Risk factors for aneurysm rupture in patients kept under ultrasound surveillance. UK Small Aneurysm Trial Participants

A clinical update on the mid-term clinical performance of the Ovation endograft

INTRODUCTION

The Ovation stent-graft uncouples the steps of fixation and sealing via a pair of polymer-filled inflatable rings. Apart from the well-documented early results, newer data emerged for mid-term results of Ovation and are presented in this review.

AREAS COVERED

Aim of this article was to report all current studies with the mid-term results of the particular endograft, the incidence of complications and failure, and discuss their management.

EXPERT COMMENTARY

The Ovation stent-graft exhibits very satisfactory clinical mid-term results in abdominal aortic aneurysms treated within the instructions-for-use. It can also have a very promising role in challenging neck anatomies with conical shape and presence of thrombus or calcification. However, this should be not considered a panacea and long-term results are needed to validate this intriguing aspect.

Successful management of critical iliac artery aneurysm which is unexpectedly accompanied by acute aortic dissection type B: A case report

Acute aortic dissection with concurrent large aortic aneurysm is a catastrophic condition. Clinicians may be faced with the dilemma of how to manage these patients. This case reports a successful management crisis in a patient with a type B aortic dissection and a large left common iliac artery aneurysm.

Abdominal aortic aneurysms

An abdominal aortic aneurysm (AAA) is a localized dilatation of the infrarenal aorta. AAA is a multifactorial disease, and genetic and environmental factors play a part; smoking, male sex and a positive family history are the most important risk factors, and AAA is most common in men >65 years of age. AAA results from changes in the aortic wall structure, including thinning of the media and adventitia due to the loss of vascular smooth muscle cells and degradation of the extracellular matrix. If the mechanical stress of the blood pressure acting on the wall exceeds the wall strength, the AAA ruptures, causing life-threatening intra-abdominal haemorrhage - the mortality for patients with ruptured AAA is 65-85%. Although AAAs of any size can rupture, the risk of rupture increases with diameter. Intact AAAs are typically asymptomatic, and in settings where screening programmes with ultrasonography are not implemented, most cases are diagnosed incidentally. Modern functional imaging techniques (PET, CT and MRI) may help to assess rupture risk. Elective repair of AAA with open surgery or endovascular aortic repair (EVAR) should be considered to prevent AAA rupture, although the morbidity and mortality associated with both techniques remain non-negligible.

Effect of Hypertension on Aortic Artery Disease-Related Mortality - 3.8-Year Nationwide Community-Based Prospective Cohort Study

BACKGROUND

Aortic artery disease (AAD), such as aortic dissection or aortic aneurysm rupture, is fatal, with an extremely high mortality. Because of its low incidence, the risk for the development of AAD has not yet been elucidated. Hypertension (HT) is an established risk factor for cardiovascular disease, but there has been no prospective study on the effect of HT on AAD-related mortality. Methods and Results: We used a nationwide database of 276,197 subjects (aged 40-75 years) who participated in the annual "Specific Health Check and Guidance in Japan" from 2008 to 2010. There were 80 AAD-related deaths during the follow-up period of 1,049,549 person-years. On multivariate Cox proportional hazard regression, HT was an independent risk factor for AAD-related death in apparently healthy subjects. On receiver operating characteristics curve analysis for AAD-related death, abnormal systolic and diastolic blood pressure (SBP and DBP) were 130 mmHg and 82 mmHg, respectively. The prediction capacity was significantly improved by the addition of SBP to confounding risk factors. Notably, further improvement of the C index was observed by addition of DBP to the model with SBP.

CONCLUSIONS

This is the first report to prospectively show that HT is a risk factor for AAD-related death. Both SBP and DBP are of critical importance in the primary prevention of AAD-related death in apparently healthy subjects.

Risk Factor Analyses of Abdominal Aortic Aneurysms Growth in Japanese Patients

BACKGROUND

This study aimed to retrospectively demonstrate the growth rate (mm/year) of abdominal aortic aneurysm (AAA) diameters (ADs) and to analyze risk factors for AAA expansion.

METHODS

We retrospectively investigated the clinical data of 319 patients with AAAs who were followed up as outpatients for >2 years after their initial visit and who underwent computed tomography >4 times.

RESULTS

The mean follow-up period was 3.7 ± 1.5 years. The annual average growth rates according to varying ADs were as follows: 1.9 ± 0.8 (AD 30-34 mm), 2.6 ± 1.2 (AD 35-39 mm), 2.8 ± 1.1 (AD 40-44 mm), 3.1 ± 1.3 (AD 45-49 mm), 3.4 ± 1.6 (AD 50-54 mm), and 3.5 ± 1.4 mm (AD ≥55 mm). Factors associated with AAA expansion were smoking (P = 0.017), hypertension (P < 0.001), and ADs (P < 0.001). In the subgroup analysis, data regarding growth rates of ≥3 mm were extracted, and a statistically significant difference between smoking status and ADs of ≥40 mm was observed.

CONCLUSIONS

Factors associated with AAA expansion in Japanese patients included smoking, hypertension, and ADs, and a statistically significant difference was observed between smoking status and ADs of ≥40 mm.

Finite element analysis in symptomatic and asymptomatic abdominal aortic aneurysms for aortic disease risk stratification

BACKGROUND

Advanced biomechanical models can provide additional information concerning rupture risk in abdominal aortic aneurysms (AAA). Here we evaluated the predictive value of finite element analysis (FEA) to assess AAA rupture risk.

METHODS

In a case-control study, we compared FEA parameters in a group of symptomatic AAA (sAAA) patients, considered as a high risk of rupture group, with FEA parameters in asymptomatic AAA patients (aAAA).

RESULTS

We included 15 sAAA and 28 aAAA patients matched for age- and maximum diameter diagnosed with infrarenal non-ruptured AAA at our center between 2009 and 2013. Mean age was 75±69 years and mean maximum diameter was 77±17 mm. Peak wall stress (PWS) was significantly higher in sAAA patients than in aAAA patients (354.3±139.6 kPa vs. 248.6±81.9 kPa; P=0.001). The C statistic for the ROC curve based on PWS was 0.748 (95% CI: 0.592-0.903; P=0.008). CART analysis classified patients into high and low PWS groups. The high-PWS group (>305.15 kPa; N.=15) had a higher incidence of sAAA (33.3% aAAA, 66.7% sAAA) than the low-PWS-group (≤305.15 kPa; N.=28. 82.1% aAAA, 17.9% sAAA).

CONCLUSIONS

In conclusion, PWS was significantly higher in sAAA patients. Measuring PWS may help estimate the individual rupture risk in patients with AAA, but larger studies are needed to confirm our results.

