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A; A case of abdominal aortic aneurysm with angulation of infrarenal neck. B; If the inflatable rings are not located perpendicularly to the centreline of the neck lumen, then their accommodation onto the neck inner surface may be suboptimal, resulting to inadequate sealing and central endoleak (type 1a, arrow). C; Proper inflation and distension of the rings with a molding balloon improves their apposition and eliminates the endoleak.
Source publication
Introduction
: The Ovation stent-graft has presented satisfactory mid-term results in the management of abdominal aortic aneurysms (AAA). Its unique design with uncoupling of fixation and sealing and the lowest profile in the market has expanded the treatment in AAA with challenging neck anatomies and, especially, in the females presenting mostly w...
Context in source publication
Context 1
... variable results of Ovation documented by different centers can be affected by expertise in the specific device, patient selection, or other criteria [16,17]. Although a recent study demonstrated that overcoming certain anatomic limitations with the Ovation can increase the AAA eligibility for EVAR by approximately 12% [9], the technical expertise needed to overcome the relevant intraoperative challenges (Figure 2a-c) affect the technical and clinical outcomes [17,31]. In other words, the promising approach to adverse anatomies with the Ovation should be tailored with caution, especially in cases where anatomic restrictions fall outside the current IFU. ...
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Citations
... However, in these cases, surgical success is associated with high consumption of materials and contrast medium, as well as extended surgical and radiation exposure. Previous studies have focused on the effects of anatomical conditions on perioperative complications and surgical outcomes [2,3]. Speziale et al. demonstrated that a higher complexity of the aneurysm neck is associated with an increased number of secondary interventions due to high-flow endoleaks and stent graft migration [2]. ...
Endovascular aortic repair (EVAR) is the primary treatment for abdominal aortic aneurysms (AAAs). To optimise patient safety during the standard EVAR procedure, we aimed to investigate the influence of patient anatomy on intraoperative radiation exposure and surgical time. This retrospective study comprised 90 patients (mean age 73.4 ± 8.2 years; 92.2% male) with an infrarenal aortic aneurysm who underwent a standard EVAR procedure. The relationships between dose area product, operating time, and anatomical conditions were investigated in preoperative computed tomography angiography using open-source software. Logistic regression analysis indicated that only body mass index (BMI) had predictive value for radiation exposure. The accuracy of the model was 98.67%, with an area under the curve of 0.72. The duration of surgery was significantly correlated with an increased BMI (odds ratio (OR) = 1.183; p < 0.05), the tortuosity of AAAs (OR = 1.124; p < 0.05), and the left common iliac artery (OR = 1.028; p < 0.05). Thus, BMI impacts the prediction of intraoperative radiation exposure more significantly than the anatomical characteristics of the infrarenal aorta and iliac arteries, and the duration of surgery significantly correlates with both BMI and the tortuosity of the infrarenal aorta and iliac arteries.
... The design of these endografts can be grouped into three broad categories. The first and most common is where a short main body around 5 cm long splits to two iliac limbs [36]. The second uses an anatomical fixation of the main body into the native aortic bifurcation, where the main body has the length of the native infra-renal aorta [37]. ...
During the vascular surgical reconstruction of aorto-iliac occlusive/aneurysmal disease, bifurcated grafts are used where vascular surgeons intra-operatively select the size and the relative lengths of the parent and daughter portions of the graft. Currently, clinical practice regarding the selection of the most favorable geometric configuration of the graft is an understudied research subject: decisions are solely based on the clinical experience of the operating surgeon. This manuscript aims to evaluate the hemodynamic performance of various diameters, D, of bifurcated aortic grafts and relate those with proximal/distal part length ratios (the angle φ between the limbs is used as a surrogate marker of the main body-to-limb length ratio) in order to provide insights regarding the effects of different geometries on the hemodynamic environment. To this end, a computationally intensive set of simulations is conducted, and the resulting data are analyzed with modern statistical regression tools. A negative curvilinear relationship of TAWSS with both φ and D is recorded. It is shown that the angle between limbs is a more important predictor for the variability of TAWSS, while the graft’s diameter is an important determinant for the variability of OSI. Large percentages of the total graft area with TAWSS < 0.4 Pa, which correspond to thrombogenic stimulating environments, are only observed for large values of φ and D > 20 mm. This variable ranges from 10% (for the smallest values of φ and D) to 55% (for the largest φ and D values). Our findings suggest that grafts with the smallest possible angle between the limbs (i.e., smallest parent-to-daughter length ratio) present the most favorable hemodynamic performance, yielding the smallest percentage of total graft area under thrombogenic simulating environments. Similarly, grafts with the smallest acceptable diameter should be preferred for the same reason. Especially, grafts with diameters greater than 20 mm should be avoided, given the abrupt increase in estimated thrombogenic areas.
