Renal Artery Implantation Angles in Thoracoabdominal Aneurysms and Their Implications in the Era of Branched Endografts

Use of target vessel ballooning to facilitate endovascular treatment in the case of branched endovascular aneurysm repair with a retrograde approach

A case of a new technique for branched endovascular aneurysm repair with a retrograde approach and ostial stenosis of the target vessel is reported. An angioplasty balloon was placed within the target vessel and used to give added stability to catheter advancement to place the stiff guidewire needed for placement of a bridging stent graft. In brief, a standard guidewire was first placed inside the target vessel through the retrograde approach. Next, the balloon was placed from outside the stent graft, again through a contralateral retrograde approach. Then, the angioplasty balloon was inflated, and a support catheter was advanced to the balloon and then slowly deflated to allow the catheter to advance. Finally, the stiff guidewire was placed. Subsequently, the bridging stent was placed and deployed. This technique is feasible and can be used in selected cases to use a retrograde approach when ostial stenosis of the target vessel is present.

Double-Cuff Bidirectional Branch in Endovascular Aortic Repair: A New Way of Increasing the Flexibility of Inner Branch Endografting

PURPOSE

The purpose of the study was to describe the design and implantation of a branched stent-graft during endovascular aortic repair incorporating double-cuff bidirectional inner branch.

TECHNIQUE

A new double-cuff bidirectional antegrade and retrograde inner branched stent-graft with large diamond-shaped fenestration was designed for incorporation of a splenic artery. The inner cuffs of the branch were accessible using brachial and/or femoral access. The splenic artery was originating from an aortic segment with narrow inner aortic luminal diameter in a patient with extent IV thoracoabdominal aortic aneurysm with bilobed configuration. The retrograde, more distal inner cuff of the branch was extended into the splenic artery using a self-expandable bridging stent-graft from the femoral approach, whereas the antegrade, more proximal inner cuff of the branch was intentionally occluded using an endovascular plug. The recovery was uneventful and a computed tomography angiography 30 days postoperatively showed patency of all the target vessels without signs of endoleaks.

CONCLUSION

This is the first design of a double-cuff bidirectional inner branched stent-graft. The technique can potentially expand the applications of directional branches to patients with more difficult anatomy in the thoracoabdominal or aortic arch segments. Potential indications are patients with target arteries that are not ideally suited for caudally-oriented branches, patients with accessory vessels, or targets with early branch bifurcations.

CLINICAL IMPACT

This report describes the use of a branched endograft with a new double-cuff bidirectional branch that can potentially address many of the limitations of current BEVAR solutions, such as early bifurcations, double arteries with adjacent origins and arteries with less favorable trajectories for the traditional caudally-oriented branches.

Geometrical Determinants Of Target Vessel Instability In Fenestrated Endovascular Aortic Repair

OBJECTIVE

To investigate geometrical determinants of target vessels instability in fenestrated endovascular aneurysm repair (FEVAR), using a computed tomography angiogram (CTA) post-implantation analysis.

METHODS

We retrospectively reviewed single-center data on consecutive patients undergoing FEVAR (2014-2021). Geometrical analysis consisted in the assessment of bridging stent lengths and diameters, stent conformation, and graft misalignment. Bridging stent length was categorized in three components: protrusion length (PL) into the main endograft, bridging length (BL) between the fenestration and the origin of the target vessel, and sealing length (SL) of apposition in the target vessel. The conformation was measured as "flare ratio" (ratio of maximum to minimum bridging stent diameter within the PL). "Horizontal misalignment" was measured as the angle between the fenestration and the target vessel ostium on CTA axial cuts. The primary endpoint was freedom from target vessel instability; secondary endpoints were target vessels primary patency and freedom from related endoleaks. Time-dependent outcomes were estimated as Kaplan-Meier curves; Cox proportional hazards were used to identify predictors of target vessel instability.

RESULTS

There were 46 patients (juxta/pararenal: n=34, 74%; thoracoabdominal: n=11, 26%), with 147 target arteries incorporated through a bridging stent. Freedom from target vessel instability was 87% (95%CI 80-94) at 42 months. Primary patency was 98% (95%CI 96-100) and freedom from endoleak was 85% (95%CI 76-93). PL (HR 1.08, 95%CI 0.22-5.28; P=.923), SL (HR 0.95, 95%CI 0.87-1.03; P=.238) and flare ratio (HR 4.66, 95%CI 0.57-37.7; P=.149) were not associated with target vessel instability. By multivariate analysis, a BL>5 mm (HR 4.98, 95%CI 1.13-21.85; P=.033) was significantly associated with instability. Patients with a BL≥5 mm had a significantly higher degree of horizontal misalignment (21±12° vs 9±13°; P=.011).

