the AFX portion that is easily shortened at the bifurcation of its stent structure. This portion might contribute to delayed migration after slight angulation of the main body. Preoperative three-dimensional computed tomography should be performed from the anteroposterior and lateral views. Although the AFX is useful for narrow bifurcations, one should consider the patient's anatomy before deciding to use an AFX endograft.

Combined AFX2 with thoracic stent graft: A different endovascular approach of an abdominal aorta aneurysm

The AFX2 endovascular repair system is a unibody, bifurcated stent graft that can be used in an abdominal aortic aneurysm associated with anatomical challenges, especially if it is combined with different aortic cuffs. The use of an AFX2 main body combined with a thoracic stent graft as a proximal aortic cuff was selected to treat a 77-year-old male patient with abdominal aortic aneurysm. The AFX2 endograft combined with a proximal thoracic aortic cuff plays a safe and effective role in treating complex infrarenal abdominal aortic aneurysm that may otherwise be technically more challenging with the open technique and inaccessible with the traditional endovascular technique.

Early Clinical Outcomes of the Active Seal Technology of the AFX Endovascular Aortic Aneurysm System With the VELA Cuff for Patients With a Conical Proximal Neck

PURPOSE

To evaluate the efficacy of the Active Seal technology employed in the AFX endovascular aortic aneurysm system (AFX), during endovascular aneurysm repair (EVAR) in patients with abdominal aortic aneurysms (AAAs) having a conical proximal neck.

MATERIALS AND METHODS

A retrospective analysis of the EVAR for AAA with a conical proximal neck using the AFX was performed at 17 Japanese hospitals between January 2016 and August 2020. The conical proximal neck was defined as a cone-shaped proximal neck, with more than 10% diameter increase within a 15 mm length at the proximal landing zone. All anatomical analyses were performed in the core laboratory, and cases with parallel walls within the proximal neck adequate for the landing zone were excluded from the study.

RESULTS

This study included 53 patients, but only 39 patients (mean age, 76.6 ± 6.7 years; 87.0% males; mean aneurysm diameter, 52.0 ± 8.0 mm) were analyzed after being characterized as having a pure conical neck by the core laboratory. The mean proximal neck diameters at the lower renal artery and proximal edge of the aneurysm were 20.0 ± 2.9 mm and 27.5 ± 4.9 mm, respectively. The mean proximal neck length was 21.5 ± 6.0 mm. Instructions for use violations other than the conical neck were observed in 15 patients (38.5%). The VELA cuff was used in all cases; however, additional proximal cuff was required in 9 more cases (23.1%). The Active Seal technology was able to significantly extend the proximal sealing zone from 21.5 ± 6.0 to 26.0 ± 12.2 mm (p = .047). Thirty-six patients completed the 12-month follow-up (one patient was lost to follow-up, and 2 patients died from causes unrelated to the aneurysm), and there were no type-1a and 3 endoleaks with only one reintervention (2.6%) related to type 1b endoleak in the 12-month period. Furthermore, there was no significant enlargement of the proximal neck diameter at 12 months (at 1 month: 20.6 ± 3.4 mm and at 12 months: 21.3 ± 3.8 mm; p = .420).

CONCLUSION

The Active Seal technology of the AFX significantly extended the proximal seal zone and no type-1a endoleak and proximal neck dilation was observed in patients with conical proximal neck at 12 months.

Surgery for late type Ia/IIIb endoleak from a fabric tear and stent fracture of AFX2 stent graft

Technical improvements and labeling updates of the AFX2 stent graft (Endologix Inc, Irvine, CA) seemed to have solved the known issues of its previous generation (AFX Strata). Although most endograft failures after endovascular abdominal aortic aneurysm repair will be managed endovascularly, a small subset of patients will still require secondary open conversion. Partial or complete endograft removal can be required, mainly dependent on the characteristics of the stent graft previously placed. We have report a case of secondary open conversion for late type Ia/IIIb endoleak due to stent fracture and fabric tear of the AFX2 stent graft 3 years after endovascular abdominal aortic aneurysm repair.

Modified Candy-Plug Device for the Dilated False Lumen Occlusion - is a Candle Better than a Candy?

