Bifurcated Stent Graft Research Articles

A heparin-functionalized woven stent graft for endovascular exclusion

With the increase of vascular diseases in recent years, it is of importance to develop an anti-occlusion stent graft, which can meet the requirements of transplants for a long term. In this paper, we describe a silk fibroin (SF)/heparin-functionalized bifurcated stent graft (BSG) using textile forming technology. The BSGs were prototyped based on seamless weaving technology, and the surface was modified with SF-loaded heparin under steam/air treatment to improve their patency. The physical properties such as thickness, water permeability, contact angle, mechanical properties, and in vitro drug release and coagulation time of the BSGs were examined. The results showed that heparin modification can improve its coagulation time, and the water permeability resistance of the BSGs reached 1.154 ± 0.854 mL/(cm2×min), while their thicknesses were just 0.085 ± 0.004 mm. The heparin release of the BSGs showed that the release time was prolonged upon steam treatment by means of the increase in the β-sheet structure and crystallinity of SF. The viability and attachment of human vascular smooth muscle (HVSM) cells cultured in the release of modified BSGs demonstrated that the modified BSGs could significantly inhibit the proliferation of HVSM cells. The heparin-functionalized BSG with satisfactory thickness, water permeability resistance and anti-occlusion function, which has potential applications in the treatment of vascular diseases.

Iliac artery deformation during EVAR.

Objectives To quantify the deformation of the common iliac artery caused by stiff guide wires and delivery systems during abdominal endovascular aortic repair (EVAR). Methods Twenty-two patients treated with abdominal EVAR were included. The following three image data-sets were acquired for each patient: (1) a preoperative computed tomography angiography (CTA), (2) an intraoperative contrast-enhanced cone beam CT (CBCT) obtained after the main trunk of the bifurcated stent graft was released and both iliac limbs were engaged with stiff guide wires, and (3) the first postoperative CTA. These data-sets were merged and compared in an image analysis work station. The length and the tortuosity index of the common iliac artery, the Euclidian displacement of the aortic and the iliac bifurcations, and the optimal C-arm angulation for projection of the iliac bifurcation were computed. Results The common iliac artery was on average 6.4 mm shorter ( p < 0.001) and tortuosity index was lower ( p = 0.003) in the intraoperative images compared to preoperative. Some of the foreshortening was reversed postoperatively, remaining mean length difference was 2.9 mm ( p = 0.007) compared to preoperative. Intraoperatively, the aortic bifurcation was mostly displaced in a cranial direction (100%) and the iliac bifurcation in a ventral direction (93%). The optimal lateral C-arm angulation for projection of the iliac bifurcation changed. Anterior contralateral angle increased from median 42° (IQR, 27–63) in the preoperative CTA to 62 (49–74) in the intraoperative CBCT ( p = 0.02). Optimal cranio-caudal angulation did not change. Conclusion Stiff guide wires and delivery systems cause significant deformation of the common iliac arteries during EVAR. The aortic bifurcation is more cranial, the common iliac arteries are shorter, and optimal C-arm angulation is more contralateral oblique when the iliac limbs are to be deployed compared to baseline measurements from preoperative CTA. This affects image fusion accuracy and stent graft selection.

Endovascular treatment of abdominal aortic aneurysm and aortic bifurcation stenosis by unibody bifurcation stent graft

To sum up experience in unibody bifurcation stent graft in the treatment of abdominal aortic aneurysm with aortic bifurcation stenosis. Clinical data of 19 cases of abdominal aortic aneurysm and aortic bifurcation stenosis received endovascular treatment using unibody bifurcation stent graft in Zhejiang Provincial People's Hospital during March 2009 and March 2018 were collected. The clinical characteristics, surgery procedure and follow-up results were reviewed. Stent graft was successful in all patients, and the average operation time was (70.0±2.3) min. Leakage was found in 3 patients, in which 2 patients with type Ⅰ leakage and 1 patient with type Ⅱ leakage. All leakage disappeared 15 days after surgery. The 19 cases were followed-up for 9-48 months with the median follow-up time of 27 months, and no displacement, leakage and lower limb ischemia was observed. Unibody bifurcation stent graft is of satisfactory long-term effect for patients with abdominal aortic aneurysm and aortic bifurcation stenosis, and can avoid displacement of stent graft after operation.