CONCLUSION

An optimal geometrical conformation between the bridging stent and the main endograft at the level of target vessels is warranted to improve the mid-term outcomes of FEVAR. A BL >5mm was associated with a higher risk of target vessel instability, likely as a result of a less accurate endograft alignment. The sizing and planning of FEVAR should be performed in order to maintain a BL< 5mm.

Impact of target visceral vessel anatomical configuration on early complications following endovascular repair of thoracoabdominal aortic aneurysms

Impact of target visceral vessel anatomical configuration on early complicatins following endovascular repair of thoracoabdominal aortic aneurysms Objectives: Fenestrated and branched endovascular aortic repair (fEVAR-bEVAR) is a viable treatment option for thoracoabdominal aortic aneurysms but target visceral stent (TVS) endoleak and thrombosis remain a limiting factor. This study aims to evaluate TVS anatomy impact on one-year risk of thrombosis and endoleak.

METHODS

Patients treated with fEVAR-bEVAR for thoracoabdominal aneurysms between 2008-2020 in our centre were enrolled. We recorded comorbidities, operative details, one-month postoperative CT scan (anatomical reference), and TVS behaviour: thrombosis and endoleak at one-year follow-up. For each TVS, different points were identified using a centre-lumen-line: (A) TVS origin, (B) end of branch/fenestration, (C) visceral vessel entry, (D) end of TVS, (E) 1-cm distally. We analyzed TVS tortuosity ((centre-lumen-line/straight distance)-1, in %), image vector analysis of each segment in 2D (antero-posterior, left-right) and 3D (craneo-caudal displacement), and centre-lumen-line analysis (bending in ABC and CDE). Three independent observers performed a blind analysis, and anatomical differences between bEVAR/fEVAR, and cases with/without 1-year thrombosis and TVS endoleak, were compared using Kaplan-Meier curves (Log-Rank test), and T-Test/Wilcoxon signed-ranks test respectively.

RESULTS

54 patients (72±713 years mean age; 182 TVS: 50 branches, 132 fenestrations) met the inclusion criteria. bEVAR cases had longer stents, with more caudal 3D angulation and greater ABC angulated segment. After excluding bEVAR cases (low case number), 97 fEVAR TVS were analyzed. Five thrombosis and seven endoleaks were observed. While anatomical configuration showed no association to thrombosis, it was related to endoleak: these cases presented more tortuous stents (5.97%±0.10, 21.40%±0,22, P=.011), with more angulated centre-lumen-line at ABC segment (5.69°±15.77°, 7.18°±7.77°, P=.012), and more upward-pointing stents in the origin of the stent (AB: 89.07°±24.46°, 109.09°±16.56°, P=.012; BC: 87.86°±21.10°, 113.11°±22.23°, P=.026).

CONCLUSIONS

Anatomical configuration of the TVS is associated with stent type I-III endoleak, but not thrombosis, at one-year following fEVAR. Cases with endoleak presented more tortuous stents, with a more angulated exit from the endograft and upward-pointing of the origin of the stent.

The Early Outcomes of BeGraft Peripheral Plus in Branched Endovascular Repair of Thoracoabdominal Aneurysms

OBJECTIVE

No bridging stent-graft (BSG) has been specifically designed for branched endovascular aortic repair (BEVAR) and therefore different "off-label" stent-grafts have been used. Recently, a third generation of balloon-expandable stent-graft has become available. Here we evaluate the outcomes of the BeGraft Peripheral Plus (B+) used as a BSG for internal/externalor inner branches during BEVAR.

MATERIALS AND METHODS

Consecutive patients undergoing BEVAR using B+ as a BSG since its release in 2017 were included into the study. The primary endpoints were technical success and target vessel patency during follow-up. Secondary endpoints included the need for adjunct extension and relining of the BSG, branch instability rate, including occlusion, reinterventions for restonosis, kink, fracture, or endoleak (types 1 and 3).

