The Receptor for Advanced Glycation End Products (Rage) and Its Ligands in Plasma and Infrainguinal Bypass Vein.

OBJECTIVE: The aim was to investigate whether RAGE and its ligands are associated with infrainguinal bypass outcome in patients with and without diabetes. METHODS: This was a prospective observational cohort. Patients (n = 68) with (n = 38) and without (n = 30) diabetes undergoing infrainguinal vein bypass for peripheral arterial disease were followed for 3 years. Endosecretory RAGE (esRAGE), S100A12, advanced glycation end products, and carboxymethyl-lysine (CML) were determined in plasma using ELISA. The influence of plasma levels on the main outcome (amputation free survival) was evaluated using Cox proportional hazard analysis. Plasma esRAGE, CML, and S100A12 in healthy controls (n = 30) without cardiovascular disease matched for sex and age were compared with patients, using the Mann-Whitney U test. Veins from bypass surgery procedures were stained and S100A12, RAGE, AGE, and CML were determined using immunohistochemistry. RESULTS: Forty-six patients survived with an intact leg during follow up. Seventeen died (median survival time 702 days, IQR 188-899 day), and six had amputations. High plasma S100A12 was associated with reduced amputation free survival (hazard ratio [HR] 2.99; 95% CI 1.24-7.24) when comparing levels above the 75th percentile with levels below. The increased risk was unchanged adjusting for age, sex, and diabetes. Diabetic patients had higher plasma S100A12 (11.75 ng/mL; 95% CI 8.12-15.38 ng/mL) than non-diabetic patients (5.0141 ng/mL; 95% CI 3.62-6.41 ng/mL), whereas plasma CML, esRAGE, and AGE were similar. Plasma CML and S100A12 were higher in patients than in controls (1.25 µg/mL, 95% CI 1.18-1.32 µg/mL vs. 0.8925 µg/mL, 95% CI 0.82-0.96 µg/mL; and 8.7 µg/mL, 95% CI 6.52-10.95 µg/mL vs. 3.47 µg/mL, 95% CI 2.95-3.99 µg/mL, respectively). The proportion of vein tissue stained for AGE (21%), RAGE (5%), CML (9%) and S100A12 (3%), were similar in patients with and without diabetes. CONCLUSIONS: Plasma S100A12 and CML are elevated in peripheral arterial disease and markers of RAGE and its ligands are found in vein used for bypass. This indicates a role for S100A12, CML, and RAGE in peripheral arterial disease complications by activation of the RAGE system.

Randomized clinical trial of mast cell inhibition in patients with a medium-sized abdominal aortic aneurysm.

BACKGROUND: Abdominal aortic aneurysm (AAA) is thought to develop as a result of inflammatory processes in the aortic wall. In particular, mast cells are believed to play a central role. The AORTA trial was undertaken to investigate whether the mast cell inhibitor, pemirolast, could retard the growth of medium-sized AAAs. In preclinical and clinical trials, pemirolast has been shown to inhibit antigen-induced allergic reactions. METHODS: Inclusion criteria for the trial were patients with an AAA of 39-49 mm in diameter on ultrasound imaging. Among exclusion criteria were previous aortic surgery, diabetes mellitus, and severe concomitant disease with a life expectancy of less than 2 years. Included patients were treated with 10, 25 or 40 mg pemirolast, or matching placebo for 52 weeks. The primary endpoint was change in aortic diameter as measured from leading edge adventitia at the anterior wall to leading edge adventitia at the posterior wall in systole. All ultrasound scans were read in a central imaging laboratory. RESULTS: Some 326 patients (mean age 70·8 years; 88·0 per cent men) were included in the trial. The overall mean growth rate was 2·42 mm during the 12-month study. There was no statistically significant difference in growth between patients receiving placebo and those in the three dose groups of pemirolast. Similarly, there were no differences in adverse events. CONCLUSION: Treatment with pemirolast did not retard the growth of medium-sized AAAs. REGISTRATION NUMBER: NCT01354184 (https://www.clinicaltrials.gov).

A novel strategy to translate the biomechanical rupture risk of abdominal aortic aneurysms to their equivalent diameter risk: method and retrospective validation.