Clinical Arterial Peripheral Vascular Pathology Does Not Impact Short- or Long-Term Survival after Transcatheter Aortic Valve Replacement

Introduction

The dramatic changes in vascular hemodynamics after transcatheter aortic valve replacement (TAVR) are well noted. However, little postprocedural data exists on the outcomes in patients with clinical arterial peripheral vascular pathology [abdominal aortic aneurysm (AAA), carotid artery stenosis (CAS), and peripheral artery disease (PAD)] undergoing TAVR for severe aortic stenosis.

Setting

A single center healthcare system.

Methodology

A retrospective chart review case-control study of 342 consecutive patients who underwent a TAVR for severe aortic stenosis at Sanford Health in Fargo; ND was performed to determine if preprocedural comorbid AAA, CAS, or PAD was associated with worse outcomes after TAVR.

Results

Patients with preprocedural comorbid AAA, CAS, or PAD had no significant difference overall survival at 1 month (94% versus 95% p =.812), 6 months (88% versus 89% p = .847), 1 year (74% versus 83%, p =.130), or 2 years (58% versus 63%, p =.611) after TAVR. Patients with clinical arterial peripheral vascular pathology also had no significant difference in preprocedural outcomes.

Conclusion

This study gives evidence to suggest that patients with a comorbid clinical peripheral arterial pathology at the time of TAVR do not have a statistically significant increase in mortality out to 2 years after TAVR and no increase in procedural complications. These results affirm the safety and feasibility of TAVR in patients with AAA, CAS, and/or PAD.

Survival and Reintervention Risk by Patient Age and Preoperative Abdominal Aortic Aneurysm Diameter after Endovascular Aneurysm Repair

BACKGROUND

Endovascular aneurysm repair (EVAR) has become the standard of care for abdominal aortic aneurysm (AAA), but questions remain regarding the benefit in high-risk and elderly patients. The purpose of this study was to examine the effect of age, preoperative AAA diameter, and their interaction on survival and reintervention rates after EVAR.

METHODS

Our integrated health system's AAA endograft registry was used to identify patients who underwent elective EVAR between 2010 and 2014. Of interest was the effect of patient age at the time of surgery (≤80 vs. >80 years old), preoperative AAA diameter (≤5.5 cm vs. >5.5 cm), and their interaction. Primary endpoints were all-cause mortality and reintervention. Between-within mixed-effects Cox models with propensity score weights were fit.

RESULTS

Of 1,967 patients undergoing EVAR, unadjusted rates for survival at 4 years after EVAR was 76.1%, and reintervention-free rate was 86.0%. For mortality, there was insufficient evidence for an interaction between age and AAA size (P = 0.309). Patient age >80 years was associated with 2.53-fold higher mortality risk (hazard ratios [HR] = 2.53; 95% confidence intervals [CI], 1.73-3.70; P < 0.001), whereas AAA > 5.5 cm was associated with 1.75-fold higher mortality risk (HR = 1.75; 95% CI, 1.26-2.45; P = 0.001). For reintervention risk, there were no significant interactions or main effects for age or AAA diameter.

CONCLUSIONS

Age and AAA diameter are independent predictors of reduced survival after EVAR, but the effect is not amplified when both are present. Age >80 years or AAA size >5.5 cm did not increase the risk of reintervention. No specific AAA size, patient age, or combination thereof was identified that would contraindicate AAA repair.

Understanding abdominal aortic aneurysm epidemiology: socioeconomic position affects outcome

Background

Low socioeconomic position (SEP) has been demonstrated to negatively influence outcome in several cardiovascular patient groups. The aim of this study was to analyse time trends of incidence of intact abdominal aortic aneurysm (iAAA) and ruptured AAA (rAAA), respectively, and to investigate whether SEP had any influence on the probability to present with rupture and, finally, to determine the impact of SEP on outcome.

Methods

Nationwide population-based study including all individuals with iAAA or rAAA in Sweden during 2001–2015.

Results

The number of individuals with an AAA was 41 222; the majority were identified as iAAA 33 254 (80.7%) and 7968 (19.3%) as rAAA. Time trends showed decreasing incidence of rAAA but increase in iAAA during the study period. Individuals with low income or low educational level were more likely to present with a rAAA rather than iAAA: OR 2.16 (95 % CI 1.98 to 2.36, p<0.001) and OR 1.33 (95 % CI 1.21 to 1.46, p<0.001), respectively. Low income was also associated with increased 90-day mortality and 1-year mortality after treatment for rAAA, OR 1.42 (95% CI 1.07 to 1.89, p=0.014) and OR 1.39 (95% CI 1.13 to 1.97, p=0.005).

Conclusion

This large nationwide study showed a decreasing incidence of rAAA. Individuals with low SEP were found to have an augmented risk of presenting with rAAA rather than iAAA and, in addition, to fare worse after repair. Consequently, SEP should be regarded as a relevant risk factor that should be included in considerations for improved care flow of patients with AAA.

Controlled hypotension versus normotensive resuscitation strategy for people with ruptured abdominal aortic aneurysm

BACKGROUND

An abdominal aortic aneurysm (AAA) is the pathological enlargement of the aorta and can develop in both men and women. Progressive aneurysm enlargement can lead to rupture. The rupture of an AAA is frequently fatal and accounts for the death from haemorrhagic shock of at least 45 people per 100,000 population. The outcome of people with ruptured AAA varies among countries and healthcare systems, with mortality ranging from 53% to 90%. Definitive treatment for ruptured AAA includes open surgery or endovascular repair. The management of haemorrhagic shock is crucial for the person's outcome and aims to restore organ perfusion and systolic blood pressure above 100 mmHg through immediate and aggressive fluid replacement. This rapid fluid replacement is known as the normotensive resuscitation strategy. However, evidence suggests that infusing large volumes of cold fluid causes dilutional and hypothermic coagulopathy. The association of these factors may exacerbate bleeding, resulting in a 'lethal triad' of hypothermia, acidaemia, and coagulopathy. An alternative to the normotensive resuscitation strategy is the controlled (permissive) hypotension resuscitation strategy, with a target systolic blood pressure of 50 mmHg to 100 mmHg. The principle of controlled or hypotensive resuscitation has been used in some management protocols for endovascular repair of ruptured AAA. It may be beneficial in preventing blood loss by avoiding the clot disruption caused by the rapid increase in systolic blood pressure; avoiding dilution of clotting factors, platelets and fibrinogen; and by avoiding the temperature decrease that inhibits enzyme activity involved in platelet and clotting factor function. This is an update of a review first published in 2016.

OBJECTIVES

To compare the effects of controlled (permissive) hypotension resuscitation and normotensive resuscitation strategies for people with ruptured AAA.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Specialised Register (August 2017), the Cochrane Register of Studies (CENTRAL (2017, Issue 7)) and EMBASE (August 2017). The Cochrane Vascular Information Specialist also searched clinical trials databases (August 2017) for details of ongoing or unpublished studies.

