Neck Angulation Research Articles

Morphological and stent design risk factors to prevent migration phenomena for a thoracic aneurysm: A numerical analysis

The primary mechanically related problems of endovascular aneurysm repair are migration and type Ia endoleaks. They occur when there is no effective seal between the proximal end of the stent-graft and the vessel. In this work, we have developed several deployment simulations of parameterized stents using the finite element method (FEM) to investigate the contact stiffness of a nitinol stent in a realistic Thoracic Aortic Aneurysm (TAA). Therefore, we evaluated the following factors associated with these complications: (1) Proximal Attachment Site Length (PASL), (2) stent oversizing value (O%), (3) different friction conditions of the stent/aorta contact, and (4) proximal neck angulation α.The simulation results show that PASL>18mm is a crucial factor to prevent migration at a neck angle of 60°, and the smoothest contact condition with low friction coefficient (μ=0.05). The increase in O% ranging from 10% to 20% improved the fixation strength. However, O%≥25% at 60° caused eccentric deformation and stent collapse. Higher coefficient of friction μ>0.01 considerably increased the migration risk when PASL=18mm. No migration was found in an idealized aorta model with a neck angle of 0°, PASL=18mm and μ=0.05. Our results suggest carefully considering the stent length and oversizing value in this neck morphology to strengthen the contact and prevent migration.

Analysis of EndoAnchors for endovascular aneurysm repair by indications for use

The proximal aortic neck remains one of the challenges of endovascular aneurysm repair (EVAR), and the risk of type Ia endoleak and endograft migration is increased in patients with short, large-diameter, or highly angulated necks. EndoAnchors have been used as an adjunct to EVAR in such patients, and the aim of this study was to assess their benefit analyzed by indication for use. During a 2-year period, 319 patients were enrolled at 43 sites in the Aneurysm Treatment Using the Heli-FX Aortic Securement System Global Registry (ANCHOR) study. This prospective, multinational, real-world analysis of EndoAnchors comprised two groups of patients, those undergoing first-time EVAR (primary arm, 242) and those with proximal neck complications remote from the time of an initial endograft implantation (revision arm, 77). The primary arm was further subdivided into patients undergoing prophylactic EndoAnchor use for hostile proximal neck anatomy (178), with a type Ia endoleak evident during initial endograft deployment (60), and in conjunction with extender cuffs after unsatisfactory endograft deployment distally in the neck (four). The revision arm was subdivided into patients presenting with a type Ia endoleak alone (45), endograft migration alone (11), and migration with endoleak (21). Technical success was site reported as satisfactory deployment of the desired number of EndoAnchors without fracture or loss of integrity. Procedural success was defined as technical success without type Ia endoleak at completion arteriography. Core laboratory analysis was performed on 249 baseline and 192 follow-up computed tomographic studies, 66 of which were available within the 1-year window. Technical and procedural success rates were highest in the prophylactically treated subset (172 of 178; 96.6%). Whereas the technical success of EndoAnchor deployment was also high in the other subsets, residual type Ia endoleaks were more frequent at completion angiography when the indication for EndoAnchor use was type Ia endoleak, both in the primary arm (17 of 60; 28%) and in the revision arm (9 of 45; 20%). During a median imaging follow-up of 7 months, 183 of 202 patients (90.1%) remained free of type Ia endoleaks. Primary prophylactic patients were free from type Ia endoleak in 110 of 114 cases (96.5%). The most challenging subset was revision patients treated for type Ia endoleak; type Ia endoleaks were evident during follow-up in 10 of 29 of the cases (34%). Sac regression >5 mm in patients with 1-year imaging was observed in 26 of 66 patients (39%) and was highest in the primary prophylaxis subset (20 of 43; 47%). EndoAnchor implantation can be a useful adjunct to EVAR as prophylaxis against proximal attachment site complications in patients with hostile aortic neck anatomy, as treatment for early and late type Ia endoleaks, or, in conjunction with aortic extension cuffs, for endograft migration. Whereas the most challenging patients are those who present with type Ia endoleaks remote from initial EVAR, EndoAnchors are still effective in treating the majority of these cases.

