Thresholds for Abdominal Aortic Aneurysm Repair in England and the United States.

BACKGROUND: Thresholds for repair of abdominal aortic aneurysms vary considerably among countries. METHODS: We examined differences between England and the United States in the frequency of aneurysm repair, the mean aneurysm diameter at the time of the procedure, and rates of aneurysm rupture and aneurysm-related death. Data on the frequency of repair of intact (nonruptured) abdominal aortic aneurysms, in-hospital mortality among patients who had undergone aneurysm repair, and rates of aneurysm rupture during the period from 2005 through 2012 were extracted from the Hospital Episode Statistics database in England and the U.S. Nationwide Inpatient Sample. Data on the aneurysm diameter at the time of repair were extracted from the U.K. National Vascular Registry (2014 data) and from the U.S. National Surgical Quality Improvement Program (2013 data). Aneurysm-related mortality during the period from 2005 through 2012 was determined from data obtained from the Centers for Disease Control and Prevention and the U.K. Office of National Statistics. Data were adjusted with the use of direct standardization or conditional logistic regression for differences between England and the United States with respect to population age and sex. RESULTS: During the period from 2005 through 2012, a total of 29,300 patients in England and 278,921 patients in the United States underwent repair of intact abdominal aortic aneurysms. Aneurysm repair was less common in England than in the United States (odds ratio, 0.49; 95% confidence interval [CI], 0.48 to 0.49; P<0.001), and aneurysm-related death was more common in England than in the United States (odds ratio, 3.60; 95% CI, 3.55 to 3.64; P<0.001). Hospitalization due to an aneurysm rupture occurred more frequently in England than in the United States (odds ratio, 2.23; 95% CI, 2.19 to 2.27; P<0.001), and the mean aneurysm diameter at the time of repair was larger in England (63.7 mm vs. 58.3 mm, P<0.001). CONCLUSIONS: We found a lower rate of repair of abdominal aortic aneurysms and a larger mean aneurysm diameter at the time of repair in England than in the United States and lower rates of aneurysm rupture and aneurysm-related death in the United States than in England. (Funded by the Circulation Foundation and others.).

Editor's Choice - Re-interventions After Repair of Ruptured Abdominal Aortic Aneurysm: A Report From the IMPROVE Randomised Trial.

OBJECTIVE/BACKGROUND: The aim was to describe the re-interventions after endovascular and open repair of rupture, and investigate whether these were associated with aortic morphology. METHODS: In total, 502 patients from the IMPROVE randomised trial (ISRCTN48334791) with repair of rupture were followed-up for re-interventions for at least 3 years. Pre-operative aortic morphology was assessed in a core laboratory. Re-interventions were described by time (0-90 days, 3 months-3 years) as arterial or laparotomy related, respectively, and ranked for severity by surgeons and patients separately. Rare re-interventions to 1 year, were summarised across three ruptured abdominal aortic aneurysm trials (IMPROVE, AJAX, and ECAR) and odds ratios (OR) describing differences were pooled via meta-analysis. RESULTS: Re-interventions were most common in the first 90 days. Overall rates were 186 and 226 per 100 person years for the endovascular strategy and open repair groups, respectively (p = .20) but between 3 months and 3 years (mid-term) the rates had slowed to 9.5 and 6.0 re-interventions per 100 person years, respectively (p = .090) and about one third of these were for a life threatening condition. In this latter, mid-term period, 42 of 313 remaining patients (13%) required at least one re-intervention, most commonly for endoleak or other endograft complication after treatment by endovascular aneurysm repair (EVAR) (21 of 38 re-interventions), whereas distal aneurysms were the commonest reason (four of 23) for re-interventions after treatment by open repair. Arterial re-interventions within 3 years were associated with increasing common iliac artery diameter (OR 1.48, 95% confidence interval [CI] 0.13-0.93; p = .004). Amputation, rare but ranked as the worst re-intervention by patients, was less common in the first year after treatment with EVAR (OR 0.2, 95% CI 0.05-0.88) from meta-analysis of three trials. CONCLUSION: The rate of mid-term re-interventions after rupture is high, more than double that after elective EVAR and open repair, suggesting the need for bespoke surveillance protocols. Amputations are much less common in patients treated by EVAR than in those treated by open repair.

