The validity of ultrasonographic scanning as screening method for abdominal aortic aneurysm

Ultrasound diagnostics of the abdominal aorta: English version

BACKGROUND AND OBJECTIVES

The ideal method for screening investigations is one which is as free as possible from side effects, is easily learnt, and can therefore be broadly used to detect abdominal aortic aneurysms (AAA) with a high degree of certainty. Although ultrasonography fulfils these criteria, the measurement method is not standardized. Different measurement methods are used in ultrasonography as well as in computed tomography (CT) studies and the measurement method is actually described sufficiently in only 57 % of cases.

METHODS

This article provides a critical review of the current literature on measurement methods and the validity of ultrasonography for the determination of aortic diameter, particularly in AAA, and presents the measurement principles for making measurements as precisely as possible.

RESULTS AND CONCLUSION

The most precise determination of aortic diameter is carried out by electrocardiogram (ECG) gating according to the leading-edge method with orthogonal slicing. Within the framework of screening investigations, sufficient measurement precision can be achieved by adherence to orthogonal slicing. Using these standardized measurement methods, ultrasonography shows valid and reproducible results even compared with CT and is the method of choice in screening investigations for AAA.

Population risk factor estimates for abdominal aortic aneurysm from electronic medical records: a case control study

BACKGROUND

Using abdominal aortic aneurysm (AAA) as a model, this case-control study used electronic medical record (EMR) data to assess known risk factors and identify new associations.

METHODS

The study population consisted of cases with AAA (n =888) and controls (n =10,523) from the Geisinger Health System EMR in Central and Northeastern Pennsylvania. We extracted all clinical and diagnostic data for these patients from January 2004 to December 2009 from the EMR. From this sample set, bootstrap replication procedures were used to randomly generate 2,500 iterations of data sets, each with 500 cases and 2000 controls. Estimates of risk factor effect sizes were obtained by stepwise logistic regression followed by bootstrap aggregation. Variables were ranked using the number of inclusions in iterations and P values.

RESULTS

The benign neoplasm diagnosis was negatively associated with AAA, a novel finding. Similarly, type 2 diabetes, diastolic blood pressure, weight and myelogenous neoplasms were negatively associated with AAA. Peripheral artery disease, smoking, age, coronary stenosis, systolic blood pressure, age, height, male sex, pulmonary disease and hypertension were associated with an increased risk for AAA.

CONCLUSIONS

This study utilized EMR data, retrospectively, for risk factor assessment of a complex disease. Known risk factors for AAA were replicated in magnitude and direction. A novel negative association of benign neoplasms was identified. EMRs allow researchers to rapidly and inexpensively use clinical data to expand cohort size and derive better risk estimates for AAA as well as other complex diseases.

Ultrasound measurement for abdominal aortic aneurysm screening: a direct comparison of the three leading methods

OBJECTIVES

Ultrasound (US) is non-invasive and cost-effective for screening abdominal aortic aneurysms (AAAs) but there is no universally accepted method to measure the aortic diameter. This study evaluates the accuracy, reproducibility, and repeatability of three methods: inner-to-inner (ITI), leading-to-leading edge (LTL), and outer-to-outer (OTO). The secondary objective of this study was to determine whether aneurysm size or grade of operator had any effect on either intra- or inter-observer variability.

METHODS

Fifty static US images were measured by six assessors (2 vascular radiologists, 2 interventional radiology trainees, and 2 sonographers) on two separate occasions 6 weeks apart. Repeatability and reproducibility were calculated and compared with computed tomography (CT) as the gold standard.

RESULTS

All three methods have high repeatability and reproducibility when static images are used. The inter-observer reproducibility coefficients between assessors were 0.48 cm, 0.35 cm, and 0.34 cm for ITI, LTL and OTO, respectively. The intra-observer repeatability coefficients between assessors were 0.30 cm, 0.20 cm, and 0.19 cm for ITI, LTL and OTO, respectively. The mean difference between CT and OTO, LTL, and ITI was 1 mm, 3 mm, and 5 mm, respectively (all underestimations) (p < .0001).