... A concern associated with the use of Ovation in EVAR is the options to manage central endoleaks, since the stiffening of the polymer-filled rings precludes the effective use of cuffs or stents to distend them due to the polymer solidification. The sealing agents most effectively used are glue and coil embolization since type 1A endoleaks cannot be treated well with cuffs, unless the aortic body has been deployed in a significantly distal position [17]. Therefore, it is imperative that the sealing rings are deployed absolutely according to plan so that the seal as planned at 7 mm immediately infrarenally is indeed achieved at this precise site and not more caudally. ...
... Additionally, as Gregory et al. underline, the Alto modification was launched by Endologix as a direct modification of the previous Ovation iX platform, based on the satisfactory 5 year results of the latter [17]. Yet, the relocation of the sealing rings more centrally, omitting the nitinol-based fabric zone, may render the caudal unsupported fabric segment prone to significant kinking in AAA with marked infrarenal angulation, especially if the orientation and apposition of the sealing rings is affected by the axis of the long suprarenal stent in marked suprarenal angles [18]. ...
... Gregory et al. [11] stated that although existing published data on the ALTO device are limited, if more published data show short-to long-term results comparable to those obtained using the Ovation iX [12][13][14][15][16][17][18][19], then the ALTO device can be used more widely. However, whether ALTO devices can be successfully used in patients with more hostile aortic anatomies remains to be seen, considering the satisfac-tory results of Ovation iX use reported by Sirignano et al. [17] and Morgan-Bates and Chaudhuri [19]. ...
The ALTO abdominal stent graft system (Endologix Inc., Irvine, CA, USA) is a latest-generation polymer-based device used to treat patients with abdominal aortic aneurysms. The present study describes the first case series of patients with abdominal aortic aneurysms, including two patients with juxtarenal aneurysms, treated using the ALTO stent graft system. Six males were treated using the ALTO device at a single public center. All procedures were uneventful, and the dosimetric results recorded in terms of kerma-area product and fluoroscopy time were similar to those reported in previous studies. At the 1-month follow-up, computed tomography angiography showed no evidence of endoleak, device migration, thrombosis, or structural graft failure. This clinical series demonstrates that the use of the ALTO stent graft system is associated with promising patient outcomes. Lifelong postoperative imaging surveillance may highlight possible late failures and suggest potential graft improvements.
... This assumption comes with a benefit in reducing aortic neck dilatation and consecutive endograft migration, a typical complication of SESGs. All these features define the revolutionary concept of "Custom Seal" as a tailored adaptation of polymer rings to the aortic wall, including wall calcification, wall thrombosis, and aortic tortuosity [75][76][77]. ...
An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta that progressively grows until it ruptures. Treatment is typically recommended when the diameter is more than 5 cm. The EVAR (Endovascular aneurysm repair) is a minimally invasive procedure that involves the placement of an expandable stent graft within the aorta to treat aortic disease without operating directly on the aorta. For years, stent grafts’ essential design was based on metallic stent frames to support the fabric. More recently, a polymer-based technology has been proposed as an alternative method to seal AAA. This review underlines the two platforms that are based on a polymer technology: (1) the polymer-filled endobags, also known as Endovascular Aneurysm Sealing (EVAS) with Nellix stent graft; and (2) the O-ring EVAR polymer-based proximal neck sealing device, also known as an Ovation stent graft. Polymer characteristics for this particular aim, clinical applications, and durability results are hereby summarized and commented critically. The technique of inflating endobags filled with polymer to exclude the aneurysmal sac was not successful due to the lack of an adequate proximal fixation. The platform that used polymer to create a circumferential sealing of the aneurysmal neck has proven safe and effective.
Hostile neck anatomy (HNA) denotes anatomically unfavourable anatomy along the segment of aorta between the lowest renal artery and commencement of the aneurysm. It is the most frequent determinant of ineligibility for endovascular repair (EVAR). HNA is associated with increased technical difficulty and a greater risk type 1a endoleak (loss of the proximal seal), reintervention, secondary rupture, renal injury, and death. This chapter delineates relevant anatomical features utilised to determine HNA, the essentials of pre-operative assessment, and available treatment options: off-the-shelf devices, use of adjuncts, fenestrated and chimney EVARs.