Early outcomes after left subclavian artery revascularisation in association with thoracic endovascular aortic repair.

Approximately 40-50% of patients undergoing thoracic endovascular aortic repair require left subclavian artery coverage for adequate proximal landing zone. Many of these patients undergo left subclavian artery revascularisation. However, outcomes data for left subclavian artery revascularisation in the context of thoracic endovascular aortic repair remain limited. In this study, 70 left subclavian artery revascularisation procedures, performed on thoracic endovascular aortic repair patients at a tertiary hospital, were retrospectively reviewed. Particular emphasis was placed on revascularisation-related outcomes during staging interval between revascularisation and thoracic endovascular aortic repair. Forty-six (66%) carotid-subclavian bypass, 17 (24%) carotid-carotid-subclavian bypass and 7 (10%) aorto-inominate-carotid-subclavian bypass procedures were performed. There were no strokes or mortalities following left subclavian artery revascularisation procedures alone. Three (10%) minor complications occurred including a seroma, a haematoma and a temporary neuropraxia. Separation of complications following left subclavian artery revascularisation from those of the associated thoracic endovascular aortic repair can be difficult. Early outcomes data from patients who underwent left subclavian artery revascularisation in isolation indicate that the procedure is safe with low complication rates.

Feature selection through validation and un-censoring of endovascular repair survival data for predicting the risk of re-intervention.

BACKGROUND: Feature selection (FS) process is essential in the medical area as it reduces the effort and time needed for physicians to measure unnecessary features. Choosing useful variables is a difficult task with the presence of censoring which is the unique characteristic in survival analysis. Most survival FS methods depend on Cox's proportional hazard model; however, machine learning techniques (MLT) are preferred but not commonly used due to censoring. Techniques that have been proposed to adopt MLT to perform FS with survival data cannot be used with the high level of censoring. The researcher's previous publications proposed a technique to deal with the high level of censoring. It also used existing FS techniques to reduce dataset dimension. However, in this paper a new FS technique was proposed and combined with feature transformation and the proposed uncensoring approaches to select a reduced set of features and produce a stable predictive model. METHODS: In this paper, a FS technique based on artificial neural network (ANN) MLT is proposed to deal with highly censored Endovascular Aortic Repair (EVAR). Survival data EVAR datasets were collected during 2004 to 2010 from two vascular centers in order to produce a final stable model. They contain almost 91% of censored patients. The proposed approach used a wrapper FS method with ANN to select a reduced subset of features that predict the risk of EVAR re-intervention after 5 years to patients from two different centers located in the United Kingdom, to allow it to be potentially applied to cross-centers predictions. The proposed model is compared with the two popular FS techniques; Akaike and Bayesian information criteria (AIC, BIC) that are used with Cox's model. RESULTS: The final model outperforms other methods in distinguishing the high and low risk groups; as they both have concordance index and estimated AUC better than the Cox's model based on AIC, BIC, Lasso, and SCAD approaches. These models have p-values lower than 0.05, meaning that patients with different risk groups can be separated significantly and those who would need re-intervention can be correctly predicted. CONCLUSION: The proposed approach will save time and effort made by physicians to collect unnecessary variables. The final reduced model was able to predict the long-term risk of aortic complications after EVAR. This predictive model can help clinicians decide patients' future observation plan.

The impact of endovascular aneurysm repair on mortality for elective abdominal aortic aneurysm repair in England and the United States.