CONCLUSIONS

US consistently underestimates aortic size when compared with CT, with ITI demonstrating the greatest underestimation (on average 5 mm). In the UK, this underestimation by the NHS Abdominal Aortic Aneurysm screening programme reduces the sensitivity of the screening test and may impact on the way in which vascular specialists interpret the findings of the screening programme.

Reliability of the measurement of the abdominal aortic diameter by novice operators using a pocket-sized ultrasound system

BACKGROUND

Despite favorable results of randomized studies and several guidelines, screening for abdominal aortic aneurysm is poorly implemented in most countries. In order to implement an effective abdominal aortic aneurysm screening programme, training of physicians other than cardiovascular imaging specialists is necessary. Also, the use of pocket-sized ultrasound systems seems an appealing alternative to conventional echography machines for large-scale screening.

AIMS

To test the hypothesis that, after a short period of specific training with a pocket-sized ultrasound system, novice operators could reliably measure the abdominal aortic diameter. We assessed the agreement between abdominal aortic diameter measurements from novice operators using a pocket-sized ultrasound system and experts using conventional machines.

METHODS

After focused training of novice operators, the abdominal aortic diameter was independently measured at least four times: by two experts using conventional ultrasound, by one expert using a pocket-sized ultrasound system and by at least one novice operator using the pocket-sized system; each operator was blinded to the others.

RESULTS

The aortic diameters of 56 patients were measured. The intraclass correlation coefficients between the four sets of measurement were all>0.91 and the mean difference between the measurements was negligible (<1mm). The interoperator variability for experts using conventional machines versus novices using pocket-sized machines was ≤ 4mm in 92.0% of cases. No learning curve over time was noted.

CONCLUSION

In order to screen for abdominal aortic aneurysm, the abdominal aortic diameter can be accurately measured by non-specialist physicians with pocket-sized ultrasound devices after a short period of training.

Molecular imaging of experimental abdominal aortic aneurysms

Current laboratory research in the field of abdominal aortic aneurysm (AAA) disease often utilizes small animal experimental models induced by genetic manipulation or chemical application. This has led to the use and development of multiple high-resolution molecular imaging modalities capable of tracking disease progression, quantifying the role of inflammation, and evaluating the effects of potential therapeutics. In vivo imaging reduces the number of research animals used, provides molecular and cellular information, and allows for longitudinal studies, a necessity when tracking vessel expansion in a single animal. This review outlines developments of both established and emerging molecular imaging techniques used to study AAA disease. Beyond the typical modalities used for anatomical imaging, which include ultrasound (US) and computed tomography (CT), previous molecular imaging efforts have used magnetic resonance (MR), near-infrared fluorescence (NIRF), bioluminescence, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). Mouse and rat AAA models will hopefully provide insight into potential disease mechanisms, and the development of advanced molecular imaging techniques, if clinically useful, may have translational potential. These efforts could help improve the management of aneurysms and better evaluate the therapeutic potential of new treatments for human AAA disease.

Medical therapy of thoracic aortic aneurysms

Thoracic aortic aneurysm is a major health problem with multiple etiologies and potentially devastating consequences. Currently, no large randomized trial has shown that medical therapy can significantly slow or halt the progressive dilatation that eventually leads to dissection and rupture. A recent study that suggested that angiotensin receptor blocking agents slow the development of aneurysm dilatation in Marfan syndrome has revived interest in medical interventions to improve outcomes for patients with aortic aneurysm. In this article, we review the available data on established medical therapies and investigational medical therapies for thoracic aortic aneurysms.

Prevalence and early detection of abdominal aortic aneurysm in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

PURPOSE

The goals of this study were to demonstrate the frequency of infrarenal abdominal aortic aneurysm (AAA) in patients with pseudoexfoliation (PEX) syndrome (PEXS) and PEX glaucoma (PEXG), and to determine whether limited screening for AAA in specific subgroups of patients with PEX is reasonable and justifiable.

MATERIALS AND METHODS

This prospective study comprised 60 patients with PEXS and 60 with PEXG (examined group), and 60 patients with primary open-angle glaucoma (POAG) and 60 with cataract (control group). Clinical ophthalmic examination included slit-lamp biomicroscopy of the anterior segment and direct slit-lamp gonioscopy (using a Goldmann three-mirror lens) of the anterior chamber angle. All patients underwent routine Color Doppler duplex ultrasonography of the infrarenal aorta and iliac arteries.

