Abdominal Aortic Aneurysm Stent Research Articles

Two cases of pararenal artery aortic aneurysm treatment after pancreaticoduodenectomy and abdominal aortic aneurysm stent grafting

BackgroundAcute pancreatitis caused by surgical procedures may occur less frequently in surgeries for aortic aneurysm involving the abdominal branch. However, in such cases, the associated mortality rate increases significantly. There have been few reports on abdominal aortic aneurysm surgery after pancreatoduodenectomy; as such the incidence of postoperative pancreatitis remains unclear.Case presentationTwo cases of pararenal artery aortic aneurysm after pancreaticoduodenectomy and endovascular aneurysm repair (EVAR) for an abdominal aortic aneurysm are reported. In the first case, a 74-year-old man was diagnosed with abdominal aortic aneurysm and duodenal cancer 6 years earlier and underwent pancreaticoduodenectomy after EVAR. Subsequently, the abdominal aorta expanded to 58 mm at the level of the renal artery proximal to the EVAR site. Graft replacement was performed through a left thoraco-retroperitoneal incision. However, the patient died from acute pancreatitis, believed to be caused by intraoperative manipulation. Given this initial experience, in the second case, a 77-year-old man had undergone a pancreaticoduodenectomy for a gastrointestinal stromal tumor 17 years earlier and EVAR for an abdominal aortic aneurysm 10 years earlier. The abdominal aorta had expanded to 50 mm immediately below the right renal artery on the proximal side of the EVAR. Subsequently, hematuria was noted, and he was diagnosed with right ureteral cancer. Autologous transplantation of the left kidney and EVAR was performed avoiding manipulation of the area around the pancreas and achieved good results. Combined right renal and ureteral resections were performed 20 days after EVAR.ConclusionsWhile performing aortic surgery after pancreaticoduodenectomy, surgeons should avoid manipulating tissues around the pancreas.

Late type III endoleaks are common in early generation Endologix AFX stent grafts

ObjectiveEarly generation Endologix AFX endovascular abdominal aortic aneurysm (AAA) stent graft devices are at risk of developing type IIIa (intercomponent/overlap-related) as well as type IIIb (fabric tear) endoleaks over time. Current follow-up studies are limited to short (<24 months) and midterm (24-48 months) reports. The purpose of this study was to identify the incidence of type III endoleaks associated with these endografts over a long-term follow-up (>4 years) period and discuss current management strategies. MethodsA retrospective, single-institution cohort analysis of all Endologix AFX endografts implanted from October 2011 to October 2016 was performed. Patient characteristics, imaging, and follow-up were obtained via chart review. Type III endoleaks were characterized based on computed tomography angiogram/operative findings and confirmed by two surgeons. Statistical analysis was performed with SAS v9.4. ResultsSixty-three patients underwent AFX stent graft implantation for aneurysmal disease. Forty-seven patients comprised the final cohort for analysis after exclusions were made for primary iliac aneurysms as well as off-label use of the device (eg, hypogastric snorkel) or primary occlusive indications. The average age was 73.3 years, with the longest follow-up being 8.7 years (median, 5.2 years). Most AAAs (89.2%) were fusiform, with initial median diameter 5.5 cm. Initial 30-day mortality was 0%. Of the initial cohort, 10 (21.3%) type III endoleaks were treated, of which six (60%) were type IIIa and four (40%) were type IIIb. By time-to-event analysis at latest follow-up, freedom from type III intervention was 48% at 8 years. The median time to type III endoleak discovery was 4.7 years (range, 1.1-7.2 years), an interval that was similar for type IIIa and type IIIb leak types (P = .73). Patients with type III endoleaks had average sac growth of 1.3 cm over the follow-up interval compared with a net decrease for patients without type III endoleaks (P < .0001). Of the 10 patients treated for type III leaks, seven (70%) underwent complete endovascular re-lining, one (10%) had partial re-lining, and two (20.0%) underwent open endograft explant with aortic graft reconstruction. Reintervention 30-day mortality was 0% for all approaches. ConclusionsEarly generation Endologix AFX stent grafts have a high rate of type III endoleaks, with freedom from type III leak <50% at 8-year follow-up. Most of these are not detected until several years (>4.5 years) after initial implantation, beyond the range of the follow-up interval of most published reports. Long-term imaging surveillance is critical, and a low threshold for complete relining should be considered with any sign of sac enlargement, even if endoleak is not clearly demonstrated in patients with early generation Endologix AFX grafts.