RESULTS

A total of 163 visceral branches in 46 patients were included with a median follow-up 15 months (4-36 months). Primary technical success was achieved in all visceral branches (69 inner branches and 94 internal/external branches) with the exception of 1 BSG that required serial dilatation until full expansion was achieved with overall branch patency was 98% at 2 years. An additional stent-graft was necessary in 35 branches (21%) following deployment of a B+ BSG to cover a longer bridging distance and optimize the distal and proximal sealing. Relining of B+ BSG was not routinely carried out during the index procedure and a self-expanding uncovered nitinol stent was necessary in only 3% of branches to smooth the distal transition zone between the BSG and target vessel. There were 4 events (2.4%) of branch related instability, including 2 occlusions and 2 late reinterventions for a partial in-stent-graft thrombosis.

CONCLUSION

Our study findings show satisfactory early outcomes of B+ as a BSG in BEVAR with low occlusion and reintervention rates. Extensions of BSG might be required to achieve adequate seal in the target vessels but routine relining BSG in branches was not required.

Preliminary Outcomes of Viabahn Balloon-Expandable Endoprosthesis as Bridging Stent in Renal Arteries During Fenestrated Endovascular Aortic Repair

PURPOSE

To report preliminary outcomes of Viabahn Balloon-Expandable Endoprosthesis (VBX) stent-graft as bridging stent for renal arteries in fenestrated endovascular aneurysm repair (FEVAR).

MATERIALS AND METHODS

Between 2018 and 2019, patients undergoing FEVAR at 3 referral Italian university hospitals were prospectively collected. During the study period, VBX was the first-line choice as bridging stent for renal arteries. Procedural and anatomical data were analyzed, including renal artery (RA) configuration. A dedicated software (3Mensio, Vascular Imaging, Bilthoeven, The Netherlands) was used and RA anatomy classified as follow: upward-oriented in case of any angle >30° above the horizontal or transverse axis perpendicular to the aortic axis, downward-oriented if there was an angle >30° measured below the transverse axis and downward + upward in case of an angle <30° associated with a renal artery angulation >90°. Primary endpoints were technical success, defined as complete deployment of the fenestrated endograft without target vessel (TV) loss, limb stenosis or occlusion and type I or III endoleak, and freedom from target artery instability (TAI), defined by target vessel-related death, occlusion, rupture or reintervention for stenosis, endoleak or disconnection. Secondary endpoints were target artery patency rate and freedom from reinterventions.

RESULTS

A total of 26 elective FEVAR for juxta/pararenal aneurysm (20), thoracoabdominal type II (3) and type IV (3) were included. Fifty-one RA were planned for revascularization. Of these, 32 were downward, 10 horizontal, 6 upward, 4 were downward + upward. Technical success was achieved in 88.5% (23/26) of patients and 94.2% (48/51) of the TVs. One occlusion (2.1%) occurred within 30 days in a patient with previous endovascular aortic repair and suprarenal fixation. During follow-up (median 10 months), there was 1 type IC endoleak after 6 months (2.1%) in a patient with upward plus downward arterial orientation. Freedom from TAI was 96.1% (CI = 0.89 to 1.04) at first month and 92.3% (CI = 0.82 to 1.03) at 6 months. No aneurysm-related mortality and renal insufficiency occurred during follow-up.

CONCLUSION

The use of VBX as bridging stent of RA in FEVAR is safe and feasible. Previous EVAR and tortuosity of RA may be a challenging on target vessel fate.

Bridging Stents in Fenestrated and Branched Endovascular Aneurysm Repair: A Systematic REVIEW

BACKGROUND

Concern exists about durability of stent grafts used to bridge aortic grafts to visceral and renal arteries during fenestrated and branched endovascular aneurysm repair (F/B-EVAR). There are no guidelines regarding the ideal technique for joining target vessels (TVs).

METHODS

We systematically reviewed data published from 2014 to 2019 using PRISMA guidelines and PICO models. Keywords were searched in MEDLINE, EMBASE, and Cochrane Library. All articles were screened by two authors (a third author in case of discrepancies). Only original articles regarding F/B-EVAR in complex aortic aneurysm, reporting the number and type of TVs mated, the onset of bridging stent complications, and reinterventions on TVs were included. Analysis included quality assessment scoring, types of stent grafts, and complications related to bridging stents.

