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A new approach for the pre-clinical optimization of a spatial configuration of bifurcated endovascular prosthesis placed in abdominal aortic aneurysms.

ABSTRACT: Complexity of the spatial configuration of an aortic implant with bifurcation in the distal part is related to changes in blood hemodynamic in the area of bifurcation which may disturb blood flow and lead to thrombus formation. This study was designed to characterize parameters which define spatial configuration of an aortic implant for which the risk of thrombus formation is the smallest. We used AngioCT data from 74 patients, aged 55 ±10 years, after endovascular procedure to prepare 3D geometries of stent-grafts. Computational Fluid Dynamics (CFD) simulations were used to reconstruct blood hemodynamic and simulate thrombus formation. Next, geometric parameters of stent-grafts included the ratio of volume of upper part to the bifurcations, the relation of inlet and outlet diameters of a stent-graft and deformations in the iliac part of the stent-graft were analyzed. We also analyzed tortuosities (spiral twisting of the flow around the flow direction) and bends (the largest angulation in distal part of a stent-graft). The CFD results were confronted with AngioCT data to verify if computer generated thrombus appeared in particular patient. Additionally, geometric parameters of analyzed stent-grafts were used to propose a mathematical tool for prediction of thrombus appearance. The results showed that tortuosities and bends of a stent-graft had the highest impact on thrombus formation. Formation of thrombi was observed in 22% to 31% of cases (at blood hematocrit Hct = 40%) even for small values of tortuosities and bends indicating that these parameters are dominant in determining blood clotting. Our calculated results overlapped with clinical data in 80% to 91%. Therefore, we conclude that tortuosities and bends have high impact on thrombus formation and should be under special attention during stent-graft recommendation and patients' follow-ups.

SUBMITTER: Polanczyk A

PROVIDER: S-EPMC5549977 | biostudies-other | 2017

REPOSITORIES: biostudies-other

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Project description:IntroductionEndovascular aneurysm repair has improved outcomes for ruptured abdominal aortic aneurysms (rAAA) compared with open repair. We examined the impact of aorto-uni-iliac (AUI) vs standard bifurcated endograft configuration on outcomes in rAAA.MethodsPatients 18 years or older in the Vascular Quality Initiative database who underwent endovascular aneurysm repair for rAAA from January 2011 to April 2020 were included. Patient characteristics were analyzed by graft configuration: AUI or standard bifurcated. Primary and secondary outcomes included 30-day mortality, postoperative major adverse events (myocardial infarction, stroke, heart failure, mesenteric ischemia, lower extremity embolization, dialysis requirement, reoperation, pneumonia, or reintubation), and 1-year mortality. A subset propensity-score matched cohort was also analyzed.ResultsWe included 2717 patients: 151 had AUI and 2566 had standard bifurcated repair. There was no significant difference between the groups in terms of age, major medical comorbidities, anatomic aortic neck characteristics, or rates of conversion to open repair. Patients who underwent AUI were more commonly female (30% vs 22%, P = .011) and had a history of congestive heart failure (19% vs 12%, P = .013). Perioperatively, patients who underwent AUI had a significantly higher incidence of cardiac arrest (15% vs 7%, P < .001), greater intraoperative blood loss (1.3 L vs 0.6 L, P < .001), longer operative duration (218 minutes vs 138 minutes, P < .0001), higher incidence of major adverse events (46.3% vs 33.3%, P = .001), and prolonged intensive care unit (7 vs 4.7 days, P = .0006) and overall hospital length of stay (11.4 vs 8.1 days, P = .0003). Kaplan-Meier survival analyses demonstrated significant differences in 30-day (31.1% vs 20.2%, log-rank P = .001) and 1-year mortality (41.7% vs 27.7%, log-rank P = .001). The propensity-score matched cohort demonstrated similar results.ConclusionsThe AUI configuration for rAAA appears to be implemented in a sicker cohort of patients and is associated with worse perioperative and 1-year outcomes compared with a bifurcated graft configuration, which was also seen on propensity-matched analysis. Standard bifurcated graft configuration may be the preferred approach in the management of rAAA unless AUI configuration is mandated by patient anatomy or other extenuating circumstances.

