Aortic Neck Angulations Decrease During and After Endovascular Aneurysm Repair

Preliminary Assessment of Intra-Aneurysm Sac Pressure During Endovascular Aneurysm Repair as an Early Prognostic Factor of Aneurysm Enlargement

Purpose

Numerous cases of abdominal aortic aneurysm (AAA) enlargement, and even rupture, despite endovascular aneurysm repair (EVAR), have been documented. This has been linked to increased aneurysm sac pressure (ASP). We decided to conduct further research with the aim to identify correlations between ASP during EVAR and subsequent aneurysm enlargement.

Patients and Methods

This experimental prospective study included 30 patients undergoing EVAR of infrarenal AAAs. Invasive ASP measurements were done using a thin pressure wire. Aortic pressure (AP) was measured using a catheter placed over the wire. Systolic pressure index (SPI), diastolic pressure index (DPI), mean pressure index (MPI), and pulse pressure index (PPI) were calculated both for ASP and AP. The results of follow-up computed tomography angiography (CTA) at 3 months were compared with baseline CTA findings.

Results

During EVAR, a significant reduction was observed for SPI (from 98% to 61%), DPI (from 100% to 87%), MPI (from 99% to 74%), and PPI (from 97% to 34%). There were no significant correlations of pressure indices with an aneurysm diameter, cross-sectional area, velocity, thrombus shape and size, number of patent lumbar arteries, length and diameter of aneurysm neck, diameter of the inferior mesenteric artery, as well as diameter and angle of common iliac arteries. On the other hand, aneurysm neck angulation was significantly inversely correlated with reduced PPI. After combining CTA findings with pressure measurements, we identified a positive correlation between PPI and aneurysm enlargement (ratio of the cross-sectional area at the widest spot at baseline and at 3 months after EVAR).

Conclusion

The study showed that ASP can be successfully measured during EVAR and can facilitate the assessment of treatment efficacy. In particular, PPI can serve as a prognostic factor of aneurysm enlargement and can help identify high-risk patients who remain prior monitoring.

Effect of vertebral compression fractures on aortic neck angulation after endovascular aneurysm repair

OBJECTIVE

Aortic neck angulation (ANA) prior to endovascular aneurysm repair (EVAR) and its changes after EVAR are considered important predictors of postoperative complications. We sought to assess the effects of vertebral body height loss on ANA in patients post-EVAR.

METHODS

All patients who had undergone EVAR for infrarenal aortic aneurysms in our institution between August 2010 and December 2018 were assessed. Anterior and posterior vertebral body heights were measured in all patients on preoperative, early postoperative, and follow-up computed tomography scans (T12-L5 vertebral bodies). Patients who had significant height loss in their follow-up period were designated as the Study group. These were matched to a Control group of the same size using propensity-score matching based on age, gender, and duration between follow-up scans. Aortic neck morphology indices including ANA and its changes were measured, and information related to postoperative endoleaks and aneurysm sac size were extracted in the Study and Control groups.

RESULTS

During the follow-up period, 10 of 185 patients had a radiologically significant vertebral body compression fracture. There was no significant difference between the Study (n = 10) and Control groups in age (77.6 ± 6.9 vs 77.2 ± 7.5 years; P = .64), gender (seven males and three females in each group; P = 1.0), duration between postoperative scans (1830 ± 665 vs 1800 ± 670 days; P = .25), preoperative ANA (36.0° ± 15.6° vs 42.4° ± 18.6°; P = .41), and early postoperative ANA (21.9° ± 11.7° vs 20.9° ± 16.3°; P = .72). Changes in ANA in the postoperative period (7.2° ± 11.1° vs -4.7° ± 6.7°; P = .009; power = .838) were significantly higher in the Study group.

CONCLUSION

Post-EVAR vertebral body compression fractures exacerbate ANA. Awareness of this can guide both preoperative assessment and postoperative management and follow-up.

Use of Chimney Technique Does Not Improve the Outcome of Endovascular Aneurysm Repair in Patients With a Hyperangulated and Short Proximal Aortic Neck

PURPOSE

We hypothesized that extending the proximal landing zone with the chimney technique could be beneficial in patients with a hyperangulated proximal aortic neck, defined as more > 60 degrees.

