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

Effect of smoking on abdominal aortic aneurysms: novel insights through murine models

Abdominal aortic aneurysm is a poorly understood and fatal disease. The etiology of the disease is believed to be multifactorial. Of all the recognized clinical associations, none has a greater impact on the incidence and progression of the disease than exposure to tobacco smoke. Novel murine models developed over the past several years present the opportunity to investigate the mechanism of this critical clinical relationship.

Daily Diurnal Variation in Admissions for Ruptured Abdominal Aortic Aneurysms

BACKGROUND

Many vascular events, such as myocardial infarction and cerebrovascular accident, demonstrate a circadian pattern of presentation. Blood pressure is intimately related to these pathologies and is the one physiological variable consistently associated with abdominal aortic aneurysm rupture. It also demonstrates a diurnal variation. The purpose of this study was to determine if rupture of an abdominal aortic aneurysm (RAAA) exhibits a diurnal variation.

METHODS

A retrospective cohort-based study was performed to determine the timing of presentation of RAAA to the vascular unit of Cork University Hospital over a 15-year period. Time of admission, symptom onset, and co-morbidities such as hypertension were noted. Fournier's analysis and chi-squared analysis were performed. To ameliorate possible confounding factors, patients admitted with perforated peptic ulcers were examined in the same manner.

RESULTS

A total of 148 cases of RAAA were identified, with a male preponderance (71.7% [124] male versus 29.3% [44] female patients) and a mean age of 74.4 +/- 7.2 years at presentation. 70.9% (105) were known to have hypertension, 52.2% (77) were current smokers, and 46.8% (69) were being treated for chronic obstructive airway disease (COAD). Time of symptom onset was recorded in 88.5% (131) of patients. There was a marked early morning peak in RAAA admissions, with the highest number of RAAA being admitted between 08.00 and 09.59. A second, smaller peak was observed at 14.00-15.59. These findings were suggestive of diurnal variation. [chi(2) =16.75, p < 0.003]. Some 40% (59) of patients were admitted between 00.00 and 06.00, an incidence significantly higher than for other time periods (06.00-12.00, 12.00-18.00, and 18.00-24.00) [chi(2) = 18.72; df = 3; p < 0.0003]. A significantly higher number of patients admitted between 00.00 and 06.00 were known hypertensives (chi(2) = 7.94; p < 0.05).

CONCLUSIONS

The findings of this study suggest a distinct circadian pattern of presentation for RAAA. Systolic blood pressure has a circadian rhythm that mirrors this pattern of presentation. Our results further support the association between RAAA and hypertension, and they may also indicate that chronotropic blood pressure control combating the early-morning peak in systolic blood pressure may assist in the management of abdominal aortic aneurysms.

Infrarenal Abdominal Aortic Aneurysm Repair: Time-trends during a 20-year Period

BACKGROUND

The goal of the present study was to investigate the number of operations for abdominal aortic aneurysm (AAA) including time-trends in treatment during a 20-year period. Operating time and anesthesia time were also studied.

METHOD

During the period 1983-2002, a total of 1,041 patients with AAA were treated with open surgery (905) or EVAR (136). Number of operations, type of graft, anesthesia time, and operating time were the variables investigated. Data were collected retrospectively from the patients' medical records.

RESULTS

There was an increase in the number of operations both for ruptured and non-ruptured AAA in men during the study period. Among women, an increase was observed only for ruptured aneurysm. Operating time and anesthesia time increased significantly during the 20-year period. The number of patients treated by EVAR increased significantly, beginning in 1995.

CONCLUSIONS

In conclusion, there has been an increase in the number of AAA operations, and the proportion of patients treated with EVAR is increasing. Furthermore, we found an increase in both anesthesia time and operating time. These trends may be important for allocation of resources needed for the treatment of patients with AAA.

Optimizing compliance, efficiency, and safety during surveillance of small abdominal aortic aneurysms

BACKGROUND

Outcome data documenting safety for observation of small abdominal aortic aneurysms (AAA 4.0 to 5.4 cm) are lacking outside of large clinical trials but requires near perfect patient compliance. This study describes a clinical pathway for AAA surveillance using a prospective database utilizing a nurse practitioner oversight to provide efficient use of clinic visits while maintaining a high level of patent participation.

METHODS

Over a 7-year period (June 1999 through June 2006), 334 patients were enrolled in an AAA surveillance pathway at our academic veterans hospital. To minimize patient travel, clinic visitation was reserved for an initial examination with patient education and for discussion of intervention options in patients demonstrating AAA growth (>5.4 cm or expansion >1 cm/yr) during follow-up. Biannual ultrasound or CT imaging was scheduled and results discussed (after physician review) via telephone or "same day" direct patient contact. An electronic database was used to update patient information and plan follow-up.

RESULTS

Compliance with the AAA surveillance pathway was achieved in 98.5% of patients, with only three patients (0.9%) lost to follow-up and two others (0.6%) choosing early repair at civilian institutions. At a mean interval of 29 months (+/-20 mo), surgical repair was performed in 225 (67%) patients by open (n = 143) or endovascular (n = 82) techniques for AAA growth to >5.4 cm (n = 219) or expansion by >1cm/yr (n = 6). One hundred six patients currently remain in surveillance. A single AAA rupture resulting in death occurred during surveillance (0.3%) and perioperative mortality (<60 days) was 0.9% in patients needing intervention for AAA growth. Cumulative aneurysm-related mortality was 0.9% for patients compliant with the AAA surveillance pathway.

CONCLUSIONS

Use of a prospectively-maintained surveillance database managed by a non-physician provider with a reliance on telephone contact resulted in a high degree of patient compliance, reduced unnecessary patient travel, and provided practical clinic use. Limited additional resources were needed to implement our pathway and a similar approach may prove useful for large volume hospital, clinic, or practice systems.

Abdominal Aortic Aneurysm

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the artery that is 1.5 times the diameter of the normal segment. The most common location for an aortic aneurysm is the infrarenal segment where a diameter that exceeds 3 cm in diameter is considered aneurysmal. Duplex ultrasonography and spiral computerized tomography are the imaging modalities most commonly performed to detect the longitudinal and transverse diameter of the aorta. The prevalence of AAA may be increasing. Smoking, male gender, and increasing age are the most powerful predictors of AAA. Considering the higher prevalence of hypertension, it is surprising that the prevalence of AAA among African-American men is 39% less than white men. The risk of rupture is independently associated with female gender, large initial aneurysm diameter, lower forced expiratory volume in the first second, current smoking, and higher mean blood pressure. Inflammation rather than atherosclerosis may be essential to the development of AAA. Treatment is directed at smoking cessation and control of blood pressure and lipids. Beta blockers (propranolol) have not been shown to modify aneurysm growth rates, but drop out rates in the studies have been high. Antibiotics do show a modest benefit. Surgery is generally performed when the aneurysm exceeds 5.5 cm in men. For women, an AAA size between 4.5 cm and 5.0 cm is recommended for elective repair.

Screening for abdominal aortic aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) is found in 5% to 10% of men aged 65 to 79 years. The major complication is rupture which presents as a surgical emergency. The mortality after rupture is high, 80% for patients reaching hospital and 50% for those undergoing surgery for emergency repair. Currently elective surgical repair is recommended for aneurysms discovered to be larger than 5.5 cm to prevent rupture. There is interest in population screening to detect, monitor and repair abdominal aortic aneurysms before rupture.