Midterm result of custom-made iliac branch device for common iliac aneurysm with and without abdominal aortic aneurysm.

Although commercial iliac branch devices offer a new and valid endovascular approach to treating iliac aneurysm and effectively preserve antegrade flow of the internal iliac artery, their use may not be suited for all types of challenging anatomy, especially isolated common iliac artery aneurysm. Our custom-made iliac bifurcation device has a unique design and excludes both combined and isolated iliac branch aneurysm. This study validated the efficacy and safety of the custom device by comparing clinical outcomes between groups receiving commercial and custom devices. Data of consecutive patients receiving iliac bifurcation device implantation for iliac aneurysm with or without concomitant endovascular repair for abdominal aortic aneurysm from January 2010 to May 2019 were reviewed. Iliac bifurcation device implantation with or without concomitant abdominal aortic aneurysm stent grafting was completed in 46 patients (commercial, n = 35; custom, n = 11). No significant differences were observed regarding postoperative complications, occlusion or endoleak. Comparisons of primary (80.8% vs 85.7%, P = 0.88) and secondary (86.5% vs 85.7%, P = 0.85) patency and freedom from reintervention (88.2% vs 100%, P = 0.33), all-cause mortality (78.6% vs 100%, P = 0.25) and aneurysm-related mortality (100% vs 100%, P = 1.00) also indicated no differences at a 5-year surveillance point. Furthermore, the iliac aneurysms of the groups displayed similar shrinkage 1 year after procedures. For iliac aneurysm, the novel custom-made iliac bifurcation device is an adaptable design not inferior to commercial devices with regard to postoperative complications, bridge occlusion, endoleak and short-term aneurysm remodelling. It provides an alternative for treatment, particularly when certain anatomic challenges are present. 2018-07-050BC, 2017-01-023ACF.

A multi-center study for instructions for use-compatible elective endovascular abdominal aneurysm repair via Lifetech Ankura™ abdominal aortic aneurysm stent graft

A multi-center study for instructions for use-compatible elective endovascular abdominal aneurysm repair via Lifetech Ankura™ abdominal aortic aneurysm stent graft

Association of High Mortality With Postoperative Myocardial Infarction After Major Vascular Surgery Despite Use of Evidence-Based Therapies

Patients undergoing vascular surgery are at high risk of postoperative myocardial infarction (POMI). Postoperative myocardial infarction is independently associated with significant risk of in-hospital mortality. To examine the association of patient and procedural characteristics with the risk of POMI after vascular surgery and determine the association of evidence-based therapies with longer-term outcomes. A retrospective cohort study of prospectively collected data within a statewide quality improvement collaborative database between January 2012 and December 2017. Patient demographics, comorbid conditions, and perioperative medications were captured. Patients were grouped according to occurrence of POMI. Univariate analysis and logistic regression were used to identify factors associated with POMI. The collaborative collects data from private and academic hospitals in Michigan. Patients undergoing major vascular surgery, defined as endovascular aortic aneurysm repair, open abdominal aortic aneurysm, peripheral bypass, carotid endarterectomy, or carotid artery stenting were included. Analysis began December 2018. The presence of a POMI and 1-year mortality. Of 26 231 patients identified, 16 989 (65.8%) were men and the overall mean (SD) age was 69.35 (9.89) years. A total of 410 individuals (1.6%) experienced a POMI. Factors associated with higher rates of POMI were age (odds ratio [OR], 1.032 [95% CI, 1.019-1.045]; P < .001), diabetes (OR, 1.514 [95% CI, 1.201-1.907]; P < .001), congestive heart failure (OR, 1.519 [95% CI, 1.163-1.983]; P = .002), valvular disease (OR, 1.447 [95% CI, 1.024-2.046]; P = .04), coronary artery disease (OR, 1.381 [95% CI, 1.058-1.803]; P = .02), and preoperative P2Y12 antagonist use (OR, 1.37 [95% CI, 1.08-1.725]; P = .009). Procedurally, open abdominal aortic aneurysm (OR, 4.53 [95% CI, 2.73-7.517]; P < .001) and peripheral bypass (OR, 2.375 [95% CI, 1.818-3.102]; P < .001) were associated with the highest risk of POMI. After POMI, patients were discharged and received evidence-based therapy with high fidelity, including β-blockade (296 [82.7%]) and antiplatelet therapy (336 [95.7%]). A high portion of patients with POMI were dead at 1 year compared with patients without POMI (113 [37.42%] vs 993 [5.05%]; χ2 = 589.3; P < .001). Despite high rates of discharge with evidence-based therapies, the long-term burden of POMI is substantial, with a high mortality rate in the following year. Patients with diabetes mellitus, coronary artery disease, congestive heart failure, and valvular disease warrant additional consideration in the preoperative period. Further, aggressive strategies to treat patients who experience a POMI are needed to reduce the risk of postoperative mortality.