RESULTS

19 studies were included with 2,796 patients and 9556 TV; 4,797 renal arteries (50.2%), 4,174 visceral arteries (43.6%), and undefined TV (n = 585; 6.1%) were bridged. Balloon-expandable stent-grafts (B-EXP) were used in 40.9% and self-expandable (S-EXP) in 22.7% and undefined stents in 36.3%. The included studies had quality assessment scores ranging between 11/15 and 15/15, with high grade of accordance on reporting general results, but a low grade of accordance on reporting detailed data. Despite study heterogeneity, high-volume analysis confirmed a higher rate of complication in renal arteries than visceral arteries, 6% (95% CI 4-8) vs. 2% (95% CI 1-3), respectively. The rate of reinterventions was similar, 3% (95% CI 2-4) and 2% (95% CI 1-3). S-EXP versus B-EXP stent complication was 4% (95% CI 2-7) vs. 3% (95% CI 2-5), respectively.

CONCLUSIONS

This systematic review underlines the low grade of accordance in reporting detailed data of bridging stents in F/B-EVAR. Renal TVs were more prone to complications, with an equivalent reintervention rate to visceral TVs. As to B-EVAR, the choice of B-EXP over S-EXP is still uncertain.

Effect of branch length and tortuosity on the outcomes of branched endovascular repair of thoracoabdominal aneurysms using self-expandable bridging stent graft

OBJECTIVE

We investigated the effect of the length and tortuosity of directional branches on the mid-term outcomes of branched endovascular aneurysm repair (BEVAR) for thoracoabdominal aortic aneurysms (TAAA).

METHODS

We retrospectively reviewed single-center data of consecutive patients who had undergone BEVAR for TAAA from 2015 to 2019. Three-dimensional computed tomography angiogram reconstructions (Aquarius iNtuition software; TeraRecon, Durham, NC) of the first postoperative imaging studies were used to measure the branch total length (TL), branch vertical length (VL), and branch tortuosity index (TI). The branch TL was measured as the centerline distance between the branch proximal radiopaque marker and the distal edge of the bridging stent. The VL was measured as the centerline distance between the branch distal radiopaque marker and the origin of the target artery. The TI was measured in accordance with the Society for Vascular Surgery reporting standard. The primary end point was freedom from branch instability, defined as any branch-related death, occlusion, or rupture and any reintervention for stenosis, endoleak, or disconnection. Cox proportional hazards were used to identify predictors of branch instability. A penalized spline function was used to identify the relationship between branch instability and the branch TL and VL.

RESULTS

Postimplantation analysis was conducted on 32 TAAAs (extent I-III, n = 18 [56%]; extent IV, n = 14 [44%]), with 123 arteries included through a directional branch. A covered self-expanding bridging stent was used in all cases. Intraoperative reinforcement with an additional bare metal stent was performed in 85 cases (69%). The overall freedom from branch instability at 3 years was 88% (95% confidence interval [CI], 81%-94%). Five cases of occlusion and eight cases of branch-related endoleak occurred. A concomitant endoleak and severe stenosis requiring intervention developed in three cases. The Cox model with splines showed that the minimal risk of branch instability was achieved with a branch TL of 60 to 100 mm (P = .002) and a branch VL of 25 to 50 mm (P = .038). A TI of >1.15 was a predictor of branch complications (hazard ratio [HR], 8.6; 95% CI, 2.4-31.4; P < .001). After multivariate analysis, aneurysm diameter (HR, 1.08; 95% CI, 0.03-1.15; P = .003), TI >1.15 (HR, 6.81; 95% CI, 2.17-27.33; P < .001), and TL <60 or >100 mm (P = .002) were significantly associated with branch instability.

CONCLUSIONS

The branch length and TI seemed to play an important role in BEVAR outcomes. The lowest branch instability rates were obtained with a branch TL of 60 to 100 mm, and this should be considered during planning and implantation. A branch TI >1.15 might require a more strict monitoring to prevent mid- and long-term complications.

Effect of celiac axis compression on target vessel-related outcomes during fenestrated-branched endovascular aortic repair

OBJECTIVE

To report the effect of median arcuate ligament (MAL) compression on outcomes and technical aspects of celiac artery (CA) stenting during fenestrated-branched endovascular aneurysm repair for thoracoabdominal aortic aneurysms (TAAA) or pararenal aortic aneurysms.

