Adoption and clinical outcomes of fenestrated endovascular aneurysm repair in a regional, multistate community hospital system.

OBJECTIVE: Complex endovascular abdominal aortic aneurysm (AAA) repair techniques have evolved over the last decade, yet patterns of physician and hospital system adoption of fenestrated endovascular aneurysm repair (FEVAR) remain poorly defined. We investigated clinical outcomes, use trends, and surgeon and hospital experience for FEVAR in a large community hospital system. METHODS: We conducted a retrospective cohort study of all FEVAR procedures within our 5-state hospital system between April 2012 and June 2021. AAA repair volumes (open, EVAR, and FEVAR) were captured at the hospital and surgeon levels using Current Procedural Terminology and International Classification of Diseases codes. Clinical and outcomes data were collected for FEVAR patients. To consider if surgeon or hospital experience influenced outcomes, sequential case number was used to divide patients into surgeon experience and hospital experience groups. Inverse probability weighted and generalized linear mixed models, adjusted for demographics and comorbidities, were built to examine risk-adjusted outcomes for surgeon and hospital experience groups. RESULTS: Of 3850 patients treated with AAA procedures of any kind between 2012 and 2021, 160 (4.2%) underwent FEVAR. FEVAR procedures were performed by 34 different surgeons at 12 hospitals, with intraoperative complications and unplanned adjunctive procedures occurring in 18.8% (n = 30) and 19.4% (n = 31) of patients, respectively. Among FEVAR patients, in-hospital mortality was 1.3% (n = 2) and postoperative morbidity was 16.9% (n = 27). Renal function decline occurred postoperatively in 5.1% of patients. Early (<30 day) postoperative endoleaks occurred in 15.3% of patients (n = 21). Target vessel patency was 95.6% on initial postoperative imaging. Surgeon and hospital experience had a small positive impact on outcomes after the first one to three cases. Significant decreases in operative time, fluoroscopy time, and estimated blood loss were observed with increased surgeon experience, relative to a surgeon's first case (P < .05). There were lower odds of intraoperative complications after a surgeon's first case (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.03-0.77, for cases 2-3) or after a hospital's first one to three cases (OR, 0.19; 95% CI, 0.04-0.89, for cases 4-8; OR, 0.12; 95% CI, 0.03-0.55 for cases 9-49). CONCLUSIONS: Clinical outcomes of FEVAR across our hospital system compare favorably with previously published reports. Although system-wide FEVAR adoption increased 3-fold over the last decade, FEVAR continued to be performed by a minority of hospitals in our system. The results from this cohort demonstrate low rates of adverse events, high rates of technical efficiency, and a small impact of surgeon and hospital experience, thereby supporting this advanced endovascular technology as a safe, efficacious, and generalizable treatment alternative to open repair for patients with complex aortic anatomy.

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

OBJECTIVE: 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. METHODS: 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. RESULTS: Mean IASL for both left and right renal arteries in the cohort was 35.7 mm. Renal arteries containing chimney IASL <30 mm 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 <40 mm (135.5 vs. 121.7°, p = .045). Mean IASL for renal arteries in chEVAR was significantly longer compared to chEVAS (39.2 vs. 26.3 mm, p = .003). No difference was noted in overall branch angle or end-stent angle based on procedure type. ChEVAR with IASL <30 mm 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 <30 mm 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). CONCLUSIONS: 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.

Trends in vascular complications and associated treatment strategies following transfemoral transcatheter aortic valve replacement.

OBJECTIVE: Vascular complications (VC) and bleeding complications impact morbidity and mortality after transfemoral transcatheter aortic valve replacement (TF-TAVR). Few contemporary studies have detailed these complications, associated treatment strategies, or clinical outcomes. We examined the incidence, predictors, treatment strategies, and outcomes of VCs in a multicenter cohort of patients undergoing TF-TAVR. METHODS: We performed a retrospective registry and chart review of all nonclinical trial TF-TAVR patients from seven centers within a five-state hospital system from 2012 to 2016. Bleeding and VC were recorded as defined by the Valve Academic Research Consortium recommendations. Procedural and 30-day outcomes and 1-year mortality were compared between patients with no, minor, or major VC. Multivariable logistic and Cox regressions were used to identify predictors of major VC and mortality, respectively. RESULTS: Over the study period, 1573 patients underwent TF-TAVR, with 96 (6.1%) experiencing a major VC and 77 (4.9%) experiencing a minor VC. The majority of VCs were access site related (74.2%), occurred intraoperatively (52.6%), and required interventional treatment (73.2%). The site, timing, and treatment method of VCs did not significantly change over the study period. Patients with VCs had a greater need for blood transfusion, longer postoperative length of stay, higher rates of cardiac events, increased vascular-related 30-day readmission, and higher 30-day mortality. Female sex (odds ratio [OR], 3.00; 95% CI, 1.91-4.72) and prior percutaneous coronary intervention (OR, 2.14 ; 95% CI, 1.38-3.31) were the strongest predictors of major VC. VCs modestly decreased over the study period: every 90-day increase in surgery date decreased the odds of major VC by 6% (95% CI, 1%-10%). Patients with major VCs had worse 1-year survival (OR, 79%; 95% CI, 69%-86%) compared with patients with minor VCs (OR, 92%; 95% CI, 82%-96%) or no VCs (OR, 88%; 95% CI, 87%-90%; P = .002). However, for patients who survived more than 30 days, the 1-year survival did not differ between groups For patients who survived more than 30 days, male sex (hazard ratio, 1.84; 95% CI, 1.30-2.60) and the logit of STS mortality risk score (hazard ratio, 1.98; 95% CI, 1.48-2.65) were the strongest predictors of mortality. After adjusting for other factors, minor and major VC were not predictors of 1-year mortality for patients who survived more than 30 days. CONCLUSIONS: In our contemporary cohort, VCs after TF-TAVR have modestly decreased in recent years, but continue to impact perioperative outcomes. Patient selection, consideration of alternative access routes, and prompt recognition and treatment of VCs are critical elements in optimizing early clinical outcomes after TF-TAVR.

