Chimney Stent Graft Research Articles

Mid-term results of a prospective study for aortic dissection with a gutter-plugging chimney stent graft.

Our goal was to access early and mid-term outcomes of a gutter-plugging chimney stent graft for treatment of Stanford type B aortic dissections in the clinical trial Prospective Study for Aortic Arch Therapy with stENt-graft for Chimney technology (PATENCY). Between October 2018 and March 2022, patients with Stanford type B aortic dissections were treated with the Longuette chimney stent graft in 26 vascular centres. The efficiency and the incidence of adverse events over 12 months were investigated. A total of 150 patients were included. The technical success rate was 99.33% (149/150). The incidence of immediate postoperative endoleak was 5.33% (8/150, type I, n = 6; type II, n = 1; type IV, n = 1) neurologic complications (stroke or spinal cord ischaemia); the 30-day mortality was 0.67% (1/150) and 1.33% (2/150), respectively. During the follow-up period, the median follow-up time was 11.67 (5-16) months. The patent rate of the Longuette graft was 97.87%. Two patients with type I endoleak underwent reintervention. The follow-up rate of the incidence of retrograde A type aortic dissection was 0.67% (1/150). There was no paraplegia, left arm ischaemia or stent migration. For revascularization of the left subclavian artery, the Longuette chimney stent graft can provide an easily manipulated, safe and effective endovascular treatment. It should be considered a more efficient technique to prevent type Ia endoleak. Longer follow-up and a larger cohort are needed to validate these results. NCT03767777.

Post-Implantation Syndrome Incidence is Higher After Complex Endovascular Aortic Procedures Than After Standard Infrarenal Repair

Post-implantation syndrome (PIS), characterised by malaise, fever, and increased inflammatory markers, is a common occurrence after endovascular aneurysm repair (EVAR), causing prolonged hospitalisation and increased cost. This study aimed to determine the incidence and short-term outcomes of PIS after fenestrated or branched procedures in aorto-iliac aneurysms compared with standard EVAR. A retrospective, comparative study from a tertiary academic institution was undertaken. All patients who underwent elective EVAR with polyester stent grafts from January 2015 to June 2021 were considered. Two groups were defined: standard EVAR (sEVAR) and complex EVAR (cEVAR). The latter included visceral fenestrated and branched or iliac branch and chimney stent grafts. The primary outcome was the incidence of PIS within three days of the index procedure. Secondary outcomes were short-term complications and risk factors for PIS. A multivariable model was constructed to correct for confounders. Overall, 253 patients were included: 165 (65.2%) sEVAR and 88 (34.8%) cEVAR. Complex EVAR patients were younger, with larger aneurysms, had longer procedures, and were more likely to have intra-operative complications. The PIS incidence was 23.7% (n= 60), significantly higher in cEVAR (34.1% vs. 18.2%; p= .005) and increased with the complexity of the procedure (EVAR: 18.2% vs. EVAR+iliac branch device: 25.0% vs. fenestrated and branched EVAR: 36.2%; p= .030). On multivariable analysis, cEVAR (OR 2.833, 95% CI 1.295 - 6.198; p= .009) was associated with a significantly increased risk of PIS. No differences in short term outcomes according to PIS status were noted. Group sub-analysis for cEVAR patients did not reveal any statistically significantly different outcomes according to PIS occurrence. In this cohort, cEVAR procedures were associated with a significantly increased risk of developing PIS compared with standard infrarenal repair. Post-implantation syndrome also appears to have a benign course with no major impact on peri-operative outcomes after cEVAR. Further research to confirm these findings is required.

Single-Center Preliminary Experience with Gutter-Plugging Chimney Stent-Graft for Aortic Dissection.