Project description:PurposeThe PEVAR Trial demonstrated that compared to open femoral exposure, elective percutaneous endovascular AAA repair (ePEVAR) is associated with decreased perioperative morbidity and access site complications. We hypothesized that PEVAR for ruptured AAA (rPEVAR) may also improve perioperative morbidity compared to open femoral exposure (rEVAR). There are currently no reports that evaluate the utility and outcomes of rPEVAR.Materials and methodsFrom 2015 to 2021, all patients who underwent an endovascular repair of a ruptured AAA at a single institution were included in the study and grouped into rPEVAR and rEVAR. Demographics, procedural details (successful preclose technique, conversion to femoral cutdown), postoperative variables (blood transfusion, ICU and hospital length of stay) and short-term outcomes (30-day major adverse events (30-day MAE) and 30-day femoral access-site complications (30-day FAAC)) were collected and compared with 50 historical ePEVAR patients from the PEVAR Trial. Statistical significance was determined using χ 2 or Fisher's exact test for categorical variables, and Mann-Whitney U-test for continuous variables.Results35 patients were identified (21 rPEVAR; 14 rEVAR), 86% were male with a mean age of 72 ± 9 years. All patients underwent emergent endovascular aortic repair with 100% technical success. Seventeen patients (49%) presented with evidence of hemorrhagic shock and 22 patients (63%) had blood transfusion. 30-day MAE occurred in 12 patients (34%) (7 rPEVAR; 5 rEVAR). There was no difference in demographic, perioperative outcomes and 30-day MAE rate between rPEVAR and rEVAR patients. Compared to ePEVAR patient (from PEVAR trial), rPEVAR patients had higher rate of 30-day MAE (34% vs. 6%; p < 0.006) but no difference in 30-day FAAC (19% vs. 12%; p = 0.54). The success rate of the preclose technique was higher in ePEVAR compared to rPEVAR (96% vs. 76%; p = 0.02), but the rate of conversion to femoral cutdown was similar between the two groups (10% vs. 4%; p = 0.57).ConclusionEmergent rPEVAR appears to have similar outcomes when compared to rEVAR. Although patients undergoing rPEVAR have higher 30-day major adverse events rate compared to ePEVAR, the method of percutaneous femoral cannulation does not appear to increase the overall procedural or 30-day femoral artery access-site complications.

Project description:Importance:Knowledge regarding the long-term outcomes of elective treatment of abdominal aortic aneurysm (AAA) using endovascular aortic repair (EVAR) is increasing. However, data with greater than 10 years' follow-up remain sparse and are lacking from population-based studies. Objective:To determine the long-term outcomes of EVAR compared with open surgical repair (OSR) for elective treatment of AAA. Design, Setting, and Participants:This retrospective, population-based cohort study used linked administrative health data from Ontario, Canada, to identify all patients 40 years and older who underwent elective EVAR or OSR for AAA repair from April 1, 2003, to March 31, 2016, with follow-up terminating on March 31, 2017. A total of 17 683 patients were identified using validated procedure and billing codes and were propensity score matched. Analysis was conducted from June 26, 2018, to January 16, 2019. Exposures:Elective EVAR or OSR for AAA. Main Outcomes and Measures:The primary outcome was overall survival. Secondary outcomes were major adverse cardiovascular event-free survival, defined as being free of death, myocardial infarction, or stroke; reintervention; and secondary rupture. Results:Among 17 683 patients who received elective AAA repairs (mean [SD] age, 72.6 [7.8] years; 14 286 [80.8%] men), 6100 (34.5%) underwent EVAR and 11 583 (65.5%) underwent OSR. From these patients, 4010 well-balanced propensity score-matched pairs of patients were defined, with a mean (SD) age of 73.0 (7.6) years and 6583 (82.1%) men. In the matched cohort, the mean (SD) follow-up was 4.4 (2.7) years, and maximum follow-up was 13.8 years. The overall median survival was 8.9 years. Compared with OSR, EVAR was associated with a higher survival rate up to 1 year after repair (91.0% [95% CI, 90.1%-91.9%] vs 94.0% [95% CI, 93.3%-94.7%]) and a higher major adverse cardiovascular event-free survival rate up to 4 years after repair (69.9% [95% CI, 68.3%-71.3%] vs 72.9% [95% CI, 71.4%-74.4%]). Cumulative incidence of reintervention was higher among patients who underwent EVAR compared with those who underwent OSR at the 7-year follow-up (45.9% [95% CI, 44.1%-47.8%] vs 42.2% [95% CI, 40.4%-44.0%]). Survival analyses demonstrated no statistically significant differences in long-term survival, reintervention, and secondary rupture for patients who underwent EVAR compared with those who underwent OSR. Kaplan-Meier analysis suggested superior long-term major adverse cardiovascular event-free survival among patients who underwent EVAR compared with those who underwent OSR (32.6% [95% CI, 26.9%-38.4%] vs 14.1% [95% CI, 4.0%-30.4%]; stratified log-rank P < .001) during a maximum follow-up of 13.8 years. Conclusions and Relevance:Endovascular aortic repair was not associated with a difference in long-term survival during more than 13 years' maximum follow-up. The reasons for these findings will require studies to consider specific graft makes and models, adherence to instructions for use, and types and reasons for reintervention.