Cardiopulmonary-induced deformations of the thoracic aorta following thoracic endovascular aortic repair.

OBJECTIVES: Thoracic endovascular aortic repair has become a preferred treatment strategy for thoracic aortic aneurysms and dissections. Yet, it is not well understood if the performance of endografts is affected by physiologic strain due to cyclic aortic motion during cardiac pulsation and respiration. We aim to quantify cardiac- and respiratory-induced changes of the postthoracic endovascular aortic repair thoracic aorta and endograft geometries. METHODS: Fifteen thoracic endovascular aortic repair patients (66 ± 10 years) underwent cardiac-resolved computed tomography angiographies during inspiratory/expiratory breath holds. The computed tomography angiography images were utilized to build models of the aorta, and lumen centerlines and cross-sections were extracted. Arclength and curvature were computed from the lumen centerline. Effective diameter was computed from cross-sections of the thoracic aorta. Deformation was computed from the mid-diastole to end-systole (cardiac deformation) and expiration to inspiration (respiratory deformation). RESULTS: Cardiac pulsation induced significant changes in arclength, mean curvature, maximum curvature change, and effective diameter of the ascending aorta, as well as effective diameter of the stented aortic segment. Respiration, however, induced significant change in mean curvature and effective diameter of the ascending aorta only. Cardiac-induced arclength change of the ascending aorta was significantly greater than respiratory-induced arclength change. CONCLUSIONS: Deformations are present across the thoracic aorta due to cardiopulmonary influences after thoracic endovascular aortic repair. The geometric deformations are greatest in the ascending aorta and decline at the stented thoracic aorta. Additional investigation is warranted to correlate aortic deformation to endograft performance.

Polar orientation of renal grafts within the proximal seal zone affects risk of early type IA endoleaks after chimney endovascular aneurysm repair.

OBJECTIVE: The objective of this study was to describe the polar orientation of renal chimney grafts within the proximal seal zone and to determine whether graft orientation is associated with early type IA endoleak or renal graft compression after chimney endovascular aneurysm repair (ch-EVAR). METHODS: Patients who underwent ch-EVAR with at least one renal chimney graft from 2009 to 2015 were included in this analysis. Centerline three-dimensional reconstructions were used to analyze postoperative computed tomography scans. The 12-o'clock polar position was set at the takeoff of the superior mesenteric artery. Relative polar positions of chimney grafts were recorded at the level of the renal artery ostium, at the mid-seal zone, and at the proximal edge of the graft fabric. Early type IA endoleaks were defined as evidence of a perigraft flow channel within the proximal seal zone. RESULTS: There were 62 consecutive patients who underwent ch-EVAR (35 double renal, 27 single renal) for juxtarenal abdominal aortic aneurysms with a mean follow-up of 31.2 months; 18 (29%) early type IA "gutter" endoleaks were identified. During follow-up, the majority of these (n = 13; 72%) resolved without intervention, whereas two patients required reintervention (3.3%). Estimated renal graft patency was 88.9% at 60 months. Left renal chimney grafts were most commonly at the 3-o'clock position (51.1%) at the ostium, traversing posteriorly to the 5- to 7-o'clock positions (55.5%) at the fabric edge. Right renal chimney grafts started most commonly at the 9-o'clock position (n = 17; 33.3%) and tended to traverse both anteriorly (11 to 1 o'clock; 39.2%) and posteriorly (5 to 7 o'clock; 29.4%) at the fabric edge. In the polar plane, the majority of renal chimney grafts (n = 83; 85.6%) traversed <90 degrees before reaching the proximal fabric edge. Grafts that traversed >90 degrees were independently associated with early type IA endoleaks (odds ratio, 11.5; 95% confidence interval, 2.1-64.8) even after controlling for other device and anatomic variables. Polar orientation of the chimney grafts was not associated with graft kinking or compression (P = .38) or occlusion (P = .10). Takeoff angle of the renal arteries was the most significant predictor of chimney graft orientation. Caudally directed arteries (takeoff angle >30 degrees) were less likely to have implanted chimney grafts that traversed >90 degrees in polar angle (odds ratio, 0.09; 95% confidence interval, 0.01-0.55). CONCLUSIONS: Renal chimney grafts vary considerably in both starting position and their polar trajectory within the proximal seal zone. Grafts that traverse >90 degrees in polar angle within the seal zone may be at increased risk of early type IA endoleaks and require more frequent imaging surveillance. Caudally directed renal arteries result in a more favorable polar geometry (eg, cranial-caudal orientation) with respect to endoleak risk and thus are more ideal candidates for parallel graft strategies.