Clinical Outcomes of Limited-Open Retrograde Intramedullary Headless Screw Fixation of Metacarpal Fractures

To evaluate clinical and radiographic outcomes in patients treated with limited-open retrograde intramedullary headless compression screw (IMHS) fixation for metacarpal neck and shaft fractures. Retrospective review of prospectively collected data on a consecutive series of 39patients (34 men; 5 women), mean age 28 years (range, 16-66 y) treated with IMHS fixation for acute displaced metacarpal neck/subcapital (N= 26) and shaft (N= 13) fractures at a single academic practice between 2010 and 2014. Preoperative magnitude of metacarpal neck angulation averaged 54° (range, 15° to 70°), and shaft angulation averaged 38° (range, 0° to 55°). Patients used a hand-based orthosis until suture removal and began active motion within the first week. Clinical outcomes were assessed with digital goniometry, pad-to-distal palmar crease distance, and grip strength. Time to union and radiographic arthrosis was assessed. Twenty patients reached minimum 3-month follow-up, with a mean of 13 months (range, 3-33 mo). All 20 patients with minimum 3 months of follow-up achieved full composite flexion, and extensor lag resolved by 3-week follow-up. All patients demonstrated full active metacarpophalangeal joint extension or hyperextension. Grip strength measured 105% (range, 58% to 230%) of the contralateral hand. No secondary surgeries were performed. There were 2 cases of shaft re-fracture from blunt trauma following prior evidence of full osseous union with the screw in place. All patients achieved radiographic union by 6 weeks. There was no radiographic arthrosis at latest follow-up. One patient reported occasional clicking with metacarpophalangeal joint motion not requiring further treatment. Limited open retrograde IMHS fixation proved to be safe and reliable for metacarpal neck/subcapital and axially stable shaft fractures, allowed for early postoperative motion without affecting union rates, and obviated immobilization. This technique offers distinct advantages in select patients. Therapeutic IV.

Results of the ANCHOR prospective, multicenter registry of EndoAnchors for type Ia endoleaks and endograft migration in patients with challenging anatomy

Proximal attachment site complications continue to occur after endovascular repair of abdominal aortic aneurysms (EVAR), specifically type Ia endoleak and endograft migration. EndoAnchors (Aptus Endosystems, Sunnyvale, Calif) were designed to enhance endograft proximal fixation and sealing, and the current study was undertaken to evaluate the potential benefit of this treatment. During the 23-month period ending in December 2013, 319 subjects were enrolled at 43 sites in the United States and Europe. EndoAnchors were implanted in 242 patients (75.9%) at the time of an initial EVAR procedure (primary arm) and in 77 patients with an existing endograft and proximal aortic neck complications (revision arm). Technical success was defined as deployment of the desired number of EndoAnchors, adequate penetration of the vessel wall, and absence of EndoAnchor fracture. Procedural success was defined as technical success without a type Ia endoleak at completion angiography. Values are expressed as mean± standard deviation and interquartile range. The 238 male (74.6%) and 81 female (25.4%) subjects had a mean age of 74.1± 8.2years. Aneurysms averaged 58± 13 (51-63) mm in diameter at the time of EndoAnchor implantation (core laboratory measurements). The proximal aortic neck averaged 16± 13 (7-23) mm in length (42.7%<10mm and 42.7% conical) and 27± 4mm (25-30mm) in diameter; infrarenal neck angulation was 24± 15 (13-34) degrees. The number of EndoAnchors deployed was 5.8± 2.1 (4-7). Technical success was achieved in 303 patients (95.0%) and procedural success in 279 patients (87.5%), 217 of 240 (89.7%) and 62 of 77 (80.5%) in the primary and revision arms, respectively. There were 29 residual type Ia endoleaks (9.1%) at the end of the procedure. During mean follow-up of 9.3± 4.7months, 301 patients (94.4%) were free from secondary procedures. Among the 18 secondary procedures, eight were performed for residual type Ia endoleaks and the others were unrelated to EndoAnchors. There were no open surgical conversions, there were no aneurysm-related deaths, and no aneurysm ruptured during follow-up. Use of EndoAnchors to treat existing and acute type Ia endoleaks and endograft migration was successful in most cases. Prophylactic use of EndoAnchors in patients with hostile aortic neck anatomy appears promising, but definitive conclusions must await longer term follow-up data.