OBJECTIVES

To determine the effects of screening asymptomatic individuals for AAA on mortality, subsequent treatment, quality of life and cost effectiveness of screening.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Trials Register (last searched 26 January 2007) and CENTRAL (last searched Issue 1, 2007).

SELECTION CRITERIA

Randomised controlled trials of population screening for AAA.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials and extracted data.

MAIN RESULTS

Four studies involving 127,891 men and 9,342 women were included in this review. Only one study included women. Results for men and women were analysed separately. Three to five years after screening there was no significant difference in all-cause mortality between screened and unscreened groups for men or women (men, odds ratio (OR) 0.95; 95% Confidence interval (CI) 0.85 to 1.07; for women OR 1.06; 95% CI 0.93 to 1.21). There was a significant decrease in mortality from AAA in men (OR 0.60; 95% CI 0.47 to 0.78), but not for women (OR 1.99; 95% CI 0.36 to 10.88). In this analysis mortality includes death from rupture and from emergency or elective surgery for aneurysm repair. There was also a decreased incidence of ruptured aneurysm in men (OR 0.45; 95% CI 0.21 to 0.99) but not in women (OR 1.49; 95% CI 0.25 to 8.94). There was a significant increase in surgery for AAA in men (OR 2.03; 95% CI 1.59 to 2.59). This was not reported in women. There were no data on life expectancy, complications of surgery or subjective quality of life.

AUTHORS' CONCLUSIONS

There is evidence of a significant reduction in mortality from AAA in men aged 65 to 79 years who undergo ultrasound screening. There is insufficient evidence to demonstrate benefit in women. The cost effectiveness may be acceptable, but needs further expert analysis. These findings need careful consideration in judging whether a co-ordinated population-based screening programme should be introduced.

Influence of sex on expansion rate of abdominal aortic aneurysms

BACKGROUND

The UK Small Aneurysm Trial suggested that female sex is an independent risk factor for rupture of abdominal aortic aneurysm (AAA). This study assessed the effect of sex on the growth rate of AAA.

METHODS

Between January 1985 and August 2005 all patients who were referred to the Royal Infirmary of Edinburgh with an AAA who were not considered for early aneurysm repair were assessed by serial abdominal ultrasonography. Maximum anteroposterior and transverse diameters of the AAAs were measured.

RESULTS

A total of 1255 patients (824 men and 431 women) were followed up for a median of 30 (range 6-185) months. A median of six examinations (range 2-37) was performed for each patient. Median diameter on initial examination was 41 (range 25-83) mm. Median growth rate overall was 2.79 (range - 4.80-37.02) mm per year. Median growth rate of AAA was significantly greater in women than men (3.67 (range - 1.2-37.02) versus 2.03 (range - 4.80-21.00) mm per year; P < 0.01). Weighted linear regression analysis revealed that large initial anteroposterior AAA diameter and female sex were significant predictors of faster aneurysm growth rate (P < 0.001 and P = 0.006 respectively).

CONCLUSION

The growth rate of AAA was significantly greater in women than in men. This may have implications for the frequency of follow-up and timing of repair of AAA in women.

Wall Stress Analysis in Small Asymptomatic, Symptomatic and Ruptured Abdominal Aortic Aneurysms

OBJECTIVES

To evaluate the potential of wall stress analysis for the identification of abdominal aortic aneurysm (AAA) at elevated risk of rupture in spite of small diameter.

MATERIALS AND METHODS

Thirty patients with small AAA, 10 asymptomatic, 10 symptomatic and 10 ruptured, were included. Demographic data and results from physical examinations were recorded in a retrospective fashion. After CT-evaluation and the creation of a patient specific 3D model, wall stress was calculated using the finite element method.

RESULTS

No differences were observed in diameter between asymptomatic, symptomatic or ruptured aneurysms (5.1+/-0.2 cm vs. 5.1+/-0.2 cm vs. 5.3+/-0.2 cm respectively; p=0.57). Peak aortic wall stress at maximal systolic blood pressure is significantly higher in ruptured than asymptomatic aneurysms (51.7+/-2.4 N/cm(2) vs. 39.7+/-3.3 N/cm(2) respectively; p=0.04). Wall stress analysis at uniform blood pressure, performed to correct for higher blood pressure in the symptomatic and rupture group did not result in significant differences in peak wall stress (asymptomatic 31.7+/-2.3 N/cm(2); symptomatic 30.5+/-1.3 N/cm(2); rupture 36.7+/-4.0 N/cm(2); p=0.26).

CONCLUSIONS

Wall stress analysis at maximal systolic blood pressure is a promising technique to detect aneurysms at elevated aneurysm rupture risk. Since no significant differences were found at uniform blood pressure, the need for adequate blood pressure control in aneurysm patients is reiterated.

Should usual criteria for intervention in abdominal aortic aneurysms be "downsized," considering reported risk reduction with endovascular repair?

Two randomized trials have demonstrated the safety of waiting until abdominal aortic aneurysm (AAA) diameter reaches 5.5 cm for repair in most patients. Other recent randomized trials have demonstrated lower perioperative mortality and morbidity with endovascular aneurysm repair (EVAR) compared to open surgery. Therefore, it is logical to assume that endovascular repair may change the appropriate threshold for intervention. However, endovascular repair is not as durable as open surgery and is associated with ongoing risks of rupture and reintervention. Decision analysis based on data available in 1998 showed that endovascular repair should not change the threshold for intervention. Since that time retrospective data have emerged to suggest that outcomes with endovascular repair are improved in smaller AAAs, although this may simply represent selection bias and the natural history of small AAAs. Randomized trials are appropriate to determine whether improved endovascular outcomes in small AAAs reduce late rupture and reintervention enough to justify early intervention in patients with appropriate anatomy. In the absence of data from these trials, the threshold for intervention should not be changed.

Challenges and opportunities in abdominal aortic aneurysm research

Abdominal Aortic Aneurysms (AAAs) are associated with advanced age, male gender, cigarette smoking, atherosclerosis, hypertension, and genetic predisposition. Basic research studies have led to a better understanding of aneurysm disease over the past two decades. There has also been a growing appreciation that fundamental knowledge regarding the process of aneurysmal degeneration is still somewhat limited. Opportunities in research include: 1) the investigation of potential new mechanism-based pharmacologic interventions; 2) identify the genetic basis for an inherited predisposition; 3) develop and refine noninvasive approaches for the early detection; 4) examine potential novel surgical approaches and design new biomaterials; and 5) initiate and promote awareness programs for diagnosis and treatment of aortic aneurysms. The optimal approach to addressing these issues will require integrative, multidisciplinary research programs that involve basic scientists working in concert with vascular and cardiothoracic surgeons, as well as other clinical specialists with expertise in vascular disease.

Current trends in the management of small abdominal aortic aneurysms

Over the past decade, there have been revolutionary changes in the diagnosis and treatment of abdominal aortic aneurysms. Minimally invasive endovascular technologies have decreased length of stay and, more importantly, improved at least the early outcomes compared with conventional open surgical therapy. Several large, randomized, prospective trials have re-evaluated the optimal size to treat abdominal aortic aneurysms. The guidelines and conclusions from these studies, the UK Small Aneurysm Trial and The Veterans Affairs Administration aneurysm Detection And Management Trial recommend intervening on aortic aneurysms when they reach 5.5 cm in transverse diameter. However, these studies do not bear direct relevance to contemporary management of aneurysms with endovascular techniques. Clinical trials are currently underway to assess the optimal size for treating abdominal aortic aneurysms with endovascular stent grafts.