METHODS

We retrospectively reviewed the clinical and anatomic data on 300 consecutive patients enrolled in a prospective nonrandomized physician-sponsored investigational device exemption study from 2013 to 2018. From this group, 230 patients with CA incorporation by fenestration or directional branch were included. MAL compression was defined by preoperative computed tomography angiogram as a J-hook narrowing of the proximal CA at the level of the ligament; the shift angle between the downward and upward segments within the CA was measured. End points were technical success, rates of intraoperative or early (30-days) CA branch revision, and freedom from target vessel instability, defined by any death or rupture owing to target vessel complication, occlusion, or reintervention for stenosis, endoleak, or disconnection.

RESULTS

CA incorporation was performed using fenestrations in 118 patients (51%) and directional branches in 112 (49%). MAL compression was present in 97 patients (42%), resulting in a stenosis of more than 50% in 48 (49%). MAL compression was more often present in patients with extent I to III TAAAs compared with extent IV TAAA-pararenal aortic aneurysms (56% vs 31%; P < .001). Technical success rate was 99%. Patients with MAL compression more often received a directional branch (65% vs 37%; P < .001), self-expanding bridging stent grafts (32% vs 16%; P = .007), adjunctive bare metal stents (46% vs 24%; P = .001), and coverage of the gastric artery (44% vs 22%; P < .001). An intraoperative (n = 6, 2.6%) or early (n = 1, 0.4%) revision of the CA branch was required in seven patients (3%) owing to dissection/occlusion (n = 2 [0.9%]), kinking/stenosis (n = 3 [1.3%]), stent dislodgement (n = 1 [0.4%]), or type IC endoleak (n = 1 [0.4%]). A shift angle of less than 120° was the most significant factor associated with CA branch revision (odds ratio, 10.9; 95% confidence interval, 2.3-88.9; P = .013). Freedom from CA branch instability was 97 ± 2% at 4 years, and this outcome was not associated with MAL compression (hazard ratio, 0.83; 95% confidence interval, 0.14-5.02; P = .588) or any other predictor.

CONCLUSIONS

MAL compression was more common in extent I to III TAAAs, and related to additional challenges for CA stenting in fenestrated-branched endovascular aneurysm repair. This process may include bare metal stenting, gastric artery coverage, or early revision, especially in presence of an angulation of less than 120°. However, durable results can be achieved for CA incorporation despite these difficulties.

Reporting standards for endovascular aortic repair of aneurysms involving the renal-mesenteric arteries

Endovascular aortic aneurysm repair of complex aortic aneurysms requires incorporation of side branches using specially designed aortic stent grafts with fenestrations, directional branches, or parallel stent grafts. These techniques have been increasingly used and reported in the literature. The purpose of this document is to clarify and to update terminology, classification systems, measurement techniques, and end point definitions that are recommended for reports dealing with endovascular repair of complex abdominal and thoracoabdominal aortic aneurysms involving the renal and mesenteric arteries.

Outcomes of the Gore Excluder Iliac Branch Endoprosthesis Using Division Branches of the Internal Iliac Artery as Distal Landing Zones