Project description:ObjectiveThere is a growing body of literature raising concerns about the long-term durability of endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs), suggesting that long-term outcomes may be better after open AAA repair. However, the data investigating these long-term outcomes largely originate from early in the endovascular era and therefore do not account for increasing clinical experience and technologic improvements. We investigated whether 4-year outcomes after EVAR and open repair have improved over time.MethodsWe identified all EVARs and open repairs for intact infrarenal AAA within the Vascular Quality Initiative database (2003-2018). We then stratified patients by procedure year into treatment cohorts of four years: 2003-2006, 2007-2010, 2011-2014, and 2015-2018. We used Kaplan-Meier analysis and Cox proportional hazards models to assess whether the survival after EVAR or open repair changed over time. In addition, we propensity matched EVAR and open repairs for each time cohort to investigate whether the relative survival benefit of EVAR over open repair changed over time.ResultsWe included 42,293 EVARs (increasing from 549 performed between 2003 and 2006 to 25,433 between 2015 and 2018) and 5189 open AAA repairs (increasing from 561 to 2306). Four-year survival increased for the periods 2003-2006, 2007-2010, 2011-2014, and 2015-2018 after both EVAR (76.6% vs 79.7% vs 83.5% vs 87.3%; P < .001) and open repair (82.2% vs 85.8% vs 87.7% vs 88.9%; P = .026). After risk adjustment, compared with 2003-2006, hazard of mortality up to 4 years after EVAR was lower for those performed between 2011 and 2014 (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.59-0.87; P = .001) and for those performed between 2015 and 2018 (HR, 0.56; 95% CI, 0.46-0.68; P < .001). In contrast, the risk-adjusted hazard of mortality was similar between open repair cohorts (2011-2014: HR, 0.81 [95% CI, 0.61-1.08; P = .15]; and 2015-2018: HR, 0.86 [95% CI, 0.64-1.17; P = .34]). Finally, in matched EVAR and open repairs, there was no difference in mortality in the first three cohorts, whereas the hazard of mortality was lower for the 2015-2018 cohort (HR, 0.65; 95% CI, 0.51-0.84; P = .001).ConclusionsFour-year survival improved in more recent years after EVAR but not after open repair. This finding suggests that midterm outcomes after EVAR are improving, perhaps because of technologic improvements and increased experience, information that should be considered by surgeons and policymakers alike in evaluating the value of contemporary EVAR and open AAA repair.