To report the early 2-year results and experience of a novel gutter-plugging chimney stent-graft in a single center that participated in the clinical trial of Prospective Study for Aortic Arch Therapy with stENt-graft for Chimney technology. Patients diagnosed with aortic dissection were treated with the novel chimney stent-grafts named Longuette™ for the left subclavian artery revascularization. Primary study outcomes were the incidence of freedom from major adverse events within 30days and success rate of the operation over 12months. A total of 34 patients were enrolled between September 2019 and December 2020. The immediate technical success rate (stent-grafts successfully deployed without fast-flow type Ia or type III endoleak intraoperatively) was 100%, and there were no conversions to open repair. Type Ia and type II endoleaks were noted in three patients (8.8%) and one patient (2.9%) at discharge, respectively. One patient (2.9%) with type Ia endoleak underwent coil embolization at 12months because of false lumen dilation, and one (2.9%) case of type Ia endoleak resolved spontaneously at 24months. One chimney stent (2.9%) was revealed with stenosis at discharge and occluded with thrombosis at 6months postoperatively. During the 2-year follow-up, there was no death, rupture, stroke, paraplegia, left arm ischemia, retrograde dissection, stent-graft induced new entry, or stent migration. The initial results of the Longuette™ stent-graft for revascularization of the left subclavian artery are encouraging with a high technical success rate. Further multicenter follow-up outcomes are required to assess the long-term durability. Level 4, Case Series.

Feasibility and Safety of Percutaneous Axillary Artery Access in a Prospective Series of 100 Complex Aortic and Aortoiliac Interventions

We aimed to review the feasibility and safe use of the percutaneous axillary artery (AxA, 100 patients) approach for endovascular repair (ER) of thoraco-abdominal aortic aneurysms (TAAA, 90 patients) using fenestrated, branched, and chimney stent grafts and other complex endovascular procedures (10 patients) necessitating AxA access. Percutaneous puncture of the AxA in its third segment was performed using sheaths sized between 6 to 14F. For closing puncture sites greater than 8F, two Perclose ProGlide percutaneous vascular closure devices (PVCDs) (Abbott Vascular, Santa Clara, CA, USA) were deployed in the pre-close technique. The median maximum diameter of the AxA in the third segment was 7.27 mm (range 4.50-10.80). Device success, defined as successful hemostasis by PVCD, was reported in 92 patients (92.0%). As recently reported results in the first 40 patients suggested that adverse events, including vessel stenosis or occlusion, occurred only in cases with a diameter of the AxA < 5 mm, in all subsequent 60 cases AxA access was restricted to a vessel diameter ≥ 5 mm. In this late group, no hemodynamic impairment of the AxA occurred except in six early cases below this diameter threshold, all of which could be repaired by endovascular measures. Overall mortality at 30 days was 8%. In conclusion, percutaneous approach of the AxA in its third segment is feasible and represents a safe alternative access to open access for complex endovascular aorto-iliac procedures. Complications are rare, especially if the maximum diameter of the access vessel (AxA) is ≥5 mm.

Impact of renal chimney intra-aortic stent length on branch and end-stent angle in chimney endovascular aneurysm repair and endovascular aneurysm sealing configurations.