SELECTION CRITERIA

We sought all published and unpublished randomised controlled trial (RCTs) that compared controlled hypotension and normotensive resuscitation strategies for the management of shock in patients with ruptured abdominal aortic aneurysms.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed identified studies for potential inclusion in the review. We used standard methodological procedures in accordance with the Cochrane Handbook for Systematic Review of Interventions.

MAIN RESULTS

We identified no RCTs that met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs that compared controlled hypotension and normotensive resuscitation strategies in the management of haemorrhagic shock in patients with ruptured abdominal aortic aneurysm that assessed mortality, presence of coagulopathy, intensive care unit length of stay, and the presence of myocardial infarct and renal failure. High quality studies that evaluate the best strategy for managing haemorrhagic shock in ruptured abdominal aortic aneurysms are required.

Abdominal Aortic Aneurysm: Evolving Controversies and Uncertainties

Abdominal aortic aneurysm (AAA) is defined as a permanent dilatation of the abdominal aorta that exceeds 3 cm. Most AAAs arise in the portion of abdominal aorta distal to the renal arteries and are defined as infrarenal. Most AAAs are totally asymptomatic until catastrophic rupture. The strongest predictor of AAA rupture is the diameter. Surgery is indicated to prevent rupture when the risk of rupture exceeds the risk of surgery. In this review, we aim to analyze this disease comprehensively, starting from an epidemiological perspective, exploring etiology and pathophysiology, and concluding with surgical controversies. We will pursue these goals by addressing eight specific questions regarding AAA: (1) Is the incidence of AAA increasing? (2) Are ultrasound screening programs for AAA effective? (3) What causes AAA: Genes versus environment? (4) Animal models: Are they really relevant? (5) What pathophysiology leads to AAA? (6) Indications for AAA surgery: Are surgeons over-eager to operate? (7) Elective AAA repair: Open or endovascular? (8) Emergency AAA repair: Open or endovascular?

Gender differences in abdominal aortic aneurysm therapy - a systematic review

This article analyses if and to what extent gender differences exist in abdominal aortic aneurysm (AAA) therapy. For this purpose Medline (PubMed) was searched from January 1999 to January 2018. Keywords were: "abdominal aortic aneurysm", "gender", "prevalence", "EVAR", and "open surgery of abdominal aortic aneurysm". Regardless of open or endovascular treatment of abdominal aortic aneurysms, women have a higher rate of complications and longer hospitalizations compared to men. The majority of studies showed that women have a lower survival rate for surgical and endovascular treatment of abdominal aneurysms after both elective and emergency interventions. Women receive less surgical/interventional and protective medical treatment. Women seem to have a higher risk of rupture, a lower survival rate in AAA, and a higher rate of complications, regardless of endovascular or open treatment. The gender differences may be due to a higher age of women at diagnosis and therapy associated with higher comorbidity, but also because of genetic, hormonal, anatomical, biological, and socio-cultural differences. Strategies for treatment in female patients must be further defined to optimize outcome.

Should Abdominal Aortic Aneurysms in Women be Repaired at a Lower Diameter Threshold?

Abdominal aortic aneurysm (AAA) primarily affects male patients; however, female patients with AAA have a faster rate of aneurysm growth, have higher risk of rupture even at smaller diameters, and have worse outcomes following repair of ruptured and intact aneurysms. Furthermore, early natural history studies and randomized controlled trials evaluating surveillance versus repair in small aneurysms were conducted primarily in male patients. Therefore, there are limited data regarding the ideal threshold for elective repair of AAA in women, either by aortic diameter or by alternative measures. We review the existing literature regarding AAA in women and consider the most appropriate threshold for repair.

Epidemiology and contemporary management of abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is most commonly defined as a maximal diameter of the abdominal aorta in excess of 3 cm in either anterior-posterior or transverse planes or, alternatively, as a focal dilation ≥ 1.5 times the diameter of the normal adjacent arterial segment. Risk factors for the development of AAA include age > 60, tobacco use, male gender, Caucasian race, and family history of AAA. Aneurysm growth and rupture risk appear to be associated with persistent tobacco use, female gender, and chronic pulmonary disease. The majority of AAAs are asymptomatic and detected incidentally on various imaging studies, including abdominal ultrasound, and computed tomographic angiography. Symptoms associated with AAA may include abdominal or back pain, thromboembolization, atheroembolization, aortic rupture, or development of an arteriovenous or aortoenteric fistula. The Screening Abdominal Aortic Aneurysms Efficiently (SAAAVE) Act provides coverage for a one-time screening abdominal ultrasound at age 65 for men who have smoked at least 100 cigarettes and women who have family history of AAA disease. Medical management is recommended for asymptomatic patients with AAAs < 5 cm in diameter and focuses on modifiable risk factors, including smoking cessation and blood pressure control. Primary indications for intervention in patients with AAA include development of symptoms, rupture, rapid aneurysm growth (> 5 mm/6 months), or presence of a fusiform aneurysm with maximum diameter of 5.5 cm or greater. Intervention for AAA includes conventional open surgical repair and endovascular aortic stent graft repair.

Circulating Vascular Basement Membrane Fragments are Associated with the Diameter of the Abdominal Aorta and Their Expression Pattern is Altered in AAA Tissue

OBJECTIVE

Abdominal aortic aneurysm (AAA) is characterised by enhanced proteolytic activity, and extracellular matrix (ECM) remodelling in the vascular wall. Type IV and XVIII collagen/endostatin are structural proteins in vascular basement membrane (VBM), a specialised ECM structure. Here the association between plasma levels of these collagens with the aortic diameter and expansion rate is studied, and their expression in aortic tissue characterised.

METHODS

This was a retrospective population based cohort study. Type IV and XVIII collagen/endostatin were analysed in plasma by ELISA assay in 615 men, divided into three groups based on the aortic diameter: 1) normal aorta ≤ 25 mm, 2) sub-aneurysmal aorta (SAA) 26-29 mm, and 3) AAA ≥ 30 mm. Follow up data were available for 159 men. The association between collagen levels and aortic diameter at baseline, and with the expansion rate at follow up were analysed in ordinal logistic regression and linear regression models, controlling for common confounding factors. Tissue expression of the collagens was analysed in normal aorta (n = 6) and AAA (n = 6) by immunofluorescence.