Early outcomes with a single-sided access endovascular stent

ObjectiveThe objective of this study was to report the 1-year follow-up study results of the new Horizon stent graft (Endospan, Herzliya, Israel) from two different prospective consecutive trials. The Horizon abdominal aortic aneurysm stent graft system is a 14F profile system requiring only a single access site. It consists of three modules, introduced separately: base limb (iliac to iliac limb); distal aortic limb; and proximal aortic limb with a bare suprarenal crown and active fixation. MethodsData from the first in man (FIM) clinical study with 10 patients enrolled and the pivotal study with 30 patients were analyzed. Outcomes measured were freedom from major adverse events (MAEs) including all-cause mortality, myocardial infarction, renal failure, respiratory failure, paraplegia, stroke, bowel ischemia, and procedural blood loss ≥1000 mL. Performance end points included successful delivery and deployment of the device, freedom from aneurysm growth ≥5 mm, type I or type III endoleak, stent graft occlusion, conversion to open surgery, rupture, and stent graft migration. ResultsIn the FIM study, one conversion to open surgery with >1000 mL of blood loss was registered perioperatively. In the pivotal study, no perioperative MAE was registered. Overall, at 1-year follow-up, two deaths and one aneurysm growth unrelated to endoleak were registered. ConclusionsThe results of both the FIM and pivotal studies demonstrated that 39 of 40 procedures were successful for delivery and deployment of the Horizon stent graft. No MAE was registered during the follow-up. The primary safety and performance end points were met in both studies.

C1QA gene mutations in a pediatric SLE cohort from North India

The objective of this study was to report the 1-year follow-up study results of the new Horizon stent graft (Endospan, Herzliya, Israel) from two different prospective consecutive trials. The Horizon abdominal aortic aneurysm stent graft system is a 14F profile system requiring only a single access site. It consists of three modules, introduced separately: base limb (iliac to iliac limb); distal aortic limb; and proximal aortic limb with a bare suprarenal crown and active fixation.Data from the first in man (FIM) clinical study with 10 patients enrolled and the pivotal study with 30 patients were analyzed. Outcomes measured were freedom from major adverse events (MAEs) including all-cause mortality, myocardial infarction, renal failure, respiratory failure, paraplegia, stroke, bowel ischemia, and procedural blood loss ≥1000 mL. Performance end points included successful delivery and deployment of the device, freedom from aneurysm growth ≥5 mm, type I or type III endoleak, stent graft occlusion, conversion to open surgery, rupture, and stent graft migration.In the FIM study, one conversion to open surgery with >1000 mL of blood loss was registered perioperatively. In the pivotal study, no perioperative MAE was registered. Overall, at 1-year follow-up, two deaths and one aneurysm growth unrelated to endoleak were registered.The results of both the FIM and pivotal studies demonstrated that 39 of 40 procedures were successful for delivery and deployment of the Horizon stent graft. No MAE was registered during the follow-up. The primary safety and performance end points were met in both studies.