BACKGROUND: Procedural mortality is of paramount importance for patients undergoing elective abdominal aortic aneurysm (AAA) repair. Previous comparative studies have demonstrated international differences in the care of ruptured AAA. This study compared the use of endovascular aneurysm repair (EVAR) and in-hospital mortality for elective AAA repair in England and the United States. METHODS: The English Hospital Episode Statistics and the U.S. Nationwide Inpatient Sample (NIS) were interrogated for elective AAA repair from 2005 to 2010. In-hospital mortality and the use of EVAR were analyzed separately for each health care system, after within-country risk adjustment for age, gender, year, and an accepted national comorbidity index. RESULTS: The study included 21,272 patients with AAA in England, of whom 86.61% were male, with median (interquartile range) age of 74 (69-79) years. There were 196,113 AAA patients in the United States, of whom 76.14% were male, with median (interquartile range) age of 73 (67-78) years. In-hospital mortality was greater in England (4.09% vs 1.96 %; P < .01) and EVAR less common (37.33% vs 64.36%; P < .01). These observations persisted in age- and gender-matched comparison. In both countries, lower mortality and greater use of EVAR were seen in centers performing greater numbers of AAA repairs per annum. In England, lower mortality and greater use of EVAR were seen in teaching hospitals with larger bed capacity. CONCLUSIONS: In-hospital survival and the uptake of EVAR are lower in England than in the United States. In both countries, mortality was lowest in high-caseload centers performing a greater proportion of cases with endovascular repair. These common factors suggest strategies for improving outcomes for patients requiring elective AAA repair.

Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.

BACKGROUND: The outcome of patients with ruptured abdominal aortic aneurysm (rAAA) varies by country. Study of practice differences might allow the formulation of pathways to improve care. METHODS: We compared data from the Hospital Episode Statistics for England and the Nationwide Inpatient Sample for the USA for patients admitted to hospital with rAAA from 2005 to 2010. Primary outcomes were in-hospital mortality, mortality after intervention, and decision to follow non-corrective treatment. In-hospital mortality and the rate of non-corrective treatment were analysed by binary logistic regression for each health-care system, after adjustment for age, sex, year, and Charlson comorbidity index. FINDINGS: The study included 11,799 patients with rAAA in England and 23,838 patients with rAAA in the USA. In-hospital mortality was lower in the USA than in England (53·05% [95% CI 51·26-54·85] vs 65·90%; p<0·0001). Intervention (open or endovascular repair) was offered to a greater proportion of cases in the USA than in England (19,174 [80·43%] vs 6897 [58·45%]; p<0·0001) and endovascular repair was more common in the USA than in England (4003 [20·88%] vs 589 [8·54%]; p<0·0001). Postintervention mortality was similar in both countries (41·77% for England and 41·65% for USA). These observations persisted in age-matched and sex-matched comparisons. In both countries, reduced mortality was associated with increased use of endovascular repair, increased hospital caseload (volume) for rAAA, high hospital bed capacity, hospitals with teaching status, and admission on a weekday. INTERPRETATION: In-hospital survival from rAAA, intervention rates, and uptake of endovascular repair are lower in England than in the USA. In England and the USA, the lowest mortality for rAAA was seen in teaching hospitals with larger bed capacities and doing a greater proportion of cases with endovascular repair. These common factors suggest strategies for improving outcomes for patients with rAAA. FUNDING: None.

Results of the Valiant Mona LSA early feasibility study for descending thoracic aneurysms.