RESULTS

Plasma levels of type XVIII collagen/endostatin (136 ng/mL [SD 29] in individuals with a normal aorta diameter, 154 ng/ml [SD 45] in SAA, and 162 ng/ml [SD 46] in AAA; p = .001) and type IV collagen (105 ng/mL [SD 42] normal aorta, 124 ng/ml [SD 46] SAA, and 127 ng/ml [SD 47] AAA; p = .037) were associated with a larger aortic diameter. A significant association was found between the baseline levels of type XVIII/endostatin and the aortic expansion rate (p = .035), but in the multivariable model, only the initial aortic diameter remained significantly associated with expansion (p = .005). Altered expression patterns of both collagens were observed in AAA tissue.

CONCLUSION

Plasma levels of circulating type IV and XVIII collagen/endostatin increase with AAA diameter. The expression pattern of VBM proteins is altered in the aneurysm wall.

Evolving clinical applications of contrast-enhanced ultrasound (CEUS) in the abdominal aorta

Ultrasound (US) represents the initial modality in the workup of abdominal aortic pathology based on the plethora of advantages including widespread availability, low cost, safety profile and repeatability. However, US has inherent limitations including limited spatial information of pathologic processes to neighboring structures, lower sensitivity to slow blood flow and aortic luminal irregularities. For evaluation of aortic pathology angiography has long been considered the gold standard. Non-invasive cross-sectional imaging techniques like computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have gradually replaced interventional angiography for the evaluation of aorta, currently being regarded as the diagnostic imaging modalities of choice for diagnosis of virtually every aortic disease. Interventional angiography is currently primarily performed for treatment purposes of aortic pathology. The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS) an evolving valuable complementary technique with markedly increased diagnostic accuracy for certain aortic applications. CEUS is characterized by the potential to be performed in patients with impaired renal function. Due to its superior spatial and temporal resolution, ability for prolonged scanning and dynamic and real-time imaging, it provides clinically significant additional information compared to the standard Duplex US. The purpose of this paper is to discuss the currently available literature regarding abdominal aortic applications of CEUS, briefly elaborate on CEUS technique and safety and present cases in order to illustrate the added value in aortic pathologies. Conditions discussed include abdominal aortic aneurysm (AAA), aneurysm rupture, aneurysm surveillance after endovascular repair, dissection and aortitis.

Two-Year Outcomes of the Nellix EndoVascular Aneurysm Sealing System for Treatment of Abdominal Aortic Aneurysms

Purpose: To analyze the 2-year outcomes of endovascular aneurysm sealing (EVAS) according to 2 versions of the instructions for use (IFU). Methods: A retrospective study was conducted involving 355 consecutive patients treated with the first-generation EVAS device from April 2013 to December 31, 2015, at 3 high-volume centers. Out of 355 patients treated with EVAS, 264 were elective asymptomatic infrarenal EVAS procedures suitable for analysis. In this cohort, 168 (63.3%) patients were treated within the IFU 2013 criteria; of these 48 (18.2%) were in compliance with the revised IFU 2016 version. Results: Overall technical success was 98.2% (165/168) in the IFU 2013 group and 97.9% (47/48) in the IFU 2016 subgroup (p=0.428). The 2-year freedom from reintervention estimates were 89.7% (IFU 2013) and 95.7% (IFU 2016), with significantly more reinterventions in the first 45 cases (p=0.005). The stenosis/occlusion estimates were 6.5% (IFU 2013) and 4.2% (IFU 2016; p=0.705). Nine (5.4%) endoleaks (8 type Ia and 1 type Ib) were observed within the IFU 2013 cohort; 3 (2.1%) were in the IFU 2016 subgroup (p=0.583). Migration ≥10 mm or ≥5 mm requiring intervention was reported in 12 (7.1%) patients in the IFU 2013 cohort but none within the IFU 2016 subgroup. Ten (6.0%) patients demonstrated aneurysm growth in the IFU 2013 cohort, of which 2 (4.2%) were in the IFU 2016 subgroup. Overall survival and freedom from aneurysm-related death estimates at 2 years were 90.9% and 97.6% in the IFU 2013 cohort (IFU 2016: 95.5% and 100.0%). The prevalence of complications seemed lower within IFU 2016 without significant differences. Conclusion: This study shows acceptable 2-year results of EVAS used within the IFU, without significant differences between the 2 IFU versions, though longer follow-up is indicated. The refined IFU significantly reduced the applicability of the technique.

Increased Risk of Peripheral Arterial Disease in Patients With Abdominal Aortic Aneurysm: A Retrospective Cohort Study (Version 5)

Studies evaluating the risk of peripheral arterial disease (PAD) in patients with abdominal aortic aneurysm (AAA) are limited. We used insurance claims data of Taiwan to establish a cohort of 6590 patients with AAA newly diagnosed from 2000 to 2008 and 6590 controls without AAA matched by propensity score. The subsequent incidence density rates of PAD were estimated in both cohorts by the end of 2011, and the AAA cohort to the non-AAA cohort hazard ratios (HRs) of PAD were calculated using Cox proportional hazards models. The incidence density of PAD in the AAA cohort was 3.7-fold greater than that in the non-AAA cohort (14.1 vs 3.66 per 1000 person-years) with an adjusted HR of 3.56 (95% confidence interval [CI] = 2.89-4.39). For those without comorbidities, PAD in the AAA cohort was 7.4-fold greater than that in the non-AAA cohort (12.0 vs 1.61 per 1000 person-years) with an adjusted HR of 6.70 (95% CI = 4.43-10.1). The incidence of PAD in patients with ruptured AAA was lower than that in patients without rupture (6.95 vs 15.0 per 1000 person-years). This study demonstrates that patients with AAA are at increased risk of developing PAD.

An evaluation of the effect of an angiotensin-converting enzyme inhibitor on the growth rate of small abdominal aortic aneurysms: a randomised placebo-controlled trial (AARDVARK)

BACKGROUND

Although data are inconsistent, angiotensin-converting enzyme inhibitors (ACE-Is) have been associated with a reduced incidence of abdominal aortic aneurysm (AAA) rupture in analysis of administrative databases.

OBJECTIVES

(1) To investigate whether or not the ACE-I perindopril (Coversyl arginine, Servier) reduces small AAA growth rate and (2) to evaluate blood pressure (BP)-independent effects of perindopril on small AAA growth and to compare the repeatability of measurement of internal and external aneurysm diameters.

DESIGN

A three-arm, multicentre, single-blind, randomised placebo-controlled trial.

SETTING

Fourteen hospitals in England.

PARTICIPANTS

Men or women aged ≥ 55 years with an AAA of 3.0-5.4 cm in diameter by internal or external measurement according to ultrasonography and who met the trial eligibility criteria.

INTERVENTIONS

Patients were randomised to receive 10 mg of perindopril arginine daily, 5 mg of the calcium channel blocker amlodipine daily or placebo daily.