Natural history of gutter-related type Ia endoleaks after snorkel/chimney endovascular aneurysm repair.

OBJECTIVE: Alternative endovascular strategies using parallel or snorkel/chimney (chimney endovascular aneurysm repair [ch-EVAR]) techniques have been developed to address the lack of widespread availability and manufacturing limitations with branched/fenestrated aortic devices for the treatment of complex abdominal aortic aneurysms. Despite high technical success and midterm patency of snorkel stent configurations, concerns remain regarding the perceived increased incidence of early gutter-related type Ia endoleaks. We aimed to evaluate the incidence and natural history of gutter-related type Ia endoleaks following ch-EVAR. METHODS: Review of medical records and available imaging studies, including completion angiography and serial computed tomographic angiography, was performed for all patients undergoing ch-EVAR at our institution between September 2009 and January 2015. Only procedures involving ≥1 renal artery with or without visceral snorkel stents were included. Primary outcomes of the study were presence and persistence or resolution of early gutter-related type Ia endoleak. Secondary outcomes included aneurysm sac shrinkage and need for secondary intervention related to the presence of type Ia gutter endoleak. RESULTS: Sixty patients (mean age, 75.8 ± 7.6 years; male, 70.0%) underwent ch-EVAR with a total of 111 snorkel stents (97 renal [33 bilateral renal], 12 superior mesenteric artery, 2 celiac). A mean of 1.9 ± 0.6 snorkel stents were placed per patient. Early gutter-related type Ia endoleaks were noted on 30.0% (n = 18) of initial postoperative imaging studies. Follow-up imaging revealed spontaneous resolution of these gutter endoleaks in 44.3%, 65.2%, and 88.4% of patients at 6, 12, and 18 months postprocedure, respectively. Long-term anticoagulation, degree of oversizing, stent type and diameter, and other clinical/anatomic variables were not significantly associated with presence of gutter endoleaks. Two patients (3.3%) required secondary intervention related to persistent gutter endoleak. At a mean radiologic follow-up of 20.9 months, no difference in mean aneurysm sac size change was observed between those with or without early type Ia gutter endoleak (-6.1 ± 10.0 mm vs -4.9 ± 11.5 mm; P = .23). CONCLUSIONS: Gutter-related type Ia endoleaks represent a relatively frequent early occurrence after ch-EVAR, but appears to resolve spontaneously in the majority of cases during early to midterm follow-up. Given that few ch-EVAR patients require reintervention related to gutter endoleaks and the presence of such endoleak did not correlate to increased risk for aneurysm sac growth, its natural history may be more benign than originally expected.

Real-World Performance of Paclitaxel Drug-Eluting Bare Metal Stenting (Zilver PTX) for the Treatment of Femoropopliteal Occlusive Disease.

BACKGROUND: The aim of this study was to evaluate the performance and predictors of stent failure of paclitaxel drug-eluting stents for the treatment of femoropopliteal disease. METHODS: A retrospective review of clinical and angiographic data was performed for patients treated for femoropopliteal disease with the Zilver PTX (Cook Medical, Bloomington, IN) stent by a single operator between 2012 and 2015 at a tertiary referral center. Clinical grading was determined by both Rutherford classification and the Society for Vascular Surgery's Wound, Ischemia, and Foot Infection (WIFi) scoring system, and lesions were classified anatomically by the TransAtlantic Intersociety Consensus (TASC) II criteria. Treated lesions included those with prior in-stent restenosis and long-segment disease. Primary clinical end points were stent failure, need for reintervention, and major adverse limb events (MALE). Kaplan-Meier methods and Cox proportional hazard models were used to evaluate factors affecting outcomes. RESULTS: Zilver PTX stents were placed in 52 limbs among 46 patients (71.1% male, mean age 72.6 years) with a median follow-up of 11.1 (range 1-26) months. Limbs were treated for life-disabling claudication in 76.9% and critical limb ischemia in 23.1%. Disease severity was highly variable, with 21 (40.4%) limbs with TASC C or D lesions and 16 (30.7%) treated for restenosis after prior endovascular treatment. During follow-up, 6 (12.7%) limbs experienced loss of stent patency (5 occlusions, one >50% restenosis). Four limbs underwent target lesion revascularization, 2 required open bypass, 2 underwent thrombolysis, and no patients required major amputation. Primary patency was 88.9%, 81.6%, and 81.6% at 6, 12, and 18 months, respectively. Treated lesion length (hazard ratio [HR] 4.99, 95% confidence interval [CI] 1.14-21.75) was the only independent predictor of patency loss. Freedom from target lesion revascularization at 6, 12, and 18 months was 94.2%, 87.8%, and 87.8%, respectively. Freedom from MALE (composite of thrombolysis, major amputation, and bypass operation) was 97.5%, 90.9%, and 79.6% at 6, 12, and 18 months, respectively. Chronic renal insufficiency was the only factor that trended toward increased risk of MALE (HR 9.92, 95% CI 0.86-113.35) within a multivariate model. CONCLUSIONS: Our real-world experience supports the continued use of the Zilver PTX for the treatment of both de novo lesions and lesions with prior endovascular revascularization in the femoropopliteal segment. Routine follow-up between 6 and 12 months postoperatively is essential for detecting early restenosis and guiding reintervention. Careful attention when treating complex lesions and long-segment disease remains important for selecting the optimal revascularization strategy for individual patients and optimizing stent patency.