Pathology, natural history and treatment of abdominal aortic aneurysms

With increasing age of the population and improvement of diagnostic tools, the incidence of abdominal aortic aneurysms (AAA) has been rising steadily. Despite an improvement in operative and interventional treatment options, AAA is the cause of death in 1-3% of men over 65 years of age in industrial countries, mostly due to rupture [1]. Therefore, routine screening for AAA by ultrasonography has been postulated in the past: a 60 year old man with an abdominal aortic diameter of less than 3 cm has a life-time risk of developing AAA close to zero. However, routine screening has not been found to be cost effective. Despite of the results of two well-designed studies, the limits of AAA qualifying the patient for surgery or intervention in contrast to conservative treatment is still a matter of debate. The present review article summarizes the current knowledge of the pathology, incidence, risks, natural course as well as symptoms and current treatment strategies of AAA on the basis of the recent literature.

Informing the efficient use of health care and health care research resources - the case of screening for abdominal aortic aneurysm in Sweden

BACKGROUND

An analytical framework using Bayesian decision theory and value-of-information analysis has recently been advocated for the economic evaluation of health technologies. The purpose of this study was to apply this framework to screening for abdominal aortic aneurysm (AAA) in Sweden and to compare the conclusions from this study with the conclusions presented in an assessment performed by the Swedish Council of Technology Assessment (SBU).

METHODS

A probabilistic decision-analytical model was developed to establish the cost-effectiveness of a screening programme for AAA relative to current clinical practice and to calculate the value-of-information.

RESULTS

The cost per quality-adjusted life-year for screening was 9700 euro. The expected value of perfect information for the assessment of overall cost-effectiveness was low, suggesting little benefit in conducting further research. Expected value of perfect partial information indicated that rupture probabilities were associated with the highest uncertainty. By contrast, the SBU report concluded there was limited evidence of cost-effectiveness and proposed further research.

CONCLUSION

The investigated screening programme for AAA is likely to be cost-effective and conducting another clinical trial is unlikely to add much valuable information to this decision problem. These recommendations contrast with the vaguer recommendations from SBU that more evidence is required of costs-effectiveness.

The Long-Term Relationship of Wall Stress to the Natural History of Abdominal Aortic Aneurysms (Finite Element Analysis and Other Methods)

For the past four decades, abdominal aortic aneurysm (AAA) rupture risk has been estimated using maximum aneurysm diameter. Although this works relatively well in general, clinicians know that some aneurysms rupture at an unusually small size, while others grow to exceptionally large sizes without rupture. We have demonstrated that finite element analysis (FEA) of AAA wall stress using three-dimensional computed tomography (CT) reconstructions is better than diameter for differentiating AAAs near the time of rupture, and that wall stress is superior to AAA diameter for predicting rupture risk in patients under observation. This article summarizes our current work, future areas of investigation, and issues related to "translational" research for FEA of aortic aneurysms.

Endovascular aneurysm repair at 5 years: does aneurysm diameter predict outcome?

OBJECTIVE

The appropriate size threshold for endovascular repair of small abdominal aortic aneurysms (AAA) is unclear. We studied the outcome of endovascular aneurysm repair (EVAR) as a function of preoperative aneurysm diameter to determine the relationship between aneurysm size and long-term outcome of endovascular repair.

METHODS

We reviewed the results of 923 patients treated in a prospective, multicenter clinical trial of EVAR. Small aneurysms were defined according to two size thresholds of 5.5 cm and 5.0 cm. Two-way analysis was used to compare patients with small aneurysms (<5.5 cm, n = 441) to patients with large aneurysms (> or =5.5 cm, n = 482). An ordered three-way analysis was used to compare patients with small AAA (<5.0 cm, n = 145), medium AAA (5.0 to 5.9 cm, n = 461), and large AAA (> or =6.0 cm, n = 317). The primary outcome measures of rupture, AAA-related death, surgical conversion, secondary intervention, and survival were compared using Kaplan-Meier estimates at 5 years.

RESULTS

Median aneurysm size was 5.5 cm. The two-way comparison showed that 5 years after EVAR, patients with small aneurysms (<5.5 cm) had a lower AAA-related death rate (1% vs 6%, P = .006), a higher survival rate (69% vs 57%, P = .0002), and a lower secondary intervention rate (25% vs 32%, P = .03) than patients with large aneurysms (> or =5.5 cm). Three-way analysis revealed that patients with small AAAs (<5.0 cm) were younger (P < .0001) and were more likely to have a family history of aneurysm (P < .05), prior coronary intervention (P = .003), and peripheral occlusive disease (P = .008) than patients with larger AAAs. Patients with smaller AAAs also had more favorable aortic neck anatomy (P < .004). Patients with large AAAs were older (P < .0001), had higher operative risk (P = .01), and were more likely to have chronic obstructive pulmonary disease (P = .005), obesity (P = .03), and congestive heart failure (P = .004). At 5 years, patients with small AAAs had better outcomes, with 100% freedom from rupture vs 97% for medium AAAs and 93% for large AAAs (P = .02), 99% freedom from AAA-related death vs 97% for medium AAAs and 92% for large AAAs (P = .02) and 98% freedom from conversion vs 92% for medium AAAs and 89% for large AAAs (P = .01). Survival was significantly improved in small (69%) and medium AAAs (68%) compared to large AAAs (51%, P < .0001). Multivariate Cox proportional hazards modeling revealed that aneurysm size was a significant independent predictor of rupture (P = .04; hazard ratio [HR], 2.195), AAA-related death (P = .03; HR, 2.007), surgical conversion (P = .007; HR, 1.827), and survival (P = .001; HR, 1.351). There were no significant differences in secondary intervention, endoleak, or migration rates between small, medium, and large AAAs.

CONCLUSIONS

Preoperative aneurysm size is an important determinant of long-term outcome following endovascular repair. Patients with small AAAs (<5.0 cm) are more favorable candidates for EVAR and have the best long-term outcomes, with 99% freedom from AAA death at 5 years. Patients with large AAAs (> or =6.0 cm) have shorter life expectancy and have a higher risk of rupture, surgical conversion, and aneurysm-related death following EVAR compared to patients with smaller aneurysms. Nonetheless, 92% of patients with large AAAs are protected from AAA-related death at 5 years. Patients with AAAs of intermediate size (5 to 6 cm) represent most of the patients treated with EVAR and have a 97% freedom from AAA-related death at 5 years.

Abdominal aortic aneurysm: pathogenesis and implications for management

Abdominal aortic aneurysm (AAA) affects approximately 5% of elderly men and is responsible for a significant number of deaths in Western Countries. At present surgery by open or endovascular means is the only widely used therapy for this condition. In this review we examine the risk factors, serum, and genetic associations of AAA. Epidemiology studies suggest that smoking cessation and control of cholesterol and blood pressure should reduce the number of patients developing AAA. Natural history studies suggest that smoking cessation should reduce the rate of progression of AAA. Clear level 1 evidence for drug treatments of AAA are presently lacking; however, animal and human in vitro studies suggest that medication targeted at reducing inflammation and proteolysis are most likely to be beneficial, with limited data to support the use of statins, Angiotensin II inhibitors, and macrolides. Work has commenced in understanding which patients, identified by clinical, serum, and genotype, are more at risk of AAA progression and thus should be selected out for aggressive treatment. Well designed large multicenter randomized controlled trials are required to examine the medical treatment of AAA.