MATERIAL AND METHODS

We retrospectively analyzed the outcome of prospectively collected data of patients treated by endovascular aneurysm repair (EVAR) for infrarenal aortic aneurysm with a hyperangulated proximal aortic neck. In all, 104 out of 130 patients were treated without (Group A) and 24 with the chimney endovascular aortic repair (ChEVAR, Group B). Primary outcome was technical and clinical success according to the reporting standards of the Society of Vascular Surgery.

RESULTS

The use of the chimney technique was associated with a significantly longer operation duration (167 vs. 93 min, p < .001), longer fluoroscopy time (44 vs.30 min, p = < .001), and larger amount of contrast medium used (149 vs. 127 ml, p = .03) but did not significantly improve technical (79.2% vs. 87.7%) and clinical success (54.2% vs. 68.9%). Aneurysm-related mortality was higher in group B (8.3% vs. = 0%, p < .001). Type IA endoleak was high in both groups at completion angiography (11.3% in Group A vs. 12.5% in Group B) and at follow-up (10.4% in Group A vs. 4.5% in Group B) without significant difference between the groups.

CONCLUSIONS

Our data did not show a benefit of the primary use of the chimney technique in patients with a hyperangulated and short neck, although more studies are required to support this conclusion. Other strategies or new technologies are required for improving EVAR results in aneurysm patients with severe angulated proximal and short neck.

Remodeling of Abdominal Aortic Angulation and Curvature After Endovascular Aneurysm Repair in Patients With vs Without Late Type Ia Endoleak or Endograft Migration

PURPOSE

To investigate aortic remodeling of the supra- and infrarenal aorta from preoperative to 1 month and midterm follow-up after endovascular aneurysm repair (EVAR) by analyzing changes in angulation and curvature in patients with vs without late type Ia endoleak or device migration.

MATERIALS AND METHODS

From a multicenter database, 35 patients (mean age 76±5 years; 31 men) were identified with late (>1 year) type Ia endoleak or endograft migration (≥10 mm) and defined as the complication group. The control group consisted of 53 patients (mean age 75±7 years; 48 men) with >1-year computed tomography angiography (CTA) follow-up and no evidence of endoleaks. Suprarenal and infrarenal angles were measured on centerline reconstructions of the preoperative, 1-month, and midterm CTA scans. The value and location relative to baseline of maximum suprarenal and infrarenal curvature were determined semiautomatically using dedicated software. Changes were determined at 1 month compared with the preoperative CTA and at midterm compared with 1 month.

RESULTS

Preoperative suprarenal angulation was significantly greater in the complication group compared to the controls (34°±18° vs 24°±17°, p=0.008). It decreased significantly at 1 month in the complication group (29°±16°, p=0.011) and at midterm follow-up in the controls (20°±19°, p<0.001). Preoperative infrarenal angulation was not significantly different (57°±15° vs 49°±24°, p=0.114). This measurement increased significantly through midterm follow-up in the complication group (63°±23°, p<0.001) but remained stable in the controls (46°±22°). Preoperative suprarenal curvature was not significantly different (38±22 m^-1 vs 29±25 m^-1, p=0.115). This variable increased significantly through midterm follow-up in the complication group (44±22 m^-1) but remained constant in the controls (28±22 m^-1). Preoperative infrarenal curvature was significantly greater in the complication group (77±29 m^-1 vs 65±28 m^-1, p=0.047) and decreased significantly in both groups during midterm follow-up (50±17 m^-1 vs 41±19 m^-1 p=0.033). The location of the maximum curvature with regard to baseline shifted significantly distally in the complication group (54±43 to 72±41 mm, p<0.001), while it remained stable in the controls (46±33 to 48±31 mm).

CONCLUSION

At midterm follow-up, significant differences in supra- and infrarenal angulation and curvature were observed between patients with vs without type Ia endoleak or migration. The location of the maximum curvature shifted distally in patients with complications. The aortic morphology is more stable during midterm follow-up in the patients without endoleaks.