Purpose: To evaluate the outcomes of the Gore Excluder Iliac Branch Endoprosthesis (IBE) using division branches of the internal iliac artery (IIA) as distal landing zones. Materials and Methods: Between January 1, 2014, and December 31, 2018, 74 patients (mean age 74±7 years; 72 men) treated for aortoiliac or common iliac artery aneurysms had an IBE deployed with distal landing of the side branch within the main trunk (n=60) of the internal iliac artery (IIA) vs within a division branch (n=25). Thirteen (17%) patients received bilateral IBE implantations for a total of 85 vessels evaluated. Early endpoints were technical success, 30-day mortality, 30-day major adverse events (MAEs), and 30-day major access complications. Late endpoints were survival, primary and secondary IIA patency, freedom from IIA branch instability, freedom from new-onset buttock claudication, and aneurysm sac diameter changes. Time-dependent outcomes were reported as Kaplan-Meier curves with differences assessed using the log-rank test. Estimates are presented with the 95% confidence interval (CI). Results: The overall technical success rate was 97%, with 1 technical failure per group (p=0.43). Two patients, one from each group, died within 30 days (p=0.43). No significant differences were seen in the rates of 30-day MAEs (7% vs 17%, p=0.35) or major access complications (9% vs 11%, p>0.99) for patients receiving distal landing in the main trunk vs a division branch, respectively. The mean follow-up for the entire cohort was 19±12 months. The overall 1-year survival rate was 94% (95% CI 74% to 99%). The primary and secondary patency rates at 1 year were 98% (95% CI 88% to 99%) vs 95% (95% CI 72% to 99%, p=0.72) and 98% (95% CI 88% to 99%) vs 100% (p=0.41) for the main trunk vs division branch groups, respectively. Freedom from IIA branch instability estimates were also similar at 1-year follow-up [93% (95% CI 82% to 97%) vs 90% (95% CI 66% to 97%), p=0.29], as were the freedom from new-onset buttock claudication estimates [98% (95% CI 86% to 99%) and 94% (95% CI 67% to 99%), respectively; p=0.62]. Mean sac diameter change was 5.4±5.3 mm, not significantly different between the groups (p=0.85). Conclusion: Use of the posterior or anterior division of the IIA as a distal landing zone for the Gore Excluder IBE was safe and efficacious in the midterm. This technique may permit extending indications for endovascular repair of aortoiliac aneurysms to cases with unsuitable anatomy within the IIA main trunk. Long-term assessment is needed to affirm the efficacy of this technique.

Endovascular Treatment of Complex Aneurysms with the Use of Covera Stent Grafts

PURPOSE

To characterize the short-term results of a newly available self-expanding covered stent (Covera; CR Bard Peripheral Vascular Inc., Murray Hill, New Jersey) for the reconstruction of target vessels in complex aneurysms.

MATERIALS AND METHODS

From August 2017 to November 2018, this self-expanding covered stent was used in 17 patients (mean 72.6 ± 7.6 years of age) during endovascular aneurysm repair (EVAR) with hypogastric preservation (11.8%), branched EVAR (29.4%), fenestrated (F)-EVAR (17.6%), chimney + F-EVAR (11.8%), or chimney EVAR (29.4%). In more than 48 stented arteries (2.8 ± 1.1/patient), 25 were preserved using this self-expanding covered stent.

RESULTS

All target vessels were successfully preserved. There was no 30-day mortality and 1 in-hospital death. Intraoperative aneurysm exclusion was successful in 14 patients (82.4%) with a perioperative technical success rate of 82.4%. The actuarial survival rate was 93.8% at 6 months and 85.9% at 12 months. Aneurysm sac regression of >5 mm was observed in 4 cases (23.5%), and the sac remained stable in the remaining patients (13 cases [76.5%]). At 12 months, the primary clinical success rate was 76.5%, and assisted primary clinical success rate was 82.4%. No type 3 endoleak was related to a disruption of the reconstruction with the self-expanding covered stent.

CONCLUSIONS

This new self-expanding covered stent provides good short-term patency in chimneys, branches, or fenestrations. Larger series with long-term follow-up are required to determine if the stent can sustain the mechanical stress to which it will be submitted in these repairs.

Imaging Obtained Up To 12 Months Preoperatively Is Adequate for Planning Fenestrated/Branched Endovascular Aortic Aneurysm Repair

OBJECTIVES

Patients referred for fenestrated/branched endovascular aortic repair (F/BEVAR) often present with a previous computed tomography angiogram (CTA), but it is unknown how recent the CTA must be to ensure accurate F/BEVAR planning. We sought to determine whether anatomic planning parameters change significantly between a CTA used for F/BEVAR planning and a CTA obtained 6 to 12 months prior.

METHODS

Two blinded observers reviewed preoperative CTAs from 21 patients who underwent F/BEVAR. Each patient had a "recent" scan obtained 0 to 6 months before F/BEVAR planning and a "prior" scan obtained 6 to 12 months before the "recent" CTA. Standard measurements included (1) target vessel separation distances, (2) target vessel origin clock position, and (3) proximal F/BEVAR device diameter. Clinically significant differences for target vessel separation distance, target vessel origin clock position, and proximal F/BEVAR device diameter were predefined as >5 mm, >30 minutes, and >4 mm, respectively. Differences between "recent"/"prior" CTA scans were examined by paired t test.