OBJECTIVE: Stent graft coverage of the left subclavian artery (LSA) may be required to achieve an adequate landing zone in up to 40% of descending thoracic aneurysms (DTAs). The Valiant Mona LSA Thoracic Stent Graft System (Medtronic, Santa Rosa, Calif) consists of a main stent graft and a branch stent graft designed to maintain LSA patency while diverting circulation through the encroaching aneurysm. Participating in the United States Food and Drug Administration's new Innovation Pathway, this first-in-human, early feasibility study evaluates early clinical experience of the Valiant Mona LSA Stent Graft System in patients with DTAs where the proximal landing zone necessitates LSA coverage. METHODS: This premarket, nonrandomized, single-arm prospective study recruited nine patients (age 72.9 ± 7.6 years). Primary end points were aneurysm-related mortality, stroke, paraplegia, left arm/hand ischemia, and treatment success. Neurologic events were assessed by imaging and by independent neurologists. Inclusion criteria required patients with a DTA or penetrating aortic ulcer to have a distance of ≥10 mm between the left common carotid artery and the LSA. Mean aneurysm diameter was 53.7 ± 10.0 mm. The indication for repair was for saccular DTA in five patients or fusiform DTA in four. Seven patients were at American Society of Anesthesiologists Physical Status Classification III/IV. RESULTS: All nine patients received one main stent graft (diameter 28 to 42 mm) and one branch stent graft (diameter 10 to 14 mm). To extend device coverage distally, a commercial Valiant Captivia device was implanted in seven patients. No uncorrected endoleaks were observed at the end of the implant procedure. Four endoleaks developed before discharge in four of eight evaluable patients. Two were identified as type II and two were of undetermined type. No endoleak resulted in a secondary intervention. Technical success, defined by the clinical investigational plan, was achieved in all nine patients intraoperatively, and treatment success was achieved in all eight evaluable patients at 1 month. There were no major, disabling strokes. Four minor nondisabling strokes were reported in three patients ≤30 days (days 1, 1, 5, and 24). To date, there have been no reports of death, left arm ischemia, paraplegia, rupture, conversion to open surgery, or secondary endovascular procedure. No patients required surgical LSA revascularization. CONCLUSIONS: The Valiant Mona LSA system demonstrates technical and treatment success, relative safety, and early durability in its initial use in DTA patients. Midterm results are expected as patients are monitored at regular intervals to 5 years.

Appearance of the Nellix endovascular aneurysm sealing system on computed tomography: implications for postoperative imaging surveillance.

PURPOSE: To describe the imaging characteristics of the Nellix Endovascular Aneurysm Sealing (EVAS) System on serial computed tomography (CT) surveillance. METHODS: Sixty-eight patients undergoing EVAS were enrolled in a surveillance protocol that included CT scans prior to hospital discharge and at 3, 6, and 9 months postoperatively. Images were analyzed for the presence of gas within the endobag, endoleak, and for maximum radiodensity measured in Hounsfield units (HU) within the uppermost, middle, and lowermost regions of each endobag. RESULTS: Gas was seen within the endobags of all 68 EVAS repairs at the first postoperative CT compared with 2 (5.6%) of 36 undergoing the 3-month scan. The endobags appeared radiodense during initial imaging, and the median (interquartile range) radiodensity of the Nellix polymer decreased from 158.3 HU (149.5; 169.5) at the postoperative CT to 81.0 HU (74.0; 88.0) at 3 months, excluding 3 cases in which contrast pre-fill was utilized. Type I endoleak was seen at the periphery of the aneurysm sac or in the cleft between the endobags, with a substantially different appearance to endoleak after endovascular aneurysm repair. CONCLUSION: The evolution of CT appearances after EVAS was characteristic and predictable. The device endobags were initially radiodense, which may impact the detection of endoleak within 3 months of EVAS. Endoleaks after EVAS were seen in a different anatomical area to endoleaks after conventional stent-graft repair.

Endovascular aneurysm sealing for the treatment of ruptured abdominal aortic aneurysms.

PURPOSE: To assess the feasibility and report preliminary results of ruptured abdominal aortic aneurysm (rAAA) repair with endovascular aneurysm sealing (EVAS), a novel therapeutic alternative whose feasibility has not been established in rAAAs due to the unknown effects of the rupture site on the ability to achieve sealing. CASE REPORT: Between December 2013 and April 2014, 5 patients (median age 71 years, range 57-90; 3 men) with rAAAs were treated with the Nellix EVAS system at a single institution. Median aneurysm diameter was 70 mm (range 67-91). Aneurysm morphology in 4 of the 5 patients was noncompliant with instructions for use (IFU) for both EVAS and standard stent-grafts; the remaining patient was outside the IFU for standard stent-grafts but treated with EVAS under standard IFU for the Nellix system. Median Hardman index was 2 (range 0-3). Two patients died of multiorgan failure after re-laparotomy and intraoperative cardiac arrest, respectively. Among survivors, all devices were patent with no signs of endoleak or failed aneurysm sac sealing at 6 months (median follow-up 9.2 months). CONCLUSION: EVAS for the management of infrarenal rAAAs appears feasible. The use of EVAS in emergency repairs may broaden the selection criteria of the current endovascular strategy to include patients with more complex aneurysm morphology.