A penalized spline fitting method to optimize geometric parameters of arterial centerlines extracted from medical images

In order to grasp the spatial and temporal evolution of vascular geometry, three-dimensional (3D) arterial bending structure and geometrical changes of arteries and stent grafts (SG) must be quantified using geometrical parameters such as curvature and torsion along the vasculature centerlines extracted from medical images. Here, we develop a robust method for constructing smooth centerlines based on a spline fitting method (SFM) such that the optimized geometric parameters of curvature and torsion can be obtained independently of digitization noise in the images. Conventional SFM consists of the 3rd degree spline basis function and 2nd derivative penalty term. In contrast, the present SFM uses the 5th degree spline basis function and 3rd and 4th derivative penalty terms, the coefficients of which are derived by the Akaike information criterion. The results show that the developed SFM can reduce the errors of curvature and torsion compared to conventional SFM. We then apply the present SFM to the centerline of the SG in an abdominal aortic aneurysm (AAA), and those of bilateral internal carotid arteries (ICA) in 6 cases: 3 cases with aneurysms and 3 cases without any aneurysm. The SG centerlines were obtained from temporal medical images at three scan times. The strong peak of the curvature could be clearly observed in the distal area of the SG, the inversion of the torsion at 0 months in the middle area of SG disappeared over time, and the torsions around the SG bifurcation at the three time periods were inverted. The curvature-torsion graphs along the ICA centerlines superimposing five aneurysmal positions were useful for investigating the relationship between arterial bending structure and aneurysmal positions. Both ICAs had curvature peak values higher than 0.4 within the ICA syphons. The ICA torsion graphs indicated that left and right ICA tended to be a right- and left-handed helix, respectively. In the left ICA syphon, the biggest aneurysm could be observed downstream of the salient torsion inversion. All aneurysms for 3 cases were positioned at the downstream of the inverted torsion.

Current evidence on aortic remodeling after endovascular repair

Anatomical changes after endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs) are thoroughly studied as they could affect the long-term postoperative outcome. The aim of the present study was to review the literature and summarize the recent data regarding the aortic remodeling and its clinical significance. A continuous aortic neck expansion is observed after EVAR and is more rapid at the first month and during the third postoperative year. This aortic neck dilation is not influenced by the type of proximal stent-graft fixation, is comparable to open surgical aneurysm repair and is most probably related with the natural progression of aneurismal disease. Aortic neck angulation reduces significantly immediately after EVAR and then continues to reduce slowly and gradually. Neck angulations ≥60° have a greater reduction compared to neck angulations <60°. An expansion of the common iliac arteries at the distal landing zone is also observed after EVAR and is more prominent in the first six postoperative months. A postoperative increase of the distance between superior mesenteric artery and iliac bifurcations (aortoiliac elongation) is described and is associated with increased type I endoleaks and reinterventions. The aneurysm sac diameter most frequently reduces after EVAR in absence of an endoleak and this aneurysm sac regression has been associated with the stent-graft type.

Aortic Curvature Remodeling after Thoracic Endovascular Aortic Repair: Assessing Device Conformability, Using Image Vector Analysis

BACKGROUND

Aortic arch curvature can be straightened by endograft placement. However, different measurement methods with dissimilar follow-up and endografts have been published. The aim of this study was to corroborate, for the first time, the pliability of the Conformable Gore TAG Thoracic Endoprosthesis (W.L. Gore and Associates, Flagstaff, AZ, USA) into the aortic arch, using different image vector analysis.

MATERIAL AND METHODS

We, retrospectively, analyzed patients primarily treated for thoracic aortic aneurysms and blunt traumatic aortic injuries by means of a Conformable Gore TAG Thoracic Endoprosthesis endograft proximally sealed into the aortic arch (zones Z1-Z3) in five different Spanish centers, between 2010 and 2017. The preoperative, one-month and six-month postoperative, computed tomography angiographies (CTAs) were obtained, creating accurate 3D center lumen line and external lumen line from the aortic valve to the renal arteries. Three different image analysis methods were used to compare modifications of the aortic curvature: first, segment analysis (angulations of the center lumen line when divided into seven precise segments, examining anterior-posterior, right-left, and cranial-caudal displacement), second, center lumen line analysis (bending of the center lumen line itself in seven definite points), and third, expected behavior (length of the endograft in the external lumen line). Two independent observers performed a blind analysis of all CTAs. Changes between preoperative and postoperative CTAs at one and six months are compared, and differences are viewed between cases sealed proximally (Z1-Z2) and distally (Z3) into the aortic arch.