RESULTS

There was a statistically significant difference (p < 0.05) between the PEXG group and control group vis-a-vis presence of AAA, which occurred more frequently in patients with greater amounts of angle pigmentation (p < 0.05). Univariate logistic regression analysis indicated statistically significant associations between AAA and PEX (p < 0.01), angle pigmentation (p < 0.05), gender (p < 0.01), diabetes mellitus (DM) (p < 0.05), and arterial hypertension (AHT) (p < 0.01). Multivariate regression analysis, adjusted to gender and age, showed that the most important clinical parameters related to AAA in patients with PEXS and PEXG are gender, presence of PEX, DM, and AHT (p < 0.05).

CONCLUSION

The frequency of AAA is significantly higher in patients with PEXS and PEXG than in patients with POAG or cataract. Restricted screening for AAA in male PEXS patients, who also have elevated degrees of angle pigmentation, arterial hypertension, and DM, is clinically warranted.

Abdominal Aortic Aneurysms

Abdominal aortic aneurysms represent both an individual risk of mortality and a socioeconomic burden for health care systems worldwide, but screening is not performed in all countries. Here, the authors summarize the pros and cons of screening to reduce abdominal aortic aneurysm–related mortality.

What is the role of screening in the management of abdominal aortic aneurysms?

A best-evidence topic in vascular surgery was written according to a structured protocol. The question addressed was whether screening asymptomatic individuals for an abdominal aortic aneurysm (AAA) is feasible and improves disease-free survival. Seven studies presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and limitations of the studies are tabulated. In total, four randomized population-based studies have evaluated ultrasound screening for AAA: two British studies, Multicentre Aneurysm Screening Study (MASS) and the Chichester trial, and one each in Viborg County, Denmark and Western Australia. Participants were randomized to receive an invitation to screen or not. The MASS trial randomized 67 770 men, followed participants over 10 years and concluded that screening would almost half AAA-related deaths in men aged 65-74 years. The smaller Chichester trial included only 6040 men but demonstrated a 42% reduction in AAA-related mortality at 5 years, with ongoing benefit at 15 years (11% reduction). The Viborg County trial recruited 12 639 men aged 64-73 years, showed a 66% reduction in AAA-related mortality over 14 years. Finally, the Western Australia trial evaluated 41 000 men but included an older population of 65-83 years old. No benefit was seen in this age group but subgroup analysis of men aged 65-74 showed a significant mortality benefit. Only a small or insignificant benefit in all-cause mortality was seen in any of these studies. A recent meta-analysis of these trials has shown a significant benefit in AAA-related mortality in the long term and concluded that AAA screening is superior to other established screening programmes. The cost-effectiveness of screening was assessed in the MASS and Viborg County trials and was found to be substantially below the cost threshold set by the National Institute of Clinical Excellence for acceptance of interventions. Quality of life was assessed in the MASS and in a case-control study and showed no adverse effects that outweigh the benefits. We concluded that ultrasound screening for AAAs has met all the criteria to become a screening programme and would substantially reduce disease-related death with no adverse effect on quality of life.

Ultrasound diagnosis of acute thrombosis of an abdominal aortic aneurysm: a case report

BACKGROUND

Point-of-care ultrasound is an effective and reliable method to diagnosis the presence of an abdominal aortic aneurysm. However, there has been limited literature regarding ultrasound diagnosis of acute aortic thrombosis.

OBJECTIVE

Discuss a patient case with acute aortic thrombosis diagnosed by point-of-care emergency ultrasound. Review common etiologies and treatment options in this rare diagnosis.

CASE REPORT

A patient with a known abdominal aortic aneurysm presented with mottled lower extremities. Point-of-care ultrasound was utilized by her physicians to diagnose acute thrombosis of her abdominal aorta. With conservative treatment the patient survived to hospital discharge.

CONCLUSION

Aortic thrombosis is a rare and devastating problem that can be diagnosed with point-of-care ultrasound.