The AFX stent graft has an active seal mechanism, which can conform to an irregular vascular lumen. We modified the candy-plug technique using an AFX VERA suprarenal extension with restricted purse-string sutures to shape it into a candle-like contraption. We treated two patients with patent, dilated false lumina (FL) after central aortic repair using this technique. This plug was deployed into the FL to block retrograde blood flow proximally. Partial or complete thrombosis of the FL was observed in both patients six months after surgery. This technique was feasible for FL occlusion.

Predictors of type IIIa endoleak after Endovascular Aortic Repair with anatomic fixation endografts

OBJECTIVE

Concern regarding the use of anatomic fixation endografts was raised as previous data suggested increased risk of late device uncoupling and type IIIa endoleak in this setting. Some risk factors have been identified as predictors of graft failure. We aim to determine if increase in aortic tortuosity index over the time is associated with increased risk of type IIIa endoleak.

METHODS

We conducted a single center retrospective cohort study of patients treated with endovascular repair of infrarenal abdominal aortic aneurysms with the Endologix platform. Patients with at least two postoperative CT scans were included in the analysis. Aortic tortuosity index was determined in the first and last available CT scan to determine any change. Multivariate analysis was performed in order to detect risk predictors of type IIIa endoleak occurrence.

RESULTS

A total of 173 patients were included in the analysis. 21 patients (12.1%) presented type IIIa endoleak. Cumulative freedom from type IIIa endoleak determined by Kaplan-Meier method was 99.4%, 92.5%, 86.1% and 83.3% at 1, 3, 5 and 8 years respectively. Time dependent optimal cutoff values of 0.03 for aortic tortuosity index increase and 15 mm for decrease in modules overlapping over time were obtained with Contal and O'Quigley method to predict type IIIa endoleak. After dichotomizing data around these critical values, a Cox proportional hazards model was obtained to predict type IIIa endoleak occurrence. Maximum preoperative AAA diameter (OR 1.09), smoking (OR 26.67), initial device components overlap (OR 0.91), aortic tortuosity index increase >0.03 (OR 4.56) and decrease in device components overlap > 15 mm (OR 6.13) were associated with type IIIa endoleak occurrence.

CONCLUSIONS

Aortic tortuosity index increase, device components overlap decrease, maximum preoperative aortic diameter, tobacco use and initial device components overlap were predictive of type IIIa endoleak occurrence. Close follow up with CT scan with aortic tortuosity index and device components overlap measure is warranted in these patients and prompt repair seems justified when any of these risk factors is present.

Use of the AFX Stent Graft in Patients with Extremely Narrow Aortic Bifurcation: A Multicenter Retrospective Study

Introduction

This study analyzed the patient outcomes following endovascular aortic aneurysm repair (EVAR) for infrarenal aortic pathologies with very narrow aortic bifurcations using the AFX stent graft.

Methods

The data was retrieved from the archived medical records of 35 patients treated for abdominal aortic aneurysm (AAA) (48.6%) or penetrating aortic ulcer (PAU) (51.4%) with very narrow aortic bifurcation between January 2013 and May 2020. Patient survival, freedom from endoleak (EL), and limb occlusion were estimated applying the Kaplan–Meier method.

Results

The mean follow-up time was 20.4 ± 22.8 months. The mean aortic bifurcation diameter was 15.8 ± 2.2 mm. Technical success was 100%, and no procedure-related deaths occurred. Two type II ELs occurred within 30-day follow-up. We observed one common iliac artery stenosis at four months and one type III EL at 54 months in the same patient, both of which required re-intervention. Overall patient survival was 95 ± 5% (AAA: 100%; PAU: 89 ± 10%), freedom from limb occlusion was 94 ± 5% (AAA: 91 ± 9%; PAU: 100%), freedom from type II EL was 94 ± 4% (AAA: 88 ± 8%; PAU: 100%), and freedom from EL type III was 83 ± 15% (AAA: 80 ± 18%; PAU: 100%) at the end of the follow-up period.

Conclusions

Very narrow aortic bifurcations may predispose patients to procedure-related complications following EVAR. Our results suggest a safe use of the AFX stent graft in such scenarios. The overall short- and long-term procedure-related patient outcomes are satisfying albeit they may seem superior for PAU when compared to AAA.