Investigating the Effect of a Single Infusion of Reconstituted High-Density Lipoprotein in Patients with Symptomatic Carotid Plaques.

BACKGROUND: Elevation of plasma high-density lipoprotein (HDL) cholesterol concentration reduces cardiovascular mortality and morbidity. HDLs have been shown to possess acute anti-inflammatory, antioxidant, and antithrombotic properties. We hypothesize that HDL therapy can acutely alter local and systemic manifestations of plaque instability. METHODS: Forty patients with early symptomatic carotid disease were randomized to either receive reconstituted HDL (rHDL) 40 mg/kg (n = 20) or placebo (n = 20). Carotid endarterectomies were performed 24 hr later. Plaques were obtained intraoperatively and used for measurement of thrombomodulatory genes expression. Plasma samples were collected before the infusion, 24 and 48 hr later to measure changes in systemic markers of plaque instability. RESULTS: No significant differences were noted in thrombomodulatory genes expression between the 2 groups. Systemic levels of tissue factor, matrix metalloproteinase 9 (MMP-9), and monocyte chemotactic factor-1 (MCP-1) were significantly reduced in the rHDL group. However, the effects on MMP-9 and MCP-1 were abolished in the immediate postoperative period. Although rHDL did not affect plasma interleukin-6 levels 24 hr following the infusion, it prevented the significant postoperative elevation seen in the placebo group. CONCLUSIONS: A single infusion of rHDL can acutely alter plasma biomarkers associated with plaque instability and cardiovascular morbidity.

International trends in patient selection for elective endovascular aneurysm repair: sicker patients with safer anatomy leading to improved 1-year survival.

BACKGROUND: To review the trends in patient selection and early death rate for patients undergoing elective endovascular repair of infrarenal abdominal aortic aneurysms (EVAR) in 3 countries. For this study, audit data from 4,163 patients who had undergone elective infrarenal EVAR were amalgamated. The data originated from Australia, Canada (Ontario), and England (London, Cambridge, and Leicester). METHODS: Statistical analyses were undertaken to determine whether patient characteristics and early death rate varied between and within study groups and over time. The study design was retrospective analysis of data collected prospectively between 1999 and 2012. RESULTS: One-year survival improved over time (P = 0.0013). Canadian patients were sicker than those in Australia or England (P < 0.001). American Society of Anesthesiologists classification (ASA) increased over time across all countries although more significantly in Canada. Age at operation remained constant, although older patients were treated more recently in London (P < 0.001). English centers treated larger aneurysms compared with Australia and Canada (P < 0.001). Australian centers treated a much larger proportion of aneurysms that were <55 mm than other countries. Preoperative creatinine levels decreased over time for all countries and centers (P < 0.001). Infrarenal neck angles have significantly decreased over time (P < 0.001). Recent data from London (UK) showed that operations were performed on longer (P < 0.001) and wider (P < 0.001) infrarenal necks than elsewhere. CONCLUSIONS: In this international comparison, several trends were noted including improved 1-year survival despite declining patient health (as measured by increasing ASA status). This may reflect greater knowledge regarding EVAR that centers from different countries have gained over the last decade and improved medical management of patients with aneurysmal disease.

Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1.

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value < 1 × 10(-5)) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p < 1 × 10(-5)). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10(-10), odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression.

Influence of foot ulceration on cause-specific mortality in patients with diabetes mellitus.