RESULTS

Mean time interval between paired "recent"/"prior" CTAs was 8.0 months (standard deviation: ±1.7). Mean difference in paired "recent"/"prior" target vessel distance (relative to celiac artery [CA]) was 2.6 mm for the superior mesenteric artery (SMA), 2.5 mm for the right renal artery (RRA), and 3.3 mm for the left renal artery (LRA). Of the 21 paired "recent"/"prior" CTAs, clinically significant differences were observed in 2, 4, and 2 patients for SMA, RRA, and LRA target vessel distance, respectively. Target vessel clock position (SMA reference at 12:00) varied by 12 minutes for the CA, 13 minutes for the RRA, and 15 minutes for the LRA. One paired "recent"/"prior" CTA was found to have a clinically significant difference for the LRA. No clinically significant differences were observed for proximal device diameter.

CONCLUSIONS

In patients who underwent successful F/BEVAR, measurement comparisons between CTAs obtained up to 1 year prior were minor and unlikely to yield clinically significant changes to F/BEVAR design.

Accuracy of implementing principles of fusion imaging in the follow up and surveillance of complex aneurysm repair

Fusion imaging is standard for the endovascular treatment of complex aortic aneurysms, but its role in follow up has not been explored. A critical issue is renal function deterioration over time. Renal volume has been used as a marker of renal impairment; however, it is not reproducible and remains a complex and resource-intensive procedure. The aim of this study is to determine the accuracy of a fusion-based software to automatically calculate the renal volume changes during follow up. In this study, computerized tomography (CT) scans of 16 patients who underwent complex aortic endovascular repair were analysed. Preoperative, 1-month and 1-year follow-up CT scans have been analysed using a conventional approach of semi-automatic segmentation, and a second approach with automatic segmentation. For each kidney and at each time point the percentage of change in renal volume was calculated using both techniques. After review, volume assessment was feasible for all CT scans. For the left kidney, the intraclass correlation coefficient (ICC) was 0.794 and 0.877 at 1 month and 1 year, respectively. For the right side, the ICC was 0.817 at 1 month and 0.966 at 1 year. The automated technique reliably detected a decrease in renal volume for the eight patients with occluded renal arteries during follow up. This is the first report of a fusion-based algorithm to detect changes in renal volume during postoperative surveillance using an automated process. Using this technique, the standardized assessment of renal volume could be implemented with greater ease and reproducibility and serve as a warning of potential renal impairment.

Impact of renal arterial morphology on fluoroscopy time in chimney endovascular aneurysm repair

Objectives To evaluate the impact of renal artery morphology on fluoroscopy time in chimney endovascular aneurysm repair. Methods Morphology of renal artery was retrospectively quantified in the preoperative CT angiography. Renal artery angulation, ostial diameter, severity of ostial stenosis, main renal artery length, and tortuosity were analyzed with a 3D workstation. The main measure outcome was fluoroscopic time as an indicator of complexity. Uni- and multivariate logistic regression analyses were performed to determine predictors of longer fluoroscopy. Secondary endpoints were amount of contrast medium, patency of renal artery, and type Ia endoleak. Results The enrolled 38 patients (mean age 75.0 years; 34 males) were stratified at the median of fluoroscopic time of 35.2 min (interquartile range, 21.5) and classified in group A ( n = 19) and group B ( n = 19) having a fluoroscopic time of 24.5 (interquartile range, 5.9) and 46.4 (interquartile range, 16.0) min, respectively. The severity of ostial stenosis (OsSte) was significantly different between group A and B of 26.3 ± 13.4% and 41.6 ± 18.0%, respectively; P < .01. ROC curve analysis revealed that 35.5% was an optimal cut-off for OsSte. The difference of renal angulation (RAng) (-22.5° and -2.0°; interquartile ranges 49 and 35; P = .13), and main renal artery length (33.4 ± 11.8 mm and 33.7 ± 14.3 mm; P = .94) were not significantly different. In multivariate analysis after dichotomizing OsSte and RAng, OsSte > 35.5% was identified as the only significant predictor for the longer fluoroscopy (HR: 4.33; 95% CI: 1.02-18.4, P = .04). As for the secondary endpoints, no significant differences were observed between the groups. No correlation between longer fluoroscopy and renal patency or type Ia endoleak was observed. Conclusion Severity of ostial stenosis seems to be a significant predictor for longer fluoroscopic time.