RESULTS

We analyzed 37 cases. At 1- and 6-month follow-ups, minimal changes occurred first in segment analysis (only a slight decrease of -2.0° in the XY plane at 10 cm from the brachiocephalic trunk at six-month follow-up was seen, P = 0.027). Second, center lumen line analysis again only showed negligible aortic curvature straightening (+3.5° at 10 cm from the brachiocephalic trunk at one month, P = 0.006, disappearing at six-month follow-up). Finally, good device length predictability was shown (interclass correlation coefficients: 0.995 and 0.994 at one and six months, P > 0.001). No differences were seen between cases proximally sealed into the proximal and distal aortic arch.

CONCLUSIONS

Conformable Gore TAG Thoracic Endoprosthesis thoracic endograft showed a good pliability into the aortic arch and proximal thoracic aorta, with minimal changes in the aortic curvature after endograft placement in the short-term follow-up (up to six months). In addition, final endograft length into outer aortic curvature is highly predictable.

Stabilization of the Abdominal Aorta During the Cardiac Cycle with the Sac-Anchoring Nellix Device

The Nellix device uses polymer-filled endobags to stabilize the abdominal aortic aneurysm (AAA) sac which is described as endovascular aneurysm sealing (EVAS). We analyzed cardiac-gated computed tomography angiography scans of repaired AAA with EVAS in 4 patients to evaluate the geometry and cardiac pulsatility-induced deformation. Graft translation and aortic curvature changes were found to be minimal during the cardiac cycle. The mean ± standard deviation changes in renal-aorta angles (1.0 ± 0.9°) were less than the changes in the superior mesenteric artery-aorta angle (4.0 ± 2.1°) (P < 0.01), during the cardiac cycle, demonstrating greater stabilization of the visceral branches closer to the device. These findings confirm stabilization of the abdominal aorta during the cardiac cycle using EVAS.

The Relationship between Temporal Changes in Proximal Neck Angulation and Stent-Graft Migration after Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

In recent years, endovascular abdominal aortic aneurysm repair (EVAR) for treating abdominal aortic aneurysms (AAA) has become quite prevalent in Japan. Though little information is available about temporal changes in proximal neck angulation due to the difficulties encountered in measuring the angle. Therefore, we examined temporal changes in proximal neck angulation and its relationship to stent-graft migration after EVAR.

METHODS

Between June 2007 and March 2010, 159 patients underwent EVAR for treatment of fusiform AAAs at our hospital. This study focuses on the 80 patients among this group whose treatment sites and subsequent stent grafts were examined by contrast computed tomographic angiography before surgery, directly after surgery (within 4 days), as well as 1 year and 2 years thereafter. We created curved planar reconstruction (CPR) images and measured the length of migration and neck angle using our method.

RESULTS

At 2 years after EVAR, the average length of proximal landing zone was 21.4 ± 9.2 mm. The average length of stent migration after 2 years was 1.41 ± 2.68 mm. The average neck angle was 33.9° preoperatively and 29.9° directly after surgery yielding a significant difference. However, 1 and 2 years after surgery the average neck angle was 28.2° and 28.4°, respectively. The number of patients experiencing a change >6° in the angle of the proximal neck between the preoperative condition and that directly after surgery was 16 (34.8%) with the use of Zenith stent grafts (n = 46) and 14 (41.2%) with the use of Excluder stent grafts (n = 34). There was no correlation between the proximal neck angle and migration of the proximal stent graft. In addition, there was no correlation between the changes in proximal neck angle and the secondary intervention rate and the occurrence of endoleak.

CONCLUSIONS

There was a significant change in the neck angle between the preoperative condition and the immediate postoperative condition. However, there was no clear relationship found between the angle of the neck and the proximal stent-graft migration. Postoperative changes in the proximal neck angle just after EVAR and subsequent temporal changes during a 2-year follow-up period do not appear to predict stent-graft migration, secondary intervention rates, or the occurrence of endoleak.

Aortic Arch and Thoracic Aorta Curvature Remodeling after Thoracic Endovascular Aortic Repair

BACKGROUND

The objective of this study was to analyze the original curvature of the aortic arch and thoracic aorta, and how it is modified after the placement of a thoracic endograft.