OBJECTIVE: The purpose of this study was to assess the odds of all-cause mortality in individuals with diabetic foot ulceration (DFU) compared with those with diabetes and no history of DFU. In addition, we sought to determine the strength of association of DFU with cardiovascular and nonvascular mortality. METHODS: We obtained data for a cohort of patients who attended a secondary care diabetic foot clinic or a general diabetes clinic between 2009 and 2010. A clinic cohort of patients with diabetes and no history of DFU provided a control group. Cause-specific mortality was recorded during a median follow-up duration of 3.6 years (interquartile range, 3.3-4.2 years). The association between DFU and all-cause mortality was evaluated by Cox regression. The association between DFU and cardiovascular mortality was determined by competing risk modeling. RESULTS: We recorded 145 events of all-cause mortality and 27 events of cardiovascular mortality among 869 patients with diabetes. After adjustment for potential confounders, DFU was associated with both cardiovascular disease (hazard ratio, 2.53; 95% confidence interval, 0.98-6.49; P = .05) and all-cause mortality (hazard ratio, 3.98; 95% confidence interval, 2.55-6.21; P < .001). The proportion of deaths attributable to cardiovascular disease was similar between the groups (18% with diabetes only and 19% with DFU; P = .91). CONCLUSIONS: DFU is associated with premature death from vascular and nonvascular causes.

Opioid Prescribing Habits for Common Arthroscopic Procedures in Opioid Naïve Patients.

BACKGROUND: With the opioid epidemic and the increasing number of opioid-related deaths, there is growing awareness in the medical community regarding the dangers of opioid overprescription. As a result, there is a willingness among physicians to abandon old norms and adopt new data-driven prescribing practices. PURPOSE: To demonstrate patient-reported consumption data of opioid medications after anterior cruciate ligament (ACL) reconstructions (ACLRs), knee arthroscopies, and rotator cuff repairs to provide data-driven guidelines for prescribing opioids after these procedures. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Included in the study were 168 patients who underwent an ACLR, knee arthroscopy, or arthroscopic rotator cuff repair over a 17-month period. Patients were excluded if they had an opioid allergy, had preexisting opioid use, had an acute postoperative complication requiring further surgery, required hospitalization, exhibited drug-seeking behaviors, or were lost to follow-up. Medical records were reviewed to determine the number of opioid pills prescribed and the number of pills taken postoperatively. Prescribing was standardized in that 15 hydrocodone/acetaminophen pills (5/325 mg) were prescribed for all knee arthroscopy procedures and 40 hydrocodone/acetaminophen pills were prescribed for all ACL and rotator cuff procedures. The mean number of pills consumed and percentage of prescribed pills taken were analyzed in association with specific procedures and patient demographics. RESULTS: Overall, the mean (±SD) reported opioid consumption overall was 13.5 ± 13.0 pills, with a utilization rate of 45.6% of the prescription. The mean reported opioid consumption for ACLRs, knee arthroscopies, and rotator cuff repairs was 19.1 ± 15.4, 7.2 ± 5.4, and 17.2 ± 14.3 pills, respectively (P < .001). This represented a utilization rate of 48%, 47%, and 41%, respectively. CONCLUSION: This study provides important information regarding opioid utilization after common arthroscopic procedures. For ACLRs, knee arthroscopies, and rotator cuff repairs, by respectively prescribing 20, 10, and 20 pills postoperatively, the amount of unused medications would decrease by 60%, 47%, and 64%, respectively. We recommend prescribing no more than 20, 10, and 20 hydrocodone/acetaminophen pills (5/325 mg) for ACLRs, knee arthroscopies, and arthroscopic rotator cuff repairs, respectively.

Vascular endothelial growth factor enhances angiotensin II-induced aneurysm formation in apolipoprotein E-deficient mice.