Immediate and Two-year Outcomes after EVAR in “On-label” and “Off-label” Neck Anatomies Using Different Commercially Available Devices. Analysis of the Experience of Two Italian Vascular Centers

Endovascular aneurysm repair (EVAR) has fast become the therapeutic strategy of choice for abdominal aortic aneurysms (AAAs). Nowadays, the most important limit to the effectiveness of this technique is represented by complex anatomical situations, especially regarding the morphology of the proximal sealing zone. The aim of this study was to evaluate the 2-year outcome of unselected, real-world patients with "off-label" (off-L) proximal necks treated in 2 high-volume Italian vascular centers. A double-center study was conducted on a prospectively compiled computerized database between January 2010 and December 2011. One hundred and ninety-six consecutive elective surgery patients were analyzed and divided into 2 groups ("on-label" [on-L] and "off-L" necks) on the basis of their aortic neck anatomy. The neck was classified as an "off-L neck" in the presence of: (1) a noncylindrical neck, (2) an angulated neck, (3) a short neck, and (4) an enlarged neck. The end points were 30-day and 2-year technical and clinical success, evaluated in terms of freedom from reintervention and death. One hundred and thirty-three elective patients were treated by standard EVAR in the presence of an "off-L" proximal neck anatomy. Technical success was achieved in all cases in both groups. Six (9.5%) unplanned adjunctive procedures were necessary in the on-L group and 16 (12%) in the off-L group (P = ns). Perioperative endoleaks, reinterventions, stent-graft migration rates, and AAA-related deaths were null. A multivariate analysis was performed to evaluate the subgroups of patients with 2 or > 2 anatomic factors that indicate a challenging neck. In patients with 2 such factors, a significant difference was observed in terms of intraoperative adjunctive procedures, intraoperative endoleaks, and all-cause mortality: 26.7% vs. 9.9% (P = 0.048), 6.7% vs. 0.5% (P = 0.023), and 13.3% vs. 1.1% (P = 0.0012), respectively. The same differences became increasingly evident when analyzing patients with > 2 criteria: 50% vs. 10% (P = 0.0022), 16.7% vs. 0.5% (P < 0.001), and 16.7% vs. 1.0% (P = 0.01). No AAA-related deaths or AAA ruptures were reported in either group at the end of the 2-year follow-up. High-flow endoleaks, stent-graft migration, and, consequently, reintervention were more frequent in the off-L group, but none of these parameters reached statistical significance. Our experience seems to show that the off-L use of EVAR could be considered effective for the treatment of patients unfit for open surgery. In patients with more than one anatomical proximal neck feature contraindicating open surgery, the rate of immediate complications and reinterventions was higher, but this did not affect the clinical benefit and success at 2-year follow-up.

Disease-specific guidelines for reporting adverse events for peripheral vascular medical devices

Disease-specific guidelines for reporting adverse events for peripheral vascular medical devices

Geometrical factors influencing the hemodynamic behavior of the AAA stent grafts: essentials for the clinician.

Endovascular aneurysm repair (EVAR) is considered to be the treatment of choice for abdominal aortic aneurysms (AAA). Despite the initial technical success, EVAR is amenable to early and late complications, among which the migration of the endograft (EG) with subsequent proximal endoleak (Type Ia) leads to repressurization of the AAA sac, exposure to excessive wall stress, and, hence, to potential rupture. This article discusses the influence that certain geometrical factors, such as neck angulation, iliac bifurcation, EG curvature, neck-to-iliac diameter, and length ratios, as well as iliac limbs configuration can exert on the hemodynamic behavior of the EGs. The information provided could help both clinicians and EG manufacturers towards further development and improvement of EG designs and better operational planning.

Monte Carlo Simulations for Assessment of Organ Radiation Doses and Cancer Risk in Patients Undergoing Abdominal Stent-graft Implantation

The aim of this work was to assess absorbed radiation doses in selected organs and to estimate cancer and mortality risks in patients undergoing abdominal stent-graft implantation, as a function of age, gender, and anatomical parameters of patients' aneurysms and arteries. 297 patients (266 males and 31 females) underwent endovascular aortic aneurysm repair (EVAR) with abdominal stent-graft implantation. Kerma-area products Gy-cm(2) for all implanted patients were collected retrospectively. Entrance surface air kerma (ESAK), doses absorbed by selected organs, and cancer/mortality risks were estimated using Monte Carlo simulation methods (CALDose_X software). The highest radiation doses were deposited in the skin, gallbladder wall, and colon wall. The highest average cancer risk was found for the youngest group of patients (<60 years old; 1:275) and the lowest for the oldest (>70 years old, 1:735). The radiation-induced risk of cancer mortality (mortality risk) was about 40% lower than radiation-induced cancer occurrence risk. Aneurysm neck angulations >45° had a significant impact on ESAK, as well as increasing cancer and mortality risks. The main factors increasing cancer risk are young age and aneurysm neck angulations >45°, which determines the difficulty of proper stent-graft placement. However, the radiation risk associated with the stent-graft implantation procedure is relatively low, and EVAR should not be avoided.