Practice patterns and durability of parallel stent graft techniques in complex endovascular aneurysm repair (EVAR) remain poorly defined. We aimed to quantify and compare the impact of renal chimney intra-aortic stent length (IASL) on geometric deformations of renal arteries in complex EVAR. Thirty-eight nonconsecutive patients underwent EVAR utilizing parallel stent graft techniques (chimney EVAR [chEVAR], n = 28; chimney endovascular aneurysm sealing [chEVAS], n = 10) between 2010 and 2016. A total of 59 renal chimney stent grafts were used. Geometric quantification was derived from three-dimensional model-based centerline extraction. Renal chimney intra-aortic stent length (IASL) was defined as the length of chimney stent that extended from the proximal edge of the chimney stent to the ostium of the corresponding renal artery. Mean IASL for both left and right renal arteries in the cohort was 35.7mm. Renal arteries containing chimney IASL <30mm trended toward a greater branch angle (135.4 vs. 127.8°, p = .06). Left renal arteries showed significantly greater branch angle among those with IASL <40mm (135.5 vs. 121.7°, p = .045). Mean IASL for renal arteries in chEVAR was significantly longer compared to chEVAS (39.2 vs. 26.3mm, p = .003). No difference was noted in overall branch angle or end-stent angle based on procedure type. ChEVAR with IASL <30mm had significantly greater end-stent angle (48.2 vs. 33.5°, p = .03). In contrast, chEVAS patients showed no difference in end-stent angle based on IASL thresholds, but did have significantly greater branch angle among those with IASL <30mm when grouped by both all renal arteries (133.5 vs. 113.5°, p = .004) and right renal arteries (134.3 vs. 111.6°, p = .02). Renal chimney stents with longer IASL appear to exhibit less renal artery deformation, suggesting a more gradual and perpendicular transition of the chimney stent across the renal ostium.

Early Results of a Novel Gutter-Free Chimney Stent-Graft System to Treat Aortic Arch Dissection: Single-Center Data from a Prospective Clinical Trial

Aims: Discuss the clinical value, technique characteristics, and early follow-up results of a newly designed gutter-free chimney stent-graft system for aortic arch pathology. Methods and Results: About 13 patients with aortic arch dissection were enrolled in a clinical trial testing a novel gutter-free stent-graft between February 2019 and December 2020. All 13 patients were male, age 52.6±10.4 years. The implantation time was 14.0±6.9 minutes; total procedure time was 89.5±19.8 minutes. The volume of contrast was 79.6±7.2 ml. And 15 aortic stent-grafts were implanted, and all 13 patients had chimney branch stent-grafts implanted into the left subclavian artery (LSA). There were 3 (23.1%) cases of immediate type Ιa endoleak after thoracic endovascular aortic repair (TEVAR), and 7.7% type Ιa endoleaks occurred in delayed fashion. Survival at 2 years was 100%, and the 2-year patency of chimney stent-grafts was 100%. Conclusions: This study reports early success with good freedom from endoleak using a novel stent-graft designed for chimney TEVAR to treat aortic arch dissection. Postoperative survival and patency of the branch stent-grafts were excellent. Additional data from this multicenter clinical trial will be forthcoming.

Pressure gradient measurement to verify hemodynamic results of the chimney endovascular aortic repair (chEVAR) technique.

PurposeThe use of the pressure gradient measurements to assess the renal artery flow hemodynamics after chimney endovascular aortic repair (chEVAR).MethodsThe study was a prospective analysis of 37 chEVAR procedures performend in 24 patients with perirenal aortic aneurysm. In all patients the measurement of: distal renal artery pressure (Pd), aortic pressure (Pa), Pd/Pa ratio (Pd/Pa) and mean gradient (MG) between the aorta and the distal renal artery were performed. Measurements were taken with 0.014 inch pressure wire catheter before and after the chEVAR procedure. MG greater than 9 mmHg and Pd/Pa ratio below 0.90 were considered as the measures of a significant decrease in distal pressure that limited flow in renal arteries. The 6 month follow-up computed tomographic angiography (CTA) was performed in all patients to diagnose potential endoleak presence and to verify the patency of the chimney stent-grafts.ResultsAll procedures were successful, and no periprocedural complications were observed in any of the patients. The mean gradient values before and after the chimney implantation did not change significantly (6,2±2,0 mmHg and 6,8±2,2 mmHg, respectively). Similarly, no significant change in Pd/Pa values was noted with the value of 0.9 observed both before and after the procedure. All chimney stents were patent on the control CTA. Type Ia endoleak was found in 4 (10.8%) patients.ConclusionsThe application of the described technique seems to be a safe method which allows a direct measurement of renal artery flow hemodynamics before and after chimney implantation during the chEVAR technique. The use of covered balloon expandable stents, ensures the proper blood flow in the renal arteries during the chEVAR technique.