Unibody bifurcated aortic endograft: device description, review of the literature and future perspectives

The unibody (Powerlink/AFX/AFX2) Endovascular AAA device (Endologix Inc., CA, USA) presents a unique design with its long main body and two innate limbs. The device is designed to be deployed and sits on the native aortoiliac bifurcation and represents the only one-piece bifurcated endograft designed to use anatomical fixation for endograft stabilization. According to published literature, the unibody device seems to represent a valid choice in the treatment of abdominal aortic aneurysms. This particular device would seem to satisfactorily perform even in the treatment of more compressed aneurysms (also in off-label association with parallel grafts) and in occlusive pathologies. Ongoing studies will provide new real-life data in a large and unselected patient population to better understand the device’s advantages and limitations.

Modeling and Computational Comparison of the Displacement Forces Exerted between the AFX Unibody Aortic Stent Graft and its Hybrid Combination with a Nitinol-based Proximal Aortic Cuff

BACKGROUND

The bifurcated AFX (Endologix, Inc, Irvine, CA, USA) aortic stent-graft is the sole unibody endograft for the management of Abdominal Aortic Aneurysms (AAA). In order to improve the AFX central sealing and clinical efficacy in challenging cases, a replacement of the central chromium-cobaltium AFX extension with a Nitinol-based proximal aortic cuff has been suggested. Yet, comparative data regarding the hemodynamic performance of this design is missing. Aim of this study was to compare the displacement forces (DF) acting on the hybrid AFX-Endurant design, with the classic AFX and Endurant endografts, in angulated and non-angulated cases based on patient-specific Computational Fluid Dynamics (CFD) simulations.

METHODS

3D endograft models of 11 treated AAA cases were reconstructed from Computed Tomography Angiography (CTA) imaging data: 5 cases of AFX, 3 cases of the combination AFX-Endurant and 3 cases of the classic Endurant design. The DF on the main-body, the iliac limbs, and the entire stent-graft was calculated by processing the velocity and pressure fields generated by pulsatile CFD simulations.

RESULTS

The range of total DF (acting on the whole endograft structure) in the AFX, hybrid AFX-Endurant and Endurant group was 2.5-5.2N, 2.0-5.9N and 1.9-2.9N respectively, with the maximum total DF being lower for Endurant. The DF on the main-body of the classic and hybrid AFX cases were higher than the right and left iliac limbs (2.5-4.9N vs. 0.6-5.3N and 0.7-3.6N respectively). Conversely, the DF on the main-body of the Endurant cases was comparable to the force exerted on the right and left limbs. When separating the cases with respect to their neck angulation, the DF on all endograft parts (main-body, limbs) and on the endograft as a whole were lower for the hybrid AFX-Endurant group compared to the classic AFX and Endurant groups, for cases with almost straight neck.

CONCLUSION

The off-label use of the hybrid AFX-Endurant stent-graft does not seem superior to the conventional AFX or Endurant endografts in angulated cases but was associated with lower DF than AFX or Endurant in non-angulated cases. The clinical value and utility of these findings remain to be elucidated.

Initial Experience and Potential Advantages of AFX2 Bifurcated Endograft System: Comparative Case Series

Purpose

Materials and Methods

Results

Conclusion

Computational Comparison Between a Classic Bifurcated Endograft and a Customized Model With "Dog Bone"-Shaped Limbs

PURPOSE

To use computational simulations to compare the hemodynamic characteristics of a classic bifurcated stent-graft to an equally long endograft design with "dog bone"-shaped limbs (DB), which have large diameter proximal and distal ends and significant narrowing at the midsection to accommodate aneurysms with an extremely narrow bifurcation.

MATERIALS AND METHODS

A 3-dimensional model was constructed using commercially available validated software. Inlet and outlet diameters were 28 and 14 mm, respectively. The total length of both models was kept constant to 180 mm, but the main body of the DB model was 20 mm shorter than the bifurcated endograft. The iliac limbs of the DB model had a 9-mm stenosis over a 30-mm segmental length in the midsection. Flow was quantified by time-averaged wall shear stress, oscillatory shear index (OSI), and relative residence time (RRT). The displacement forces in newtons (N) and maximum wall shear stress (WSS) in pascals (Pa) were compared during a cardiac cycle at 3 segments (main body, bifurcation, and iliac limbs) of both models with computational fluid dynamics analysis.