Dynamic Geometric Analysis of the Renal Arteries and Aorta following Complex Endovascular Aneurysm Repair.

BACKGROUND: Aneurysm regression and target vessel patency during early and mid-term follow-up may be related to the effect of stent-graft configuration on the anatomy. We quantified geometry and remodeling of the renal arteries and aneurysm following fenestrated (F-) or snorkel/chimney (Sn-) endovascular aneurysm repair (EVAR). METHODS: Twenty-nine patients (mean age, 76.8 ± 7.8 years) treated with F- or Sn-EVAR underwent computed tomography angiography at preop, postop, and follow-up. Three-dimensional geometric models of the aorta and renal arteries were constructed. Renal branch angle was defined relative to the plane orthogonal to the aorta. End-stent angle was defined as the angulation between the stent and native distal artery. Aortic volumes were computed for the whole aorta, lumen, and their difference (excluded lumen). Renal patency, reintervention, early mortality, postoperative renal impairment, and endoleak were reviewed. RESULTS: From preop to postop, F-renal branches angled upward, Sn-renal branches angled downward (P < 0.05), and Sn-renals exhibited increased end-stent angulation (12 ± 15°, P < 0.05). From postop to follow-up, branch angles did not change for either F- or Sn-renals, whereas F-renals exhibited increased end-stent angulation (5 ± 10°, P < 0.05). From preop to postop, whole aortic and excluded lumen volumes increased by 5 ± 14% and 74 ± 81%, whereas lumen volume decreased (39 ± 27%, P < 0.05). From postop to follow-up, whole aortic and excluded lumen volumes decreased similarly (P < 0.05), leaving the lumen volume unchanged. At median follow-up of 764 days (range, 7-1,653), primary renal stent patency was 94.1% and renal impairment occurred in 2 patients (6.7%). CONCLUSIONS: Although F- and Sn-EVAR resulted in significant, and opposite, changes to renal branch angle, only Sn-EVAR resulted in significant end-stent angulation increase. Longitudinal geometric analysis suggests that these anatomic alterations are primarily generated early as a consequence of the procedure itself and, although persistent, they show no evidence of continued significant change during the subsequent postoperative follow-up period.

Renal function changes after fenestrated endovascular aneurysm repair.

OBJECTIVE: Limited data exist regarding the effect of fenestrated endovascular aneurysm repair (fEVAR) on renal function. We performed a comprehensive analysis of acute and chronic renal function changes in patients after fEVAR. METHODS: This study included patients undergoing fEVAR at two institutions between September 2012 and March 2015. Glomerular filtration rate was estimated using the Modification of Diet in Renal Disease formula with serum creatinine levels obtained during the study period. Acute and chronic renal dysfunction was assessed using the RIFLE (Risk, Injury, Failure, Loss, End-stage renal disease) criteria and the chronic kidney disease (CKD) staging system, respectively. RESULTS: fEVAR was performed in 110 patients for juxtarenal or paravisceral aortic aneurysms, with a mean follow-up of 11.7 months. A total of 206 renal stents were placed, with a mean aneurysm size of 62.9 mm (range, 45-105 mm) and a mean neck length of 4.1 mm. Primary renal stent patency was 97.1% at the latest follow-up. Moderate kidney disease (CKD stage ≥ 3) was present in 51% of patients at baseline, with a mean preoperative glomerular filtration rate of 60.0 ± 19.6 mL/min/1.73 m2. Acute kidney injury occurred in 25 patients (22.7%), although 15 of these (60%) were classified as having mild dysfunction. During follow-up, 59 patients (73.7%) were found to have no change or improved renal disease by CKD staging, and 19 (23.7%) had a CKD increase of one stage. Two patients were noted to have end-stage renal failure requiring hemodialysis. Clinically significant renal dysfunction was noted in 21 patients (26.2%) at the latest follow-up. Freedom from renal decline at 1 year was 76.1% (95% confidence interval, 63.2%-85.0%). Surrogate markers for higher operative complexity, including operating time (P = .001), fluoroscopy time (P < .001), contrast volume (P = .017), and blood loss (P = .002), served as dependent risk factors for acute kidney injury, although though no independent predictors were identified. Age (P = .008) was an independent risk factor for long-term decline, whereas paradoxically, baseline kidney disease (P = .032) and longer operative times (P = .014) were protective of future renal dysfunction. CONCLUSIONS: Acute and chronic renal dysfunction both occur in approximately one-quarter of patients after fEVAR; however, most of these cases are classified as mild according to consensus definitions of renal injury. The presence of mild or moderate baseline kidney disease should not preclude endovascular repair in the juxtarenal population. Routine biochemical analysis and branch vessel surveillance remain important aspects of clinical follow-up for patients undergoing fEVAR.