OBJECTIVE: To translate the individual abdominal aortic aneurysm (AAA) patient's biomechanical rupture risk profile to risk-equivalent diameters, and to retrospectively test their predictability in ruptured and non-ruptured aneurysms. METHODS: Biomechanical parameters of ruptured and non-ruptured AAAs were retrospectively evaluated in a multicenter study. General patient data and high resolution computer tomography angiography (CTA) images from 203 non-ruptured and 40 ruptured aneurysmal infrarenal aortas. Three-dimensional AAA geometries were semi-automatically derived from CTA images. Finite element (FE) models were used to predict peak wall stress (PWS) and peak wall rupture index (PWRI) according to the individual anatomy, gender, blood pressure, intra-luminal thrombus (ILT) morphology, and relative aneurysm expansion. Average PWS diameter and PWRI diameter responses were evaluated, which allowed for the PWS equivalent and PWRI equivalent diameters for any individual aneurysm to be defined. RESULTS: PWS increased linearly and PWRI exponentially with respect to maximum AAA diameter. A size-adjusted analysis showed that PWS equivalent and PWRI equivalent diameters were increased by 7.5 mm (p = .013) and 14.0 mm (p < .001) in ruptured cases when compared to non-ruptured controls, respectively. In non-ruptured cases the PWRI equivalent diameters were increased by 13.2 mm (p < .001) in females when compared with males. CONCLUSIONS: Biomechanical parameters like PWS and PWRI allow for a highly individualized analysis by integrating factors that influence the risk of AAA rupture like geometry (degree of asymmetry, ILT morphology, etc.) and patient characteristics (gender, family history, blood pressure, etc.). PWRI and the reported annual risk of rupture increase similarly with the diameter. PWRI equivalent diameter expresses the PWRI through the diameter of the average AAA that has the same PWRI, i.e. is at the same biomechanical risk of rupture. Consequently, PWRI equivalent diameter facilitates a straightforward interpretation of biomechanical analysis and connects to diameter-based guidelines for AAA repair indication. PWRI equivalent diameter reflects an additional diagnostic parameter that may provide more accurate clinical data for AAA repair indication.

Regional variation in the incidence of abdominal aortic aneurysm in Sweden.

BACKGROUND: The risk factor profile is similar between patients with abdominal aortic aneurysm (AAA) and coronary heart disease (CHD). CHD is more common in the north of Sweden. It is unknown whether similar regional differences in the incidence of AAA exist. The aims of this study were to investigate whether there is a regional gradient of AAA incidence, and to compare time trends and the frequency of interventions between regions. METHODS: Swedish citizens have a 12-digit personal identification number. The Swedish Hospital Discharge Register covers inpatient care (diagnosis, admission, procedure codes, sex, date of birth, county). Population size was obtained from the central statistical bureau. Regions were south, mid and north. RESULTS: All records for 1990-2005 were extracted and 35 418 individuals with AAA were identified (74.8 per cent men). The highest age-standardized incidence (102.7 per 100,000) was found in men in the north region. The age-adjusted incidence ratio for men in the north region compared with the south was 1.38 (95 per cent confidence interval 1.34 to 1.42). Similar differences were found in women: incidence ratio for north compared with south region 1.39 (1.07 to 1.81). The proportion treated was larger in men and varied by region: 46.9 per cent of men in the mid region compared with 43.7 per cent in the south received treatment (P < 0.001), whereas 29.8 per cent of women in the north region versus 25.4 per cent in the south had an intervention (P = 0.001). The incidence did not increase over time. CONCLUSION: The higher incidence of AAA in the north of Sweden corresponds well with reported CHD patterns. The incidence of AAA in the population did not increase significantly over time, in contrast to the increasing intervention rates.

Correlations between clinical variables and gene-expression profiles in carotid plaque instability.