METHODS

We retrospectively analyzed all patients primarily treated for thoracic aortic aneurysms and blunt traumatic aortic injuries by means of an endograft sealed into the aortic arch (zones, Z1-Z3) in 2 different centers (Vascular Surgery Division, Hospital Clinic, UB; and Vascular and Endovascular Surgery Department, Hospital Vall d'Hebron, UAB; Barcelona, Spain), between 2010 and 2015. The last preoperative and early (1-month) postoperative computed tomography angiography (CTA) was obtained for all cases, and an accurate 3-dimensional (3D) center lumen line was created, from the aortic valve to the renal arteries. Angles in 2-dimensional (2D; XY-plane) and 3D (referred to cranial-caudal Z-axis) were analyzed in: the distal ascending aorta, aortic arch, and thoracic aorta (at 5, 10, 15, and 20 cm from the brachiocephalic trunk [BCT]) and celiac trunk (CT). Changes in preoperative-postoperative CTA were compared independently for both diseases. Thirty-six cases were included (20 aneurysms, 16 blunt traumatic injuries; mean age, 69.5 and 42.5 years).

RESULTS

After placement of an aortic endograft (sealed in Z1-Z2 in 30% of aneurysms and 75% of traumatic injuries; mean endograft length: 22.6 cm and 11.3 cm, respectively), a global left anterior displacement of the ascending aorta was observed (2D examination: -13.1° and -7.5°, P = 0.049 and 0.041, respectively). The 3D examination showed an average increase of the aortic angle at 5 and 10 cm from the BCT in the whole sample (+4.0°, +4.9° in reference to the vertical; P = 0.017, 0.001), softening the curvature of the proximal descending thoracic aorta. In addition, in traumatic injuries, a decrease in the aortic arch angle was observed (-3.5°, P = 0.030).

CONCLUSIONS

Placement of an endograft into the aortic arch and proximal thoracic aorta engenders a softening of the proximal descending thoracic aorta curvature, increasing its angle from the vertical. In blunt traumatic aortic injuries (with shorter and more proximally sealed endografts), an additional decrease of the aortic arch angle (3.5° more vertical), was observed.

The effect of anatomical factors on mortality rates after endovascular aneurysm repair

Objective

The objective of this study was to investigate the effect of anatomical characteristics on mortality rates after endovascular aneurysm repair (EVAR).

Methods

We investigated 56 EVAR procedures for infrarenal aortic aneurysms performed between January 2010 and December 2013, and the data were supplemented with a prospective review. The patients were divided into two groups according to the diameter of the aneurysm. Group I (n = 30): patients with aneurysm diameters less than 6 cm, group II (n = 26): patients with aneurysm diameters larger than 6 cm. The pre-operative anatomical data of the aneurysms were noted and the groups were compared with regard to postoperative results.

Results

There were no correlations between diameter of aneurysm (p > 0.05), aneurysm neck angle (p > 0.05) and mortality rate. The long-term mortality rate was found to be high in patients in whom an endoleak occurred.

Conclusion

We found that aneurysm diameter did not have an effect on postoperative mortality rates. An increased EuroSCORE value and the development of endoleaks had an effect on long-term mortality rates.

Immediate Change in Suprarenal Neck Angulation After Endovascular Aneurysm Repair