Diferencias entre la planificación del tratamiento endovascular de aneurismas de aorta abdominal con reconstrucción tridimensional vs tomografía computarizada y angiografía, y su impacto clínico

ObjectivesThe primary endpoint of this study is to compare endovascular aneurysm repair (EVAR) planning using a three-dimensional study with the one based on computed axial tomography and calibrated aortography. The impact of the variability in the measurements on the clinical and technical outcomes was also analyzed. Material and methodsRetrospective and observational study of 35EVAR procedures between the years 2006-2008. Measurements made with CT and calibrated aortography were collected and then compared with measurements made in a three-dimensional study. The CT studies were processed at a workstation using two techniques with two different interpretations: pure central lumen line (CLL) and rectified CLL (estimating the path of the graft in the aorta). The correlation between the lengths and diameters were assessed. Intra- and inter-observer agreement and variability between measurement methods were analyzed using the intraclass correlation coefficient (ICC). The anatomical and technical variables associated with differences were also analyzed. χ2, Fischer, and Student-t tests were used for statistical analysis, considering P<.05 as statistically significant. ResultsThe correlation between different measurement techniques was high, close to 0.9 ICC for diameters; and 0.83, 0.75 and 0.76 for L1, L2, and L3, respectively (L1: length in millimeters from the aortic neck to the iliac bifurcation; L2 and L3: length in millimeters from the aortic neck to the right and left iliac bifurcation). The intra- and inter-observer agreement was higher than 0.8 in all measurements. The aneurysm diameter, the tortuosity of the iliac vessels and aortic neck angulation, were associated with greater variability (P<.05). There was a longer surgery and fluoroscopy time, and a need for more limb extensions, and modifications of planned graft in the group with variability in length measurements. ConclusionsIn our experience the classical method is effective, and the results obtained with both measurement techniques are comparable. Additionally, the three-dimensional study provides greater accuracy in planning, gives more knowledge of the anatomical characteristics of the aneurysm, and provides clinical and technical benefits.

Results of the Anaconda endovascular graft in abdominal aortic aneurysm with a severe angulated infrarenal neck

Proximal neck anatomy of an abdominal aortic aneurysm (AAA), especially a severe angulated neck of more than 60 degrees, predicts adverse outcome in endovascular aneurysm repair. In the present study, we evaluate the feasibility of the use of the Anaconda endovascular graft (Vascutec, Terumo, Inchinnan, Scotland) for treating infrarenal AAA with a severe angulated neck (>60 degrees) and report the midterm outcomes. In total, nine Dutch hospitals participated in this prospective cohort study. From December 2005 to January 2011, a total of 36 AAA patients, 30 men and six women, were included. Mean and median follow-up were both 40 months. Mean infrarenal neck angulation was 82 degrees. Successful deployment was reached in 34 of 36 patients. Primary technical success was achieved in 30 of 36 patients (83%). There was no aneurysm-related death. Four-year primary clinical success was 69%. In the first year, eight clinical failures were reported including four leg occlusions which could be solved using standard procedures. After the first year, three patients with additional failures occurred; two of them were leg occlusions. Four patients needed conversion to open AAA exclusion. In six of 36 patients, one or more reinterventions were necessary. Three of them were performed for occlusion of one Anaconda leg and two were for occlusion of the body. The use of the Anaconda endovascular graft in AAA with a severe angulated infrarenal neck is feasible but has its side effects. Most clinical failures occur in the first year. Thereafter, few problems occur, and midterm results are acceptable. Summarizing the present experiences, we conclude that open AAA repair is still a preferable option in patients with challenging aortic neck anatomy and fit for open surgery.