Women with abdominal aortic aneurysm (AAA) have a higher incidence of complications after Endovascular aneurysm repair (EVAR), most of which are related to the migration of stent-graft. The different force acting on the stent-graft after EVAR caused by different abdominal artery anatomy of male and female AAA patients may be the reason for the sex-different complications. This article aims to explore the possible biomechanical mechanisms of sex differences by making a comparison of displacement force acting on the stent graft of male and female AAA patients. To explore the effect of different vascular anatomy on stent-graft migration, the uniformed models were constructed according to the specific vascular anatomy parameters of AAA patients of different sex, which have been measured before. The computational fluid dynamics method was used to quantitate the pulsatile force acting on the stent-graft after EVAR in a cardiac cycle. Then the displacement force was calculated with the pressure and the wall shear stress, and the total and area-weighted average of displacement force acting on the stent-graft were compared respectively. In one cardiac cycle, the wall pressure for the male model is greater than that of the female model (2.7-4.4 vs. 2.2-3.4 N), and the wall shear force for the female model is slightly greater (0-0.0065 vs. 0-0.0055 N). The displacement force is mainly provided by the wall pressure, which is also greater in the male model. However, the area-averaged displacement force is greater for the female model than that for the male model (180-290 vs. 160-250 Pa). Because of the different vascular anatomies, the impact caused by the pulsating aortic blood flow on the AAA stent-graft of women after EVAR was greater than that of men. Women's vascular anatomy leads to greater area-averaged displacement force after stent-graft implantation, resulting in a greater risk of stent-graft migration, which might be one of the reasons why women had a higher incidence of complications after EVAR.
Objective
Patients with wide aortic necks undergoing Endovascular Aneurysm Repair (EVAR) have been shown to be at a higher risk for neck-related complications. We aim to examine outcomes of EVAR with an endograft exerting minimal outward pressure (Ovation-Endologix) in patients with a large baseline neck diameter.
Methods
We performed a retrospective single center study, including consecutive patients undergoing EVAR with the Ovation system from 05/2011 to 04/2021. Patients were divided in Groups 1 and 2 if the 20,23,26,29mm or the 34mm proximal diameter main body was used, respectively. According to the instructions for use of the device, for neck diameters 27-30mm the 34mm main body is required. Primary endpoint was rate of neck related complications during follow-up, (type Ia endoleak, migration >10mm and neck-related re-interventions) and rate of aortic neck dilatation (AND). AND was determined based on multiple aortic neck diameters that were recorded and compared between the 1-month computed tomography angiography (CTA) after EVAR and the last available follow-up CTA.Secondary endpoints were peri-procedural and follow-up outcomes such as endoleaks, reinterventions and overall mortality.
Results
In total 281 patients were included, 222 in Group 1 and 59 in Group 2. Patients in Group 2 presented significantly shorter neck length, higher neck angulation and more common reversed tapered configuration. Median follow-up was 36 months (Range:6-106). Early and late type Ia endoleak was observed in 4 and 2 patients in each group, respectively (P=0.063 and P=0.195, respectively). Distal migration was observed in 2 patients in Group 2 and AND was recorded in 2 patients in each group (P=0.195). Freedom from the primary endpoint was estimated at 98%, 94%, 94% at 12-, 36-, 60-months for Group 1 and at 98%, 95%, 86% for Group 2 (P-Value 0.266). Probability of survival was 95%, 86%, 75% at 12-, 36-, 60-months for Group 1 and 83%, 77%, 72% for Group 2 (P-Value 0.226).Multivariate regression analysis identified neither Group 1 vs Group 2 nor absolute value of aortic neck diameter as significant predictors of neck-related adverse events. Neck diameters did not display significant differences over time in any of the levels evaluated.
Conclusions
EVAR with the Ovation endograft results in low rates of late neck related complications which is also true for patients with wide baseline aortic necks.
Introduction
The Ovation ALTO is the next generation aortic stent graft from Endologix for the treatment of infra-renal abdominal aortic aneurysms. The device uses polymer-injected rings to create a proximal seal at the aneurysm neck.
Areas Covered
Results from the first clinical study of the ALTO graft are analysed and the potential benefits of the graft in minimising post-treatment aneurysmal neck dilation discussed. The implications of the ALTO’s Instructions-For-Use (IFU) and low-profile delivery system are also reviewed.
Expert Opinion
The re-positioning of the sealing rings higher on the graft and an integrated compliant balloon are the most significant improvements on the Ovation iX, facilitating accurate placement of the proximal sealing ring and prompt balloon dilation of the polymer rings. The expansion the IFU to include neck lengths of ≥ 7mm will mean more patients are eligible for infra-renal EVAR within IFU with the ALTO device. The published data on the device to date is limited. With over 1000 implants worldwide we would hope for more published data to become available. If this demonstrates similar mid-term results to that seen with the Ovation iX in arguably more hostile neck anatomy, then the Ovation ALTO is likely to be more widely used.