OBJECTIVE: Strokes, a major cause of disability, are often caused by embolism from unstable carotid plaques. The aim of this study was to validate a biobank of human carotid endarterectomies as a platform for further exploration of pathways for plaque instability. For this purpose, we investigated the relationship between clinical parameters of plaque instability and expression of genes previously shown to be associated with either plaque instability or healing processes in the vessel wall. METHODS: A database of clinical information and gene-expression microarray data from 106 carotid endarterectomies were used. RESULTS: Expression of matrix metalloproteinase (MMP)-9 and MMP-7 was 100-fold higher in plaques than in normal artery. In general, genes associated with inflammation (such as RANKL and CD68) were overexpressed in symptomatic compared with asymptomatic plaques. Plaques obtained from patients undergoing surgery within 2 weeks after an embolic event showed up-regulation of genes involved in healing reactions in the vessel wall (including elastin and collagen). Statin treatment, as well as echodense lesions, were associated with a more stable phenotype. CONCLUSION: Here, we demonstrate that gene-expression profiles reflect clinical parameters. Our results suggest that microarray technology and clinical variables can be used for the future identification of central molecular pathways in plaque instability.

The impact of intraluminal thrombus failure on the mechanical stress in the wall of abdominal aortic aneurysms.

OBJECTIVES: The role of the intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) rupture is controversial, and it is still not clear if an ILT increases or decreases AAA rupture risk. Specifically, signs of bleeding in the ILT are considered to increase AAA rupture risk. To further explore this hypothesis, intact AAAs (n = 4) with clear signs of fissures in the ILT, identified by computed tomography angiography (CTA) were investigated. METHODS: Two different cases of ILT fissuring were investigated, where (1) ILT fissures were extracted directly from the CTA data and (2) a hypothetical fissure was introduced in the otherwise-intact ILT tissue. Wall stress distributions were predicted based on detailed Finite Element (FE) models. RESULTS: ILT fissures extracted from CTA data locally increase the mechanical stress in the underlying wall by up to 30%. The largest impact on wall stress was observed if the ILT crack reaches the aneurysm wall, or if it involves large parts of the ILT. By contrast, a concentric failure in the medial ILT, which does not reach the aneurysm wall, has almost no impact on wall stress distribution. Hypothetical ILT fissures that connect the lumen with the wall cause a twofold increase of the stress in the underlying wall. CONCLUSIONS: ILT fissures increase the stress in the underlying wall, whereas regions other than that remain unaffected. If ILT fissures reach the wall or involve large parts of the ILT, the resulting increase in wall stress could possibly cause AAA rupture.

Expression of fatty acid-binding protein 4/aP2 is correlated with plaque instability in carotid atherosclerosis.

OBJECTIVE: the molecular basis for atherosclerotic plaque vulnerability with high risk of plaque rupture and thromboembolism is complex. We investigated whether clinical estimates of plaque stability correlate with differentially expressed mRNA transcripts within the lesion. METHODS AND RESULTS: endarterectomy samples from patients undergoing surgery for symptomatic and asymptomatic carotid stenosis were prospectively collected and clinical parameters recorded in the Biobank of Karolinska Carotid Endarterectomies. mRNA expression profiling (n = 40) and quantitative RT-PCR (n = 105) revealed increased levels of fatty acid-binding protein 4 (FABP4/aP2) in lesions from patients with recent symptoms of plaque instability compared to asymptomatic patients (array: FC = 2, P < 0.05; RT-PCR: P < 0.05). At the mRNA level, FABP4/aP2 correlated with the cell markers CD36, CD68 and CD163 of monocyte/macrophage lineage as well as with CD4-positive T cells. FABP4/aP2 mRNA expression was also correlated with enzymes of the leukotriene pathway, 5-lipoxygenase and leukotriene A4 hydrolase. In addition, analysis of transcript profiles identified CD52 and adipophilin as the mRNAs with the highest correlation with FABP4/aP2. Expression of FABP4/aP2 by macrophages and CD52 by T cells in the lesion was confirmed by immunohistochemistry. CONCLUSIONS: expression of FABP4/aP2 is increased at the mRNA level in unstable carotid plaques. Immunohistochemical analyses showed localization of FABP4/aP2 to macrophage populations. These FABP4/aP2-positive macrophages constitute an important and prevalent phenotype and could provide a new link between scavenging-mediated lipid uptake and cellular metabolic stress in plaque. In addition FABP4/aP2 correlates with other important signs of inflammation and plaque instability, such as T cells and leukotriene enzymes. Taken together, these results indicate that FABP4/aP2 is a key factor connecting vascular and cellular lipid accumulation to inflammation.

