Importance of sac regression after EVAR and the role of EndoAnchors.

The initial success and widespread adoption of endovascular aneurysm repair (EVAR) for the treatment of abdominal aortic aneurysms have been tempered by numerous reports of secondary interventions and increased long-term mortality compared with open repair. Over the past decade, several studies on postoperative sac dynamics after EVAR have suggested that the presence of sac regression is a benign feature with a favorable prognosis. Conversely, increasing sacs and even stable sacs can be indicators of more unstable sac behavior with worse outcomes in the long-term. Endoleaks were initially perceived as the main drivers of sac behavior. However, the observation that sac regression can occur in the presence of endoleaks, and vice versa - increasing sacs without evidence of endoleak - on imaging studies, suggests the involvement of other contributing factors. These factors can be divided into anatomical factors, patient characteristics, sac thrombus composition, and device-related factors. The shift of interest away from especially type 2 endoleaks is further supported by promising results with the use of EndoAnchors regarding postoperative sac behavior. This review provides an overview of the existing literature on the implications and known risk factors of post-EVAR sac behavior, describes the accurate measurement of sac behavior, and discusses the use of EndoAnchors to promote sac regression.

Determination of the gained proximal sealing zone length after debranching of the left subclavian artery in thoracic endovascular aortic repair.

BACKGROUND: For descending thoracic aortic aneurysms (TAA) in proximity of the aortic arch, debranching of the left subclavian artery (LSA) may be necessary to extend proximal sealing in zone 2. The aim of this study was to determine the added proximal apposition length gained from LSA debranching during thoracic endovascular aortic repair (TEVAR). METHODS: This multicenter retrospective study (2010-2020) included patients who underwent elective TEVAR in zone 2 for a degenerative TAA where the LSA was surgically debranched. The endograft position on the first postoperative computed tomography angiography (CTA) scan was assessed using post-processing software. The analysis included the shortest apposition length (SAL), the tilt of the proximal edge of the endograft, and the distance between the endograft and the left common carotid artery. Clinical endpoints (neurological complications and endoleaks) at 30 days were also reported. RESULTS: Twenty-two patients were included. The median interval between TEVAR and the first postoperative CTA was 3 days (2-10 days). Median SAL was 9.2 mm (1.3-26.4 mm), of which 8.6 mm (1.3-16.2 mm) was gained proximal of the LSA, including the LSA orifice. In 12 patients (55.5%) the SAL was <10 mm. The median tilt was 18.3° (13.9°-22.2°). Seven endoleaks were reported on the first CTA: 1 type Ia, 2 type Ib, 3 type II, and 1 type III. CONCLUSIONS: Debranching the LSA adds valuable sealing length in zone 2, but the SAL was still relatively short in many patients, putting these patients at risk for a future type Ia endoleak. Accurate assessment of the circumferential apposition on postoperative CTA follow-up in these high-risk patients with short, complex landing zones seems mandatory. Evaluation of apposition in a larger population with longer follow-up is advised.

Midterm changes in iliac limb apposition after endovascular aortic aneurysm repair.

BACKGROUND: Literature is scarce on the course of iliac endograft limb apposition after endovascular aortic aneurysm repair (EVAR), which is why this study was conducted. METHODS: A retrospective observational imaging study was performed to measure iliac apposition of endograft limbs on the first post-EVAR computed tomography angiography (CTA) scan and on the latest available follow-up CTA scan. With center lumen line reconstructions and CT-applied dedicated software, the shortest apposition length (SAL) of the endograft limbs was assessed as well as the distance between the end of the fabric and the proximal border of the internal iliac artery or the endograft-internal artery distance (EID). RESULTS: Ninety-two iliac endograft limbs were eligible for measurements, with a median follow-up of 3.3 years. At the first post-EVAR CTA, the mean SAL was 31.9±15.6 mm, and the mean EID was 19.5±11.8. At the last follow-up CTA, there was a significant decrease in apposition of 10.5±14.1 mm (P<0.001) and a significant increase in EID of 5.3±9.5 mm (P<0.001). A type Ib endoleak developed in three patients due to a reduced SAL. The apposition was <10 mm in 24% of limbs at the last follow-up vs. 3% at the first post-EVAR CTA. CONCLUSIONS: This retrospective study documented a significant decrease in post-EVAR iliac apposition over time, partly due to retraction of iliac endograft limbs at mid-term CTA follow-up. Further research is required to identify whether regular determination of iliac apposition may predict and prevent type IB endoleaks.

Mid-term proximal sealing zone evaluation after fenestrated endovascular aortic aneurysm repair.

BACKGROUND: Fenestrated endovascular aortic aneurysm repair (FEVAR) is used in pararenal abdominal aortic aneurysms to achieve a durable proximal seal. This study investigated the mid-term course of the proximal fenestrated stent graft (FSG) sealing zone on the first and latest available post-FEVAR computed tomographic angiography (CTA) scan in a single-center series. METHODS: In 61 elective FEVAR patients, the shortest length of circumferential apposition between the FSG and the aortic wall (shortest apposition length [SAL]) was retrospectively assessed on the first and last available postoperative CTA scans. Patient records were reviewed for FEVAR-related procedural details, complications, and reinterventions. RESULTS: The median (interquartile range) time between the FEVAR procedure and the first and last CTA scan was 35 (30-48) days and 2.6 (1.2-4.3) years, respectively. The median (interquartile range) SAL was 38 (29-48) mm, and 44 (34-59) mm on the first and last CTA scans, respectively. During follow-up, the SAL increased >5 mm in 32 patients (52%), and decreased >5 mm in six patients (10%). Reintervention was performed for a type 1a endoleak in one patient. Twelve other patients needed 17 reinterventions for other FEVAR-related complications. CONCLUSIONS: Good mid-term apposition of the FSG in the pararenal aorta was achieved post-FEVAR, and the occurrence of type 1a endoleaks was low. The number of reinterventions was substantial, however, but for reasons other than loss of proximal seal.