Gender Differences in Relative Dilatation of Abdominal Aortic Aneurysms

It has been postulated that gender differences in abdominal aortic aneurysm (AAA) rupture risk are due to variation in proportional dilatation. This study's purpose was to examine differences in relative dilatation of AAAs as related to rupture risk and repair thresholds. During a recent 20-month period (August 2003-March 2005), all patients receiving elective endovascular repair of an AAA underwent computer-generated computed tomographic measurements, including suprarenal aortic diameter (D1) and maximum aneurysm diameter (D3). As a measure of proportional dilatation, a D3/D1 ratio was calculated for each patient and compared between genders. Values for males and females were plotted separately (D3 vs. D3/D1), and the resulting linear regression equations allowed for the comparison of proportional dilatation of aneurysms between genders. In 129 patients (108 males, 21 females), mean D3 did not differ between genders (62 +/- 9.0 vs 63.4 +/- 10.8 mm, p = 0.89), while relative dilatation (D3/D1) was significantly greater in females compared to males (2.82 +/- 0.52 vs. 2.55 +/- 0.42, p = 0.02). Linear regression analysis allowed for comparison of D3 as a function of D3/D1 and correlated a 55 mm AAA in males with one of 52 mm in females. These differences became greater with increasing AAA diameters (e.g., 60 and 70 mm AAAs in a male were proportionally similar to 56 and 62 mm AAAs in a female). AAAs of equal diameter represent a greater proportional dilatation in females than in males. This supports the recommendation for a smaller aneurysm diameter (52 mm) threshold for repair in females rather than the commonly used 55 mm threshold in males. Also, these data suggest that the gender difference in rupture risk widens exponentially as aneurysm diameter, and thereby proportional dilatation, increases above this repair threshold.

Angiotensin-converting enzyme inhibitors and aortic rupture: a population-based case-control study

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors prevent the expansion and rupture of aortic aneurysms in animals. We investigated the association between ACE inhibitors and rupture in patients with abdominal aortic aneurysms.

METHODS

We did a population-based case-control study of linked administrative databases in Ontario, Canada. The sample included consecutive patients older than 65 (n=15,326) admitted to hospital with a primary diagnosis of ruptured or intact abdominal aortic aneurysm between April 1, 1992, and April 1, 2002.

FINDINGS

Patients who received ACE inhibitors before admission were significantly less likely to present with ruptured aneurysm (odds ratio [OR] 0.82, 95% CI 0.74-0.90) than those who did not receive ACE inhibitors. Adjustment for demographic characteristics, risk factors for rupture, comorbidities, contraindications to ACE inhibitors, measures of health-care use, and aneurysm screening yielded similar results (0.83, 0.73-0.95). Consistent findings were noted in subgroups at high risk of rupture, including patients older than 75 years and those with a history of hypertension. Conversely, such protective associations were not observed for beta blockers (1.02, 0.89-1.17), calcium channel blockers (1.01, 0.89-1.14), alpha blockers (1.15, 0.86-1.54), angiotensin receptor blockers (1.24, 0.71-2.18), or thiazide diuretics (0.91, 0.78-1.07).

INTERPRETATION

ACE inhibitors are associated with a reduced risk of ruptured abdominal aortic aneurysm, unlike other antihypertensive agents. Randomised trials of ACE inhibitors for prevention of aortic rupture might be warranted.

Increasing incidence of ruptured abdominal aortic aneurysm: A population-based study

OBJECTIVE

The aim of the present population-based study was to assess the trends of age- and gender-specific incidence of ruptured abdominal aortic aneurysm (rAAA).

METHODS

Patients with rAAA from the city of Malmö, Sweden, were studied between 2000 and 2004. An analysis of trends of incidence and mortality of rAAA in Malmö was possible because of a previous population-based study on patients with rAAA between 1971 and 1986 (autopsy rate 85% compared with 25% for the time period 2000 to 2004). The in-hospital registry of Malmö University Hospital and the databases at the Department of Pathology, Malmö, and the Institution of Forensic Medicine, Lund, identified patients with rAAA, and the in-hospital registry identified all elective repairs for AAA.

RESULTS

Compared with the time period 1971 to 1986, the overall incidence of rAAA significantly increased from 5.6 (95 % confidence interval [CI], 4.9 to 6.3) to 10.6 (95% CI, 8.9 to 12.4) per 100,000 person-years (standardized mortality ratio, 1.6; 95% CI, 1.0 to 2.1). In men aged 60 to 69 and 70 to 79 years, the incidence increased significantly from 16 (95% CI, 11 to 21) and 56 (95% CI, 43 to 69) to 46 (95% CI, 28 to 63) and 117 (95% CI, 84 to 149) per 100,000 person-years, respectively, whereas no increase in the age-specific incidence in women could be demonstrated. The overall incidence of elective repair of AAA increased significantly from 3.4 (95% CI, 2.8 to 4.0) to 7.0 (95% CI, 5.6 to 8.4) per 100,000 person-years and increased most significantly from 12 (95% CI, 3.4 to 32) to 68 (95% CI, 34 to 102) per 100,000 person-years in men aged 80 to 89 years and from 5.1 (95% CI, 2.4 to 9.3) to 28 (95% CI, 15 to 41) per 100,000 person-years in women aged 70 to 79 years. The elective-acute repair ratio in women increased from 2.4 to 5.6 and decreased in men from 2.1 to 1.0.

CONCLUSIONS

Between 1971 to 1986 and 2000 to 2004, the incidence of rAAA increased significantly, despite a 100% increase in elective repairs and notwithstanding a potential for bias towards underestimation due to lower autopsy rates in recent years. The reason behind this increase is unclear, and further studies are needed to identify risk groups for direction of effective prevention and screening.

Concomitant Detection of Systemic Atherosclerotic Disease while Screening for Abdominal Aortic Aneurysm

INTRODUCTION

Although population screening for abdominal aortic aneurysm (AAA) has/had a significant impact on disease-specific mortality, coexisting systemic atherosclerosis represents the major impediment to improved longevity. We examined the feasibility and yield of full cardiovascular assessment concomitant with screening for AAA detection.

METHODS

A total of 1032 asymptomatic men over the age of 50 years (328 were >60 years) underwent a detailed cardiac health questionnaire, sphygmomanometry, body mass index calculation, fasting lipid profiling, ultrasonographic (US) examination of their infrarenal aorta and carotid arteries, and treadmill exercise stress testing. Framingham and SCORE project estimations of the 10-year risk of ischemic heart disease (IHD) and fatal cardiovascular disease (CVD) of any cause were calculated for the men with an AAA and in those>60 years but with neither AAA nor known cardiac disease.

RESULTS

Overall, we detected an AAA>3 cm in 30 men (2.9%). Unaddressed obesity, smoking, hypertension, impaired glucose metabolism, and hypercholesterolemia were commonly identified in individuals both with and without an AAA, being notably frequent in those>60 years without an AAA. The 10-year risk of IHD and CHD in those>60 years was similar regardless of whether an AAA was present. Doppler screening for significant carotid stenosis had detection rates similar to those for aortic US scanning, being most useful in those>65 years of age. Exercise stress testing, however, was of only limited value when used nonselectively.

CONCLUSIONS

Modifiable atherosclerotic disease and cardiovascular risk can be readily detected in individuals presenting for AAA screening and are present to a significant degree at an earlier age. Consideration of selected, additional investigations is required to maximize the value of generalized screening programs.