Reproducibility of ultrasound measurement of the abdominal aorta

BACKGROUND

Abdominal aortic aneurysm (AAA) screening and surveillance programmes use ultrasound imaging to measure the anteroposterior (AP) diameter of the infrarenal aorta. The aim of this study was to examine potential observer bias and variability in ultrasound measurements.

METHODS

Studies were identified for review via a MEDLINE database search (1966-2009). References supplied in accessed papers were also checked for potential relevance. Consistent search terminology, and inclusion and exclusion criteria were used to ensure quality of data. Nine papers were available to review.

RESULTS

Variation in intraobserver repeatability and interobserver reproducibility was identified. Six studies reported intraobserver repeatability coefficients for AP aortic diameter measurements of 1·6-4·4 mm. These were below the 5-mm level regarded as acceptable by the UK and USA AAA screening programmes. Five studies had interobserver reproducibility below the level of 5 mm. Four studies, however, reported poor reproducibility (range from -2 to +5·2 to -10·5 to +10·4); these differences may have had a significant clinical impact on screening and surveillance.

CONCLUSION

The studies used different methodologies with no standardized measurement techniques. Measurements were taken by observers from different medical disciplines of varying grade and levels of training. Standard training and formal quality assurance of ultrasound measurements are important components of an effective AAA screening programme.

Diagnosis and monitoring of abdominal aortic aneurysm: current status and future prospects

Abdominal aortic aneurysm (AAA) remains an important cause of morbidity and mortality in elderly men, and prevalence is predicted to increase in parallel with a global aging population. AAA is commonly asymptomatic, and in the absence of routine screening, diagnosis is usually incidental when imaging to assess unrelated medical complaints. In the absence of approved diagnostic and prognostic markers, AAAs are monitored conservatively via medical imaging until aortic diameter approaches 50-55 mm and surgical repair is performed. There is currently significant interest in identifying molecular markers of diagnostic and prognostic value for AAA. Here we outline the current guidelines for AAA management and discuss modern scientific techniques currently employed to identify improved diagnostic and prognostic markers.

Diagnostic and therapeutic strategies for small abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) affect 5% of the population in developed countries and are characterized by progressive aortic dilatation with an unpredictable time course. This condition is more common in men than in women, and in smokers than in nonsmokers. If left untreated, AAA can result in aortic rupture and death. Pathologically, aortic extracellular matrix degradation, inflammation, and neovascularization are hallmarks of AAA. Diagnosis of AAA and subsequent surveillance utilize established aortic imaging methods, such as ultrasound, CT, and MRI. More-speculative diagnostic approaches include molecular and cellular imaging methods that interrogate the underlying pathological processes at work within the aneurysm. In this Review, we explore the current diagnostic and therapeutic strategies for the management of AAA. We also describe the diagnostic potential of new imaging techniques and therapeutic potential of new treatments for the management of small AAA.

Proteins associated with the size and expansion rate of the abdominal aortic aneurysm wall as identified by proteomic analysis

OBJECTIVES

Identification of biomarkers for the natural history of abdominal aortic aneurysms (AAA) holds the key to non-surgical intervention and improved selection for AAA repair. We aimed to associate the basic proteomic composition of AAA wall tissue with the expansion rate and size in patients with AAA.

METHODS

A proteomic approach was used, consisting of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry (MS) to identify differentially expressed proteins in AAA tissue. Relevant protein spots were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

Spearman's correlation analysis revealed 16 protein spots were strongly correlated with AAA expansion rate (ρ>±0.75). Nine protein spots were identified. Six protein spots showed correlation with AAA size (ρ>±0.5). Three protein spots were identified: vitronectin with traces of calreticulin, albumin and a spot containing two proteins: collagen α-3(VI) chain and vitamin D binding protein. Interestingly, in our previous study vitronectin was shown to be down-regulated in a ruptured AAA group compared with non-ruptured AAA. Western blot analysis in the present study confirmed a correlation of vitronectin bands with AAA size in aortic aneurysm tissue.

CONCLUSION

A proteomic approach seems valuable, and identified several candidates not previously associated with AAA. Larger studies are required to confirm the potential and clinical role of the identified proteins.