MAIN OUTCOME MEASURES

The primary outcome was AAA diameter growth using external measurements in the longitudinal plane, which in-trial studies suggested was the preferred measure. Secondary outcome measures included AAA rupture, AAA repair, modelling of the time taken for the AAA to reach the threshold for intervention (5.5 cm) or referral for surgery, tolerance of study medication (measured by compliance, adverse events and quality of life) and a comparison of the repeatability of measures of internal and external AAA diameter. Patients were followed up every 3-6 months over 2 years.

RESULTS

In total, 227 patients were recruited and randomised into the three groups, which were generally well matched at baseline. Multilevel modelling was used to determine the maximum likelihood estimates for AAA diameter growth. No significant differences in the estimates of annual growth were apparent [1.68 (standard error 0.02) mm, 1.77 (0.02) mm and 1.81 (0.02) mm in the placebo, perindopril and amlodipine groups, respectively]. Similarly, no significant differences in the slopes of modelled growth over time were apparent between perindopril and placebo (p = 0.78) or between perindopril and amlodipine (p = 0.89). The results were essentially unaffected by adjustment for potential confounders. Compliance, measured by pill counts, was good throughout (> 80% at all visit time points). There were no significant in-trial safety concerns. Six patients withdrew because of adverse events attributed to the study medications (n = 2 perindopril, n = 4 amlodipine). No patients ruptured their AAA and 27 underwent elective surgery during the trial (n = 9 placebo, n = 10 perindopril, n = 8 amlodipine).

CONCLUSIONS

We were unable to demonstrate a significant impact of perindopril compared with placebo or amlodipine on small AAA growth over a 2-year period. Furthermore, there were no differences in the times to reach a diameter of 5.5 cm or undergo surgery among the three groups. Perindopril and amlodipine were well tolerated by this population. External AAA measurements were found to be more repeatable than internal measurements. The observed AAA growth measurement variability was greater than that expected pre trial. This, combined with slower than expected mean growth rates, resulted in our having limited power to detect small differences between growth rates and hence this adds uncertainty to the interpretation of the results. Several further analyses are planned including a multivariate analysis of determinants of AAA growth, an evaluation of the possible differential effect of perindopril on fast AAA growth and an investigation into the roles of central BP and BP variability on AAA growth.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN51383267.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 59. See the NIHR Journals Library website for further project information. The NIHR Biomedical Research Centre based at Imperial College NHS Trust supported the trial. Servier provided perindopril at no charge.

Gender differences in abdominal aortic aneurysms in Germany using health insurance claims data

Abstract. Background: Endovascular aortic repair (EVAR) has emerged as standard of care for abdominal aortic aneurysm (AAA). Real-world evidence is limited to compare this technology to open repair (OAR). Major gaps exist related to short-term and long-term outcomes, particularly in respect of gender differences. Materials and methods: Health insurance claims data from Germany’s third largest insurance provider, DAK-Gesundheit, was used to investigate invasive in-hospital treatment of intact (iAAA) and ruptured AAA (rAAA). Patients operated between October 2008 and April 2015 were included in the study. Results: A total of 5,509 patients (4,966 iAAA and 543 rAAA) underwent EVAR or OAR with a median follow-up of 2.44 years. Baseline demographics, comorbidities, and clinical characteristics of DAK-G patients were assessed. In total, 84.6 % of the iAAA and 79.9 % of the rAAA were male. Concerning iAAA repair, the median age (74 vs. 73 years, p < .001) compared to men was higher in females, but their EVAR-rate (66.8 % vs. 71.1 %, p = .018) was lower. Besides higher age of female patients (80 vs. 75 years, p < .001), no further statistically significant differences were seen following rAAA repair. In-hospital mortality was slightly lower in males compared to females following iAAA (2.3 % vs. 3.1 %, p = .159) and rAAA (37.3 % vs. 43.1 %, p = .273) repair. Concerning iAAA repair, a higher rate of female patients was transferred to another hospital (3.7 % vs. 2.0 %, p = 0.008) or discharged to rehabilitation (6.0 % vs. 2.7 %, p < .001) compared to male patients. Conclusions: In this large German claims data cohort, women are generally older and more often transferred to another hospital or discharged to rehab following iAAA repair. Nonetheless, no significantly increased risk of in-hospital or late death appeared for women in multivariate analyses. Further studies are necessary to evaluate the impact of recent gender-specific treatment strategies on overall outcome under real-world settings.

Potential biomechanical roles of risk factors in the evolution of thrombus-laden abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) typically harbour an intraluminal thrombus (ILT), yet most prior computational models neglect biochemomechanical effects of thrombus on lesion evolution. We recently proposed a growth and remodelling model of thrombus-laden AAAs that introduced a number of new constitutive relations and associated model parameters. Because values of several of these parameters have yet to be elucidated by clinical data and could vary significantly from patient to patient, the aim of this study was to investigate the possible extent to which these parameters influence AAA evolution. Given that some of these parameters model potential effects of factors that influence the risk of rupture, this study also provides insight into possible roles of common risk factors on the natural history of AAAs. Despite geometrical limitations of a cylindrical domain, findings support current thought that smoking, hypertension, and female sex likely increase the risk of rupture. Although thrombus thickness is not a reliable risk factor for rupture, the model suggests that the presence of ILT may have a destabilizing effect on AAA evolution, consistent with histological findings from human samples. Finally, simulations support two hypotheses that should be tested on patient-specific geometries in the future. First, ILT is a potential source of the staccato enlargement observed in many AAAs. Second, ILT can influence rupture risk, positively or negatively, via competing biomechanical (eg, stress shielding) and biochemical (ie, proteolytic) effects. Although further computational and experimental studies are needed, the present findings highlight the importance of considering ILT when predicting aneurysmal enlargement and rupture risk.

Mortality After Elective and Ruptured Abdominal Aortic Aneurysm Surgical Repair: 12-Year Single-Center Experience of Estonia

Background and Aims:

Abdominal aortic aneurysm is a degenerative vascular pathology with high mortality due to its rupture, which is why timely treatment is crucial. The current single-center retrospective study was undertaken to analyze short- and long-term all-cause mortality after operative treatment of abdominal aortic aneurysm and to examine the factors that influence outcome.

Material and Methods:

The data of all abdominal aortic aneurysm patients treated with open repair or endovascular aneurysm repair in 2004–2015 were retrospectively retrieved from the clinical database of Tartu University Hospital. The primary endpoint was 30-day, 90-day, and 5-year all-cause mortality. The secondary endpoint was determination of the risk factors for mortality.