N. Tratamento cirúrgico dos aneurismas da aorta abdominal: existe diferença dos resultados entre homens e mulheres?

OBJETIVO: Avaliar os resultados cirúrgicos após o tratamento convencional e eletivo do aneurisma da aorta abdominal, verificando se existe diferença entre homens e mulheres na mortalidade e morbidade cirúrgicas, bem como nos resultados a longo prazo. PACIENTES E MÉTODOS: Entre dezembro de 1983 e dezembro de 2003, 675 pacientes foram submetidos ao tratamento cirúrgico do aneurisma da aorta abdominal infra-renal, sendo divididos em dois grupos: homens (n = 575) e mulheres (n = 100). Os dados demográficos e aqueles relacionados ao procedimento cirúrgico, bem como os resultados perioperatórios, foram coletados pela revisão dos prontuários. Os pacientes com alta hospitalar formaram uma coorte retrospectiva, onde foram avaliadas as causas tardias de óbito e a sobrevida. RESULTADOS: A média das idades foi similar, sem diferença estatística entre mulheres e homens (68,9 ± 9,1 versus 67,4 ± 7,1 anos; P = 0,089). A presença de hipertensão arterial foi significativamente superior nas mulheres (73 versus 62,4%; P = 0,042), e a cardiopatia isquêmica e história de tabagismo foram mais freqüentes nos homens (P <0,05). A mortalidade operatória total foi de 2,8%, não havendo diferença significativa entre mulheres e homens (4 versus 2,6%, respectivamente; P = 0,43). A morbidade cirúrgica envolveu 14% dos pacientes femininos e 18,4% dos masculinos (P 0,05). A taxa de sobrevida global em 1, 3, 5 e 10 anos não diferiu entre os grupos, sendo a sobrevida em 5 anos de 71% para as mulheres e 72% para os homens (P 0,05). A principal causa de morte tardia foi de origem cardiovascular, seguida de complicações renais nas mulheres e neoplasia nos homens. CONCLUSÂO: A taxa de mortalidade e morbidade cirúrgicas não aumentou significativamente nas mulheres após a correção eletiva do aneurisma da aorta abdominal infra-renal. Além disso, os resultados a longo prazo são semelhantes entre os dois gêneros.

Flow Dynamics in Expansions Characterizing Abdominal Aorta Aneurysms

Our purpose was to identify and quantify hemodynamic factors contributing to the generation, proliferation, and rupturing of abdominal aorta aneurysms (AAAs) using a computational investigation of steady laminar and turbulent flow in AAA models. Steady laminar and turbulent flows were computed using the incompressible Navier-Stokes equations. Flow fields in symmetric shapes of different extents and degrees of expansion are presented first. Two representative cases of asymmetric AAAs are considered next: an aneurysm with an elliptic cross section and an aneurysm with preferential expansion in one direction. For symmetric aneurysms, parametric studies are presented. For asymmetric aneurysms, flow fields are computed only for high flow rates representative of systolic flow. For all cases, a recirculating flow region was found in the expanded part of the AAA. Recirculation is accompanied by a minor increase in pressure but a significant increase in wall shear stress. For cases where turbulent flow was considered, it was found that the recirculation zone diminishes but the computed wall shear stress reaches levels higher than laminar flow. The levels of wall shear stress reached in turbulent flow may cause lesions of the aneurysmal wall. The minor variation of pressure within the aneurysms with smooth expansions indicates that the structural properties of the arterial wall tissue may play a significant role for the generation and subsequent proliferation of the aneurysm. However, the high values of the wall shear stress in AAAs appear to be an important hemodynamic factor that may contribute to wall degeneration and eventual rupturing. The recirculating flow in AAAs may explain the generation of intraluminal thrombi. Furthermore, the asymmetry and complexity of the flow in asymmetric AAAs may explain the frequently observed asymmetric thrombi distribution.

Reduced lung function in patients with abdominal aortic aneurysm is associated with activation of inflammation and hemostasis, not smoking or cardiovascular disease

OBJECTIVE

Abdominal aortic aneurysms often coexist with reduced lung function and chronic obstructive pulmonary disease (COPD). These conditions are each associated with cigarette smoking, cardiovascular disease, and evidence of increased inflammatory and hemostatic activity. The aim of this study was to determine if these factors accounted for the link between aneurysms and pulmonary disease.

METHODS

The design was a case-control study comparing patients with an asymptomatic abdominal aortic aneurysm with population-based controls without an aneurysm. Aneurysms were diagnosed by ultrasound scan, and pulmonary function was measured by respiratory questionnaire and spirometry. Activation of inflammation and hemostasis was measured by assay of plasma interleukin-6 (IL-6), fibrinogen, von Willebrand factor (vWF), tissue plasminogen activator (tPA) antigen, fibrin D-dimer, and plasmin antiplasmin complexes.

RESULTS

Cases with an abdominal aortic aneurysm (n = 89) had more COPD and worse expiratory lung function as measured by forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) than controls (n = 98) (FEV1, 1.9 vs 2.2 L, P < .01; FEV1/FVC, 0.67 vs 0.75, P < .001) and did not differ in restrictive function (FVC, 2.9 vs 3.0 L, P = .33). Cases also had higher levels of lifetime cigarette smoking (30 vs 24 pack-years, P < 0.01), cardiovascular disease (35% vs 18%, P = .01), plasma fibrinogen (3.5 vs 3.1 g/L, P = .02), IL-6 (2.8 vs 1.8, pg/mL, P < .001), plasmin antiplasmin complexes (596 vs 384 microg/L, P = .01), and D-dimer (442 vs 93 ng/mL, P < .001). On multiple logistic regression analysis of lung function and COPD on the risk of aneurysm, both cigarette smoking and cardiovascular disease had little effect on the relationships. For the markers of activated inflammation and hemostasis, plasmin antiplasmin complexes and D-dimer had the most important confounding effect on the odds ratios. All markers combined had a substantial effect: odds ratio of aneurysm for a one standard deviation decrease in FEV1 fell from 2.3 (95% confidence interval [CI], 1.5 to 3.5) (P < .01) to 1.3 (95% CI, 0.55 to 2.4) (P > or = .05).

CONCLUSION

The association between reduced respiratory function and abdominal aortic aneurysm was not accounted for by cigarette smoking or cardiovascular disease. We hypothesize that activation of inflammation and hemostasis in response to injury may be an important explanation of the association between aneurysm formation and reduced respiratory function. Further studies are required to test this hypothesis.

Biomechanical properties of ruptured versus electively repaired abdominal aortic aneurysm wall tissue

OBJECTIVE

The purpose of this study was to evaluate and compare the biomechanical properties of abdominal aortic aneurysm (AAA) wall tissue from patients who experienced AAA rupture with that of those who received elective repair.

METHODS

Rectangular, circumferentially oriented AAA wall specimens (approximately 2.5 cm x 7 mm) were obtained fresh from the operating room from patients undergoing surgical repair. The width and thickness were measured for each specimen by using a laser micrometer before testing to failure with a uniaxial tensile testing system. The force and deformation applied to each specimen were measured continuously during testing, and the data were converted to stress and stretch ratio. The tensile strength was taken as the peak stress obtained before specimen failure, and the distensibility was taken as the stretch ratio at failure. The maximum tangential modulus and average modulus were also computed according to the peak and average slope of the stress-stretch ratio curve.