Endovascular Repair for Acute Type B Aortic Dissection With Unfavorable Proximal Landing Zone

BackgroundThe study aimed to compare the safety and effectiveness between fenestrated technique with or without chimney stent and single-branched stent graft for isolated left subclavian artery revascularization during endovascular repair of acute type B aortic dissection with unfavorable proximal landing zone. MethodsFrom January 2016 to December 2019, 65 acute type B aortic dissection patients with unfavorable proximal landing zone were treated with either the fenestrated technique (n = 34, group A) or single-branched stent graft (n = 31, group B). Type I endoleak, retrograde type A dissection, stroke, left subclavian artery patency, 30-day mortality, and aortic remodeling were systematically recorded and retrospectively analyzed. ResultsTechnical success rates for groups A and group B were 94.12% and 100%, respectively. Left subclavian artery primary patency was achieved for all enrolled patients. The incidence of type I endoleak, retrograde type A dissection, stroke, and 30-day mortality was 5.9%, 5.9%, 2.9%, and 2.9% in group A, respectively, but none were encountered in group B. Left subclavian artery occlusion was observed in 3 patients in group A and 2 patients in group B during a mean follow-up of 16.18 ± 2.08 months and 15.19 ± 2.68 months, respectively. After the procedure, significant aortic remodeling was detected in both groups during follow-up. ConclusionsBoth techniques are feasible and safe for isolated left subclavian artery revascularization during endovascular repair for acute type B aortic dissection. Apart from the associated perioperative risks of complications and mortality for the fenestrated technique, both procedures contributed to favorable aortic remodeling.

Emergent Chimney Endovascular Repair of an Aortoenteric Fistula in the Setting of a Solitary Kidney

Open surgery remains the definitive therapy for secondary aortoenteric fistula, but mortality is as high as 40%. Endovascular repair has emerged as a viable option, particularly in the critically ill. We present a case of an emergent chimney endovascular repair of a juxtarenal secondary aortocolonic fistula complicated by septic and hemorrhagic shock in a patient with a solitary kidney. A 68-year-old morbidly obese man with a history of myocardial infarction, peripheral artery disease, and a solitary kidney (prior kidney donation to wife) underwent an open tube graft repair of a ruptured abdominal aortic aneurysm at an outside facility. His recovery was complicated by a large proximal anastomotic pseudoaneurysm with an aortocolonic fistula. On postoperative day 30, he was transferred to our institution for worsening hemodynamic status and evolving sepsis. Shortly after arrival, superimposed hemorrhagic shock developed after 1 L of lower gastrointestinal bleed. Imaging had demonstrated a fistula at the level of the left renal artery ostium with a broad-based communication with the mid-transverse colon (Fig, A). Given the patient’s acutely deteriorating clinical status and hostile anatomy, we decided to pursue the least invasive treatment option. A left renal artery chimney stent graft was delivered through the left brachial artery while an Endurant II (Medtronic, Santa Rosa, Calif) proximal aortic cuff was deployed to promptly seal the fistula. To exclude the entire tube graft from the systemic circulation, to avoid the need for contralateral gate cannulation, and to concomitantly address bilateral iliac occlusive disease, the AFX platform (Endologix, Irvine, Calif) was deployed with adequate overlap with the proximal cuff (Fig, B and C). The patient then underwent laparotomy for an extended left hemicolectomy and transverse colostomy. We noted prompt postoperative improvement in sepsis and hemodynamic status. Serial postoperative imaging up to 9 months has shown near-resolution of periaortic inflammatory changes and widely patent aortic and left renal artery repairs. Suppressive oral antibiotics are maintained. Chimney endovascular aortic repair is a viable option for emergent repair of secondary aortoenteric fistula in a select group of high-risk patients.