Using bifurcated endoprosthesis after iliac artery recanalization for concomitant abdominal aortic aneurysm and chronic total occlusions of access routes

ObjectiveConcurrent abdominal aortic aneurysm (AAA) and unilateral iliac occlusion is a challenge in the implantation of bifurcated stent grafts (BFGs). The endovascular approach is less invasive than open surgery; the aortouni-iliac (AUI) graft with crossover femorofemoral bypass (CFFB) has many problems associated with extra-anatomic reconstruction. We attempted endovascular aneurysm repair (EVAR) using BFGs in such cases and evaluated the outcomes. MethodsThis was a retrospective study. Between October 2012 and December 2017, there were 649 patients who underwent surgery for AAA, of whom 32 patients underwent open reconstruction and 617 patients underwent endovascular aneurysm repair; 15 patients with unilateral occluded iliac arteries and AAA were included. The analysis included patients with unilateral iliac chronic total occlusion (CTO). The intraoperative, postoperative, and follow-up variables were reviewed. ResultsThe occluded lesions were the common iliac artery in 5 patients, the common iliac artery-external iliac artery (EIA) in 2 patients, the EIA in 7 patients, and the EIA-common femoral artery in 1 patient. The mean occlusive length was 89.7 ± 43.6 mm, and the mean AAA size was 54.6 ± 5.6 mm. Technical success was achieved in 13 patients (87%). All patients underwent recanalization through the true lumen and stent placement. The only procedure-related complication was distal embolism, which was treated with intraoperative thrombectomy. Recanalization of CTO lesions was not possible in two patients (13%), who underwent AUI graft placement with CFFB. The 30-day mortality and morbidity rates were 0%. The mean follow-up periods were 12 and 32 months for patients who underwent BFG placement and AUI graft placement with CFFB, respectively. During follow-up, the primary patency rate of successfully recanalized arteries was 100%. Aneurysm size decreased in four patients who underwent BFG placement; no change was seen in the other 11 patients. Freedom from aneurysm-related events was 100%; no patient needed secondary interventions. All patients with claudication pain preoperatively reported improvement in their symptoms during follow-up. In addition, the ankle-brachial index improved significantly from 0.51 ± 0.25 preoperatively to 0.88 ± 0.20 postoperatively (P < .001) in patients who underwent BFG placement. ConclusionsRecanalization of unilateral iliac CTO lesions and placement of BFG in cases with concomitant aneurysmal disease and unilateral iliac occlusive disease demonstrated a significant primary patency rate with improvements in claudication and ankle-brachial index.

Numerical and Experimental Investigation of Novel Blended Bifurcated Stent Grafts with Taper to Improve Hemodynamic Performance.

The typical helical flow within the human arterial system is widely used when designing cardiovascular devices, as this helical flow can be generated using the “crossed limbs” strategy of the bifurcated stent graft (BSG) and enhanced by the tapered structure of arteries. Here, we propose the use of a deflected blended bifurcated stent graft (BBSG) with various tapers, using conventional blended BSGs with the same degree of taper as a comparison. Hemodynamic performances, including helical strength and wall shear stress- (WSS-) based indicators, were assessed. Displacement forces that may induce stent-graft migration were assessed using numerical simulations and in vitro experiments. The results showed that as the taper increased, the displacement force, helicity strength, and time-averaged wall shear stress (TAWSS) within the iliac grafts increased, whereas the oscillating shear index (OSI) and relative residence time (RRT) gradually decreased for both types of BBSGs. With identical tapers, deflected BBSGs, compared to conventional BBSGs, exhibited a wider helical structure and lower RRT on the iliac graft and lower displacement force; however, there were no differences in hemodynamic indicators. In summary, the presence of tapering facilitated helical flow and produced better hemodynamic performance but posed a higher risk of graft migration. Conventional and deflected BBSGs with taper might be the two optimal configurations for endovascular aneurysm repair, given the helical flow. The deflected BBSG provides a better configuration, compared to the conventional BBSG, when considering the reduction of migration risk.

Numerical and Experimental Investigation of the Hemodynamic Performance of Bifurcated Stent Grafts with Various Torsion Angles

The “crossed limbs” strategy for bifurcated stent grafts (BSGs) is widely employed when abdominal aortic aneurysm (AAA) patients have unfavorable neck or highly splayed iliac arteries. Helical flow is regarded as a typical flow pattern within the human arterial system and is believed to have the positive physiological effects of inhibiting thrombosis formation and atherosclerosis. The “crossed limbs” strategy may induce helical flow and improve the stent graft outcome. To verify the performance of this strategy by considering hemodynamics, we constructed a series of idealized BSGs with various torsion angles and evaluated the hemodynamic performance, including the helical strength, time-averaged wall shear stress (TAWSS), oscillatory shear index, relative resident time (RRT), and displacement force. Our numerical results indicate that an increased torsion angle enhances the helicity strength at the iliac outlets. However, with increasing torsion angle, the TAWSS in the iliac graft decreases and the RRT increases. In addition, our numerical simulations and in vitro experiments reveal that the displacement force increases gradually with increasing torsion angle. In summary, the “crossed limbs” strategy may have benefits for AAA treatment in terms of helical flow, but because of the unfavorable hemodynamic performance verified by analyzing the hemodynamic indicators, the risk of stent graft migration increases with increasing torsion angle. Therefore, the “crossed limbs” strategy should be carefully employed in surgical AAA treatment.