Increased levels of thioredoxin in patients with abdominal aortic aneurysms (AAAs). A potential link of oxidative stress with AAA evolution

OBJECTIVE

Oxidative stress is a main mechanism involved in vascular pathologies. Increased thioredoxin (TRX) levels have been observed in several oxidative stress-associated cardiovascular diseases. We aim to test the potential role of TRX as a biomarker of oxidative stress in abdominal aortic aneurysm (AAA).

METHODS

TRX levels were analysed in both AAA intraluminal thrombus (ILT) tissue and in tissue-conditioned media by immunohistochemistry, Western blot and ELISA. Moreover, serum TRX levels were assessed in AAA Caucasian patients by ELISA.

RESULTS

TRX was mainly localized in the luminal part of ILT in AAA. Compared with the abluminal layer, TRX release was increased in the luminal layer of the ILT of AAA (31+/-9 ng/ml vs. 9+/-3 ng/ml, p<0.05). The interest of this approach is that we can identify proteins potentially released into the blood compartment, which could serve as biomarkers of the pathology. In a training population, serum TRX levels were significantly increased in patients with AAA relative to healthy subjects (50+/-6 ng/ml vs. 26+/-3 ng/ml, p<0.05). These results were validated in a second independent group of patients. Moreover, a positive correlation between TRX and AAA size (rho=0.5, p<0.001) was observed. Finally, in AAA samples with follow-up, TRX was positively associated to aneurismal growth rate (rho=0.25, p=0.027).

CONCLUSIONS

TRX release is increased in the luminal part of AAA and TRX serum levels are increased in AAA patients compared with healthy subjects. TRX levels correlates with AAA size and expansion, suggesting its potential role as a biomarker of AAA evolution.

Analysis of a vascular screening program in a rural community

BACKGROUND

Implementation and adaptation of a vascular screening program in a rural community.

METHODS AND RESULTS

A vascular screening program was offered free to the general population aged 55 years and older. It comprised of ultrasound screening of the carotid arteries, abdominal aorta, and the lower extremity segmental Doppler with ankle brachial index measurements. The program was initially developed in Annapolis, MD, and adapted to rural Warren, PA. Between March 2008 and June 2009, a total of 758 screenings were completed. Mild disease was detected in 12.7% of the population, moderate disease in 2.5% of the population, and severe disease in 1.3% of the population; 61.7% of all the participants had atherosclerotic plaques without stenosis and 45.9% of the participants had a history of smoking, 12.1% diabetes, 81.4% dyslipidemia, 58.3% hypertension, and 9.8% heart disease.

CONCLUSION

This model of vascular screening program is an important tool for the detection of vascular disease and preventive health counseling. It detects not only vascular disease but its associated risk factors. Adequate treatment decreases cardiovascular disease mortality. This program, through local sponsorship, is adaptable to the rural community.

The management of abdominal aortic aneurysms

Abdominal aortic aneurysms cause about 6000 deaths per year in England and Wales, predominantly from rupture. Significant progress has been made in recent years in developing minimally invasive, endovascular methods of treatment. This review evaluates the current management options for abdominal aortic aneurysm.

Ultrasonographic screening for the detection of abdominal aortic aneurysms

BACKGROUND

The prevalence of abdominal aortic aneurysms (AAA) with a maximal diameter of 3 cm or more is age-dependent; among persons over age 65, it lies between 4% and 8% in men and between 0.5% and 1.5% in women. About 10% of all AAAs have a maximum diameter of 5 cm or more. The prognosis of ruptured AAA (rAAA) is dismal, with an overall mortality of at least 80%. Ultrasonography of the abdominal aorta is a safe and technically simple method of detecting AAAs.

METHODS

Evaluation of population-based, randomized studies of ultrasonographic screening for the detection of AAA, based on a selective review of the literature.