Results and Conclusion:

Elective abdominal aortic aneurysm repair was performed on 228 patients (mean age 71.8 years), of whom 178 (78%) were treated with open repair and 50 (22%) with endovascular aneurysm repair. A total of 48 patients with ruptured abdominal aortic aneurysm were treated with open repair (mean age 73.8 years) at the Department of Vascular Surgery, Tartu University Hospital, Estonia. Mean follow-up period was 4.2 ± 3.3 years. In patients with elective abdominal aortic aneurysm, 30-day, 90-day, and 5-year all-cause mortality rates were 0.9%, 2.6%, and 32%, respectively. In multivariate analysis, the main predictors for 5-year mortality were preoperative creatinine value and age (p < 0.05). In patients with ruptured abdominal aortic aneurysm, 30-day, 90-day, and 5-year all-cause mortality rates were 22.9%, 33.3%, and 55.1%, respectively. In multivariate analysis, the risk factors for 30-day mortality in ruptured abdominal aortic aneurysm were perioperative hemoglobin and lactate levels (p < 0.05). According to this study, the all-cause mortality rates of elective abdominal aortic aneurysm and ruptured abdominal aortic aneurysm at our hospital were comparable to those at other centers worldwide. Even though some variables were identified as potential predictors of survival, the mortality rates after ruptured abdominal aortic aneurysm remain high. Early diagnosis, timely treatment, and detection of the risk factors for abdominal aortic aneurysm progression would improve survival in patients with abdominal aortic aneurysm.

Biomechanical changes during abdominal aortic aneurysm growth

The biomechanics-based Abdominal Aortic Aneurysm (AAA) rupture risk assessment has gained considerable scientific and clinical momentum. However, such studies have mainly focused on information at a single time point, and little is known about how AAA properties change over time. Consequently, the present study explored how geometry, wall stress-related and blood flow-related biomechanical properties change during AAA expansion. Four patients with a total of 23 Computed Tomography-Angiography (CT-A) scans at different time points were analyzed. At each time point, patient-specific properties were extracted from (i) the reconstructed geometry, (ii) the computed wall stress at Mean Arterial Pressure (MAP), and (iii) the computed blood flow velocity at standardized inflow and outflow conditions. Testing correlations between these parameters identified several nonintuitive dependencies. Most interestingly, the Peak Wall Rupture Index (PWRI) and the maximum Wall Shear Stress (WSS) independently predicted AAA volume growth. Similarly, Intra-luminal Thrombus (ILT) volume growth depended on both the maximum WSS and the ILT volume itself. In addition, ILT volume, ILT volume growth, and maximum ILT layer thickness correlated with PWRI as well as AAA volume growth. Consequently, a large ILT volume as well as fast increase of ILT volume over time may be a risk factor for AAA rupture. However, tailored clinical studies would be required to test this hypothesis and to clarify whether monitoring ILT development has any clinical benefit.

Molecular targets in aortic aneurysm for establishing novel management paradigms

Aortic aneurysm (AA) is a lethal disease and presents a large challenge for surgeons in the clinic. Although surgical management remains the major choice of AA, operative mortality remains high. With advances in understanding of the mechanisms of AAs, molecular targets, such as matrix metalloproteinases (MMPs), D-dimer, and inflammation markers, including C-reactive protein, interleukins and phagocytes, are important in the pathology of development of AA. These markers may become important for improving the diagnostic quality and provide more therapeutic choices for treatment of AA. Although these new markers require long-term trials before they can be translated into the clinic, they can still be helpful in determining new directions. The main aim of this review is to discuss the current findings of molecular targets in progression of AA and discuss the potential application of these new targets for managing this disease.

MicroRNAs and Current Concepts on the Pathogenesis of Abdominal Aortic Aneurysm

OBJECTIVE

Abdominal aortic aneurysm is an important cause of morbidity and mortality in the elderly. Currently, the only way to prevent rupture and death related to abdominal aortic aneurysms is through surgical intervention. Endovascular treatment is associated with less morbidity than conventional treatment. The formation of an aneurysm is a complex multifactorial process, involving destructive remodeling of the connective tissue around the affected segment of the aorta wall. MicroRNAs are small sequences of non-coding RNAs that control diverse cellular functions by promoting degradation or inhibition of translation of specific mRNAs. A profile aberrant expression of miRNAs has been linked to human diseases, including cardiovascular dysfunction.

Effects of Chemotherapy in Patients with Concomitant Aortic Aneurysm and Malignant Disease

BACKGROUND

The aim of the study is to present the results in a consecutive series of patients affected by aortic abdominal aneurysm and to underline the aneurysmal growth and evolution in oncological patients submitted to dedicated oncological medical therapy.

METHODS

Between January 2010 and June 2016 we treated in our center 19 patients for coexisting aortic aneurysms (>3 cm) and malignancy. We observed patients undergoing oncological treatment and patients who did not undergo medical treatment. We studied computed tomography (CT) scan at the time when patients were addressed at our follow-up or treatment and we analyzed retrospectively prior CT scan at 6 and 12 months.

RESULTS

Among those 19 patients, 7 patients were affected by colorectal cancer (36.8%), 6 by urinary tract cancer (31.6%), 4 by lymphoma (21%), and 2 by lung cancer (10.6%). In 8 patients who did not undergo oncological therapy, we did not observe any aortic growth; instead, in other 4 patients who underwent oncological medical therapy (3 abdominal aortic aneurysms and 1 thoracic aneurysm), we observed a mean sac growth of 2.9 cm in 6 months with 2 cases of aortic rupture treated in urgent fashion. The treatment was open surgery in 2 cases and endovascular in other cases.

CONCLUSIONS

We observed that oncological drugs may play a role in aneurysm growth. Few case reports are found in the literature and more evidences are to be found. Those information may influence intention-to-treat small aneurysms in short life expectancy patients.

STATISTICAL ANALYSIS FOR RUPTURE RISK PREDICTION OF ABDOMINAL AORTIC ANEURYSMS (AAA) BASED ON ITS MORPHOMETRY

The morphometry of the abdominal aortic aneurysms (AAA) has been recognized as one of the main factors that may predispose its rupture. The variation of the AAA morphometry, over time, induces modifications in hemodynamic behavior which, in turn, alters the spatial and temporal distribution of hemodynamic stress on the aneurismatic wall, establishing a bidirectional process that can influence the rupture phenomenon. In order to evaluate potential correlations between the main geometric parameters characterizing the AAA and hemodynamic stresses, 13 unrupture AAA patient-specific models were created. To AAA geometric characterization, 12 indices based on lumen center line were defined and determined. The computing of temporal and spatial distributions of hemodynamic stresses was conducted through Computational Fluid Dynamics. Statistical techniques were used to assess the relationships between the hemodynamic parameters and the different geometrical indices of the AAA. Regression analyses were conducted to obtain linear predictor models for hemodynamic stresses using the different indices defined in this paper as predictor variables. The statistical analysis confirmed that the length L, the asymmetry and the saccular index significantly influenced the hemodynamic stresses. The results obtained show the potential of the use of statistical techniques in predicting the rupture risk of patient-specific AAA.