Short-term results in canines of novel stent-graft design for chimney technique in TEVAR

IntroductionParallel stent-stent grafting is a major endovascular technique used to preserve the supra-aortic branches during thoracic endovascular aortic repair (TEVAR) of aortic pathologies involving the aortic arch. The short- and mid-term results of this technique are satisfactory; however, endoleak remains a major concern. Thus, here we designed a new chimney stent-graft to decrease the endoleak rate. AimTo testify the feasibility and safety of the new chimney stent-graft system in a canine model. Material and methodsSix Labrador retrievers were used. Pre-operative data were collected and all operations were performed under general anesthesia. The main and chimney stent-grafts were implanted through the abdominal aorta and left subclavian artery approaches, respectively. Completion digital subtraction angiography (DSA) was performed to confirm the immediate outcomes. All dogs were fed separately for 6 months and sacrificed after aortic angiography. The thoracic aorta and the main and chimney stent-grafts were harvested for histopathologic examination. ResultsNo complications were found in follow-up DSA. All branch arteries were patent. Inflammatory responses were observed around the stent-grafts in 3 experimental animals, and slight hyperplasia was observed in the surrounding tissues compared with the normal vessels. There was no mural thrombus in the stent, endothelial cells were noted on the inner surface of the stent, and thrombus was formed in the outer skirt and gutter area. The histopathologic examinations revealed similar results to those of gross necropsy observations. ConclusionsThis study demonstrated the feasibility and safety of the Longuette stent-graft and the first to report a revised stent-graft specific for chimney technique.

First-in-Human Implantation of Gutter-Free Design Chimney Stent Graft for Aortic Arch Pathology

This report describes first-in-human experiences and early results of gutter-free chimney stent graft implantation for aortic arch pathologies. The gutter-free chimney stent graft consists of an inner stent and an outer skirt fabric to form an integrated structure. The inner and outer layers are nickel-titanium self-expanding skeletal structures with double polytetrafluoroethylene coating. The outer skirt fabric fits the gutter to prevent endoleak, and the proximal inner stent has a larger radial force to ensure the blood flow. All these designs have the advantages to overcome the native defects of current chimney techniques. We reported 2 patients who were diagnosed as having aortic arch pathologies and received the gutter-free chimney stent graft implantation during thoracic endovascular aortic repair. In all patients, aortic arch lesions were covered, and supraaortic branches were patent without complications after thoracic endovascular aortic repair and during the 17 months of follow-up. Novel gutter-free chimney stent graft may be safely and effectively utilized for endovascular repair in aortic arch pathologies. Long-term durability should be confirmed by larger studies and ongoing research.

Chimney Endovascular Repair of Primary Mycotic Aneurysms Involving the Paravisceral Aorta