Biomechanical rupture risk assessment of abdominal aortic aneurysms: model complexity versus predictability of finite element simulations.

OBJECTIVE: Investigation of the predictability of finite element (FE) models regarding rupture risk assessment of abdominal aortic aneurysms (AAAs). MATERIALS AND MATERIALS: Peak wall stress (PWS) and peak wall rupture risk (PWRR) of ruptured (n = 20) and non-ruptured (n = 30) AAAs were predicted by four FE models of different complexities derived from computed tomography (CT) data. Two matching sub-groups of ruptured and non-ruptured aneurysms were used to investigate the usability of different FE models to discriminate amongst them. RESULTS: All FE models exhibited a strong positive correlation between PWS and PWRR with the maximum diameter. FE models, which excluded the intra-luminal thrombus (ILT) failed to discriminate between ruptured and non-ruptured aneurysms. The predictability of all applied FE models was strengthened by including wall strength data, that is, computing the PWRR. The most sophisticated FE model applied in this study predicted PWS and PWRR 1.17 (p = 0.021) and 1.43 (p = 0.016) times higher in ruptured than diameter-matched non-ruptured aneurysms, respectively. CONCLUSIONS: PWRR reinforces PWS as a biomechanical rupture risk index. The ILT has a major impact on AAA biomechanics and rupture risk, and hence, needs to be considered in meaningful FE simulations. The applied FE models, however, could not explain rupture in all analysed aneurysms.

Abdominal aortic aneurysm in the interval 5.0-5.5 cm, art or evidence?

The risk of rupture for aneurysms 5-5.5 cm in diameter has not been specifically studied. Two large randomised trials, the United Kingdom Small Aneurysm Trial and the Aneurysm Detection And Management Study Trial concluded that immediate surgical repair did not offer any benefit compared to surveillance and surgical repair if the aneurysm reached 5.5 cm or became symptomatic. Despite these findings many indications today suggest that a lower threshold should be used in patients with higher risk for rupture e.g. women or low risk of mortality in connection with AAA repair such as patients in the lower range of ages.

The most wanted trials for abdominal aortic aneurysm treatment.

This overview contains suggestions for two different types of trials, medical treatment of small aneurysms and methods for selection of aneurysms in need of intervention. Questions in need of answers are evaluation of the influence on growth and rupture by medical treatment and parameters other than absolute diameter for selection of patients for open surgical or endovascular intervention. These questions need not necessarily be answered by randomised controlled trials.

Different disease profiles for women and men with abdominal aortic aneurysms.

OBJECTIVE: The overall aim with this study was to investigate causes of death and mortality rates for women and men treated for abdominal aortic aneurysm (AAA) in Sweden. MATERIALS AND METHOD: All patients treated for ruptured and non-ruptured AAA 1987-2002 in Sweden were identified in national registries (n=12917). Age, sex, diagnosis, surgical procedure and mortality were analysed on a patient specific level. Logistic regression and analysis of standardised mortality rates (SMR) were performed. RESULTS: Post operative mortality was similar between the sexes. Age (p<0.0001), and surgery for rupture (p=0.0005), but not gender (p=0.65) were significant risk factor for poor long term survival. SMR revealed increased risk for both sexes compared to the population with significantly higher values for women than men (2.26, CI 2.10-2.43 vs. 1.63, CI 1.57-1.68, p<0.0001). The higher risk for women could be explained by the higher risk for aneurysm related death (ie.thoracic or abdominal aorta) compared to men (Hazard ratio 1.57 vs. 1.0, p<0.0001). CONCLUSION: Women do not have an increased surgical risk compared to men, but treated women have an increased risk of premature death compared to men and women in the population. They also have a higher risk for aneurysm related death compared to men with AAA.

Influence of perioperative blood glucose levels on outcome after infrainguinal bypass surgery in patients with diabetes.