Results of the multicenter pELVIS Registry for isolated common iliac aneurysms treated by the iliac branch device

ObjectiveWe evaluated the short- and long-term results of off-label use of iliac branch devices (IBDs) in isolated common iliac artery aneurysms compared with the manufacturer-recommended configuration with additional extension in the infrarenal aorta based on the pELVIS Registry (pErformance of iLiac branch deVIces for aneurysmS involving the iliac bifurcation). MethodsBetween January 2005 and April 2017, 804 patients underwent endovascular aneurysm repair with 910 IBDs owing to aneurysmal involvement of the iliac bifurcation in nine high-volume European vascular centers. Among this cohort, 231 IBDs were implanted in 207 patients to treat an isolated common iliac aneurysm; 91 IBDs (group 1) were implanted without proximal aortic extension in the infrarenal aorta, and in the remaining cases (n = 140; group 2) an aortic bifurcated stent graft was deployed proximally as stated in the instructions for use. Primary outcomes were IBD and target hypogastric artery occlusions, type I and III endoleaks, procedure-related reinterventions, and aneurysm-related deaths. ResultsTechnical success was achieved in 90 cases (98.9%) in group 1 versus 137 cases (97.8%) in group 2 (P = .55). The overall aneurysm-related early reintervention rate for the two groups was 4.4% (4 of 91) and 2.1% (3 of 140), respectively (P = .33). The 30-day mortality was 1.1% in group 1 (n = 1), and 0% in group 2 (P = .21). The median postoperative follow-up in groups 1 and 2 were 34.1 months (range, 1-108 months) and 17.5 months (range, 1-90 months), respectively. The estimated rates of freedom from IBD occlusion at 60 months were 86% in group 1 and 83% in group 2 (P = .69). The estimated rates of freedom from target hypogastric artery occlusion at 60 months were 98.3% in group 1 and 91.3% in group 2 (P = .45). The estimated freedom from reintervention rates at 60 months for types I, types III, and IBD stenosis-occlusion were 78.2% in group 1 and 79.9% in group 2 (P = .79). The estimated freedom from all cause reintervention at 60 months was 64.5% in group 1 and 66.1% in group 2 (P = .44). The estimated freedom from aneurysm-related death at 60 months was 97.9% in group 1 and 100% in group 2 (P = .83). ConclusionsSingle IBD placement for isolated common iliac artery aneurysms seems to be a safe and effective treatment option, when a proper anatomic patient selection is provided. Major benefits are represented by the decrease in X ray exposure, overall procedural time, and use of contrast medium, without affecting perioperative and long-term results in comparison with more extensive procedures.

Technical issues and clinical outcomes of endovascular repair of isolated iliac artery aneurysms: A single-center experience.

Isolated iliac artery aneurysms are the relatively uncommon condition. This study aims to evaluate the technical issues and clinical outcomes of endovascular repair in a cohort of isolated iliac artery aneurysms treated. We retrospectively reviewed 22 consecutive patients with isolated iliac artery aneurysms between December 2006 and September 2016. Iliac artery aneurysms were treated in one of the three ways: (1) standard bifurcated aortic stent graft placement with limb extension; (2) coverage of iliac artery aneurysms with covered stent grafts; and (3) embolization of the arterial branches distal to the aneurysms with coils or vascular plugs. Twenty-two patients (20 men) with a mean age 64.7 years underwent endovascular repair during the study period. The median diameter of the isolated iliac artery aneurysms was 5.9 ± 1.7 cm (2.9-9.0 cm). Technical success was 95.5%. Conversion to open surgery was performed in one patient with bilateral internal iliac artery aneurysms. Four patients underwent placement of a bifurcated stent graft. A covered stent graft was deployed in 16 patients, with embolization of internal iliac artery in 14 patients. Simple coil embolization of isolated internal iliac artery aneurysm was performed in one patient. There was one sudden cardiac death on day 4 after the procedure due to heart failure. During the follow-up period (range: 1-50 months, mean 19.8 months), five patients died of causes not related to isolated iliac artery aneurysms, and transient buttock claudication was observed in one patient. Our study documents the safety and effectiveness of endovascular repair of isolated iliac artery aneurysms with low morbidity and mortality.