Primary mycotic aneurysm of the aorta (MAA) is a rare and potentially life-threatening disease. Endovascular aneurysm repair (EVAR) of MAAs involving the paravisceral aorta has been rarely reported. The purpose of this study is to report our experience with chimney EVAR (CHEVAR) in patients with MAAs involving the paravisceral aorta. We performed a retrospective review of all patients treated with EVAR at our institution during the years 2009-2019. Of those, we identified the patients who were treated with CHEVAR for MAAs. Diagnosis of MAAs was based on clinical presentation, abnormal laboratory results, and a computed tomography scan suggestive of a MAA. The data collected included patient demographics, clinical presentation, the antibiotic regimen before and after the surgery, preoperative imaging, surgical details, and perioperative and long-term morbidity and mortality. During the study period, we performed 54 cases of CHEVARs for aortic aneurysms. Of those, 8 (15%) were performed for mycotic aneurysms involving the visceral segment. Six (75%) were men, and the mean age was 68 years (range: 59-76). All patients were symptomatic at the time of diagnosis, presenting with either back or abdominal pain. A total of 16 visceral vessels (celiac trunk, 2; superior mesenteric artery, 7; right renal artery, 4; and left renal artery, 3) were revascularized with parallel grafts (PGs). Six patients required 2 PGs, 1 patient required 3 PGs, and 1 patient had a single PG inserted. Fifteen (94%) PGs were upward-pointing chimney stent grafts, and 1 was placed in a downward-pointing "periscope" configuration. Eight visceral arteries in 6 patients were sacrificed, either by preoperative occlusion or intentional coverage with the endograft during the procedure. The vessels sacrificed included 4 celiac trunks and 4 renal arteries (3 main branches and 1 accessory renal artery). Technical success was achieved in all patients. One patient expired in the perioperative period. One patient developed an infection-related complication. One patient experienced worsening of his renal function and eventually required dialysis. Of the 4 patients who underwent intentional sacrifice of a kidney, all experienced a moderate decrease in renal function from the baseline ( mean preoperative and postoperative serum creatinine 0.76mg/dL and 1.2mg/dL, respectively, increase of 43%). The mean follow-up was 8months (range: 3-28months). During this period, 2 patients expired, 1 from an aneurysm-related cause. No stent occlusion of the PGs occurred and no reintervention due to endoleaks was required. No patient required explanation of the stent grafts or conversion to an open repair. CHEVAR is a feasible and safe treatment modality for MAAs involving the visceral segment. Occasionally, intentional occlusion of the selected visceral arteries may be required to minimize the risk of gutter endoleaks in this urgent setting. Further follow-up is needed to accurately assess the durability of this repair.

Chimney stent graft for left subclavian artery preservation during thoracic endograft placement

ObjectiveCarotid to subclavian artery bypass (CSB) has been the standard for revascularizing the left subclavian artery during coverage by thoracic endovascular aortic repair (TEVAR). The purpose of this study is to determine if a chimney stent graft (CSG) offers similar outcomes as an alternative to open bypass. MethodsA retrospective review of a single vascular surgery registry between February 2011 and September 2017 was performed of all left subclavian revascularization during elective TEVAR. Arch reconstructions involving more than just the left subclavian artery were excluded. Indications, demographics, procedural details, and outcomes were analyzed using standard statistical analysis. ResultsEighty-one patients with a mean age of 68 years (range, 32-87 years) had left subclavian revascularization (64 [79%] CSB vs 17 [21%] CSG) during TEVAR. Median follow-up for CSG was 8 months (range, 0-52 months) and for CSB was 14.5 months (range, 3-72). Demographics between the groups were similar except for more males in both groups (43 [67%] in CSB vs 10 [59%] in CSG; P = .28). The CSB group had significantly more aneurysms than dissections compared with CSG (45 [70%] vs 6 [35%]; P = .008). There were no perioperative occlusions or ischemic issues for either group in the perioperative period. Postoperative hematoma rates trended higher in the CSB (7.11% vs 1.6%; P = .53) with three (4.6%) of the CSB requiring evacuation of hematoma. Left hemispheric strokes were 6% in the CSB with none occurring in the CSG group. Perioperatively, the CSB group had one recurrent laryngeal nerve and one graft infection. Length of stay was similar in both groups (CSB, 8.4 days vs CSG, 9.1 days). Perioperative mortality was not statistically significant between both groups with two deaths (3%) in the CSB and none in the CSG group. No gutter leaks were identified on follow-up computed tomography scan during long-term follow-up. Patency rates were similar with only one occlusion in the CSB group at 23 months. ConclusionsLeft common carotid to subclavian artery bypass has been the standard for revascularization of the left subclavian artery during coverage by TEVAR. Chimney stent grafting to perfuse the left arm appears to offer equivalent results as a minimally invasive alternative.

Parallel stenting for the left subclavian works in some, but selective use is warranted

Darling and colleagues present a contemporary cohort of patients undergoing zone 2 thoracic endovascular aortic repair (TEVAR) placement with left subclavian revascularization either by carotid-subclavian bypass (CSB) or chimney stent graft (CSG).1 Given the limited existing data in the literature, the authors' work serves as additional proof of concept for parallel stent grafting for left subclavian artery (LSA) revascularization. They have demonstrated excellent early results, notable for no type 1A endoleaks during the study period.