OBJECTIVE: Abdominal aortic aneurysm (AAA) development is associated with increased angiogenesis and overexpression of vascular endothelial growth factor (VEGF). Inhibition of angiogenesis results in attenuation of experimental aneurysms. This study investigated the effects of recombinant human (rh)VEGF on experimental aneurysms. METHODS: Apolipoprotein E-deficient (apoE(-/-)) mice were assigned to one of four groups: (1) normal saline infusion (sham), (2) angiotensin-II (AngII) infusion, (3) AngII infusion plus 100 microg daily rhVEGF for 14 days (AngII+14dVEGF), or (4) AngII infusion plus 100 microg daily rhVEGF for 21 days (AngII+21dVEGF). Aortic maximum diameter and cross-sectional area were determined by magnetic resonance imaging and microscopy. All mice were sacrificed at day 28. RESULTS: Aneurysms developed in all mice in the AngII+14dVEGF and AngII+21dVEGF groups by day 21 compared with 40% in the AngII group. Treatment with rhVEGF increased maximum aortic diameter (P < .002) and cross-sectional area of aneurysms (P < .005) at day 21. This effect was maintained at day 28 (P < .0005). Decreasing rhVEGF treatment from 21 to 14 days did not attenuate aneurysm formation. Treatment with rhVEGF upregulated matrix metalloproteinase 2 gene expression within the aortic wall (P < .0009). CONCLUSIONS: Treatment with rhVEGF intensified the formation of AngII-induced aneurysms. Further studies are needed to investigate if antiangiogenic therapy may be a valid medical therapy against aneurysm expansion or rupture.

Endovascular repair of ruptured abdominal aortic aneurysm: A strategy in need of definitive evidence.

INTRODUCTION: Endovascular strategies have been increasingly used to manage patients with ruptured abdominal aortic aneurysm (AAA) in an attempt to improve patient survival. We analyzed the evidence to support such an approach. METHODS: We performed a systematic literature review of endovascular aneurysm repair (EVAR) of ruptured AAA from 1994 to 2009. The literature analyzed included systematic reviews and population-based studies of ruptured AAA. RESULTS: Seven systematic reviews were identified, all demonstrating from published data that patients with EVAR of ruptured AAA had significantly reduced mortality compared with controls. Six recently published population-based studies from the United States demonstrated low mortality rates associated with EVAR; however, only a small proportion of ruptured AAAs were treated by EVAR. Systematic reviews and population-based studies both raised concerns about patient selection and publication bias. Two randomized trials are in progress, and one is due to commence 2009. CONCLUSIONS: The outcome of EVAR in a nonselected patient population remains unknown. One or more definitive randomized trials could provide the level I evidence to resolve these issues.

Blood leucocyte telomere DNA content predicts vascular telomere DNA content in humans with and without vascular disease.

AIMS: Previous studies have suggested that reduced telomere length in circulating leucocytes in humans is associated with premature vascular disease and by implication, accelerated vascular ageing. Importantly, a link between telomere length in circulating leucocytes and the blood vessel wall has never been established. We, thus, investigated the relationship between vascular wall and circulating leucocyte telomere length in humans with and without overt vascular disease. METHODS AND RESULTS: Aortic biopsies and paired blood leucocytes were obtained from 20 patients with asymptomatic abdominal aortic aneurysms (AAAs), undergoing elective open repair, and 12 morphologically normal aortas from a group of cadaveric organ donors of similar mean age. Telomere content was compared by quantitative PCR and expressed as telomere:genomic DNA ratio. The telomere:genomic DNA content was significantly reduced in wall biopsies of AAA vs. normal aorta, and this difference remained after adjusting for age and gender. There were strong correlations between leucocyte and vascular telomere content when the AAA and control groups were analysed either separately or grouped irrespective of the presence of vascular disease (r = 0.62, P < 0.001). CONCLUSION: The findings demonstrate that leucocyte DNA content is predictive of vascular telomere content and is an accurate surrogate for human vascular age.

Matrix metalloproteinase-8 and -9 are increased at the site of abdominal aortic aneurysm rupture.