Gender, smoking, body size, and aneurysm geometry influence the biomechanical rupture risk of abdominal aortic aneurysms as estimated by finite element analysis

OBJECTIVE

Finite element analysis (FEA) has been suggested to be superior to maximal diameter measurements in predicting rupture of abdominal aortic aneurysms (AAAs). Our objective was to investigate to what extent previously described rupture risk factors were associated with FEA-estimated rupture risk.

METHODS

One hundred forty-six patients with an asymptomatic AAA of a 40- to 60-mm diameter were retrospectively identified and consecutively included. The patients' computed tomography angiograms were analyzed by FEA without (neutral) and with (specific) input of patient-specific mean arterial pressure (MAP), gender, family history, and age. The maximal wall stress/wall strength ratio was described as a rupture risk equivalent diameter (RRED), which translated this ratio into an average aneurysm diameter of corresponding rupture risk.

RESULTS

In multivariate linear regression, RRED_neutral increased with female gender (3.7 mm; 95% confidence interval [CI], 0.13-7.3) and correlated with patient height (0.27 mm/cm; 95% CI, 0.11-0.43) and body surface area (BSA, 16 mm/m²; 95% CI, 8.3-24) and inversely with body mass index (BMI, -0.40 mm/kg m^-2; 95% CI, -0.75 to -0.054) in a wall stress-dependent manner. Wall stress-adjusted RRED_neutral was raised if the patient was currently smoking (1.1 mm; 95% CI, 0.21-1.9). Age, MAP, family history, and patient weight were unrelated to RRED_neutral. In specific FEA, RRED_specific increased with female gender, MAP, family history positive for AAA, height, and BSA, whereas it was inversely related to BMI. All results were independent of aneurysm diameter. Peak wall stress and RRED correlated with aneurysm diameter and lumen volume.

CONCLUSIONS

Female gender, current smoking, increased patient height and BSA, and low BMI were found to increase the mechanical rupture risk of AAAs. Previously described rupture risk factors may in part be explained by patient characteristic-dependent variations in aneurysm biomechanics.

Renal failure caused by a partly calcified aortic aneurysm in a patient with dabigatran therapy: A case report

RATIONALE

Abdominal aortic aneurysms (AAAs) are mostly asymptomatic. If aortic aneurysms become symptomatic, complications include peripheral embolization, acute aortic occlusion, and aortic rupture. However, there are also unusual complications caused by aortic aneurysms.

PATIENT CONCERNS

An 87-old male with dabigatran therapy presented with newly developed melena and acute renal failure. Radiological imaging revealed an AAA with thrombotic and calcified deposits which affected the renal arteries.

DIAGNOSES

Gastrointestinal bleeding and hypercoagulation caused by renal failure which was triggered in turn due to an AAA.

INTERVENTIONS

Adapted antihypertensive therapy and initiation of simvastatin 40mg once daily as well as antiplatelet therapy with aspirin 50 mg once daily due to patient's refusal of any aneurysm intervention.

OUTCOME

Neither bleeding event nor aneurysm rupture occurred with the adapted antihypertensive therapy, simvastatin and aspirin.

LESSONS

Nonruptured AAAs can cause rare, unusual, and even life-threatening complications depending on their size and anatomical position.

Pharmacological treatment of vascular risk factors for reducing mortality and cardiovascular events in patients with abdominal aortic aneurysm

BACKGROUND

Pharmacological prophylaxis has been proven to reduce the risk of cardiovascular events in individuals with atherosclerotic occlusive arterial disease. However, the role of prophylaxis in individuals with abdominal aortic aneurysm (AAA) remains unclear. Several studies have shown that despite successful repair, those people with AAA have a poorer rate of survival than healthy controls. People with AAA have an increased prevalence of coronary heart disease and risk of cardiovascular events. Despite this association, little is known about the effectiveness of pharmacological prophylaxis in reducing cardiovascular risk in people with AAA. This is an update of a Cochrane review first published in 2014.

OBJECTIVES

To determine the long-term effectiveness of antiplatelet, antihypertensive or lipid-lowering medication in reducing mortality and cardiovascular events in people with abdominal aortic aneurysm (AAA).

SEARCH METHODS

For this update the Cochrane Vascular Information Specialist (CIS) searched the Cochrane Vascular Specialised Register (14 April 2016). In addition, the CIS searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 3) and trials registries (14 April 2016) and We also searched the reference lists of relevant articles.

SELECTION CRITERIA

Randomised controlled trials in which people with AAA were randomly allocated to one prophylactic treatment versus another, a different regimen of the same treatment, a placebo, or no treatment were eligible for inclusion in this review. Primary outcomes included all-cause mortality and cardiovascular mortality.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, and completed quality assessment and data extraction. We resolved any disagreements by discussion. Only one study met the inclusion criteria of the review, therefore we were unable to perform meta-analysis.

MAIN RESULTS

No new studies met the inclusion criteria for this update. We included one randomised controlled trial in the review. A subgroup of 227 participants with AAA received either metoprolol (N = 111) or placebo (N = 116). There was no clear evidence that metoprolol reduced all-cause mortality (odds ratio (OR) 0.17, 95% confidence interval (CI) 0.02 to 1.41), cardiovascular death (OR 0.20, 95% CI 0.02 to 1.76), AAA-related death (OR 1.05, 95% CI 0.06 to 16.92) or increased nonfatal cardiovascular events (OR 1.44, 95% CI 0.58 to 3.57) 30 days postoperatively. Furthermore, at six months postoperatively, estimated effects were compatible with benefit and harm for all-cause mortality (OR 0.71, 95% CI 0.26 to 1.95), cardiovascular death (OR 0.73, 95% CI 0.23 to 2.39) and nonfatal cardiovascular events (OR 1.41, 95% CI 0.59 to 3.35). Adverse drug effects were reported for the whole study population and were not available for the subgroup of participants with AAA. We considered the study to be at a generally low risk of bias. We downgraded the quality of the evidence for all outcomes to low. We downgraded the quality of evidence for imprecision as only one study with a small number of participants was available, the number of events was small and the result was consistent with benefit and harm.

AUTHORS' CONCLUSIONS

Due to the limited number of included trials, there is insufficient evidence to draw any conclusions about the effectiveness of cardiovascular prophylaxis in reducing mortality and cardiovascular events in people with AAA. Further good-quality randomised controlled trials that examine many types of prophylaxis with long-term follow-up are required before firm conclusions can be made.