Use of a proactive duplex ultrasound protocol for hemodialysis access.

OBJECTIVE: Arteriovenous fistula (AVF) creation is the preferred approach for hemodialysis access; however, the maturation of AVFs is known to be poor. We established a proactive early duplex ultrasound (DUS) surveillance protocol for evaluating AVFs before attempted access. This study determined the effect of this protocol related to improving AVF maturation. METHODS: From 2008 to 2013, 153 patients received new upper extremity AVFs and an early DUS surveillance protocol at a single academic institution. The protocol involved an early DUS evaluation before hemodialysis cannulation of the AVF at 4 to 8 weeks after AVF creation. A positive DUS result was identified as a peak systolic velocity of >375 cm/s or a >50% stenosis on gray scale imaging, along with decreased velocity in the outflow vein. Patients with positive DUS findings underwent prophylactic endovascular or open intervention to assist with AVF maturation. Nature of secondary interventions, as well as AVF patency and maturation, were assessed. Overall clinical outcomes and fistula patency were investigated. RESULTS: During the study period, 183 upper extremity AVFs were created in 153 patients, including 82 radiocephalic, 63 brachiocephalic, and 38 brachiobasilic AVFs. A mortality rate of 43% (n = 66) was observed in a median follow-up period of 34.5 months (interquartile range, 19.6-46.9). A total of 164 early DUS were performed at a median of 6 weeks (interquartile range, 3.4-9.6 weeks) after the initial creation. Early DUS showed nine AVFs were occluded and were excluded from further analysis. Hemodynamically significant lesions were found in 62 AVFs (40%); however, only 17 (11%) were associated with an abnormal physical examination. Positive DUS finding prompted a secondary intervention in 81% of the patients. Among those with positive early DUS findings, AVF maturation was 70% in those undergoing a secondary intervention compared with 25% in those not undergoing a prophylactic intervention (P = .011). Primary-assisted patency for AVFs with early positive and negative DUS findings were 83% and 96% at 6 months, 64% and 89% at 1 year, and 52% and 82% at 2 years, respectively (P < .001). CONCLUSIONS: Early DUS surveillance of AVFs before initial access is reasonable to identify problematic AVFs that may not be reliably detected on clinical examination. Although DUS criteria for AVFs have yet to be universally accepted, proactive early postoperative DUS interrogation assists in the early detection of dysfunctional AVFs and improvement of fistula maturation. Despite improved patency in those with positive DUS findings who undergo prophylactic secondary intervention, overall patency remains inferior to those without an abnormality detected on early DUS imaging.

Comparative geometric analysis of renal artery anatomy before and after fenestrated or snorkel/chimney endovascular aneurysm repair.

OBJECTIVE: The durability of stent grafts may be related to how procedures and devices alter native anatomy. We aimed to quantify and compare renal artery geometry before and after fenestrated (F-) or snorkel/chimney (Sn-) endovascular aneurysm repair (EVAR). METHODS: Forty patients (75 ± 6 years) underwent computed tomographic angiography before and after F-EVAR (n = 21) or Sn-EVAR (n = 19), with a total of 72 renal artery stents. Renal artery geometry was quantified using three-dimensional model-based centerline extraction. The stented length was computed from the vessel origin to the stent end. The branch angle was computed relative to the orthogonal configuration with respect to the aorta. The end-stent angle was computed relative to the distal native renal artery. Peak curvature was defined as the inverse of the radius of the circumscribed circle at the highest curvature within the proximal portion from the origin to the stent end and the distal portion from the stent end to the first renal artery bifurcation. RESULTS: Sn-renals had greater stented length compared to F-renals (P < .05). From the pre- to the postoperative period, the origins of the Sn-left renal artery and right renal artery (RRA) angled increasingly downward by 21 ± 19° and 13 ± 17°, respectively (P < .005). The F-left renal artery and RRA angled upward by 25 ± 15° and 14 ± 15°, respectively (P < .005). From the pre- to the postoperative period, the end-stent angle of the Sn-RRA increased by 17 ± 12° (P < .00001), with greater magnitude change compared to the F-RRA (P < .0005). Peak curvature increased in distal Sn-RRAs by .02 ± .03 mm(-1) (P < .05). Acute renal failure occurred in 12.5% of patients, although none required dialysis following either F- and Sn-EVAR. Renal stent patency was 97.2% at mean follow-up of 13.7 months. Three type IA endoleaks were identified, prompting one secondary procedure, with the remainder resolving at 6-month follow-up. One renal artery reintervention was performed due to a compressed left renal stent in an asymptomatic patient. CONCLUSIONS: Stented renal arteries were angled more inferiorly after Sn-EVAR and more superiorly after F-EVAR due to stent configuration. Sn-EVAR induced significantly greater angle change at the stent end and curvature change distal to the stent compared to F-EVAR, although no difference in patency was noted in this small series with relatively short follow-up. Sn-RRAs exhibited greater end-stent angle change from the pre- to the postoperative period as compared to the F-RRA. These differences may exert differential effects on long-term renal artery patency, integrity, and renal function following complex EVAR for juxta- or pararenal abdominal aortic aneurysms.