RESULTS

The DB accommodation was associated with higher forces at the main body (range 3.15-4.9 Ν) compared with the classic configuration (1.56-2.34 N). On the contrary, the forces at the bifurcation (3.81-5.98 vs 3.76-5.54 N) and at the iliac limbs (0.34-0.85 vs 0.49-0.74 N) were comparable for both models. Accordingly, maximum WSS was detected at the iliac sites for both models throughout the cardiac cycle. The highest values were detected at peak systole and equaled 26.6 and 12 Pa for the DB and bifurcated configurations, respectively. The narrow segments in the DB model displayed high stress values but low OSI and very low RRT.

CONCLUSION

The DB accommodation seems to correlate with higher displacement forces at the main body and higher stresses at the iliac limbs. Consequently, regular imaging follow-up of the DB design deems necessary to delineate its mid- and long-term clinical performance.

Retrospective Review of Billowing Phenomenon-A Mimic of Endoleak Following Placement of Endologix Covered Stent for the Treatment of Abdominal Aortic Aneurysm

BACKGROUND

Billowing is a unique computed tomography (CT) finding of the Endologix stent graft where a rim of contrast is observed outside the stent's endoskeleton but still contained within the graft cover. The purpose of this study is to evaluate the incidence and clinical outcome of billowing following an Endologix stent-graft placement.

METHODS

All patients who underwent abdominal aortic aneurysm (AAA) repair with endovascular placement of an Endologix stent graft from January 2002 to September 2013 and who were followed with imaging were included in the study. The images were evaluated for the incidence of billowing. Demographics and clinical outcomes were also analyzed.

RESULTS

One hundred twenty-two patients received an Endologix stent graft for AAA repair at our institution. One hundred patients qualified for this study. Eighty-four patients had billowing with the majority (70 patients) having crescentic billowing, and the remaining 14 patients having focal outpouching. Average billowing thickness measured 4.2 mm (range 1-13). Sixty-three patients with billowing had multiple follow-up CT angiograms to allow serial monitoring. Twelve patients had resolution of billowing, 11 patients had reduction in billowing size, 14 patients had no change in billowing size, and 26 patients had increase in billowing size. Patients with billowing had a statistically significant reduction in aneurysm sac size in anteroposterior and transverse dimensions (P = 0.014 and 0.009, respectively). Five cases of billowing were misdiagnosed as endoleak. Nineteen true endoleaks were identified, of which 13 cases were associated with billowing.

CONCLUSIONS

Billowing does not seem to be associated with increased morbidity, mortality, increase in aneurysm size, or presence of endoleak. Billowing should be recognized as a common and benign finding of the Endologix stent.

Initial Clinical Experience with the Endologix AFX Unibody Stent Graft System for Treating Patients with Abdominal Aortic Aneurysms: A Case Controlled Comparative Study

Purpose

The newly designed unibody AFX endograft system for endovascular aortic aneurysm repair is the only graft with anatomical fixation to the aortic bifurcation in comparison to most other grafts that use the infrarenal neck as the main fixation point. The aim of this study was to assess the preliminary results of the AFX stent-graft system used with infrarenal aortic component and compare them with those obtained in patients treated with a well established endograft of the same material and pure infrarenal fixation as the Gore Excluder.

Materials and Methods

A retrospective analysis of prospectively collected data from March 2014 to December 2014 identified 10 elective abdominal aortic aneurysm patients treated with the AFX endograft, in comparison to a matched group of 20 patients treated with the Excluder stent-graft. Endpoints included technical and clinical success, freedom from any secondary intervention, any type of endoleak and aneurysm related death.

Results

Primary technical success was achieved in all patients and no 30-day device related complications or deaths were occurred. The two groups were similar in terms of radiation burden, contrast media, duration of the procedure, post implantation syndrome and in-hospital stay. During a median follow-up period of 23 months (range, 18–26 months) there were no differences in clinical success, freedom from reintervention and aneurysm related death. No type I endoleak was observed in either group. Five of the 6 type II endoleaks (1 in the AFX and 4 in the Excluder group) spontaneously resolved, while in only one patient (Excluder) the endoleak remained without however any change in aneurysm sac diameter (log rank=0.34).

Conclusion

The initial experience with the AFX stent graft system is promising, with successful aneurysm exclusion and good short-term results. Further and larger studies are needed to fully evaluate the sort as well as the long-term results.