Percutaneous Axillary Artery Access for the Endovascular Treatment of Complex Thoraco-Abdominal Aortic Aneurysms

Introduction - Our aim is to study the feasibility of percutaneous trans-axillary artery approach using percutaneous closure devices in the treatment of complex endovascular repair of thoraco-abdominal aortic aneurysms using branched, fenestrated and chimney stent grafts.

Percutaneous Axillary Artery Access for Endovascular Treatment of Complex Thoraco-abdominal Aortic Aneurysms

The aim of this study was to determine the feasibility and safety of percutaneous axillary artery (AxA) access using vascular closure devices (VCD) for endovascular repair (ER) of thoraco-abdominal aortic aneurysms (TAAA) using fenestrated, branched, and chimney stent grafts. Between September 2013 and December 2017, 40 high risk patients (27 men; mean age: 72.7±7.4 years) with TAAA underwent total percutaneous endovascular aortic repair by percutaneous puncture of the third segment of the left AxA, using a 12F sheath for delivery of the bridging visceral stent grafts. Percutaneous closure was performed using ultrasound guidance and two Perclose ProGlide VCDs per puncture site. Endpoints were device success defined as successful haemostasis of the axillary puncture site by VCD, procedure success defined as endovascularly assisted haemostasis of the AxA, major cerebrovascular and peripheral neurological complications, and 30 day mortality. The median diameter of the AxA in the third segment was 6.5mm (range 4.4-10.4mm). The procedure success was 100%. Device success was achieved in 33 patients (82.5%). Device success in patients with AxA diameter >5mm was 97%. All patients with diameter of the AxA <5mm developed stenosis or occlusions of the vessel (n=6), which were treated by percutaneous stent implantation. One bleeding at the AxA puncture site was treated with trans-femoral implantation of a covered stent. No secondary open procedures were required. No neurological deficit of the left upper limb was seen at discharge. Overall mortality at 30 days was 10%. Direct puncture of the AxA in the third segment and its use as an access vessel for large sheaths during total percutaneous treatment of complex endovascular aortic procedures appear to be feasible and safe in arteries with a diameter >5mm. Complications can be managed using endovascular techniques.

Assessment of changes in stent graft geometry after chimney endovascular aneurysm sealing