Retrospective morphometric study of the suitability of renal arteries for renal denervation according to the Symplicity HTN2 trial criteria

OBJECTIVE

The aim of this study was to describe the renal arteries of humans in vivo, as precisely as possible, and to formulate an expected value for the exclusion of renal denervation due to the anatomical situation based on the criteria of the Symplicity HTN trials.

DESIGN AND SETTING

In a retrospective cohort study, the renal arteries of 126 patients (57 women, 69 men, mean age 60 ± 17.2 years (CI 57.7 to 63.6)) were segmented semiautomatically from high-contrast CT angiographies.

RESULTS

Among the 300 renal arteries, there were three arteries with fibromuscular dysplasia and one with ostial renal artery stenosis. The first left renal artery was shorter than the right (34 ± 11.4 mm (CI 32 to 36) vs 45.9 ± 15 mm (CI 43.2 to 48.6); p<0.0001), but had a slightly larger diameter (5.2 ± 1.4 mm (CI 4.9 to 5.4) vs 4.9 ± 1.2 mm (CI 4.6 to 5.1); p>0.05). The first left renal arteries were 1.1 ± 0.4 mm (CI 0.9 to 1.3), and the first right renal arteries were 0.3 ± 0.6 mm (CI 0.1 to 0.5) thinner in women than in men (p<0.05). Ostial funnels were up to 14 mm long. The cross-sections were elliptical, more pronounced on the right side (p<0.05). In 23 cases (18.3%), the main artery was shorter than 2 cm; in 43 cases (34.1%), the diameter was not >4 mm. Some 46% of the patients, or 58.7% when variants and diseases were taken into consideration, were theoretically not suitable for denervation.

CONCLUSIONS

Based on these precise measurements, the anatomical situation as a reason for ruling out denervation appears to be significantly more common than previously suspected. Since this can be the cause of the failure of treatment in some cases, further development of catheters or direct percutaneous approaches may improve success rates.

Impact of Renal Artery Angulation on Procedure Efficiency During Fenestrated and Snorkel/Chimney Endovascular Aneurysm Repair

Purpose: To determine the impact of renal artery angulation on time to successful renal artery cannulation and procedure efficiency during fenestrated and snorkel/chimney endovascular aneurysm repair (EVAR). Methods: The imaging and procedure logs of 77 patients (mean age 74.2 years; 63 men) who underwent complex EVAR (24 fenestrated, 53 snorkel/chimney) from 2009 to 2013 were reviewed. Renal artery angulation was measured on preoperative computed tomographic angiography scans. Time to renal artery cannulation was retrieved from the EVAR procedure logs and compared to preoperative renal artery angulation and other metrics of procedure efficiency (eg, procedure time, fluoroscopy time, blood loss, etc). In all, 111 renal arteries were available for renal artery angulation measurement (39 fenestrated, 72 snorkel/chimney); 22 renal cannulations were inappropriate for the comparative analyses due to concomitant visceral artery stenting (n=15), combined procedures (n=6), or unsuccessful cannulation (n=1). Results: For patients undergoing fenestrated EVAR, mean renal artery angulation was -28°±21° (range +37° to -60°), not significantly different (p=0.66) from patients receiving snorkel/chimney grafts (mean -30°±19°, range +22° to -65°). Comparative analysis using median renal artery angulation (−30° for both groups) demonstrated that renal artery cannulation during fenestrated EVAR was performed significantly faster in arteries with less downward (≥ −30°) angulation (16.0 vs 32.8 minutes, p=0.04), whereas cannulation in snorkel/chimneys was faster in arteries with greater downward (< −30°) angulation (10.9 vs 17.3 minutes, p=0.05). Fenestrated EVAR cases involving less downward (≥ −30°) renal artery angulation were also associated with shorter overall procedure time (187.7 vs 246.2 minutes, p=0.01) and decreased fluoroscopy time (70.3 vs 98.2 minutes, p=0.04). Immediate renal function decline, procedural complications, and postoperative issues were not associated with renal artery angulation. Conclusion: Procedural efficiency may be optimized by considering renal artery angulation as one of several objective variables used in the selection of an appropriate endovascular strategy. The fenestrated approach is more efficient with less downward angulation to the renal arteries, while the snorkel/chimney strategy is facilitated by more downward renal artery angulation.