Early experiences of endovascular aneurysm repair for ruptured abdominal aortic aneurysms.

PurposeThe use of endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysms (r-AAA) is steadily increasing. We report early experiences of EVAR for r-AAA performed in two tertiary referral centers in Korea.MethodsWe retrospectively reviewed r-AAA patients treated by EVAR from May 2013 to December 2017. An EVAR-first strategy for r-AAA was adopted whenever feasible. The demographic information, anatomic characteristics, operative details, postoperative complications with special attention to abdominal compartment syndrome (ACS), and 30-day mortality were collected and analyzed.ResultsWe identified 13 patients who underwent EVAR for r-AAA. Mean age was 74.2 years and mean AAA size was 74.2 mm. Two patients underwent cardiopulmonary resuscitation at initial presentation. Bifurcated stent grafts were used in 12 out of 13 cases and physician-modified endografts with fenestrated/chimney techniques were performed in 2 cases with short neck. Successful stent graft deployment was achieved in all cases. Three patients were suspected of having ACS and 2 of them underwent laparotomy for decompression. The 30-day mortality was 7.7% (1 of 13), the only mortality being a patient that refused decompressive laparotomy for suspected ACS.ConclusionDespite the small numbers, the outcomes of EVAR for treatment of r-AAA were very promising, even in selected cases with unfavorable anatomy. These outcomes were achieved by a dedicated and well-trained team approach, and by use of high-end angiographic technology. Finally, ACS after EVAR is not uncommon, and requires a high index of suspicion as well as liberal use of decompressive surgery.

Contemporary Results of Endovascular Repair of Isolated Abdominal Aortic Dissection with Unibody Bifurcated Stent Grafts

To report the midterm safety and efficacy of the Aegis™-B (Microport, Shanghai, China) unibody bifurcated stent graft for endovascular treatment of isolated abdominal aortic dissection (IAAD). Isolated abdominal aorta dissection (IAAD) is a rare event. Endovascular stent grafts seem to offer an efficient therapeutic approach to treat IAAD. However, the relatively small diameter of the infrarenal aorta and aortic bifurcation remains the main anatomical limitation to endovascular repair. Between 2008 and 2015, we retrospectively evaluated 32 IAAD patients (21 men; mean age 58±18years), who underwent endovascular repair using Aegis™-B unibody bifurcated stent graft. Narrow proximal landing zone and narrow distal aorta was present in 11 (34.4%) patients and 10 (31.3%) patients, respectively. In the follow-up period, aortic remodeling was observed with computed tomography angiography. All patients were treated by endovascular means, with a primary technical success rate of 100%. During a mean follow-up period of 30.71±16.36months (range, 8-56months), no death, rupture, stent fracture, material failure, or device migration was observed. Complete false lumen thrombosis was observed in all patients at 1year, and all patients were free from false lumen growth in the follow-up. Endovascular treatment of IAAD using the Aegis™-B system appears to be safe and effective. Results from this study suggest this algorithm can provide stable, secure fixation for IAAD patients with narrow proximal landing zone, and distal aorta.

企業製分岐型ステントグラフト解剖学的不適合症例に対するDouble D Techniqueの有用性

企業製分岐型ステントグラフト解剖学的不適合症例に対するDouble D Techniqueの有用性

Neck diameter and inner curve seal zone predict endograft-related complications in highly angulated necks after endovascular aneurysm repair using the Aorfix endograft