Spleno-renal artery transposition in a solitary functioning kidney for treatment-resistant hypertension and acute kidney injury

Renal Artery Stenosis (RAS) is an important cause of treatment-resistant hypertension. Uncontrolled hypertension with RAS can cause progressive chronic kidney disease (CKD) leading to end-stage kidney disease. Therapeutic revascularisation can...

Comparison of Renal Outcomes in Patients Treated by Zenith® Fenestrated and Zenith® Abdominal Aortic Aneurysm Stent grafts in US Prospective Pivotal Trials

Fenestrated endovascular repair (FEVAR) has been used to treat complex abdominal aortic aneurysms (AAAs). The risk of renal function deterioration compared with infrarenal endovascular aortic repair (EVAR) has not been determined. Patients with preserved renal function (estimated glomerular filtration rate [eGFR] > 45 mL/minute) enrolled in two prospective, non-randomised studies evaluating Zenith fenestrated and AAA stent grafts were matched (1:2) by propensity scores for age, sex, hypertension, diabetes, and pre-operative eGFR. Sixty-seven patients were treated by FEVAR and 134 matched controls treated by EVAR. Mean follow-up was 30 ± 20 months. Outcomes included acute kidney injury (AKI) defined by RIFLE and changes in serum creatinine (sCr), eGFR, and chronic kidney disease (CKD) staging up to 5 years. AKI at 1 month was similar between groups, with > 25% decline in eGFR observed in 5% of FEVAR and 9% of EVAR patients (p = .39). There were no significant differences in > 25% decline in eGFR at 2 years (FEVAR 20% vs. EVAR 20%; p > .99) or 5 years (ng follow-up, there were more renal artery stenosis/occlusions (15/67 [22%] vs. 3/134 [2%]; p < .001) and renal related re-interventions (12/67 [18%] vs. 4/134 [3%]; p < .001) in patients treated by FEVAR. Rate of progression to renal failure requiring dialysis was low and identical in both groups (1.5% vs. 1.5%; p > .99). Aortic repair with FEVAR and EVAR was associated with similar rates of renal function deterioration in patients with preserved pre-operative renal function. Renal related re-interventions were higher following FEVAR, although net changes in renal function were similar in both groups.

Editor's Choice – Comparison of Renal Outcomes in Patients Treated by Zenith® Fenestrated and Zenith® Abdominal Aortic Aneurysm Stent grafts in US Prospective Pivotal Trials

Fenestrated endovascular repair (FEVAR) has been used to treat complex abdominal aortic aneurysms (AAAs). The risk of renal function deterioration compared with infrarenal endovascular aortic repair (EVAR) has not been determined. Patients with preserved renal function (estimated glomerular filtration rate [eGFR]>45 mL/minute) enrolled in two prospective, non-randomised studies evaluating Zenith fenestrated and AAA stent grafts were matched (1:2) by propensity scores for age, sex, hypertension, diabetes, and pre-operative eGFR. Sixty-seven patients were treated by FEVAR and 134 matched controls treated by EVAR. Mean follow-up was 30±20 months. Outcomes included acute kidney injury (AKI) defined by RIFLE and changes in serum creatinine (sCr), eGFR, and chronic kidney disease (CKD) staging up to 5 years. AKI at 1 month was similar between groups, with > 25% decline in eGFR observed in 5% of FEVAR and 9% of EVAR patients (p=.39). There were no significant differences in > 25% decline in eGFR at 2 years (FEVAR 20% vs. EVAR 20%; p>.99) or 5 years (FEVAR 27% vs. EVAR 50%; p=.50). Progression to stage IV-V CKD was similar at 2 years (FEVAR 2% vs. EVAR 3%; p>.99) and 5 years (FEVAR 7% vs. EVAR 8%; p>.99), with similar sCrand eGFR up to 5 years. During follow-up, there were more renal artery stenosis/occlusions (15/67 [22%] vs. 3/134 [2%]; p<.001) and renal related re-interventions (12/67 [18%] vs. 4/134 [3%]; p<.001) in patients treated by FEVAR. Rate of progression to renal failure requiring dialysis was low and identical in both groups (1.5% vs. 1.5%; p>.99). Aortic repair with FEVAR and EVAR was associated with similar rates of renal function deterioration in patients with preserved pre-operative renal function. Renal related re-interventions were higher following FEVAR, although net changes in renal function were similar in both groups.