Purpose: To compare the immediate suprarenal neck angulation change between the Ovation stent-graft, with its inflatable sealing rings, and a stent-graft with a conventional sealing mechanism. Methods: A case-control study was conducted in which 30 consecutive patients (mean age 67 years; all men) with abdominal aortic aneurysm (AAA) treated with the Ovation stent-graft (group O) were retrospectively compared with 24 patients (mean age 77 years; all men) contemporaneously treated with the Endurant stent-graft (group E) at 3 high-volume tertiary vascular centers. The variables recorded were the aortic neck length, preoperative and postoperative angulation, minimum and maximum diameters of the infrarenal neck, as well as the maximum AAA diameter. All patients had undergone preoperative and postoperative (within 30 days) computed tomographic angiography. Multiple regression analysis compared the relative contribution to neck angulation change of each geometric parameter and the type of endograft. Data are presented as the mean ± standard deviation. Results: The mean preoperative suprarenal neck angulation in group O was 23.2°±18.0° compared with 23.8°±22.9° in group E ( t test, p=0.91). The neck lengths were 29.2±14.6 and 23.2±11.0 mm in groups O and E, respectively (p=0.1). Similarly, the minimum and maximum neck diameters were 22.4±2.6 and 25±3.5 mm, respectively, in group O vs 23.3±3.6 mm and 27.0±5.7 mm, respectively, in group E (p=0.3 and 0.12, respectively). The maximum transverse diameters of the AAA in the 2 groups were comparable, that is, 57.0±9.0 mm in group O vs 53.2±11.1 mm in group E (p=0.17). The Ovation stent-graft caused greater decrease in the aortic neck angulation postoperatively compared with the Endurant device (13.2°±16.1° vs 6.1°±5.9°, p=0.04). Multiple regression analysis revealed that preoperative neck angulation (β coefficient 0.37, p<0.001) and the type of endograft (β coefficient −7.91, p=0.01) had significant influence on the postoperative neck angulation change. The intraclass correlation coefficient ranged from 0.951 to 0.990 for the preoperative measurements and from 0.911 to 0.999 for the postoperative measurements for each examiner or the total of estimates at the measurement time points. Conclusion: The Ovation stent-graft induces greater postoperative reduction in the AAA neck angulation compared to an endograft with stent-supported graft seal. Expanded research to infrarenal angle as well to greater angles and correlation to clinical events is justified.

Studying the Interaction of Stent-Grafts and Treated Abdominal Aortic Aneurysms

Since the advent of endovascular repair of aortic aneurysms (EVAR), clinical focus has been on preventing loss of sealing at the level of the infrarenal neck, which leads to type I endoleak and repressurization of the aneurysm sac. Enhanced mechanisms for central fixation and seal have consequently lowered the incidence of migration and endoleaks. However, endograft limb thrombosis and its causal mechanisms have not been addressed adequately in the literature. This article reviews the pathophysiological mechanisms associated with limb thrombosis in order to facilitate better clinical judgment to prevent iliac adverse effects.

Changes in suprarenal and infrarenal aortic angles after endovascular aneurysm repair

Purpose

We investigated whether suprarenal and infrarenal aortic angles change after the endovascular aneurysm repair (EVAR) procedure and during follow-up, and investigated the correlation between infrarenal aortic angle after EVAR and type Ia endoleaks.

Methods

Data collected on 70 EVAR procedures for a fusiform infrarenal aortic aneurysm performed between May 2006 and December 2012 were supplemented with a retrospective review of charts and radiographs.

Results

The greater the preoperative infrarenal aortic angle, the greater the suprarenal aortic angle (r = 0.72, P < 0.001). The infrarenal aortic angle decreased after the EVAR procedure and continued to decrease slowly thereafter (all P < 0.001). Suprarenal aortic angle decreased immediately after the EVAR procedure and continued to decrease during the first month (P < 0.001). No differences in angulation were observed based on stent graft type. Type Ia endoleaks occurred with significantly greater incidence in patients with a larger post EVAR infrarenal angle (P = 0.037).

Conclusion

The infrarenal aortic angle decreased significantly immediately after the EVAR procedure and continued to decrease slowly thereafter. Suprarenal aortic angle decreased immediately after the EVAR procedure and continued to decrease during the first month. We found a correlation between infrarenal and suprarenal aortic angle. Type Ia endoleaks occurred with greater incidence in patients with a larger infrarenal angle immediately after EVAR.

Treatment of Hostile Proximal Necks During Endovascular Aneurysm Repair

Endovascular aneurysm repair (EVAR) is a therapy that continues to evolve rapidly as advances in technology are incorporated into new generations of devices and surgical practice. Although EVAR has emerged as a safe and effective treatment for patients with favorable anatomy, treatment of patients with unfavorable anatomy remains controversial and is still an off-label indication for endovascular treatment with some current stent-grafts. The proximal neck of the aneurysm remains the most hostile anatomic barrier to successful endovascular repair with long-term durability. Open surgery for unfavorable necks is still considered the gold standard treatment in contemporary practice, despite the increased mortality and morbidity attributed to suprarenal cross-clamping, particularly in high-risk patients. Evolving technology may overcome the obstacles preventing endovascular treatment of unfavorable proximal neck anatomy; current approaches include purely endovascular as well as hybrid approaches, and generally include strategies that either extend the length of the short neck, move the proximal neck more proximally, or keep the short neck intact. These approaches include the use of debranching techniques, banding, chimneys, fenestrated and branched devices, filling the sac with endobags, endoanchors, and other novel devices. These newer-generation devices appear to have promising short- and midterm results. However, lack of good evidence of efficacy with long-term results for these newer approaches still precludes wide dissemination of endovascular solutions for the hostile proximal neck.