BACKGROUND: Abdominal aortic aneurysm (AAA) expansion is characterized by extracellular matrix degradation and widespread inflammation. In contrast, the processes that characterize AAA rupture are not well understood. The aim of this study was to investigate the proteolytic and cellular activity of ruptured AAA, focusing on matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). METHODS AND RESULTS: Anterior aneurysm wall biopsies were taken from 55 nonruptured and 21 ruptured AAAs. A further biopsy from the site of rupture was taken from 12 of the ruptured AAAs. MMP-1, -2, -3, -8, -9, and -13, as well as TIMP-1 and -2, were quantified in each biopsy with ELISA. A comparison of anterior aneurysm biopsies showed no difference in MMP or TIMP concentrations between nonruptured and ruptured AAA. In a comparison of ruptured AAA biopsies, MMP-8 and -9 levels were significantly elevated in the 12 rupture site biopsies compared with their 12 paired anterior wall biopsies, whereas other MMPs and TIMPs showed no difference (MMP-8, P<0.001; MMP-9, P=0.01). MMP-8 and -9 expression was mediated by native mesenchymal cells and was independent of the inflammatory infiltrate. CONCLUSIONS: A localized increase in MMP-8 and -9, mediated by native mesenchymal cells, presents a potential pathway for collagen breakdown and AAA rupture.

Abdominal aortic aneurysm rupture is associated with increased medial neovascularization and overexpression of proangiogenic cytokines.

OBJECTIVE: Matrix metalloproteinase (MMP) activity has been linked to abdominal aortic aneurysm (AAA) rupture. Medial neovascularization (MNV), a histopathologic characteristic of AAAs, involves proteolytic degradation of extracellular matrix by MMPs to facilitate endothelial cell migration. The role of MNV in aneurysm rupture is unknown. This study investigated whether MNV is increased in aneurysm rupture. METHODS AND RESULTS: Biopsy samples from aneurysm rupture edge were compared with control biopsy samples from aneurysm wall at the level of rupture and from anterior sac in 12 ruptured AAAs. Further controls were obtained from anterior sac of 10 nonruptured AAAs. MNV, microvessel diameter, maturity index, and inflammatory infiltrate were quantified using morphometric analyses following immunohistochemistry. Expression of proangiogenic mediators was quantified using quantitative real-time-polymerase chain reaction. Compared with anterior sac and aneurysm wall at level of rupture, MNV was increased (P<0.001) in rupture edge biopsy samples and consisted of smaller diameter (P<0.001) and more immature microvessels (P<0.001). mRNA expression of alpha(v)-integrin, vascular endothelial growth factor, vascular endothelial-cadherin, monocyte chemoattractant protein-1, and vimentin was increased (P<0.05) in rupture edge biopsy samples. CONCLUSIONS: This study demonstrated increased medial neovascularization and overexpression of proangiogenic cytokines at aneurysm rupture edge. Further investigations into whether this angiogenic response was a causative factor of aneurysm rupture are needed.

Using multiple classifiers for predicting the risk of endovascular aortic aneurysm repair re-intervention through hybrid feature selection.

Feature selection is essential in medical area; however, its process becomes complicated with the presence of censoring which is the unique character of survival analysis. Most survival feature selection methods are based on Cox's proportional hazard model, though machine learning classifiers are preferred. They are less employed in survival analysis due to censoring which prevents them from directly being used to survival data. Among the few work that employed machine learning classifiers, partial logistic artificial neural network with auto-relevance determination is a well-known method that deals with censoring and perform feature selection for survival data. However, it depends on data replication to handle censoring which leads to unbalanced and biased prediction results especially in highly censored data. Other methods cannot deal with high censoring. Therefore, in this article, a new hybrid feature selection method is proposed which presents a solution to high level censoring. It combines support vector machine, neural network, and K-nearest neighbor classifiers using simple majority voting and a new weighted majority voting method based on survival metric to construct a multiple classifier system. The new hybrid feature selection process uses multiple classifier system as a wrapper method and merges it with iterated feature ranking filter method to further reduce features. Two endovascular aortic repair datasets containing 91% censored patients collected from two centers were used to construct a multicenter study to evaluate the performance of the proposed approach. The results showed the proposed technique outperformed individual classifiers and variable selection methods based on Cox's model such as Akaike and Bayesian information criterions and least absolute shrinkage and selector operator in p values of the log-rank test, sensitivity, and concordance index. This indicates that the proposed classifier is more powerful in correctly predicting the risk of re-intervention enabling doctor in selecting patients' future follow-up plan.