The Impact of Aortic Tortuosity on Delayed Type I or III Endoleak after Endovascular Aortic Repair

Endovascular aneurysm repair (EVAR) becomes the treatment of choice for patients with abdominal aortic aneurysm (AAA). Type I or III endoleak is related to high risk of rupture and reintervention, but little is known about the delayed presentation of these. We sought to evaluate the delayed type I or III endoleak after EVAR and assess the early morphological portending factors. We retrospectively reviewed a database of 249 patients who underwent endovascular repair with a Zenith AAA stent graft (Cook Medical, Bloomington, IN) in a single institute from October 2005 to December 2013. Age, aneurysm size, angulation, tortuosity index (TI), and follow-up evaluations were recorded and analyzed. Patients having <1year of follow-up were excluded. One hundred eighteen patients were included in this study. There was no delayed type Ia endoleak. Ten patients (9.3%) were found to have a delayed type Ib or III endoleak. The mean diagnosis time was 49.1months (range, 22-91months) after EVAR. All of them were treated with endovascular repair except one had combined open revision. Three of the patients (30%) with delayed endoleaks presented with a ruptured aneurysm, and two of them (20%) died after reintervention. Postoperative TI was found to be the most significant morphological factor associated with increased risk of type Ib or III endoleak. Delayed type Ib or III endoleak was not rare in our study population and was found to have a high risk of rupture and mortality. Aneurysm tortuosity is associated with increased risk of endoleaks, and postoperative TI can be an indicator in the early period of follow-up.

Chimney stent grafts in the era of custom-made devices: A comparative review of complex abdominal aortic aneurysm stenting

Introduction: Surgical treatment of abdominal aortic aneurysms (AAA) has evolved over the past 15 years. Fenestrated endovascular of AAAs (FEVAR) and Chimney endovascular of AAA (Chimney EVAR) are techniques that have been introduced and utilized over the past few years as alternatives to open surgical repair with its high associated morbidity and mortality. The purpose of this study is to compare the results of FEVARs and Chimney endografts in a single institution from an Asian perspective. Materials and Methods: We retrospectively reviewed all patients who underwent FEVAR and Chimney EVAR from January 2011 to August 2014 in a tertiary vascular institution. Results: During this study period, a total of 19 patients underwent Chimney EVAR, and 12 patients underwent FEVAR. All FEVAR patients were operated electively while five patients who underwent Chimney EVAR were operated in an emergency setting. Operative time was longer for FEVAR and more vessels were reconstructed. There was no difference in intraoperative technical events, postoperative general and specific complications between the two groups. One patient passed away within 30 days of repair with Chimney EVAR. Conclusion: In this limited retrospective series, short-term results of FEVAR and Chimney EVAR had no statistical difference. Chimney EVAR is an attractive and useful alternative for patients who are unable to undergo FEVAR.

Decreased Serum Levels of High Mobility Group Box 1 (HMGB-1) after Graft Replacement or Stenting of Abdominal Aortic Aneurysm

High-mobility group box 1 (HMGB-1) is a key substance mediating inflammation and development of atherosclerotic lesions (ALs), including abdominal aortic aneurysms (AAA). Serum levels of HMGB-1 are increased in patients with AAA than those in normal controls because the ALs in AAAs secrete HMGB-1. We therefore postulate that the serum HMGB-1 level should decrease after endovascular aortic repair (EVAR) or open aortic repair (OAR). However, there is no evidence of this in the literature. The purpose of this study was to investigate the changes in HMGB-1 levels after surgical intervention for AAA. We also aimed to determine if the HMGB-1 levels varied between the two procedures. Serum HMGB-1 levels were determined in 24 patients with AAA and 25 healthy controls. Twelve of the 24 AAA patients underwent EVAR, whereas the other half underwent OAR. The relationship between HMGB-1 levels and presence of AAA or influence of operative methods on the serum HMGB-1 level were prospectively investigated. Serum HMGB-1 levels in AAA patients were significantly higher than those in healthy controls (9.4±5.7 vs. 4.1±2.0ng/mL, P<0.01). The serum HMGB-1 levels in both the EVAR group and the OAR group were significantly decreased from baseline at both 3mo and 1y after surgery. Removal or isolation of AL via surgical intervention significantly decreases serum HMGB-1 levels. The significant postoperative reduction in HMGB-1 levels suggests that important endocrinological changes occur after surgical treatment of AAA.