Anterior Retroperitoneal Spine Exposure following Prior Endovascular Aortic Aneurysm Repair.

BACKGROUND: We describe successful anterior retroperitoneal spine exposure to facilitate anterior lumbar interbody fusion (ALIF) in a patient with a prior endovascular aneurysm repair (EVAR). METHODS: A 74-year-old male with an extensive spine surgical history presented with progressive neurogenic claudication and paresthesia involving both feet. In addition, his surgical history was notable for an EVAR performed elsewhere 5 years earlier, with subsequent right renal stent placement for encroachment of the right renal artery. Diagnostic evaluation identified severe L3-4 and L4-5 canal stenosis, and a 48 × 36-mm aneurysm sac with a type II endoleak. Revision L3-L5 fusion from an anterior approach with vascular surgery assistance was recommended. RESULTS: The retroperitoneum was accessed through a left paramedian abdominal incision. The abdominal aortic aneurysm sac was visualized and noted to be nonpulsatile. The distal aorta and left iliac vessels were dissected and retracted medially to facilitate anterior exposure of the L3-4 and L4-5 disk spaces. Successful ALIF of the L3-5 vertebrae was then performed. Retractors were removed and the aortoiliac vessels were carefully returned to anatomic position. The aneurysm sac remained nonpulsatile, with normal pulses in the iliac arteries. Postoperative imaging demonstrated stable appearance of aortic stent graft. At 1-year follow-up, the patient reports complete resolution of symptoms and imaging demonstrates a patent aortic stent graft with a stable type II endoleak. CONCLUSIONS: Widespread application of ALIF will inevitably include an increasing subgroup of patients with previous EVAR. Such patients require thorough clinical and radiographic perioperative considerations for the access surgeon.

Snorkel/Chimney Stent Morphology Predicts Renal Dysfunction after Complex Endovascular Aneurysm Repair.

BACKGROUND: Despite the high technical success and midterm patency of snorkel stents, concerns remain about structural durability and its effect on long-term renal function. We sought to evaluate the luminal stability of renal snorkel stents to investigate morphologic predictive factors of renal dysfunction after snorkel/chimney endovascular aneurysm repair (sn-EVAR). METHODS: Patients with high quality computer tomography angiography after sn-EVAR between 2009 and 2013 were included for analysis. Luminal diameters of renal snorkel stents were measured on a 3-dimensional workstation at the proximal, main-body junction, and distal locations. Creatinine values and estimated glomerular filtration rates (eGFR) were recorded throughout the preoperative, perioperative, and postoperative course. Acute kidney injury (AKI) and chronic renal decline were evaluated using the risk, injury, failure, loss of function, end stage renal disease (RIFLE) criteria and chronic kidney disease (CKD) staging system, respectively. RESULTS: 52 patients underwent sn-EVAR (33 double renal, 19 single renal) with a 2-year primary patency of 95% at a mean follow-up of 21 months, of which 34 had suitable imaging protocols. In this subset, snorkel stents had mean deformations of -0.14 ± 0.52 (2.8%), -0.23 ± 0.52 (4.6%) and -0.04 ± 0.16 mm (1.8%) at the proximal, junction, and distal segments. Four cases of significant >50% stent collapse occurred during follow-up, all of which occurred at the junctional segment. In the total cohort, 17 (32.6%) and 16 (30.7%) patients developed AKI and chronic renal decline, respectively. Multivariate regression identified larger proximal luminal diameters at latest follow-up (odds ratio 0.67; confidence interval [CI] 0.006-0.740; P = 0.037) as the only protective morphologic risk factor for developing chronic renal decline. No independent predictor factors for AKI were found. Rates of renal decline were significantly worse with smaller measured proximal lumens with a 1-year freedom from renal decline of 50% vs. 77-83% for diameters measured less than 4 mm vs. greater than 4 mm (P = 0.010). Degree of oversizing also affected rates of decline with greater oversizing associated with improved freedom from renal decline at 1 year of 100% vs. 57% (P = 0.012). Using a multivariate Cox model, stent oversizing (hazard ratio [HR], 0.039; P = 0.018) and baseline CKD (HR 0.033, P = 0.004) were the only independent factors, both of which resulted in slower rates of renal decline during follow-up. CONCLUSIONS: Renal snorkel stent grafts maintain a high degree of patency and luminal stability at 2-year follow-up. However, stent collapse remains a rare but concerning risk, with the junctional segment most prone to significant stent deformation. Renal snorkel stents must be critically sized relative to native renal anatomy, and we recommend using at least stents sized ≥6 mm to minimize the risk of renal dysfunction. Frequent and regular radiographic and laboratory follow-up remains important as we further optimize the approach to complex EVAR.