Feasibility of Endovascular Abdominal Aortic Aneurysm Repair Outside of the Instructions for Use and Morphological Changes at 3 Years after the Procedure

We retrospectively analyzed outcomes of patients who had undergone endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) more than 3 years previously in a single institution. We compared outcomes between patients who underwent EVAR within and outside of the devices' instructions for use (IFU) and examined mid-term morphological changes in AAA. A total of 275 patients who underwent EVAR for AAA were selected. IFU parameters included aneurysmal neck length, angulation and presence of massive atheroma. Patients were divided into 2 groups: the Within IFU group (W-IFU: n = 193) and the Outside of IFU group (O-IFU: n = 82). Patients in the O-IFU group were older and had a larger AAA diameter. Other comorbid factors were similar between the 2 groups. There was no difference in overall survival rates and reintervention rates between the 2 groups. The most common cause for reintervention was AAA enlargement 3 years after EVAR. Irrespective of the IFU, mid-term morphological changes, including neck angulation, neck diameter, sac re-expansion, and Palmaz stent displacement, were found. Outcomes of EVAR were considered acceptable in the O-IFU group. Careful follow-up is necessary considering the morphological changes in AAAs after EVAR.

In House Enhanced 3D Printing of Complex AAA for EVAR Treatment Planning and Preoperative Simulation

Three dimensional printing (3D printing) is becoming a common useful technology in many areas in medicine. This technology allows better appreciation of complex anatomical and pathologic conditions. In vascular medicine and surgery 3d modeling may become of help in Endovascular Aortic Repair (EVAR) treatment planning, especially in cases of complex angulations and branching at the aneurysm neck. Accurate and rapid solid 3d models were prepared in house using common and freely available software programs, and an accurate 3D printer. These solid models allowed palpation and manual handling and visual inspection for a better appreciation of complex AAA necks. Color enhancement of these models added another dimension of comprehension, even for experienced surgeons and invasive radiologists. A full sized model may allow more accurate measurements of branch distances and angles in space when tortuosity is severe. Fenestrations and “Chimney” branches may be easily envisioned preoperatively. In addition, 3D hollow outer shells were constructed to obtain a workable AAA arterial wall-like model for rehearsal and preoperative stent graft deployment simulation. Various commercial stent grafts from several manufacturers were deployed under fluoroscopy to evaluate feasibility of the planned procedure. In simple AAA cases device deployment simulation was always successful, but in one AAA case with a severely angulated neck all devices failed. We conclude that 3D printing and modeling and outer shell fabrication for preoperative simulation are helpful in EVAR planning of complex AAA.

Experience with a novel custom-made fenestrated stent graft in the repair of juxtarenal and type IV thoracoabdominal aneurysms

Fenestrated stent grafting has become increasingly popular as a means to manage complex aortic pathology, including juxta- and pararenal aneurysms. The design of a recently developed custom-made fenestrated stent graft, in theory, confers advantages when managing anatomically challenging aortic morphology. This study evaluated its feasibility in anatomically challenging scenarios. Over a 12-month period, 20 patients received fenestrated stent grafts. Among those, 13 patients with juxtarenal or type IV thoracoabdominal aortic aneurysms underwent endovascular repair with the novel fenestrated stent graft at a single UK institution. Data on aneurysm morphology and immediate and short-term results were collected prospectively. The mean aneurysmal sac size was 7.3 cm (range, 5.5-10.0 cm). The mean infrarenal neck length was 4.4 mm (range, 0-9 mm), and in three cases was lined by a pre-existing infrarenal stent graft. Nine cases had an infrarenal neck angulation of 60(°) or more in either the anteroposterior or coronal planes. Five cases had ≥50% thrombus at the proximal landing zone. A total of 35 target vessels were cannulated, of which six right renal and four left renal arteries were angulated ≥120(°). Two-thirds of cannulated celiac trunks were angulated ≥120(°), and one cannulated superior mesenteric artery was angulated ≥ 140(°). Seven of the cannulated targets were stenosed more than 60%. One patient had two right renal arteries arising 3 mm from each other. Four right and four left common iliac arteries were angulated ≥90(°) in relation to the infrarenal aorta. Technical success was 100%. Median time from date of procedure to most recent follow-up with computed tomography scanning was 33 weeks. There was no type I or III endoleak. One type II endoleak was observed at the time of most recent computed tomography scanning and treated expectantly. There was a single incident of left renal artery occlusion. One patient required repair of a brachial artery, fasciotomies, and temporary haemofiltration. One patient died from ischemic heart disease 77 weeks after the procedure. The use of the novel fenestrated stent graft system in patients with hostile aortic aneurysmal morphology is feasible with acceptable short-term outcomes.