Sex differences in mortality and morbidity following repair of intact abdominal aortic aneurysms

OBJECTIVE

Medicare studies have shown increased perioperative mortality in women compared with men following endovascular and open abdominal aortic aneurysm (AAA) repair. However, a recent regional study of high-volume centers, adjusting for anatomy but limited in sample size, did not show sex to be predictive of worse outcomes. This study aimed to evaluate sex differences after intact AAA repair in a national clinical registry.

METHODS

The targeted vascular module of the National Surgical Quality Improvement Program was queried to identify patients undergoing endovascular aneurysm repair (EVAR) or open repair for intact, infrarenal AAA from 2011 to 2014. Univariate analysis was performed using the Fisher exact test and Mann-Whitney test. Multivariable logistic regression was used to account for differences in comorbidities, aneurysm details, and operative characteristics.

RESULTS

We identified 6611 patients (19% women) who underwent intact AAA repair (87% EVAR; 83% women vs 88% men; P < .001). Women were older (median age, 76 vs 73 years; P < .001), had smaller aneurysms (median, 5.4 vs 5.5 cm; P < .001), and had more chronic obstructive pulmonary disease (22% vs 17%; P < .001). Among patients undergoing EVAR, women had longer operative times (median, 138 [interquartile range, 103-170] vs 131 [106-181] minutes; P < .01) and more often underwent renal (6.3% vs 4.1%; P < .01) and lower extremity (6.6% vs 3.8%; P < .01) revascularization. After open repair, women had shorter operative time (215 [177-304] vs 226 [165-264] minutes; P = .02), but women less frequently underwent lower extremity revascularization (3.1% vs 8.2%; P = .03). Thirty-day mortality was higher in women after EVAR (3.2% vs 1.2%; P < .001) and open repair (8.0% vs 4.0%; P = .04). After adjusting for repair type, age, aneurysm diameter, and comorbidities, female sex was independently associated with mortality (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.1-2.6; P = .02) and major complications (OR, 1.4; CI, 1.1-1.7; P < .01) after intact AAA repair. However, after adjusting for aortic size index rather than for aortic diameter, the association between female sex and mortality (OR, 1.5; CI, 0.98-2.4; P = .06) and major complications (OR, 1.1; CI, 0.9-1.4; P = .24) was reduced.

CONCLUSIONS

Women were at higher risk for 30-day death and major complications after intact AAA repair. Some of this disparity may be explained by differences in aortic size index, which should be further evaluated to determine the ideal threshold for repair.

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.).

Chronic Kidney Disease Is Positively and Diabetes Mellitus Is Negatively Associated with Abdominal Aortic Aneurysm

BACKGROUND AND AIMS

Chronic kidney disease (CKD) and diabetes mellitus (DM) are considered as risk factors for cardiovascular diseases. The purpose of this study was to clarify the relationship of CKD and DM with the presence of abdominal aortic aneurysm (AAA).

METHODS

We enrolled 261 patients with AAA (AAA+) and age-and-sex matched 261 patients without AAA (AAA-) at two hospitals between 2008 and 2014, and examined the association between the risk factors and the presence of AAA. Furthermore, in order to investigate the prevalence of AAA in each group, we enrolled 1126 patients with CKD and 400 patients with DM.

RESULTS

The presence of CKD in patients with AAA+ was significantly higher than that in patients with AAA- (AAA+; 65%, AAA-; 52%, P = 0.004). The presence of DM in patients with AAA+ was significantly lower than that in patients with AAA- (AAA+; 17%, AAA-; 35%, P < 0.001). A multivariate logistic regression analysis demonstrated that hypertension, ischemic heart disease and CKD were independent determinants, whereas, DM was a negatively independent determinant, for the presence of AAA. The prevalence of AAA in patients with CKD 65 years old and above was 5.1%, whereas, that in patients with DM 65 years old and above was only 0.6%.

CONCLUSION

CKD is a positively associated with the presence of AAA. In contrast, DM is a negatively associated with the presence of AAA in Japanese population.

Investigation of long chain omega-3 PUFAs on arterial blood pressure, vascular reactivity and survival in angiotensin II-infused Apolipoprotein E-knockout mice

Abdominal aortic aneurysm (AAA) is an inflammatory vascular disease. Long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs) decrease inflammation and oxidative stress in an angiotensin II-infused apolipoprotein E-knockout (ApoE(-/-)) mouse model of AAA. This study investigated the effects of LC n-3 PUFAs on blood pressure and vascular reactivity in fourteen angiotensin II-infused ApoE(-/-) male mice. Blood pressure was obtained using a non-invasive tail cuff method and whole blood was collected by cardiac puncture. Vascular reactivity of the thoracic aorta was assessed using wire myography and activation of endothelial nitric oxide synthase (eNOS) was determined by immunohistochemistry. A high LC n-3 PUFA diet increased the omega-3 index and reduced the n-6 to n-3 PUFA ratio. At day 10 post-infusion with angiotensin II, there was no difference in systolic blood pressure or diastolic blood pressure in mice fed the high or low n-3 PUFA diets. The high LC n-3 PUFA diet resulted in a non-significant trend for delay in time to death from abdominal aortic rupture. Vascular reactivity and eNOS activation remained unchanged in mice fed the high compared to the low LC n-3 PUFA diet. This study argues against direct improvement in vascular reactivity in ApoE(-/-) mice that were supplemented with n-3 PUFA for 8 weeks prior to infusion with angiotensin II.

A Methodology for the Derivation of Unloaded Abdominal Aortic Aneurysm Geometry With Experimental Validation

In this work, we present a novel method for the derivation of the unloaded geometry of an abdominal aortic aneurysm (AAA) from a pressurized geometry in turn obtained by 3D reconstruction of computed tomography (CT) images. The approach was experimentally validated with an aneurysm phantom loaded with gauge pressures of 80, 120, and 140 mm Hg. The unloaded phantom geometries estimated from these pressurized states were compared to the actual unloaded phantom geometry, resulting in mean nodal surface distances of up to 3.9% of the maximum aneurysm diameter. An in-silico verification was also performed using a patient-specific AAA mesh, resulting in maximum nodal surface distances of 8 μm after running the algorithm for eight iterations. The methodology was then applied to 12 patient-specific AAA for which their corresponding unloaded geometries were generated in 5-8 iterations. The wall mechanics resulting from finite element analysis of the pressurized (CT image-based) and unloaded geometries were compared to quantify the relative importance of using an unloaded geometry for AAA biomechanics. The pressurized AAA models underestimate peak wall stress (quantified by the first principal stress component) on average by 15% compared to the unloaded AAA models. The validation and application of the method, readily compatible with any finite element solver, underscores the importance of generating the unloaded AAA volume mesh prior to using wall stress as a biomechanical marker for rupture risk assessment.