Protocol for prevention of spinal cord ischemia after thoracoabdominal aortic surgery.

OBJECTIVE: This manuscript was written to present a systemic protocol for the prevention, early detection, and treatment of spinal cord ischemia following open and endovascular thoracoabdominal aortic operations. METHODS: This protocol was a collaborative effort between surgeons, anesthesiologists and intensivists. It was implemented at our institution in November 2007. Nurses are trained to prevent, rapidly detect and ultimately aid in the treatment of spinal cord ischemia. RESULTS: Implementation of this protocol has aided in prevention, detection and treatment of spinal cord ischemia in patients after open and endovascular thoracoabdominal aortic operations. CONCLUSION: Standardized care and reliance on trained nursing staff to monitor for symptoms following thoracoabdominal aortic operations are safe and aid in the rapid detection, treatment and reversal of spinal cord ischemia.

Safety and efficacy of antiplatelet/anticoagulation regimens after Viabahn stent graft treatment for femoropopliteal occlusive disease.

OBJECTIVE: We aimed to determine the safety and efficacy of antiplatelet/anticoagulation regimens after placement of Viabahn stent graft (W. L. Gore & Associates, Flagstaff, Ariz) for the treatment of femoropopliteal occlusive disease. METHODS: Clinical, angiographic, and procedural data for patients undergoing endovascular treatment of femoropopliteal occlusive disease using Viabahn covered stent grafts at a single institution between 2006 and 2013 were retrospectively reviewed. Graft patency and freedom from thrombolysis, major adverse limb event, and reintervention were determined by Kaplan-Meier analysis. The influence of relevant variables on clinical outcome was determined through univariate and multivariate Cox proportional hazards analyses. RESULTS: Viabahn stent grafts were placed in a total of 91 limbs in 61 patients (66% men; mean age, 69 ± 12 years) during the study period. Indication for intervention was either claudication (n = 59) or critical limb ischemia (n = 32), with the majority (70%) classified as TransAtlantic Inter-Society Consensus II C (n = 33) or D (n = 31) lesions. Mean follow-up was 38.3 months (range, 1-91 months). Postprocedural pharmacologic regimens included aspirin, clopidogrel, and warfarin (47%); indefinite aspirin and clopidogrel (46%); or aspirin and temporary clopidogrel (7%). Primary and secondary patency rates were 60%, 44%, and 36% and 95%, 82%, and 74% at 1 year, 3 years, and 5 years, respectively. Kaplan-Meier analysis demonstrated more aggressive antiplatelet/anticoagulation regimens to be associated with improved primary patency and freedom from reintervention. Cox proportional hazards analysis demonstrated TransAtlantic Inter-Society Consensus II D lesions, tobacco use, coronary artery disease, and smaller stent diameter to be independent risk factors for stent graft failure. Bleeding events were limited to those in the aspirin, clopidogrel, and warfarin group (11.6% [n = 5]; P = .052), although the majority of these events were not life-threatening, and only two cases required blood transfusion. CONCLUSIONS: Increasingly aggressive antithrombotic regimens after Viabahn stent graft placement trended toward improved overall clinical outcomes, although the marginal patency benefit observed with the addition of warfarin to dual antiplatelet therapy was tempered by an observed increased risk of bleeding complications. Longer term follow-up and multicenter studies are needed to further define optimal type and duration of antithrombotic therapy after endovascular peripheral interventions.

Geometry and respiratory-induced deformation of abdominal branch vessels and stents after complex endovascular aneurysm repair.