3D Printing of an Aortic Aneurysm to Facilitate Decision Making and Device Selection for Endovascular Aneurysm Repair in Complex Neck Anatomy

To describe rapid prototyping or 3-dimensional (3D) printing of aneurysms with complex neck anatomy to facilitate endovascular aneurysm repair (EVAR). A 75-year-old man had a 6.6-cm infrarenal aortic aneurysm that appeared on computed tomographic angiography to have a sharp neck angulation of ~90°. However, although the computed tomography (CT) data were analyzed using centerline of flow, the true neck length and relations of the ostial origins were difficult to determine. No multidisciplinary consensus could be reached as to which stent-graft to use owing to these borderline features of the neck anatomy. Based on past experience with rapid prototyping technology, a decision was taken to print a model of the aneurysm to aid in visualization of the neck anatomy. The CT data were segmented, processed, and converted into a stereolithographic format representing the lumen as a 3D volume, from which a full-sized replica was printed within 24 hours. The model demonstrated that the neck was adequate for stent-graft repair using the Aorfix device. Rapid prototyping of aortic aneurysms is feasible and can aid decision making and device delivery. Further work is required to test the value of 3D replicas in planning procedures and their impact on procedure time, radiation dose, and procedure cost.

The effect of prolapse repair on urinary flow rates and the relationship to changes in the ultrasound appearance of the bladder neck

ObjectiveTo assess whether specific changes in bladder neck morphology, caused by an anterior repair operation, are associated with resolution of overactive bladder and improved urinary flow rates. Study designSixty-four women with urgency documented on the urgency perception scale (UPS) underwent an anterior repair. Their preoperative flow studies were compared to those 8 weeks postoperatively. Flow rates were compared in those women who reported improved or cured urgency to those who reported no effect. Resolution of urgency was correlated with the change in bladder neck angulation (posterior urethrovesical angle-PUA). Results55% (35/64) women reported no urgency after the anterior repair. A further 19% (12/64) were improved and 26% (17/64) were no better. Patients who were cured or improved showed a significant increase in their flow rates after surgery (mean flow=15 before and 17.6ml/s after) (Mann–Whitney p=0.04). There was a significant change (increase in the PUA angle/straightening of the angle between the bladder and urethra) from a mean value of 123 degrees (SD 49.3) preoperatively to a mean value of 146.8 (SD 29.2) post operatively (p<0.001). Despite an increase in PUA, this was not correlated with an increase in the maximum flow rate centile (p=0.45, r=0.10). ConclusionsAn anterior repair results in increased maximum urinary flow rates but this does not correlate to changes in the appearance of the bladder neck.

Single center experience of endovascular abdominal aortic aneurysms repair

Methods Since May 2010 51 patients with a median age of 69 years were included. Among them there were 32 (89%) men and 4 (11%) women. 28 (78%) patients had infrarenal localization of abdominal aortic aneurysms, 8 (22%) patients had juxtarenal localization of AAA. In 34 patients (94%) abdominal aortic aneurysms were etiologicaly atherosclerotic and in 2 patients (6%) it was Marfan syndrome to be the definite reason for aneurysmatic disease. The maximum dimensions of the abdominal aorta averaged 59 ± 18mm. All patients had challenging anatomy: short and severely angulated and/or conic proximal aortic neck, unsuitable distal ”landing zone”, thrombus, calcification and complicated morphology, complex aneurysms and dissections of iliac and femoral arteries.

Endovascular Repair of Abdominal Aortic Aneurysms With Reverse Taper Neck Anatomy Using the Endurant Stent-Graft: Analysis of Stent-Graft Oversizing

To evaluate endovascular repair of infrarenal abdominal aortic aneurysms (AAA) using the Endurant stent-graft and compare the outcomes of patients with different neck anatomies, particularly as pertains to stent-graft oversizing. A retrospective review was conducted of 75 consecutive patients (69 men; mean age 75 years) undergoing endovascular AAA repair using the Endurant Stent Graft System from December 2008 to September 2011. The mean AAA size was 57±10 mm (range 51-92), with a mean proximal neck length of 33±10 mm (9-127) and a mean infrarenal neck angulation of 25°±15° (0°-91°). Patients were stratified according to neck anatomy [reverse taper (n=22) vs. inside (n=44) and outside (n=9) the Instructions for Use (IFU) criteria]. Standard safety and efficacy outcome measures were augmented by measurements of the percent oversizing at the proximal and distal neck and volumes of the proximal neck and stent-graft. Technical success was 100% in all groups, with no early or late type Ia endoleak detected in any group. Procedure time, contrast volumes, and radiation dosages were comparable in all groups. The reverse taper neck group had stent-graft diameters and volumes that were significantly larger (p=0.007) than the other groups. The proximal neck oversizing of the endograft was significantly greater (p=0.008) in the reverse taper neck group (42.9%±17.5%) compared to the within the IFU group (30.1%±11.7%). Over a mean follow-up of 20 months (range 14-46), there were no aneurysm-related deaths and 9 type II endoleaks (5 in the reverse taper neck group; overall, 3 were treated and 6 resolved spontaneously). The outside the IFU group suffered no endoleak of any type and had no secondary interventions. The Endurant stent-graft can be utilized with acceptable results in more challenging neck anatomies, such as those with a reverse taper, as long as there is adequate oversizing of the stent-graft.