RESULTS

A meta-analysis of four randomized controlled studies showed that ultrasonographic screening was associated with a significant lowering of AAA-related mortality in men aged 65 to 80 after it had been performed for 3-5 years (risk reduction 44%, odds ratio [OR] 0.56, 95% confidence interval [CI] 0.44-0.72) and after it had been performed for 7-15 years (risk reduction 53%, OR 0.47, 95% CI 0.25-0.90). AAA screening was also associated with a significant lowering of the overall mortality after 7-15 years, but not in the first 5 years. Ultrasonographic screening led to a significant increase in the number of elective AAA operations performed and to a 50% reduction of the number of emergency operations for rAAA.

CONCLUSION

Ultrasonographic screening for AAA is a technically simple diagnostic test that is associated with a major reduction of AAA-related mortality. In view of the higher prevalence of AAA among the elderly, it is recommended that all men aged 65 or older and all men and women with a family history of AAA should be systematically screened. A national ultrasound screening program should be urgently implemented in Germany in order to bring about a major reduction in AAA-associated mortality.

Intermittent Roxithromycin for Preventing Progression of Small Abdominal Aortic Aneurysms: Long-Term Results of a Small Clinical Trial

Background: Antibodies against Chlamydia pneumoniae are associated with an increased rate of expansion of small abdominal aortic aneurysms (AAAs). Short-term follow-up trials have shown a transient reduction AAA growth rate, in macrolide treated compared with placebo. Therefore we analysed the influence of intermittent, long-term roxithromycin treatment on AAA expansion and referral for surgery. Methods: Eighty-four patients with small AAAs were randomized to either an annual 4 weeks’ treatment with roxithromycin or placebo, and followed prospectively. Results: Intermittent, long-term Roxithromycin-treatment reduced mean annual growth rate by 36% compared with placebo after adjustment for potential confounders. Long-term roxithromycin-treated patients had a 29% lower risk of being referred for surgical evaluation, increasing to 57% after adjusting for potential confounders. Conclusion: Annual 4 week treatment with 300 mg roxithromycin daily may reduce the progression of small AAAs, and later need for surgical repair. However, more robust studies are needed for confirmation.

Basic Science Review: Vascular Distensibility as a Predictive Tool in the Management of Small Asymptomatic Abdominal Aortic Aneurysms

Background: This study investigates whether baseline aortic wall distensibility serves as a supplemental bio-marker for AAA progression and need for later repair. Methods: In 1998, 61 males with a small asymptomatic AAAs had a baseline measurement of elasticity and stiffness, using an echo-tracking ultrasound system (Diamove). The cohort was followed till 2005 concerning Dmax, expansion rate, operations for AAA, hospitalisation do to cardiovascular disease and death. Results: During follow-up, 49% died, and 45.9% were hospitalised do to cardiovascular disease, compared to Dmax, Ep and b no significant associations were found. Elasticity correlated moderately to annual expansion rate and Dmax. Good correlation was found between annual expansion rate and Dmax. ROC-curve analysis showed that elasticity, stiffness and Dmax all tended to predict future need for AAA-repair. Conclusion: Baseline aortic wall distensibility may provide an additional parameter for AAA to optimize the indication and time for elective repair.

Are Statins an Option in the Management of Abdominal Aortic Aneurysms?

Medline was searched for studies investigating the perioperative and long-term results that derive from statin use in patients with abdominal aortic aneurysm and the clinical and experimental evidence dealing with aneurysm expansion. Data suggest that statins improve the perioperative and long-term outcomes of aneurysm operations and may also reduce expansion rates. International guidelines recommend the use of statins in these patients because abdominal aortic aneurysms are considered as a coronary heart disease equivalent. These guidelines do not appear to have been widely implemented. Preliminary results suggest that statins might play a role in the management of abdominal aortic aneurysms. Verification of these results in large-scale trials may hold implications for a more comprehensive approach of patients with abdominal aortic aneurysms as well as population-wide aneurysm screening programs. Irrespective of the role of statins on aneurysm expansion rates, it is important to ensure that all abdominal aortic aneurysm patients receive statin therapy to improve perioperative and long-term morbidity and mortality.