ObjectiveMany studies have found that preoperative aneurysm anatomy can determine the postoperative complication rates for endovascular aneurysm repair (EVAR). With continual improvement in endograft technology, patients with challenging anatomy are increasingly able to undergo successful treatment with EVAR. This study aimed to quantify the influence of proximal neck anatomy on contemporary outcomes in a cohort of abdominal aortic aneurysm patients with highly angulated aneurysm necks. MethodsThe study included 205 patients originally enrolled in the Prospective Aneurysm Trial: High Angle Aorfix Bifurcated Stent Graft (PYTHAGORAS) trial, the largest study to date to enroll patients with aortic aneurysm neck angles >60 degrees. Anatomic parameters included measurements of the proximal aneurysm neck as well as seal zones modeled in preoperative computed tomography scans. Follow-up up to 5 years postoperatively was available, for which stent-related complications (defined as sac expansion, stent migration, and type Ia endoleak) were assessed. Predictive anatomic parameters were assessed by Cox regression models, and a final multivariate model was created to predict complications. The cohort was also stratified by neck diameter for further comparison of complication rates. ResultsOf 205 patients enrolled in the trial, 67 stent-related complications occurred in 36 patients (17.6%) at 5 years after EVAR. Median follow-up was 48 months. Demographic and medical comorbidities did not predict risk of complications, nor did proximal neck length or neck angle. Independent predictors of post-EVAR complications included increasing proximal neck diameter (hazard ratio, 1.14; 95% confidence interval, 1.03-1.27; P < .05) and decreasing seal zone inner curve length (hazard ratio, 1.03; 95% confidence interval, 1.01-1.06; P < .05), which yielded a fair discriminatory utility (concordance, 0.67). Stratification by median neck diameter of 22.5 mm yielded two groups; patients with larger aortic necks (mean diameter, 24.8 ± 2.1 mm) had a 21.8% complication rate vs 12.6% in patients with smaller necks (mean diameter, 20.1 ± 1.6 mm; P < .05). ConclusionsProximal aortic neck diameter and the seal zone inner curve length were found to be the best predictors of complications related to Aorfix (Lombard Medical, Oxfordshire, United Kingdom) in this population with highly angulated neck anatomy. Modeled seal zones are better able than traditional measurements to capture the limitations of a short, angled neck. These findings may inform preoperative risk stratification and planning in patients with hostile aortic neck anatomy undergoing EVAR.

Outcomes of Endovascular Repair for Abdominal Aortic Aneurysms: A Nationwide Survey in Japan.

Objective:To analyze data on patients treated with a bifurcated stent graft for abdominal aortic aneurysm (AAA).Background:The Japan Committee for Stentgraft Management (JACSM) was established in 2007 to manage the safety of endovascular aortic aneurysm repair (EVAR) in Japan. The JACSM registry includes detailed anatomical and clinical data of all patients who undergo stent graft insertion in Japan.Methods:Among 51,380 patients treated with bifurcated stent graft for AAA, we identified 38,008 eligible patients (excluding those with rupture or insufficient data). The analyzed factors included age, sex, comorbidities, AAA pathology and etiology, aneurysm and neck diameters, 7 anti-instructions for use (IFU) factors, and endoleaks at hospital discharge. The endpoints were death, adverse events, sac dilatation (≥5 mm), and reintervention.Results:The rates of intraoperative and in-hospital mortality were 0.08% and 1.07%, respectively. Infectious aneurysm and pseudo-aneurysm were associated with overall survival and reintervention. Older age, large aneurysm diameter, and all types of persistent endoleaks were strong predictors of adverse events, sac dilatation, and reintervention. Comorbid cerebrovascular disease, renal dysfunction, and respiratory disorders were also risk factors. In total, 47.6% of patients violated the IFU; among the anti-IFU factors assessed, poor access and severe neck calcification were strong risk factors for mortality, reintervention, and adverse events. The sac dilatation rate at 5 years was 23.3%.Conclusions:Although the analysis included EVAR with poor anatomy, the perioperative mortality rate was acceptable compared with that in previous large population studies.

Clinical experience in treatment of the isolated abdominal aortic dissection

Objective This retrospective study is to analyze and summarize the clinical features and therapeutic experience of the isolated abdominal aortic dissection(IAAD). Methods Totally 17 patients of IAAD, who were admitted to our hospital from January 2009 to January 2016, were included in this retrospective analysis. Five patients with obvious pain or abdominal aorta diameter of 30 mm accompanied with sub-renal anchorage area of 15 mm, underwent endovascular repair. In these 5 patients, 4 cases were subjected to bifurcated stent graft endovascular repair and 1 case received the aorta uni-iliac endovascular repair combined with femoral-femoral artery bypass treatment. Moreover, 2 patients with sub-renal anchorage area of less than 15 mm were subjected to surgical treatment. In these 2 patients, 1 case with obvious pain and abdominal aorta diameter of 30 mm underwent the abdominal aorta-right iliac artery bypass combined with femoral-femoral artery bypass, while the other case with abdominal aorta diameter of 30 mm but no pain received the abdominal aorta-bilateral iliac artery bypass. Furthermore, 8 patients with no obvious pain and abdominal aorta diameter of less than 30 mm received conservative medical treatment. In addition, there were 2 patients with obvious pain and abdominal aorta diameter of 30 mm suffering from sudden death during the surgical preparation. Important complications of these patients during hospitalization and follow-up period were recorded, analyzed, and compared. Results For the 5 patients undergoing endovascular repair, the averaged hospitalization duration was (15.4±2.9) d, one of whom died during hospitalization. There were 3 cases with follow-up period of ≥ 12 months, and 1 case reported left iliac branch occlusion. For the 2 patients subjected to surgical treatment, the follow-up period was less than 12 months, and no serious complications occurred during hospitalization or follow-up period. For the 8 patients receiving conservative medical treatment, the averaged hospitalization duration was (11.1±5.2) d. There were 4 cases with follow-up period of ≥ 12 months, and no serious complications occurred during hospitalization or follow-up period. Conclusions Endo or open surgical treatment is recommended for patients with isolated abdominal aortic dissection with obvious pain or abdominal aortic diameter of 30 mm. For the patients with no pain and abdominal aortic diameter of less than 30 mm, conservative medical treatment is recommended. Key words: Aneurysm, dissecting; Aorta, abdominal; Clinical protocols; Comparative effectiveness research