Mid-Term Results and Morphological Neck Changes After EVAR in Patients With Severe Proximal Neck Angulation

Mid-Term Results and Morphological Neck Changes After EVAR in Patients With Severe Proximal Neck Angulation

Endovascular Treatment of Abdominal Aortic Aneurysms Should Not Be Denied to High-Surgical-Risk Patients

To analyze the initial and long-term results of endovascular aneurysm repair (EVAR) in high-surgical-risk patients (i.e., age ≥ 80 years, serum creatinine level ≥ 3 mg/dL, severe pulmonary dysfunction, severe cardiac dysfunction) with favorable anatomy (ie, proximal neck length of at least 15mm, proximal neck angulation < 60°, absence of thrombus in the proximal neck). From April 2002 to November 2012, 80 consecutive high-surgical-risk patients (65 men; mean age 74 years, range 54-91 years) with an abdominal aortic aneurysm (AAA; mean diameter 66.6 mm) who were treated electively using a bifurcated aortic endograft (39 Excluder, 40 Zenith, 1 Endurant) were entered in a prospective registry. Fifty-five (68.7%) patients were classified ASA III and 25 (31.3%) were ASA IV. High-surgical-risk status was corroborated using the validated Customized Probability Index score. All patients used statins and betablockers in the perioperative period. Primary end points were operative mortality and long-term survival; secondary end points were the frequency of reintervention, evolution of the aneurysm sac, rates of primary and secondary patency and rupture. The mean Customized Probability Index score in our patients was 12.1. Operative mortality was 1.25% (1/80). There were 5 endoleaks and 2 endograft limb occlusions. Four patients required reintervention during the mean follow-up of 35.9 months. Survival at 3 years was 91.25%. Primary and secondary patency rates at 3 years were 97.5% and 100%, respectively. There were no ruptures. Our initial and long-term results with EVAR in high-risk patients were satisfactory and appear to justify this approach in this patient population. The most important factor for improvement of the short and long-term results of aortic endografts is respect of anatomic feasibility conditions.

Geometric Factors Affecting the Displacement Forces in an Aortic Endograft With Crossed Limbs: A Computational Study

To compare the hemodynamic behavior between an aortic endograft model in the "crossed-limbs" configuration and the customary bifurcated deployment position under the influence of several geometric factors. A crossed-limbs graft and its analogue model with uncrossed limbs were computationally reconstructed. The displacement forces acting over the entire endograft and at the bifurcation and iliac sites separately were calculated using a fluid structure interaction simulation under a range of specific geometric characteristics, namely, the lateral and anteroposterior (AP) neck angulation, the iliac bifurcation angulation, and the endograft curvature. The variations of lateral neck angulation caused a constantly higher total displacement force for the crossed-limbs graft, whereas the force at the bifurcation of the two configurations differed only within a narrow range of 30° to 50°. On the contrary, the displacement force at the iliac site was higher in the crossed-limbs configuration only with lateral neck angulation >50°, reaching its highest value at 70°. The variations of AP neck angulation also caused higher total displacement forces in the crossed-limbs graft. Increasing AP neck angulation values caused generally lower forces at the crossed iliac limbs and higher at its bifurcation, respectively, compared to the uncrossed limbs model. Similarly, the influence of high iliac bifurcation angulation and endograft curvature was associated with slightly elevated forces over the entire crossed-limbs graft and its bifurcation, whereas the opposite held true at the iliac site. Apart from minor differentiations due to geometric alterations, the customary bifurcated and crossed-limbs endografts present similar hemodynamic performance. Further clinical studies should be conducted to confirm the clinical applicability of these findings.