RESULTS

Twenty-six specimens were obtained from 16 patients (aged 73 +/- 3 years [mean +/- SEM]) undergoing elective repair of their AAA (diameter, 7.0 +/- 0.5 cm). Thirteen specimens were resected from nine patients (aged 73 +/- 3 years; P = not significant in comparison to the electively repaired AAAs) during repair of their ruptured AAA (diameter, 7.8 +/- 0.6 cm; P = not significant). A significant difference was noted in wall thickness between ruptured and elective AAAs: 3.6 +/- 0.3 mm vs 2.5 +/- 0.1 mm, respectively (P < .001). The tensile strength of the ruptured tissue was found to be lower than that for the electively repaired tissue (54 +/- 6 N/cm2 vs 82 +/- 9.0 N/cm2; P = .04). Considering all specimens, no significant correlation was noted between tensile strength and diameter (R = -0.10; P = .55). Tensile strength, however, had a significant negative correlation with wall thickness (R = -0.42; P < .05) and a significant positive correlation with the tissue maximum tangential modulus (R = 0.76; P < .05).

CONCLUSIONS

Our data suggest that AAA rupture is associated with aortic wall weakening, but not with wall stiffening. A widely accepted indicator for risk of aneurysm rupture is the maximum transverse diameter. Our results suggest that AAA wall strength, in large aneurysms, is not related to the maximum transverse diameter. Rather, wall thickness or stiffness may be a better predictor of rupture for large AAAs.

Strain estimation in abdominal aortic aneurysms from 2-D ultrasound

The rupture risk of abdominal aortic aneurysms (AAAs) is routinely inferred from the maximum diameter of the AAA. However, clinical experience indicates that this criterion has poor accuracy and that noninvasive assessment of the elastic properties of the vessel might give better correspondence with the rupture risk. We have developed a method for analysis of circumferential strain in AAAs from sequences of cross-sectional ultrasound B-mode images. The algorithm is fast, semiautomatic and well-suited for real-time applications. The method was developed and evaluated using data from 10 AAA patients. The preliminary results demonstrate that the method is sufficiently accurate and robust for clinically acquired data. An important finding is that local strain values may exceed the circumferential average strain significantly. Furthermore, the calculated strain shows no apparent covariation with the diagnosed diameter. This implies that the method may give new and essential information on the clinical condition of the AAA.

French women from multiplex abdominal aortic aneurysm families should be screened

BACKGROUND

Multiplex abdominal aortic aneurysm families (MAAAFs) (> or =1 subject plus the proband) represent 1% to 34% of abdominal aortic aneurysm (AAA), but the percentage in France is unknown.

METHOD

The MAAAF rate was retrospectively defined by analysis of 3 groups: 72 of 104 consecutive individuals undergoing AAA surgery during 1994, 24 of 53 women and 35 of 76 men with giant (> or =9 cm) AAA operated on during 1986 to 1994. MAAAF characteristics were determined based on 10 families issued from these 3 groups and 34 others identified nationwide. Data were obtained from a standardized questionnaire for probands and relatives, detailed pedigrees of each family, and computed tomography (CT) scans without contrast medium of the aorta and lower limb arteries for first-degree relatives > or =40-year-of age.

RESULTS

The MAAAF rate was 4.2% for the consecutive-surgery patients (proband M/F ratio, 17:1; mean age at surgery, 68.5 +/- 8.5 years). CT detected no additional AAA among them (screened individuals M/F ratio, 0.63; mean age, 54.0 +/- 11.2 years). MAAAF rates were 8.3% and 14.3% for the women's and giant-AAA groups with CT screening, respectively. Characteristics were investigated in 104 affected subjects from 44 MAAAFs: female relatives were more often affected than probands (P < 0.025). Compared with men, affected female relatives were significantly older at diagnosis and surgery (P < 0.05 and P < 0.02, respectively), as were affected women (P < 0.02 and P < 0.01, respectively). CT scan screening identified significantly more AAA and abdominal aortic dilatations among the 44 MAAAFs than the consecutive-surgery group (5 and 4, respectively; P < 0.001).

CONCLUSION

Although the MAAAF rate seems low in France, women from MAAAF were affected more often and later, suggesting that they should be screened.

Midterm clinical success and behavior of the aneurysm sac after endovascular AAA repair with the Excluder graft

OBJECTIVE

Recent studies have reported different sac behavior after endovascular repair of abdominal aortic aneurysms, depending on the endografts. This study was designed to evaluate mid-term outcome and sac behavior after treatment with the Gore Excluder stent-graft.

METHODS

Between June 1999 and January 2005, 109 selected patients with suitable anatomy were treated electively for abdominal aortic aneurysm with the Excluder stent graft. Data were prospectively collected in a computerised database and included demographics, details of the aortoiliac anatomy, procedural and clinical success, and postoperative complications. Postoperative sac size and the presence of endoleaks were assessed with computed tomography scans obtained at 1, 6, and 12 months, and yearly thereafter. All diameter measures in patients followed for > 1 year (84.4%) were analyzed.

RESULTS

Assisted primary technical success was achieved in 108 cases (99.1%). No type I endoleaks and 12 (11.1%) type II endoleaks were recorded < or = 1 month from the procedure. Mean follow-up was 29.6 +/- 16.1 months. We recorded one new-onset type IA endoleak, complete resolution of five type II endoleaks, and eight new-onset type II endoleaks. The overall prevalence of type II endoleaks was 14%. Shrinkage at 1, 2, 3, and 4 years was observed in 20.7%, 30.5%, 38.9%, and 36.8% of cases. The presence of type II endoleak influenced the trend of aneurysm size throughout the 4 years. Aneurysms without endoleak shrank more than aneurysms with type II endoleak (P < .0001). We observed two cases of sac enlargement due to the presence of endoleaks. No cases of endotension with sac enlargement, late open conversion, or aneurysm-related deaths were observed. Unchanged aneurysmal sacs remained stable during follow-up, with no adverse events.

CONCLUSIONS

Endovascular treatment with the Excluder device in selected patients produces low rates of shrinkage, but this peculiar sac behavior does not affect mid-term clinical success.

Abdominal aortic aneurysm (AAA): cost-effectiveness of screening, surveillance of intermediate-sized AAA, and management of symptomatic AAA

Physicians must make decisions about screening patients for abdominal aortic aneurysms (AAAs), monitoring or referring for surgery patients with AAAs of various sizes, and assessing patients with symptoms that may be related to AAAs. This review article analyzes the evidence for each scenario. The effectiveness and cost-effectiveness of screening for AAA is based on results from four randomized controlled trials. A cost-effectiveness analysis using a Markov model showed that ultrasound screening of white men beginning at age 65 is both effective and cost-effective in preventing AAA-related death. Such screening would have a small but real impact over a 20-year period in these men. For patients with a known AAA-which is often detected incidentally-the evidence clearly suggests periodic ultrasound surveillance for those with small AAAs (3.0-3.9 cm in diameter) and elective surgical repair for those with large AAAs (>or=5.5 cm). Two recent randomized controlled trials have shown that early surgical repair confers no survival benefit compared with periodic surveillance for patients with intermediate-sized AAAs (4.0-5.5 cm in diameter), so those patients can also be monitored. Some centers choose to increase the frequency of monitoring to every 3 to 6 months when the AAA reaches 5.0 cm. Factors to consider in assessing symptomatic patients include the high risk of life-threatening conditions, the potential increased risk of death or poor outcome with delay in diagnosis, the limitations of ultrasound in identifying whether symptoms are due to known or suspected AAA, and the timely availability of computed tomography or other imaging tests. If available, computed tomography is preferred in patients with recent or severe symptoms, since it is better at detecting retroperitoneal hemorrhage and other complications and in providing preoperative definition of the anatomy.