BACKGROUND: High glucose levels are associated with increased morbidity and mortality after coronary surgery and in intensive care. The influence of perioperative hyperglycaemia on the outcome after infrainguinal bypass surgery among diabetic patients is largely unknown. The aim was to determine whether high perioperative glucose levels were associated with increased morbidity after infrainguinal bypass surgery. METHODS: Ninety-one consecutive diabetic patients undergoing primary infrainguinal bypass surgery were identified from a prospective vascular registry. Risk factors, indication for surgery, operative details and outcome data were extracted from the medical records. Exposure to perioperative hyperglycaemia was measured using the area under the curve (AUC) method; the AUC was calculated using all blood glucose readings during the first 48 h after surgery. RESULTS: Multivariable analysis showed that the AUC for glucose (odds ratio (OR) 13.35, first versus fourth quartile), renal insufficiency (OR 4.77) and infected foot ulcer (OR 3.38) was significantly associated with poor outcome (death, major amputation or graft occlusion at 90 days). Similarly, the AUC for glucose (OR 14.45, first versus fourth quartile), female sex (OR 3.49) and tissue loss as indication (OR 3.30) was associated with surgical wound complications at 30 days. CONCLUSION: Poor perioperative glycaemic control was associated with an unfavourable outcome after infrainguinal bypass surgery in diabetic patients.

The role of coagulation and inflammation after angioplasty in patients with peripheral arterial disease.

PURPOSE: Restenosis remains a frequent complication after angioplasty in peripheral arterial disease. Inflammation plays a critical role in the vascular response to injury. Effective medical treatment to improve patency after angioplasty is still elusive. The aims of this prospective clinical study were to investigate changes in blood coagulation and inflammatory markers after angioplasty and their significance for restenosis. METHODS: Thirty-four patients with peripheral arterial disease underwent angioplasty of the iliac and superficial femoral arteries. Ten patients undergoing diagnostic angiography were included in the study as controls. Plasma levels of tissue factor, prothrombin fragment 1 + 2, D-dimer, P-selectin, C-reactive protein (CRP), and fibrinogen were analyzed before and after angioplasty. Patients were followed up with angiography after 6 months to assess restenosis. RESULTS: CRP was elevated the day after angioplasty (6.6 mg/l, p = 0.0001) and tended to peak after 1 week (11 mg/l, p = 0.09). There was a significant increase of D-dimer and P-selectin 1-4 hr after angioplasty (0.4 mg/l, p = 0.001 and 68 ng/ml, p = 0.05, respectively). None of the biochemical markers was a statistically significant predictor of restenosis. CONCLUSION: We have observed a much more prolonged inflammatory response than previously noted, but only minor changes in coagulation activity after angioplasty. The biochemical markers, before and after angioplasty, were not related to restenosis. Further studies are needed to delineate the molecular mechanisms behind these observations and their involvement in thrombosis and restenosis. If these pathways are further defined, improved treatment strategies, including antithrombotic treatments and statins, could be tailored to modulate postprocedural inflammation.

Outcome after abdominal aortic aneurysm repair. Difference between men and women.

OBJECTIVES: To evaluate short- and long-term outcome after open repair for ruptured and non-ruptured abdominal aortic aneurysm (AAA) with special emphasis on the difference between men and women. DESIGN: Single center retrospective study. Time and cause of death were determined from hospital charts, the National Bureau of Statistics and the Department for National Health and Welfare. Materials. Eight hundred and forty-six patients were followed-up, 597 were operated on for non-ruptured and 249 for ruptured aneurysms. METHODS: Case fatality was analyzed by multiple logistic regression considering year of surgery, age at surgery, and gender as covariates. The mortality rate for patients surviving 60 days after surgery was compared with the mortality in the general population by calculating the standardised mortality ratio (SMR). Mortality was also stratified according to gender and type of surgery. RESULTS: The SMR for patients surviving 60 days after surgery was significantly increased. SMR was significantly higher for women than for men. There was no statistically significant difference in SMR between patients operated for rupture compared to those operated for non-ruptured aneurysms. CONCLUSIONS: Women with AAA have a poorer outcome than women in the general population. This finding may relate to the large number of risk factors present in this patient sub-group.

The use of recombinant activated factor VII to control bleeding during repair of a suprarenal abdominal aortic aneurysm.