Project description:PurposeOctogenarians are known to have less-favorable outcomes following ruptured abdominal aortic aneurysm (rAAA) repair compared with their younger counterparts. Accurate information regarding perioperative outcomes following rAAA-repair is important to evaluate current treatment practice. The aim of this study was to evaluate perioperative outcomes of octogenarians and to identify factors associated with mortality and major complications after open surgical repair (OSR) or endovascular aneurysm repair (EVAR) of a rAAA using nationwide, real-world, contemporary data.MethodsAll patients that underwent EVAR or OSR of an infrarenal or juxtarenal rAAA between January 1, 2013, and December 31, 2018, were prospectively registered in the Dutch Surgical Aneurysm Audit (DSAA) and included in this study. The primary outcome was the comparison of perioperative outcomes of octogenarians versus non-octogenarians, including adjustment for confounders. Secondary outcomes were the identification of factors associated with mortality and major complications in octogenarians.ResultsThe study included 2879 patients, of which 1146 were treated by EVAR (382 octogenarians, 33%) and 1733 were treated by OSR (410 octogenarians, 24%). Perioperative mortality of octogenarians following EVAR was 37.2% versus 14.8% in non-octogenarians (adjusted OR=2.9, 95% CI=2.8-3.0) and 50.0% versus 29.4% following OSR (adjusted OR=2.2, 95% CI=2.2-2.3). Major complication rates of octogenarians were 55.4% versus 31.8% in non-octogenarians following EVAR (OR=2.7, 95% CI=2.1-3.4), and 68% versus 49% following OSR (OR=2.2, 95% CI=1.8-2.8). Following EVAR, 30.6% of the octogenarians had an uncomplicated perioperative course (UPC) versus 49.5% in non-octogenarians (OR=0.5, 95% CI=0.4-0.6), while following OSR, UPC rates were 20.7% in octogenarians versus 32.6% in non-octogenarians (OR=0.5, 95% CI=0.4-0.7). Cardiac or pulmonary comorbidity and loss of consciousness were associated with mortality and major complications in octogenarians. Interestingly, female octogenarians had lower mortality rates following EVAR than male octogenarians (adjusted OR=0.7, 95% CI=0.6-0.8).ConclusionBased on this nationwide study with real-world registry data, mortality rates of octogenarians following ruptured AAA-repair were high, especially after OSR. However, a substantial proportion of these octogenarians following OSR and EVAR had an uneventful recovery. Known preoperative factors do influence perioperative outcomes and reflect current treatment practice.

Project description:Several reports suggest unexpectedly high rates of late abdominal aortic aneurysm (AAA) rupture occur after endovascular AAA repair (EVAR). However, a population-based study examining causes of late death after EVAR vs open surgical repair has not been performed.We performed a retrospective cohort study of patients undergoing infrarenal AAA repair using information from the Medicare inpatient hospital discharge records (MedPAR files), physician claim files (Part B files, 20% sample), and Medicare Denominator Files for the years 2001 to 2004. Using the Social Security Death Index, we identified all "late" deaths, defined as deaths occurring >30 days and after hospital discharge. We used the National Death Index to identify cause of death information; in particular, those deaths that were likely caused by late rupture. We compared causes of late death and survival between EVAR and open repair using Wilcoxon log-rank and rank-sum tests.Between 2001 and 2004, 13,971 patients underwent AAA repair (6119 EVAR, 7852 open repair). After a mean follow-up of 1.6 years in the EVAR cohort and 1.9 years in the open cohort, mortality rates were similar across repair type (15.4% EVAR, 15.9% open repair), with an adjusted odds ratio for death after open repair of 0.98 (95% confidence interval, 0.90-1.07). Of the 2194 documented deaths, 523 occurred before discharge or <or=30 days, and 1671 occurred >30 days and after hospital discharge. Cause of death information for the 1671 late deaths was available from the National Death Index for 1515 (91%). The 15 most common codes for causes of late death were dominated by cardiac disease (atherosclerotic heart disease, acute myocardial infarction) and pulmonary disease (lung cancer, respiratory failure). Causes of late death with specific mention of aneurysm were identified in 37 patients (2.4% of all deaths), but this event was not more common in EVAR or open repair (15 [0.3%] in the EVAR group, 22 [0.3%], in the open repair group; P = .71).Late deaths from aneurysm rupture after EVAR or open repair appear to be relatively infrequent and similarly distributed across procedure type. Our results emphasize that the effectiveness of EVAR is comparable to open AAA repair in preventing aneurysm-related death.

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A new approach for the pre-clinical optimization of a spatial configuration of bifurcated endovascular prosthesis placed in abdominal aortic aneurysms.

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