Endovascular aortic aneurysm repair: a method of treatment of abdominal aortic aneurysm stent implantation.

2016;11(3-4):130. VII. nacionalni sastanak o kardiovaskularnim intervencijama s međunarodnim sudjelovanjem VI. sastanak intervencijskih kardioloskih medicinskih sestara i tehnicara Abdominal aortic aneurysm, along with myocardial infarction and stroke is one of the most common diseases of blood vessels, and it is estimated that almost 10% of the male population over age 60 has an aneurysm. The mortality of ruptured abdominal aortic aneurysm in some cases is growing to an alarming 90%. With the former techniques of treating aneurysms, such as conservative (drug therapy) treatment and open surgery, in 1991 the endovascular aortic repair was introduced as a significantly less invasive method than surgery.

Evaluation of the Zenith low-profile abdominal aortic aneurysm stent graft

Low-profile (LP) stent grafts are now commercially available in Europe for endovascular aortic aneurysm repair (EVAR). In this study the midterm outcomes and characteristics of patients treated with this last generation of stent grafts were compared with a cohort of patients treated with "standard-profile" (SP) stent grafts. The current study enrolled all patients treated for elective EVAR by the SP Zenith Flex stent graft (Cook Medical, Bloomington, Ind) between March 2010 and November 2011 and patients treated for elective EVAR by the Zenith LP stent graft (Cook Medical) between November 2011 and March 2013. All patients had a follow-up >18 months. Preoperative computed tomography angiograms were analyzed on a dedicated three-dimensional workstation. All data were prospectively collected in an electronic database and retrospectively analyzed. A comparative study was conducted. The present study included 208 patients (107 SP and 101 LP). Patients' physiologic characteristics were similar in both groups. The iliac anatomy was considered "more challenging" in LP patients: respectively, 7% and 22% (P = .002) of SP and LP patients had bilateral external iliac diameter <7 mm; and 16% and 34% (P = .005) had a combination of an external iliac diameter <7 mm and an iliac tortuosity ratio index >1.5. No 30-day deaths were documented. The 24-month freedom from reintervention and overall survival rates after SP and LP were, respectively, 88% and 91% (P = .450) and 92% and 96% (P = .153). The 24-month rates for freedom from sac expansion and from limb occlusion were 96.4% and 98.7% (P = .320) and 92% and 95% (P = .293), respectively. One patient in each group presented with a type I endoleak during follow-up, and two LP patients presented with a type III endoleak (P = .235). This study demonstrates that the last-generation LP stent grafts have favorable midterm outcomes similar to SP stent grafts despite being used to treat more patients with unfavorable iliac anatomy.

The Evidence for Vascular Surgery, 2nd edn.

This textbook offers the reader a comprehensible and wellillustrated journey through the evidence available for the management of all of the most commonly encountered vascular patient conditions. From vascular consultants, trainees and nurse specialists to stroke specialists, cardiologists, anaesthetists and diabetologists this book offers easily accessible review material of issues that are faced every day in the management of vascular disease. The second edition has come along way from the original with the addition of several new chapters, which include the designation of accepted grading of evidence levels and recommendations for clinical practice. Each chapter topic has been the product of a systematic review of the literature performed by designated members of the Joint Vascular Research Group. The chapters follow a traditional format of introduction and background, and give a discussion of the literature sometimes tabulating the salient studies with their evidence grades and ending with recommendations for clinical practice. Interestingly, there is a conflict between chapters covering arterial and venous topics as to whether they reference National Institute for Health and Clinical Excellence (NICE) guidelines. NICE guidance and systematic reviews are not referred to in chapters covering carotid artery stent placement, abdominal aortic aneurysm stent placement or stent graft replacement in the thoracic aortic aneurysm. NICE guidance and systematic review work is, however, acknowledged and described briefly in the chapter covering new interventions for varicose veins. Nonetheless, the brevity of the reference may leave the reader having to look up the guidelines to befully in the picture. We also note that, unusually for a comprehensive 270-page text, there is no index. This is one thing that has not changed since the first edition. Taken as a whole, the authors are to be congratulated on the very readable text with superb colour illustrations and photographs that are featured throughout every chapter. In this respect, the book is certainly ahead of others with which it might compete and with its new more sophisticated presentation we welcome its arrival.