OBJECTIVE: This study quantified the geometry and respiration-induced deformation of abdominal branch vessels and stents after fenestrated (F-) and snorkel (Sn-) endovascular aneurysm repair (EVAR). METHODS: Twenty patients (80% male; mean age, 75.2 ± 7.4 years; mean aneurysm diameter, 6.2 ± 1.8 cm) underwent computed tomography angiography during inspiratory and expiratory breath hold protocols after F-EVAR (n = 11) or Sn-EVAR (n = 9). Centerlines for the aorta and visceral vessels were extracted from three-dimensional models. Branch angles were computed relative to the orthogonal plane at the branch ostia, and end-stent angles of the left renal artery (LRA) and right renal artery (RRA) were computed relative to the distal stent orientation. The radius of peak curvature was defined by the circumscribed circle at the highest curvature. RESULTS: Sn-renal branches were more downward-angled than F-renal branches (P < .04). At the distal ends of the RRA stents, Sn-RRAs were angled greater than F-RRAs (P < .03) and had a smaller radius of peak curvature (P < .03). With expiration, the end-stent angle of Sn-LRAs increased by 4° ± 4° (P < .02) and exhibited a significant reduction of radius of curvature (P < .04). The unstented celiac arteries were more downward-angled (P < .02, inspiration), with a smaller radius of curvature (P < .00001), than the unstented superior mesenteric arteries. With expiration, the celiac arteries angled upwards by 9° ± 9° (P < .0005), which was greater than the superior mesenteric arteries (P < .03). At a median postoperative follow-up of 12.6 months (range, 1.0-37.1 months), branch vessel patency was 100%, serum creatinine levels remained stable, and one reintervention was required for a type III endoleak at the main body-LRA stent interface. CONCLUSIONS: Sn-renals were angled more inferiorly at the branch and more angulated at the stent end than F-renals due to stent placement strategies. Sn-LRAs exhibited a significant change in end-stent angle and curvature during respiration, a finding that may compromise long-term durability for parallel stent graft configurations. Further investigation is warranted to better optimize anatomic, patient, and branch vessel stent selection between fenestrated and snorkel strategies and their relationship to long-term patency.

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.

Cheese wire fenestration of a chronic juxtarenal dissection flap to facilitate proximal neck fixation during EVAR.

BACKGROUND: To describe successful endovascular repair of a complex chronic aortoiliac dissection facilitated by a unique endovascular fenestration technique at the proximal neck. METHODS: A 57-year-old man presented with disabling lower extremity claudication and a remote history of medically treated type B aortic dissection. Computed tomographic angiography demonstrated a complex dissection with 7.1-cm false lumen aneurysmal dilatation and significant true lumen compression within bilateral iliac aneurysms and no suitable proximal infrarenal neck free of dissection. RESULTS: Using intravascular ultrasound, guidewires were introduced into true and false lumens. A 9F sheath was placed on the right side, and a 20-ga Chiba needle was positioned at the level of the celiac artery and oriented toward the dissection flap. The needle was advanced to puncture the flap, and a 0.014-in wire was then snared from the true to the false lumen. Shearing of the dissection flap in the juxtarenal segment was performed using a "cheese wire" technique, whereby both ends of the guidewire were pulled caudally in a sawing motion down through the infrarenal neck and into the aneurysm sac. Angiography confirmed absence of residual dissection and perfusion of the visceral vessels via the true lumen. Given the newly created infrarenal neck, standard endovascular aortic repair (EVAR) was performed and antegrade and retrograde false lumen flow was obliterated from the visceral vessels. Postoperative imaging confirmed aneurysm exclusion, no endoleak, and patent bilateral common iliac arteries with resolution of claudication symptoms and normal ankle-brachial indices. CONCLUSIONS: Endovascular management of false lumen aneurysms in the setting of chronic dissection is limited by the ability of stent grafts to obtain adequate proximal or distal fixation. Endovascular fenestration of these chronic flaps facilitates generation of suitable landing zones, thereby serving as a useful adjunct to standard EVAR.

Bilateral reperfusion injury after carotid endarterectomy with contralateral carotid occlusion.

Cerebral hyperperfusion syndrome represents a clinical spectrum characterized by severe unilateral headache, acute changes in mental status, vomiting, seizures, focal neurologic deficits, and, in its most severe form, intracranial hemorrhage. With the exception of one early case report, reperfusion injury to the brain following carotid endarterectomy has been reported only ipsilateral to the side of surgery. We report the unique case of a patient with symptomatic severe right internal carotid artery stenosis and contralateral carotid occlusion who underwent carotid endarterectomy complicated by cerebral hyperperfusion syndrome and associated bilateral intracranial hemorrhage.

Reversible spinal cord ischemia as a complication of acute aortic intramural hematoma.

Aortic intramural hematoma is a variant of acute aortic dissection characterized by localized hemorrhage into the aortic media causing a separation of the intimal and adventitial layers of the aorta. Malperfusion represents an unusual presenting sign of acute intramural hematoma. Herein, we describe the case of a patient with an acute Type A IMH who developed reversible ischemic spinal cord syndrome after presenting with paraplegia as a consequence of malperfusion. A decision was made to delay operative repair and, instead, emergently apply medical interventions to increase spinal cord perfusion pressure. Medical treatment was effective for the treatment of spinal cord ischemia and operative repair of the intramural hematoma was accomplished after complete recovery of neurologic function. This is the third case ever reported of an intramural hematoma presenting in the form of spinal cord ischemia.