Theoretical mechanism of temporary renal function improvement after abdominal aortic aneurysm surgery: Applications for clinical imaging and laboratory data.

We evaluated the effects of changes in blood flow due to abdominal aortic aneurysm (AAA) surgery by using a simple zero-dimension model and applied theoretical values to clinical data.The zero-dimension electronic circuit model and diagram of blood flow distribution were created by setting the resistance of the aorta, bilateral iliac arteries, renal arteries, and aneurysm. Resistance of the aneurysm and resistance of the aorta before surgery were compared with that of the aorta after surgery. We set the radius length of each anatomical parameter to calculate theoretical values.Renal flow increased 13.4% after surgery. Next, we analyzed contrast-enhanced computed tomography data of 59 patients who underwent AAA surgery. A total of 19 patients were treated with a Y graft and 7 patients were treated with a straight graft during open surgery. However, 33 patients were treated with a bifurcated stent graft. A significant linear relationship between the increased estimated glomerular filtration rate (eGFR) ratio and the decreased aneurysm ratio was found only for the straight graft group.Using a circuit model, renal blood flow theoretically increased after AAA surgery. Clinically, there was a correlation between volume regression and eGFR improvement only in the limited AAA group.

Endovascular treatment of abdominal aortic aneurysms with narrow aortic bifurcation using Excluder bifurcated stent grafts

ObjectiveThis study investigated the influence of the aortic bifurcation anatomy on the endovascular treatment of abdominal aortic aneurysms using Excluder (W. L. Gore & Associates, Flagstaff, Ariz) bifurcated stent grafts. MethodsThis was a retrospective single-center study of patients treated with the Excluder stent graft. Analysis included anatomical factors of the aortic bifurcation (aortic bifurcation diameter [ABD], calcification, thrombus), characteristics of the stent graft limbs (sum of stent graft limbs diameters [SLD]), and the SLD/ABD ratio. Narrow bifurcation was defined as ABD <20 mm. Primary outcomes were intraoperative stenosis, need for additional intraoperative measures, limb stenosis, and occlusion during follow-up. ResultsThe study included 232 patients. Mean ABD was 24.6 ± 6 mm, with 53 patients (23%) presenting with narrow bifurcation (range, 12.5-19.5 mm). Median SLD in these patients was 28 mm, and the SLD/ABD ratio was 1.64. Calcification involving >50% of the bifurcation circumference was present in 32% of the patients, with 17% presenting thrombus in this area. Of 53 patients with narrow bifurcation, intraoperative stenosis >50% occurred in three (5.7%), which required adjunctive treatment. Computed tomography at 1 month showed limb stenosis >50% in nine patients (17%). No limb occlusions were recorded with a median follow-up of 34 months. Multivariate analysis of the overall series showed a higher risk of limb stenosis on the computed tomography at 1 month in patients with peripheral artery disease (hazard ratio [HR], 5.3; 95% confidence interval [CI], 1.2-24.4; P = .032), narrow bifurcation (HR, 5.7; 95% CI, 2-15.8; P = .001), higher SLD/ABD ratio (HR, 29.3; 95% CI, 4-215.2; P = .001), and calcium >50% (HR, 3; 95% CI, 1.1-8; P = .03), and lower in bifurcations with thrombus (HR, 0.3; 95% CI, 0.1-0.8; P = .017). ConclusionsAbdominal aortic aneurysms with narrow bifurcation can be treated with the bifurcated Excluder device without additional adjunctive measures. The presence of limb stenosis during follow-up is not associated with occlusion. Long-term follow-up studies are needed to confirm these results.