Periods of low atmospheric pressure are associated with high abdominal aortic aneurysm rupture rates in Northern Ireland

Seasonal and circadian variation in the incidence of ruptured abdominal aortic aneurysm (RAAA) has been reported. We explored the role of atmospheric pressure changes on rupture incidence and its relationship to cardiovascular risk factors. During a three year-period, 1st April 1998 and 31st March 2001, data was prospectively acquired on 144 Ruptured Abdominal Aortic Aneurysm (RAAA) presenting to the Regional Vascular Surgery Unit at the Royal Victoria Hospital, Belfast, Northern Ireland. For each patient the chronology of acute onset of symptoms and presentation to the regional vascular unit was recorded, along with details of standard cardiovascular risk factors. During the same period meteorological data including atmospheric pressure and air temperature were recorded daily at the regional meteorological research unit, Armagh. We then analyzed the monthly mean values for daily rupture incidence in relation to the monthly values for atmospheric pressure, pressure change and temperature. Furthermore atmospheric pressure on the day of rupture, and day preceding rupture, were also analyzed in relation to days without rupture presentation and between individual ruptures for various cardiovascular risk factors. Data demonstrated a significant monthly variation in aneurysm rupture frequency, (p<0.03, ANOVA). There was also a significant monthly variation in mean barometric atmospheric pressure, (p<0.0001, ANOVA), months with high rupture frequency also exhibiting low average pressures in the months of April (0.24 +/- 0.04 ruptures per day and 1007.78 +/- 1.23 mB) and September (0.16 +/- 0.04 ruptures per day and 1007.12 +/- 1.14 mB), respectively. The average barometric pressures were found to be significantly lower on those days when ruptures occurred (n=1127) compared to days when ruptures did not occur (n=969 days), (1009.98 +/- 1.11 versus 1012.09 +/- 0.41, p<0.05). Full data on risk factors was available on 103 of the 144 rupture patients and was further analyzed. Interestingly, RAAA with a known history of hypertension, (n=43), presented on days with significantly lower atmospheric pressure than those without, (n=60), (1008.61 +/- 2.16 versus 1012.14 +/- 1.70, p<0.05). Further analysis of ruptures grouped into those occurring on days above or below mean annual atmospheric pressure 1013.25 (approximately 1 atmosphere), by Chi-square test, revealed three cardiovascular risk factors significantly associated with low-pressure rupture, (p<0.05). Data represents mean +/- SEM, statistical comparisons with Student t-test and ANOVA. These data demonstrate a significant association between periods of low barometric pressure and high incidence of ruptured aneurysm, especially in those patients with known hypertension. The association between rupture incidence and barometric pressure warrants further study as it may influence the timing of elective AAA repair.

A Review of Biological Factors Implicated in Abdominal Aortic Aneurysm Rupture

Abdominal aortic aneurysm (AAA) rupture is the 13th commonest cause of death in the Western World. Although considerable research has been applied to the aetiology and mechanism of aneurysm expansion, little is known about the mechanism of rupture. Aneurysm rupture was historically considered to be a simple physical process that occurred when the aortic wall could no longer contain the haemodynamic stress of the circulation. However, AAAs do not conform to the law of Laplace and there is growing evidence that aneurysm rupture involves a complex series of biological changes in the aortic wall. This paper reviews the available data on patient variables associated with aneurysm rupture and presents the evidence implicating biological factors in AAA rupture.

Genotype–phenotype relationships in an investigation of the role of proteases in abdominal aortic aneurysm expansion

Background

The aim of the study was to investigate the effect of functional polymorphisms in promoters of matrix metalloproteinase (MMP) 2, MMP-3, MMP-9, MMP-12 and plasminogen activator inhibitor (PAI) 1 genes on the growth rate of small abdominal aortic aneurysms (AAA).

Methods

Some 455 individuals with a small AAA (4·0–5·5 cm) were monitored for aneurysm growth by ultrasonography (mean follow-up 2·6 years). They also provided a DNA sample for analysis of the −1306 C &gt; T, −1171 5A &gt; 6A, −1562 C &gt; T, −82 A &gt; G and −675 4G &gt; 5G alleles of MMP-2, MMP-3, MMP-9, MMP-12 and PAI-1, respectively. Mean linear AAA growth rates were calculated by flexible modelling; the sample size was sufficient to detect variants that influenced the growth rate by 25 per cent.

Results

For MMP-2, MMP-9 and MMP-12 genotypes, growth rates were similar to the mean linear growth rate of 3·08 mm per year. For MMP-3, growth rates were 3·05 (for 5A5A), 3·19 (for 5A6A) and 2·90 (for 6A6A) mm per year. For PAI-1, patients with 4G4G, 4G5G and 5G5G genotypes had growth rates of 3·18, 2·92 and 3·47 mm per year, respectively, for aneurysms with a baseline diameter of 45·1, 44·6 and 46·2 mm. The increased growth rate for patients with PAI-1 5G5G genotype was not statistically significant (P = 0·061), although these patients had the lowest plasma PAI-1 concentrations (P = 0·018).

Conclusion

There was no evidence that any specific MMP polymorphism had a clinically significant effect on AAA expansion. The plasminogen system may have a small but clinically significant role in AAA development. Much larger studies would be needed to evaluate genes of smaller effect.

Decision-analytical model with lifetime estimation of costs and health outcomes for one-time screening for abdominal aortic aneurysm in 65-year-old men

Background

Abdominal aortic aneurysm (AAA) causes about 2 per cent of all deaths in men over the age of 65 years. A major improvement in operative mortality would have little impact on total mortality, so screening for AAA has been recommended as a solution. The cost-effectiveness of a programme that invited 65-year-old men for ultrasonographic screening was compared with current clinical practice in a decision-analytical model.

Methods

In a probabilistic Markov model, costs and health outcomes of a screening programme and current clinical practice were simulated over a lifetime perspective. To populate the model with the best available evidence, data from published papers, vascular databases and primary research were used.

Results

The results of the base-case analysis showed that the incremental cost per gained life-year for a screening programme compared with current practice was €7760, and that for a quality-adjusted life-year was €9700. The probability of screening being cost-effective was high.

Conclusion

A financially and practically feasible screening programme for AAA, in which men are invited for ultrasonography in the year in which they turn 65, appears to yield positive health outcomes at a reasonable cost.

The Management of Abdominal Aortic Aneurysms in Patients with Concurrent Renal Impairment

INTRODUCTION

Patients with concurrent renal impairment and abdominal aortic aneurysms present a significant challenge in terms of pre-operative, intra-operative and post-operative management. This aim of this review was to determine the risks of surgery in this patient group and determine whether any clear management strategies exist to enhance their clinical management.

METHODS

Systematic review of published literature giving details of the outcome of open or endovascular abdominal aortic aneurysm repair in patients with pre-operative renal impairment. Papers concerning the management of post-operative acute renal failure in patients with normal pre-operative renal function has not been included.

RESULTS

There is little data regarding patients with end-stage renal failure and AAA although these patients appear to have a high peri-operative mortality rate. In contrast, those with renal impairment do not have a significantly higher mortality rate than those with normal renal function, rather they have a higher risk of complications associated with surgery and may require more intensive post-operative organ system support than normal patients. Many have a transient deterioration in renal function in the immediate peri-operative period that will resolve. In the case of patients with ruptured AAA, it is not clear whether pre-operative renal impairment affects mortality.

Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR trial 2): randomised controlled trial

BACKGROUND

Endovascular aneurysm repair (EVAR) to exclude abdominal aortic aneurysm (AAA) was introduced for patients of poor health status considered unfit for major surgery. We instigated EVAR trial 2 to identify whether EVAR improves survival compared with no intervention in patients unfit for open repair of aortic aneurysm.

METHODS

We did a randomised controlled trial of 338 patients aged 60 years or older who had aneurysms of at least 5.5 cm in diameter and who had been referred to one of 31 hospitals in the UK. We assigned patients to receive either EVAR (n=166) or no intervention (n=172). Our primary endpoint was all-cause mortality, with secondary endpoints of aneurysm-related mortality, health-related quality of life (HRQL), postoperative complications, and hospital costs. Analyses were by intention to treat.

FINDINGS

197 patients underwent aneurysm repair (47 assigned no intervention) and 80% of patients adhered to protocol. The 30-day operative mortality in the EVAR group was 9% (13 of 150, 95% CI 5-15) and the no intervention group had a rupture rate of 9.0 per 100 person years (95% CI 6.0-13.5). By end of follow up 142 patients had died, 42 of aneurysm-related factors; overall mortality after 4 years was 64%. There was no significant difference between the EVAR group and the no intervention group for all-cause mortality (hazard ratio 1.21, 95% CI 0.87-1.69, p=0.25). There was no difference in aneurysm-related mortality. The mean hospital costs per patient over 4 years were UK pound sterling 13,632 in the EVAR group and pound sterling 4983 in the no intervention group (mean difference pound sterling 8649, SE 1248), with no difference in HRQL scores.

INTERPRETATION

EVAR had a considerable 30-day operative mortality in patients already unfit for open repair of their aneurysm. EVAR did not improve survival over no intervention and was associated with a need for continued surveillance and reinterventions, at substantially increased cost. Ongoing follow-up and improved fitness of these patients is a priority.

Management of Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are a lethal disease. Ultrasound is the modality of choice for screening patients for AAAs. It is reasonable to screen patients over age 60, particularly men, women with cardiovascular risk factors, smokers, and patients with a family history of AAAs. Patients with small (< 5.5 cm) AAAs should be followed with serial ultrasound. Medical management should focus on treating comorbidities, particularly those that put patients at risk for other cardiovascular diseases. Smoking cessation is mandatory in these patients. Patients with large or symptomatic AAAs should be evaluated for surgery; this includes careful imaging of the abdomen, aggressive treatment of comorbidities, and perioperative beta blockade. Endovascular repair has lower short-term morbidity compared with conventional open repair. Trials assessing long-term results are in progress. Basic science and translational research focusing on the underlying pathogenesis of AAAs will likely pave the way for medical therapies in the future.

Elective Open Operation for Abdominal Aortic Aneurysm in Octogenarians—Survival Analysis of 105 Patients

OBJECTIVES

To study early mortality and long-term survival of patients more than 80 years of age having elective open repair for abdominal aortic aneurysm (AAA).

DESIGN

Retrospective multicenter cohort study.

MATERIAL

One hundred and five patients, 23 women and 82 men, with a median age of 82 years, operated at three Norwegian hospitals during the period 1983-2002.

METHOD

Survival analyses were based on data from medical records and the Norwegian Registrar's Office of Births and Deaths. Expected survival was based on mortality rates of the general population, matched by age, sex, and calendar period. Relative survival was calculated as the ratio between the observed and the expected survival.

RESULTS

During the study period there has been a 10 fold increase in octogenarians treated with open operation for AAA. Early mortality (30-day) for the whole group of patients was 10.5% (95% confidence interval (95% CI) 5.3-18.0), and similar for both genders. The 5-year survival rate was 47% (95% CI 35.9-57.4), and not significantly different from that of a matched group in the general population. Patients aged 84 years or more had a median survival time of 35 months (95% CI 18.5-51.6).

CONCLUSION

The number of AAA operations in octogenarians has increased considerably during 20 years. Octogenarians operated electively for AAA has higher 30-day mortality as compared to younger patients. Their long-term survival appears similar to a matched control group. The benefit of surgery must be carefully considered against the perioperative risk, especially for the oldest octogenarians.

Endovascular Repair or Surveillance of Patients with Small AAA

OBJECTIVE

To compare the outcome of patients with small abdominal aortic aneurysms (AAA) treated in a prospective trial of endovascular aneurysm repair (EVAR) to patients randomized to the surveillance arm of the UK Small Aneurysm Trial.

METHOD

All patients with small AAA (< or = 5.5 cm diameter) treated with a stent graft (EVARsmall) in the multicenter AneuRx clinical trial from 1997 to 1999 were reviewed with follow up through 2003. A subgroup of patients (EVARmatch) who met the age (60-76 years) and aneurysm size (4.0-5.5 cm diameter) inclusion criteria of the UK Small Aneurysm Trial were compared to the published results of the surveillance patient cohort (UKsurveil) of the UK Small Aneurysm Trial (NEJM 346:1445, 2002). Endpoints of comparison were aneurysm rupture, fatal aneurysm rupture, operative mortality, aneurysm related death and overall mortality. The total patient years of follow-up for EVAR patients was 1369 years and for UK patients was 3048 years. Statistical comparisons of EVARmatch and UKsurveil patients were made for rates per 100 patient years of follow up (/100 years) to adjust for differences in follow-up time.

RESULTS

The EVARsmall group of 478 patients comprised 40% of the total number of patients treated during the course of the AneuRx clinical trial. The EVARmatch group of 312 patients excluded 151 patients for age < 60 or > 76 years and 15 patients for AAA diameter < 4 cm. With the exception of age, there were no significant differences between EVARsmall and EVARmatch in pre-operative factors or post-operative outcomes. In comparison to the UKsurveil group of 527 patients, the EVARmatch group was slightly older (70 +/- 4 vs. 69 +/- 4 years, p = 0.009), had larger aneurysms (5.0 +/- 0.3 vs. 4.6 +/- 0.4 cm, p < 0.001), fewer women (7 vs. 18%, p < 0.001), and had a higher prevalence of diabetes and hypertension and a lower prevalence of smoking at baseline. Ruptures occurred in 1.6% of EVARmatch patients and 5.1% of UKsurveil patients; this difference was not significant when adjusted for the difference in length of follow up. Fatal aneurysm rupture rate, adjusted for follow up time, was four times higher in UKsurveil (0.8/100 patient years) than in EVARmatch (0.2/100 patient years, p < 0.001); this difference remained significant when adjusted for difference in gender mix. Elective operative mortality rate was significantly lower in EVARmatch (1.9%) than in UKsurveil (5.9%, p < 0.01). Aneurysm-related death rate was two times higher in UKsurveil (1.6/100 patient years) than in EVARmatch (0.8/100 patient years, p = 0.03). All-cause mortality rate was significantly higher in UKsurveil (8.3/100 patient years) than in EVARmatch (6.4/100 patient years, p = 0.02).

CONCLUSIONS

It appears that endovascular repair of small abdominal aortic aneurysms (4.0-5.5 cm) significantly reduces the risk of fatal aneurysm rupture and aneurysm-related death and improves overall patient survival compared to an ultrasound surveillance strategy with selective open surgical repair.