BackgroundChimney endovascular aneurysm sealing (ch-EVAS) could potentially minimize gutter-associated endoleaks in patients with juxtarenal abdominal aortic aneurysms resulting from the use of the conformable endobags surrounding the chimney stent grafts (ch-SGs). The aim of the present study was to quantify the (non)apposition of the endobags in the proximal aortic neck, migration of the endograft stent frames, and changes in geometry of the ch-SGs during the follow-up period. MethodsThe prospective data from 20 patients undergoing elective ch-EVAS were retrospectively reviewed. The aortic anatomy was analyzed on preoperative and postoperative computed tomography scans. The (non)apposition of the endobags in the aortic neck, Nellix (Endologix, Irvine, Calif) stent frame migration, and chimney graft geometry and migration were assessed. ResultsThe median preoperative infrarenal neck length was 4.0 mm (interquartile range [IQR], 0-6.0 mm). The median seal length in the juxtarenal aortic neck at the first follow-up was 23.0 mm (IQR 18.0-30.8 mm). Five type IA endoleaks were identified on postoperative imaging; one at 1 month and four newly diagnosed at 1 year. Of these five type IA endoleaks, two were type Is1 (not extending into the aneurysm sac) and did not need reintervention and other three were type Is2 (extending into the aneurysm sac). One of these patients died of malignancy before reintervention could be performed. Bilateral ch-SG occlusions in one patient were documented at the 1-month follow-up (patient needed hemodialysis) and two patients with a new single ch-SG occlusion were found at the 1-year follow-up. No reinterventions were performed for the ch-SG occlusions. An occluded Nellix stent frame in one patient was treated with femorofemoral crossover bypass. Kaplan-Meier estimate of reintervention-free survival was 85.0% after 1 year. Migration ≥5 mm of the proximal end of the Nellix stent frames was observed in 20.0% of the patients, but no reintervention was performed at the 1-year follow-up. Imaging showed 20.1% of the available sealing surface was not used, and the nonapposition surface increased to 30.6% of the preoperative aortic neck surface at 1 year. Median migration was 3.5 mm (IQR, 2.4-5.0 mm) and 3.1 mm (IQR, 2.0-4.8 mm) for the left and right proximal end of the Nellix stent frames, respectively, and was 3.0 mm (IQR, 2.2-4.8 mm) for the proximal end of the ch-SGs at 1 year of follow-up. ConclusionsSubstantial distal migration of the Nellix endograft and positional changes of the ch-SGs in the juxtarenal aortic neck were observed at 1 year of follow-up, resulting in a 25.0% type IA endoleak rate, with three of these type IA endoleaks extending into the aneurysm sac. The reintervention-free survival rate was 85.0% at 1 year in this cohort of 20 patients. Careful follow-up after ch-EVAS is advised because changes are often subtle. The authors have stopped the ch-EVAS procedure so far. Long-term follow-up data on the stability of the Nellix endograft and the consequences of migration on ch-SGs is required before this technique should be used in clinical practice.

SS10. Feasibility and Safety of Endovascular Docking Station With Chimney Stent Grafts for Staged Crawford Types I to IV Thoracoabdominal Aortic Aneurysm Repair

SS10. Feasibility and Safety of Endovascular Docking Station With Chimney Stent Grafts for Staged Crawford Types I to IV Thoracoabdominal Aortic Aneurysm Repair

NESVS9. Chimney Stent Graft for Left Subclavian Artery Revascularization During Thoracic Endograft Placement

NESVS9. Chimney Stent Graft for Left Subclavian Artery Revascularization During Thoracic Endograft Placement

Hemodynamic and Anatomic Predictors of Renovisceral Stent-Graft Occlusion Following Chimney Endovascular Repair of Juxtarenal Aortic Aneurysms

Purpose: To identify anatomic and hemodynamic changes associated with impending visceral chimney stent-graft occlusion after endovascular aneurysm repair (EVAR) with the chimney technique (chEVAR). Methods: A retrospective evaluation was performed of computed tomography scans from 41 patients who underwent juxtarenal chEVAR from 2008 to 2012 to identify stent-grafts demonstrating conformational changes following initial placement. Six subjects (mean age 74 years; 3 men) were selected for detailed reconstruction and computational hemodynamic analysis; 4 had at least 1 occluded chimney stent-graft. This subset of repairs was systematically analyzed to define the anatomic and hemodynamic impact of these changes and identify signature patterns associated with impending renovisceral stent-graft occlusion. Spatial and temporal analyses of cross-sectional area, centerline angle, intraluminal pressure, and wall shear stress (WSS) were performed within the superior mesenteric and renal artery chimney grafts used for repair. Results: Conformational changes in the chimney stent-grafts and associated perturbations, in both local WSS and pressure, were responsible for the 5 occlusions in the 13 stented branches. Anatomic and hemodynamic signatures leading to occlusion were identified within 1 month postoperatively, with a lumen area <14 mm2 (p=0.04), systolic pressure gradient >25 Pa/mm (p=0.03), and systolic WSS >45 Pa (p=0.03) associated with future chimney stent-graft occlusion. Conclusion: Chimney stent-grafts at increased risk for occlusion demonstrated anatomic and hemodynamic signatures within 1 month of juxtarenal chEVAR. Analysis of these parameters in the early postoperative period may be useful for identifying and remediating these high-risk stent-grafts.