Medical management of small abdominal aortic aneurysms

Abdominal aortic aneurysm is a common condition that may be lethal when it is unrecognized. Current guidelines suggest repair as the aneurysm diameter reaches 5.0 to 5.5 cm. Most aortic aneurysms are detected incidentally when imaging is done for other purposes or through screening programs. Ninety percent of these aneurysms are below the threshold for intervention at the time of detection. A number of studies have sought to determine factors that lead to progression of aneurysmal disease that might be amenable to intervention during this period of observation. We review these studies and make recommendations for the medical management of small abdominal aortic aneurysms. On the basis of our current knowledge of the causes of aneurysm, a number of approaches have been proposed to prevent progression of aneurysmal disease. These include hemodynamic management, inhibition of inflammation, and protease inhibition. The American College of Cardiology/American Heart Association clinical practice guidelines rules of evidence have helped to define strength of evidence to support these approaches. Level A evidence (from large randomized trials) is available to indicate that observation of small aneurysms in men is safe up to a size of 5.5 cm and that propranolol does not inhibit aneurysm expansion. Level B evidence (from small randomized trials) suggests that roxithromycin or doxycycline will decrease the rate of aneurysm expansion. A number of studies agree that tobacco use is associated with an increased rate of aneurysm expansion. Level B and C evidence is available to suggest that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may inhibit aneurysm expansion. There are animal data but no human data demonstrating that angiotensin-converting enzyme inhibitors or losartan, an angiotensin receptor blocker, will decrease the rate of AAA expansion. A pharmacological agent without important side effects that inhibited aneurysm expansion could change current approaches to aneurysm treatment. Additional studies are needed to clarify the potential role of doxycycline, roxithromycin, and statin therapy in the progression of aneurysmal disease.

Aneurysmal wall calcification predicts natural history of small abdominal aortic aneurysms

BACKGROUND

The biomechanical properties of the abdominal aortic aneurysm (AAA) wall may hold predictive potential. This study aims to study the potential role of wall calcification in small AAAs.

METHODS

Initial AAA calcification was determined by ultrasonography to be either more or less than 50% of the initial maximal AAA circumference in 122 men with an initial AAA sized 30-49 mm in maximal diameter. The patients were offered annual control scans and refered for surgery, if the AAA diameter exceeded 50 mm. Surgery for AAA from the date of inclusion to 15 March 2005 was identified in the national vascular registry "Karbase". Mean follow time was 6.15 years.

RESULTS

The mean annual growth rate was significantly lower in men with an AAA wall calcification above than below 50% (1.72 mm versus 2.97 mm, P=0.001). The finding persisted after multivariate linear regression analysis adjusting for age, smoking and aspirin use. A total of 12 men with AAA calcification above 50% were operated compared with 25 men with an AAA calcification below 50% (risk ratio: 0.35 (0.18-0.71), P=0.003). The difference in risk persisted after adjustment for age, smoking and use of aspirin (risk ratio: 0.36 (0.18-0.74), P=0.008).

CONCLUSION

The calcification content in small AAA predicts the natural history of small AAA.

Low-Dose Aspirin May Prevent Growth and Later Surgical Repair of Medium-Sized Abdominal Aortic Aneurysms

Experimental data suggest that aspirin-induced platelet inhibition may retard growth of abdominal aortic aneurysms. In this article, whether low-dose aspirin use is associated with reduced aneurysm progression and subsequent need for surgery is examined. In this observational cohort study within a screening trial, 148 patients with small aneurysms (maximum diameter 30-48 mm) annually are followed. Patients were referred for surgery when the aneurysmal diameter exceeded 50 mm. Median follow-up time was 6.6 years. Among patients whose abdominal aortic aneurysms were initially 40 to 49 mm in size, the abdominal aortic aneurysm expansion rate for low-dose aspirin users compared with nonusers was 2.92 mm/y versus 5.18 mm/y (difference 2.27 mm/y, 95% CI, 0.42-4.11). No difference in expansion rates and risk ratios for operative repair was found for patients with abdominal aortic aneurysms <40 mm. For medium-sized abdominal aortic aneurysms, low-dose aspirin may prevent abdominal aortic aneurysm growth and need for subsequent repair, but residual confounding cannot be excluded.