Unknown pages in the history of vascular stent grafting

Unknown pages in the history of vascular stent grafting

Analysis of the Influence of Endograft Geometry on Blood Hemodynamics in Abdominal Aortic Aneurysm by Computational Fluid Dynamics

Objectives: Endovascular Aneurysm Repair (EVAR) is considered the treatment of choice for Abdominal Aortic Aneurysm (AAA). However, thrombotic deposits found incidentally in abdominal aortic endografts are common and the deposition of thrombus is reported to be influenced by the geometry of the aortic stent graft. We used computational fluid dynamic techniques to analyze the biomechanical factors associated with different stent graft morphologies Methods and models: Computational fluid dynamic models were constructed to investigate the biomechanical factors affecting both tuburlent flow and the drag force in modular AAA stent grafts. The resultant flow separation and drag force as a net change of fluid momentum were calculated on the basis of varying three-dimensional geometry. Modular AAA stent grafts with four different lengths of graft mani body were compared. Computational fluid dynamic simulations were then performed on each stent graft model according to its geometric parameters to determine the flow separation and the actual change in drag force experienced by the stent graft. Results: In all these simulations, the blood flow created as adverse pressure gradient when blood flow decelerated. Flow separation occurred when the boundary layer velocity gradient dropped almost to zero causing recirculation and vortices to be formed downstream of the main graft body and leading to intraprosthetic thrombosis and endograft limb obstruction. With a shorter length graft main body, it was possible to avoid flow separation, reducing the probability of occurrences of the flow recirculation and vortices. The drag force causing device migration was higher with elevated blood pressure and unchanged with the main body length. Conclusion: Flow separation in modular AAA stent grafts is common and occurs more often in endografts with a longer main body. The shorter main body design of the endograft can be applied without the expense of increasing drag force.

Toward smart utilization of two X-ray images for 2-D/3-D registration applied to abdominal aortic aneurysm interventions

Minimally invasive abdominal aortic aneurysm stenting can be greatly facilitated by overlaying the pre-operative 3-D model of the abdominal aorta onto the intra-operative 2-D X-ray images. Accurate 2-D/3-D registration in 3-D space makes the 2-D/3-D overlay robust to the change of C-Arm angulations. Typically at least two X-ray images showing the abdominal aorta with contrast medium from different angles are needed for an accurate registration in 3-D space. In this paper, a novel 2-D/3-D registration technique is proposed for using only one image with contrast medium in the abdominal aorta and one native image showing the spine to achieve accurate registration of the abdominal aorta in 3-D. The proposed method utilizes the two X-ray images in an integrated but differentiated way in order to best utilize the complementary information provided by the two types of images. A hierarchical registration scheme is deployed by a sensible partition of the registration parameter space based on the image acquisition protocol. The proposed method was validated using both synthetic and clinical datasets, and achieved significantly improved accuracy and robustness compared to the conventional methods.

Infection of endovascular abdominal aortic aneurysm stent graft after urosepsis: case report and review of the literature

Infection of endovascular abdominal aneurysm stent grafts is an uncommon but known complication. Inoculation with bacteria of the endovascular abdominal aneurysm stent graft during the actual implantation, in the periprocedural hospitalization or later due to an aortoenteric fistula, has been described in the literature. We report a case of endovascular abdominal aortic aneurysm stent graft infection occurring 40 months after implantation in a patient doing well up to an episode of urosepsis. In conclusion, we postulate that poor intraluminal healing of stent grafts, as observed in several explant studies, may result in a higher susceptibility to episodes of bacteremia than prosthetic vascular grafts inserted during open repair. We therefore consider the administration of prophylactic antibiotics in patients with endovascular stent grafts during periods with a likelihood of bacteremia.