Meta-analysis of Outcomes Following Aneurysm Repair in Patients with Synchronous Intra-abdominal Malignancy

OBJECTIVES

The management of concomitant intra-abdominal malignancy (IAM) and abdominal aortic aneurysm (AAA) remains a challenge, even though malignancy is common in an elderly population. By means of systematic review and meta-analysis, the aim was to investigate outcomes in patients undergoing open (OAR) or endovascular AAA repair (EVAR) that have a concomitant malignancy.

METHODS

A systematic literature review was performed (Medline and EMBASE databases) to identify all series reporting outcomes of AAA repair (OAR or EVAR) in patients with concomitant IAM. Meta-analysis was applied to assess mortality and major morbidity at 30 days and long term.

RESULTS

The literature review identified 36 series (543 patients) and the majority (18 series) reported on patients with colorectal malignancy and AAA. Mean weighted mortality for OAR at 30 days was 11% (95% CI: 6.6% to 17.9%); none of the EVAR patients died peri-operatively. The weighted 30-day major complication rate for EVAR was 20.4% (10.0-37.4%) and for OAR it was 15.4% (7.0-30.8%). Most patients had their AAA and malignancy treated non-simultaneously (56.6%, 95% CI, 42.1-70.1%). In the EVAR cohort, three patients (4.6%) died at last follow-up (range 24-64 months). In the OAR cohort 23 (10.6%) had died at last follow up (range from 4 to 73 months).

CONCLUSION

In this meta-analysis, OAR was associated with significant peri-operative mortality in patients with an IAM. EVAR should be the first-line modality of AAA repair. The majority of patients were not treated simultaneously for the two pathologies, but further investigation is necessary to define the optimal timing for each procedure and malignancy.

Endovascular Management of Abdominal Aortic Aneurysms: the Year in Review

OPINION STATEMENT

Endovascular aneurysm repair (EVAR) has become the predominant method of treatment for abdominal aortic aneurysms (AAA). The use of conscious sedation with local anesthesia and percutaneous femoral access has further decreased the morbidity of the procedure. Current devices can more effectively manage increasingly "hostile" aneurysm necks, while chimney grafts or dedicated fenestrated stent-grafts can be used for juxta-renal disease with favorable results. However, endovascular repair does present a new set of challenges, and endoleaks remain an area of concern. While there is general consensus that type I and type III endoleaks require treatment, type II endoleaks are the topic of ongoing research and debate. Development of devices and techniques to prevent and treat endoleak continues to progress. Advances in contrast-enhanced ultrasound are reducing reliance on computed tomography for post-operative monitoring. This is an important step in this population at high risk for the development of kidney failure. Despite these many innovations, further research is needed to optimize the care of patients with AAA.

Non-Invasive Pulse Wave Analysis in a Thrombus-Free Abdominal Aortic Aneurysm after Implantation of a Nitinol Aortic Endograft

Endovascular aneurysm repair has been associated with changes in arterial stiffness, as estimated by pulse wave velocity (PWV). This marker is influenced by the medical status of the patient, the elastic characteristics of the aneurysm wall, and the presence of intraluminal thrombus. Therefore, in order to delineate the influence of the endograft implantation in the early post-operative period, we conducted non-invasively pulse wave analysis in a male patient with an abdominal aortic aneurysm containing no intraluminal thrombus, unremarkable past medical history, and absence of peripheral arterial disease. The estimated parameters were the systolic and diastolic pressure calculated at the aortic level (central pressures), PWV, augmentation pressure (AP) and augmentation index (AI), pressure wave reflection magnitude (RM), and peripheral resistance. Central systolic and diastolic pressure decreased post-operatively. PWV showed subtle changes from 11.6 to 10.6 and 10.9 m/s at 1-week and 1-month, respectively. Accordingly, the AI decreased from 28 to 14% and continued to drop to 25%. The AP decreased gradually from 15 to 6 and 4 mmHg. The wave RM dropped from 68 to 52% at 1-month. Finally, the peripheral resistance dropped from 1.41 to 0.99 and 0.85 dyn × s × cm⁻⁵. Our example shows that the implantation of an aortic endograft can modify the pressure wave reflection over the aortic bifurcation without causing significant alterations in PWV.