Recombinant activated factor VII (rFVIIa) was first used to control bleeding in haemophilia patients. More recently, it has been used to prevent severe bleeding in patients without pre-existing coagulopathy. We report a case where rFVIIa was used to successfully control postoperative bleeding in a patient undergoing suprarenal abdominal aortic aneurysm (AAA) repair.

In vitro endothelialization of bioprosthetic heart valves provides a cell monolayer with proliferative capacities and resistance to pulsatile flow.

OBJECTIVES: Degeneration of bioprosthetic heart valves has been suggested to be at least partly an immunogenic reaction toward the xenogeneic tissue. An autologous endothelial lining has been proposed to overcome this problem. We examined in vitro endothelialization of such tissue and retention of endothelial cells after exposure to flow resembling the in vivo situation. METHODS: Cultured human saphenous vein endothelial cells were used to in vitro endothelialize photo-oxidized bioprosthetic heart valves. The endothelialized valves were mounted in a specially designed flow device, creating a pulsatile flow through the valve. Maintenance of a confluent cell layer and deposition of basement membrane markers were determined with immunohistochemical labeling. RESULTS: Labeling of the main components of the basement membrane, laminin and collagen type IV, was verified within 6 hours after in vitro endothelialization. Under static conditions, 4-mm wide denudations were completely re-endothelialized in 4 days, which was similar to the growth rate on gelatin-coated cell culture plastic, which served as a control material. After exposure of endothelialized valves to pulsatile flows for 24 hours (80 beats/min, 3.4 L/min), there were minimal cell losses from the bioprostheses. The cell layer adapted to the pulsatile flow, as verified by rearrangement of morphology and intracellular stress fibers. CONCLUSIONS: This study shows the feasibility of in vitro endothelialization of photo-oxidized bioprosthetic heart valves. The cells are able to withstand a pulsatile flow in vitro, to develop basement membrane-like structures, and to re-endothelialize denuded areas. This technology may be used to enhance the performance of bioprosthetic heart valve prostheses.

Fucoidan inhibits smooth muscle cell proliferation and reduces mitogen-activated protein kinase activity.

OBJECTIVES AND DESIGN: fucoidan has previously been shown to inhibit the proliferation of arterial smooth muscle cells both in animal models and in vitro. However, the mechanisms behind the anti-proliferative effects of this polysulfated polysaccharide are not known in detail. Here, the inhibitory effect of fucoidan on rat aortic smooth muscle cell proliferation was examined and compared with the effects of heparin after stimulation with fetal calf serum, platelet-derived growth factor BB, basic fibroblast growth factor, heparin-binding epidermal growth factor, and angiotensin II. MATERIALS AND METHODS: the cultures were analysed with respect to cell proliferation and DNA synthesis by cell counting and measurement of(3)H-thymidine incorporation. Phosphorylation of mitogen-activated protein kinase and nuclear translocation of phosphorylated mitogen-activated protein kinase were studied by immunoblotting and immunocytochemistry. RESULTS: fucoidan was shown to be a more potent inhibitor of smooth muscle cell proliferation than heparin. Fucoidan also reduced growth factor-induced activation of mitogen-activated protein kinase and prevented nuclear translocation of phosphorylated mitogen-activated protein kinase. CONCLUSION: fucoidan is a more potent anti-proliferative polysulphated polysaccharide than heparin and may mediate its effects through inhibition of the mitogen-activated protein kinase pathway in a similar manner as heparin.

Growth of thrombus may be a better predictor of rupture than diameter in patients with abdominal aortic aneurysms.

OBJECTIVES: to investigate the relationships between diameter, surface and thrombus area in abdominal aortic aneurysms (AAAs) <5 cm. METHODS AND MATERIAL: sixty-seven patients with AAA underwent at least 2 CT examinations. At the point of maximal diameter, surface area and thrombus area were calculated and related to rupture, or impending rupture, during follow-up. RESULTS: the mean increase in measured diameter, surface area and thrombus area were 3.4 mm, 1.9 cm(2)and 1.7 cm(2)per year respectively. Patients with AAA >4 cm and whose thrombus area increased >1.5 cm(2)/year were more likely to rupture (6/24 vs 1/23). CONCLUSIONS: a rapid increase of thrombus area may be a better predictor of AAA rupture than increase in maximal diameter.