Remodeling of proximal neck angulation after endovascular aneurysm repair

OBJECTIVE

This study investigated the remodeling of proximal neck (PN) angulations of abdominal aortic aneurysms (AAAs) after endovascular aneurysm repair (EVAR).

METHODS

A 64-row multidetector computed tomography scan of AAAs treated with EVAR was reviewed, and the PN angulation was measured on a volume-rendered three-dimensional image. The computed tomography scan was examined preoperatively, after EVAR at 1 week, 1 month, 6 months, 1 year, 1.5 years, 2 years, and then yearly. The study enrolled 78 patients, comprising 54 Zenith devices (Cook Medical, Bloomington, Ind) and 24 Excluder devices (W. L. Gore and Associates, Flagstaff, Ariz).

RESULTS

PN angulation was 50° ± 20° preoperatively, and after EVAR was 36° ± 14° at 1 week, 32° ± 14° at 1 year, and 28° ± 13° at 3 years. PN angulations ≤ 60° (n = 70, 77%) were 41° ± 13° preoperatively, 31° ± 12° 1 week after EVAR, 28° ± 12° at 1 year, and 26° ± 13° after 3 years. An angulation >60° (n = 18, 23%) was 78° ± 14° preoperatively, 51° ± 11° 1 week after EVAR, 44° ± 11° at 1 year, and 40° ± 12° after 3 years. The greater the preoperative PN angulation, the greater its reduction immediately after EVAR (r = .72, P < .001). The diameter shrinkage of AAAs with a PN angulation >60° was 3 ± 6 mm after 1 year; a significantly smaller shrinkage than with a PN angulation ≤ 60° (7 ± 7 mm, P < .05). AAAs with a PN angulation >60° had a larger angulation reduction and a smaller diameter shrinkage after the EVAR procedure. The PN angulation of the 54 AAAs treated by Zenith was 49° ± 22° preoperatively, 34° ± 14° 1 week after EVAR, and 25° ± 13° after 3 years. The corresponding angulation of the 24 AAAs treated by Excluder devices was 52° ± 17°, 41° ± 14°, and 38° ± 9°, respectively. The PN angulation reduction of Zenith and Excluder was similar 1 week after the EVAR procedure. Unlike Excluder, however, the PN angulation in Zenith continued to reduce for a long period at a slow pace. There were no significant correlations between PN angulation reduction and diameter change and between PN length and diameter change (P = .86 and .18, respectively).

CONCLUSIONS

Although the instructions for use of most commercially available stent grafts provide for a PN angulation of ≤ 60°, PN angulation was not a major issue in a midterm follow-up of AAAs with adequate PN length for patients in this series who received a Zenith or Excluder graft.

Technical advances with newer aortic endografts provide additional support to withhold the early endovascular repair of small abdominal aortic aneurysms until it is really needed

The idea of early endovascular aortic repair (EVAR) of "small" abdominal aortic aneurysms (AAAs) has gained attention over "watchful waiting," mostly due to the concern for losing the anatomic suitability for endovascular repair over time. Generally, small AAAs have longer, smaller, less angulated necks, and less tortuous iliac arteries than larger ones. Though the borderline anatomic characteristics were assumed to be contraindications for older generation endografts, the modifications of modern devices seem promising to overcome those limitations, in order to treat the small AAAs when reaching the 5.5 cm threshold. Moreover, early endovascular intervention has been proven neither cost effective nor beneficial for the patients' quality of life. This article evaluates the technical progress that could overcome the difficulties of those small AAAs that present technically demanding anatomies, thus advocating endovascular intervention when they reach the diameter threshold.