Project PROMIS: Peoria Regional Outpatient Medical Imaging Study

BACKGROUND

Abdominal aortic aneurysm (AAA) accounts for > 15,000 reported deaths annually. Early screening in high-risk populations is important to decrease morbidity and mortality from rupture.

METHODS

A prospective, population-based study of free ultrasound-based AAA screening was conducted from July 2004 to December 2006. Before examination, subjects completed surveys asking their medical history, including known AAA risk factors. Incidence rates and comparison analyses were performed.

RESULTS

The final analysis included 979 patients, of whom AAA was discovered in 27 (2.8%). AAA was found in only male patients > 60 years old (4% of the male population). AAA size ranged from 3 to 10 cm. Of patients diagnosed with AAA, 85% were current or past smokers, and 70% had hypercholesterolemia. There was a 6% incidence of AAA in male smokers > or = 60 years old who had hypercholesterolemia.

CONCLUSIONS

Four factors were predominant in our population of patients with AAA: patient age, male sex, smoking history, and hypercholesterolemia.

Results of a single center vascular screening and education program

BACKGROUND

Vascular screening events have become a popular way to increase vascular awareness. Most screenings programs involve multiple locations on a single date and do not explore the local impact of screening. We evaluated the economic and community impact of the Dare to C.A.R.E. (DTC) program, a large, single center, continuous vascular screening and education program in Annapolis, Maryland.

METHODS

Between July 2000 and July 2006, DTC was offered free to the public for those over 60 or over 50 with risk factors of hypertension, diabetes, smoking, or elevated cholesterol. DTC consisted of a 2-hour educational lecture, completing a risk factor questionnaire, and testing blood pressure, carotid duplex, abdominal aortic aneurysm (AAA) ultrasound, and pedal pulse/ankle-brachial index (ABI). Mild disease (MD) was defined as 1% to 39% carotid stenosis or an ABI between .7 and .95; intermediate disease (ID) as carotid stenosis >or=40%, AAA >or=3 cm, or an ABI <or=0.7; and severe disease (SD) as carotid stenosis >or=60%, AAA >or=5 cm, or an ABI <or=0.5. Results were discussed with the participants and forwarded to their primary physicians. Questionnaire data and screening results were analyzed and local hospital data was examined to determine the effects of screening.

RESULTS

A total of 12,055 screenings were performed in DTC, 439 were excluded due to age less than 40 or repeat visits, leaving 11,616 unique patients for this report. Participation grew from 189 in 2000 to over 6400 in 2005. Age ranged from 40 to 95 (median 65 years) and females comprised 58.7%. Demographics included past smokers (51.3%), current smokers (7.3%), diabetes mellitus (10.6%), hypertension (46.7%), hyperlipidemia (49.4%), and prior myocardial infarction (MI) (11.9%). 47% participants had evidence of at least mild disease (MD) with intermediate disease (ID) found in 6.9% and severe disease (SD) found in 2.2% of patients screened. Statistical analysis showed a greater prevalence of ID and SD in patients with risk factors. Diabetes alone doubled the prevalence of disease in all age groups. Over 340 hospital vascular cases were identified in DTC patients in the first 5 years of the program.

CONCLUSIONS

The Dare to C.A.R.E. vascular screening and education program is an effective way to detect early and significant vascular disease. It has a powerful effect on procedural and testing volumes.

[Abdominal aortic aneurysm and renovascular disease]

Recent technological advances in the diagnosis and therapy of abdominal aortic aneurysm and renovascular disease are continuing to bring about changes in the way patients suffering from these conditions are treated. The prevalence of both these conditions is increasing. This is due to greater life-expectancy in patients with arteriosclerosis, a pathogenetic factor underlying both conditions. The application of diagnostic imaging techniques to non-vascular conditions has led to the early diagnosis of abdominal aortic aneurysm. Clinical suspicion of reno-vascular disease can be confirmed easily using high-resolution diagnostic imaging modalities such as CT angiography and magnetic resonance angiography. Endovascular intervention is successfully replacing conventional surgical repair techniques, with the result that it may be possible to improve outcome in both conditions using effective and minimally invasive approaches. Future technological developments will enable these endovascular techniques to be applied in the large majority of patients with abdominal aortic aneurysm or renovascular disease.