Single-center results of the Gore Excluder Conformable Endoprosthesis with active control system in endovascular aneurysm repair.

BACKGROUND: The GORE EXCLUDER Conformable Endoprosthesis with active control (CEXC) was developed to treat challenging aortic neck anatomy. This study investigated the clinical results and changes in endograft (ap)position during follow-up. METHODS: Patients treated with the CEXC between 2018 and 2022 were included in this prospective single-center study. Computed tomography angiography (CTA) follow-up was grouped into three categories: 0 to 6 (FU1), 7 to 18 (FU2), and 19 to 30 (FU3) months. Clinical end points were endograft-associated complications and reinterventions. CTA analysis included the shortest apposition length (SAL) between the endograft fabric and the first slice where circumferential apposition was lost, shortest fabric distance (SFD) between both renal arteries and the endograft fabric, and maximum infrarenal and suprarenal aortic curvature. FU2 and FU3 were compared with FU1 to establish changes. RESULTS: Included were 46 patients, of whom 36 (78%) had at least one hostile neck feature and 13 (28%) were treated outside instructions for use. Technical success was 100%. Median CTA follow-up was 10 months (2-20 months); 39 patients had a CTA available at FU1, 22 at FU2, and 12 at FU3. At FU1, the median SAL was 21.4 mm (13.2-27.4 mm), which did not significantly change during follow-up. No type I endoleaks, and one type III endoleak at an IBD occurred during follow-up. Two cases of endograft migration (SFD increase >10 mm) were seen during follow-up (one treated outside the instructions for use). Maximum infrarenal and suprarenal aortic curvature did not significantly change during follow-up. CONCLUSIONS: The use of the CEXC in challenging aortic necks enables stable apposition without significant changes in aortic morphology at short-term follow-up.

Subtraction computed tomography imaging to detect endoleaks after endovascular aneurysm sealing with sac anchoring.

Background Early detection of small type I endoleaks after endovascular aneurysm sealing is mandatory because they can rapidly progress and lead to severe complications. Recognition of endoleaks can be challenging due to the appearances on computed tomography unique to endovascular aneurysm sealing. We aimed to validate the accuracy and added value of subtraction computed tomography imaging using a post-processing software algorithm to improve detection of endovascular aneurysm sealing-associated endoleaks on postoperative surveillance imaging. Methods The computed tomography scans of 17 patients (16 males; median age: 78, range: 72-84) who underwent a post-endovascular aneurysm sealing computed tomography including both non-contrast and arterial phase series were used to validate the post processing software algorithm. Subtraction images are produced after segmentation and alignment. Initial alignment of the stent segmentations is automatically performed by registering the geometric centers of the 3D coordinates of both computed tomography series. Accurate alignment is then performed by translation with an iterative closest point algorithm. Accuracy of alignment was determined by calculating the root mean square error between matched 3D coordinates of stent segmentations. Results The median root mean square error after initial center of gravity alignment was 0.62 mm (IQR: 0.55-0.80 mm), which improved to 0.53 mm (IQR: 0.47-0.69 mm) after the ICP alignment. Visual inspection showed good alignment and no manual adjustment was necessary. Conclusions The possible merit of subtraction computed tomography imaging for the detection of small endoleaks during surveillance after endovascular aneurysm sealing was illustrated. Alignment of different computed tomography phases using a software algorithm was very accurate. Further studies are needed to establish the exact role of this technique during surveillance after endovascular aneurysm sealing compared to less invasive techniques like contrast-enhanced ultrasound.

Fluid displacement from intraluminal thrombus of abdominal aortic aneurysm as a result of uniform compression.

Objectives The results after aneurysm repair with an endovascular aneurysm sealing (EVAS) system are dependent on the stability of the aneurysm sac and particularly the intraluminal abdominal aortic thrombus (ILT). The postprocedural ILT volume is decreased compared with preprocedural ILT volume in aortic aneurysm patients treated with EVAS. We hypothesize that ILT is not stable in all patients and pressurization of the ILT may result in displacement of fluids from the ILT, no differently than serum is displaced from whole blood when it settles. To date, the mechanism and quantification of fluid displacement from ILT are unknown. Methods The study included 21 patients who underwent elective open abdominal aortic aneurysm repair. The ILT was harvested as a routine procedure during the operation. After excision of a histologic sample of the ILT specimen in four patients, ILT volume was measured and the ILT was compressed in a dedicated compression setup designed to apply uniform compression of 200 mmHg for 5 min. After compression, the volumes of the remaining thrombus and the displaced fluid were measured. Results The median (interquartile-range) of ILT volume before compression was 60 (66) mL, and a median of 5.7 (8.4) mL of fluid was displaced from the ILT after compression, resulting in a median thrombus volume decrease of 11% (10%). Fluid components can be up to 31% of the entire ILT volume. Histologic examination of four ILT specimens showed a reduction of the medial layer of the ILT after compression, which was the result of compression of fluid-containing canaliculi. Conclusions Applying pressure of 200 mmHg to abdominal aortic aneurysm ILT resulted in the displacement of fluid, with a large variation among patients. Fluid displacement may result in decrease of ILT volume during and after EVAS, which might have implications on pre-EVAS volume planning and on stability of the endobags during follow-up which may lead to migration, endoleak or both.