Bifurcated-bifurcated aneurysm repair is a novel technique to repair infrarenal aortic aneurysms in the setting of iliac aneurysms

BackgroundUp to 40% of abdominal aortic aneurysms (AAAs) have coexistent iliac artery aneurysms (IAAs). In the past, successful endovascular repair required internal iliac artery (IIA) embolization, which can lead to pelvic or buttock ischemia. This study describes a technique that uses a readily available solution with a minimally altered off-the-shelf bifurcated graft in the IAA to maintain IIA perfusion. MethodsFrom August 2009 to May 2015, 14 patients with AAAs and coexisting IAAs underwent repair with a bifurcated-bifurcated approach. A 22-mm or 24-mm bifurcated main body device was used in the IAA with extension of the “contralateral” limb into the IIA. Intraoperative details including operative time, fluoroscopy time, and contrast agent use were recorded. Outcome measures assessed were operative technical success and a composite outcome measure of IIA patency, freedom from reintervention, and clinically significant endoleak at 1 year. ResultsFourteen patients underwent bifurcated-bifurcated repair during the study period. Technical success was achieved in 93% of patients, with successful treatment of the AAA and IAA and preservation of flow to at least one IIA. The procedure was performed with a completely percutaneous bilateral femoral approach in 92% of patients. Three patients had a type II endoleak on initial follow-up imaging, but none were clinically significant. There were no cases of bowel ischemia or erectile dysfunction. One patient had buttock claudication ipsilateral to IIA coil embolization (contralateral to bifurcated iliac repair and preserved IIA) that resolved by 6-month follow-up. Two patients required reinterventions. One patient presented to his first follow-up visit on postoperative day 25 with thrombosis of the right external iliac limb ipsilateral to the bifurcated iliac repair, which was successfully treated with thrombectomy and stenting of the limb. This same patient presented at 83 months with growth of the preserved IIA to 3.9 cm and underwent coil embolization of the aneurysm. Another patient presented for surveillance 44 months after his original repair with component separation of the mating stent and the iliac bifurcated stent grafts. This was treated with a limb extension and endoanchors to fuse the endografts. Of the 13 patients who underwent bifurcated-bifurcated repair, 100% of the preserved IIAs remained patent at last follow-up. The composite outcome measure of IIA patency and freedom from reintervention and clinically significant endoleak at 1 year was 92% (n = 12/13). ConclusionsIn this small retrospective review, bifurcated-bifurcated aneurysm repair of aortoiliac aneurysms with preservation of perfusion to the IIA is technically feasible and safe with good short-term and midterm results in male patients.

Five-year outcomes of the PYTHAGORAS U.S. clinical trial of the Aorfix endograft for endovascular aneurysm repair in patients with highly angulated aortic necks

ObjectiveEarly and midterm outcomes of the Prospective Aneurysm Trial: High Angle Aorfix Bifurcated Stent Graft (PYTHAGORAS) trial in patients with highly angulated aortic necks (≥60 degrees) have already been published and shown comparable outcomes to other endografts in normal anatomy. Herein, we present the long-term outcomes of the PYTHAGORAS trial of Aorfix (Lombard Medical, Irvine, Calif) for patients with highly angulated aortic neck anatomy. MethodsThe Aorfix endograft is a highly conformable nitinol/polyester device designed for transrenal fixation. The U.S. trial enrolled 218 patients and observed all patients at 1 month, 6 months, and 12 months and then annually for a total of 5 years. Endovascular aneurysm repair (EVAR)-specific complications were compared between the standard-angle (<60 degrees) and highly angulated (≥60 degrees) neck groups at 5 years using standard statistical methods. Kaplan-Meier analysis was performed to evaluate the overall 5-year survival and freedom from aneurysm rupture, aneurysm-related mortality, and reintervention. ResultsOf the 218 patients enrolled in the trial, there were 67 patients in the standard-angle neck group (I) and 151 patients in the highly angulated neck group (II). Mean proximal neck angle was 45 degrees in group I vs 83 degrees in group II (P < .001). At 5 years, 87% of surviving patients were followed up. The 5-year EVAR-specific results showed no type I or type III endoleak in either group, 4% migration in group I vs 3% in group II, and 4% sac expansion in group I vs 15.0% in group II (P ≥ .27). The 5-year freedom from all-cause mortality was 69% (73% in group I vs 68% in group II; P = .43); from aneurysm-related mortality, 96% (99% vs 95%; P = .44); from aneurysm rupture, 99% (99% vs 99%; P = 1.0); and from device-related secondary intervention, 83% (88% vs 80%; P = .18). None of these differed between groups. ConclusionsThe U.S. PYTHAGORAS trial of the Aorfix endograft is the first EVAR clinical trial to include a majority of highly angulated (≥60 degrees) infrarenal aortic necks and is the first to produce evidence after 5 years of implantation. Despite predictors of worse short- and long-term outcomes, pertinent outcomes were better than or similar to those of trials with less severe anatomy. These results support the use of this “on-label” endovascular option, particularly in patients with highly angulated aortic neck anatomy.

Predisposing Factors for Re-interventions with Additional Iliac Stent Grafts After Endovascular Aortic Repair

Endoleaks of type Ib and III are relatively common causes of re-intervention after EVAR. The aim was to determine underlying causes and identify anatomical factors associated with these re-interventions. A total of 444 patients with standard bifurcated stent grafts were included in a retrospective observational study. Patients requiring additional iliac stent grafts (n=24) were compared to those who did not (n=420). Pre- and post-operative CT examinations were reviewed in patients with additional iliac stents. Reasons for re-interventions were defined as migration (>5mmat the distal end or at interconnections), progression of disease (iliac artery diameter exceeding graft diameter), inadequate distal seal length at primary repair, or a combination of these factors. Twenty-four patients received 31 additional grafts in 30 limbs after a median 46 months (range 2-92 months). Five re-interventions (21%) were due to rupture. Re-intervened limbs had a larger iliac artery diameter 18mm (25th and 75th percentile 20-25) versus 15mm (13-18mm), p<.001. The degree of iliac limb oversizing at primary EVAR was lower in re-intervened patients (11% (8-18%) versus 18% (12-26%), p=.003). In re-intervened patients, iliac attachment zones were shorter in treated limbs than in untreated 23mm (11-34) versus 34mm (25-44), p<.001). Sixteen of 31 re-interventions (51%) were caused by migration (10at the distal landing site, 6at interconnections), nine of 31 (29%) by disease progression, and nine of 31 (29%) had inadequate initial stent graft placement. Three of 31 re-interventions (10%) were done as proactive procedures. Additional iliac stent grafting occurred late after primary repair; a considerable number were caused by rupture. A low degree of oversizing, migration at the distal landing site, separation of stent graft interconnections, disease progression at the distal landing site, and inadequate initial stent graft placement may all contribute. Patients with large iliac dimensions and short attachment zones may need a larger degree of oversizing and more vigorous surveillance.

Endovascular treatment of aneurysms using fenestrated-branched endografts with distal inverted iliac limbs

Open aortoiliac grafts have typically been constructed with a short aortic bifurcation sewn near or to the visceral vessels to avoid limb kinking. Similarly, the majority of endovascular bifurcated stent grafts have short aortic main body ranging from 3 to 5cm. In these patients, endovascular salvage with fenestrated stent grafts is technically challenging because of the short distance between the renal arteries and the flow divider of the graft. Custom fenestrated stent grafts can be extended into the prior open surgical graft or stent graft using a short distal bifurcated stent graft with inverted iliac limb for the contralateral gate. The aim of this study was to evaluate outcomes of patients treated with fenestrated stent grafts coupled with inverted iliac limbs for salvage of failed open surgical and endovascular stent grafts. The clinical data of three U.S. aortic centers that use fenestrated stent grafts was entered into prospectively maintained databases from 2011 to 2014. All patients received customized distal bifurcated devices constructed with a main body less than 70mm and an inverted iliac limb to dock the contralateral gate. End points were technical success, 30-day mortality, type I or III endoleak, limb occlusion, and secondary reintervention. The Institutional Review Board of each institution approved the use of the modified graft, and each patient provided informed consent. There were 56 patients (41 male), with mean age of 75years treated by fenestrated stent grafts using distal bifurcated devices with inverted iliac limbs. Forty-seven patients had a previous aortic repair with a short main body device, and nine had short distances between the native renal artery and aortic bifurcation requiring inverted limbs. A total of 184 visceral arteries were targeted by fenestrations. Technical success was 96.4% with no 30-day deaths. At a mean follow-up of 11months, seven patients developed endoleaks, with one device migration, no occlusions, or other complications associated with the inverted limb. On the inverted iliac limb side, there were four complications. Two patients developed type Ib endoleaks treated by limb extension and angioplasty, and one patient developed distal limb ischemia secondary to embolization treated by thrombectomy. One additional patient developed a component separation of the inverted limb discovered with follow-up imaging treated with aortouni-iliac repair. Patients with a short distance between the renal arteries and the aortic bifurcation can be challenging for endovascular treatment using currently available devices. The use of inverted limb custom devices avoids the need for aortouni-iliac repair with femoral-femoral bypass preserving antegrade perfusion. In the short term, rates of complication are similar to what has been reported for universal bifurcated devices with noninverted iliac limbs.