Prevalence of abdominal aortic aneurysm in a hypertensive population.

Two studies were undertaken to estimate the prevalence of abdominal aortic aneurysm in a hypertensive population. The initial study screened hypertensive people from three local general practices. In this study 918 patients underwent ultrasound scanning of the abdominal aorta (498 men and 420 women). A total of 24 abdominal aortic aneurysms were identified; 20 in men (4%) and four in women (0.9%). Of these, 11 were > 4 cm in transverse diameter. Following this study, only hypertensive men over the age of 60 years and women over the age of 65 years were screened from a total of 29 general practices. Regular scanning sessions were held at each practice and 1328 patients attended (744 men and 584 women). A total of 43 abdominal aortic aneurysms were detected; 39 in men (5.2%) and four in women (0.7%). Hypertensive men are at increased risk of developing abdominal aortic aneurysms and should be offered an initial ultrasound scan at 60 years of age. Female hypertensives yield a much lower detection rate and screening hypertensive females would probably be an inappropriate use of available resources.     

Epidemiology of abdominal aortic aneurysm in an Asian population

Background: Abdominal aortic aneurysms (AAA) are common in the Caucasian population. Apart from reported differences in the occurrence of AAA in the black and white populations, there are few studies on the incidence of AAA in the Asian population. Methods: A prospective database of all patients with AAA seen between 1996 and 1999, in the South‐East Asian state of Sarawak in Borneo Island, was analysed. The demographic data included patient's age, sex, ethnic group, date of diagnosis, comorbidities, presentations and treatment outcomes. These were compared with the state population's demographic statistics. Results: Diagnoses of AAA were made in 123 patients during the study period. The male to female ratio was 3.5 : 1. The age range was 39?88 years with a median age of 70 years. Four patients were younger than 55 years. The incidence rate for the at‐risk male population older than 50 years was 25.6/100 000. The incidence rate reached 78.3/100 000 for males older than 70 years. The incidence rate for females older than 50 years was 7.6/100 000 and for those older than 70 years it was 18.7/100 000. All races were affected. Smoking, hypertension or respiratory disorders were present in more than 40% of the patients. Half of the patients underwent surgical repair. Conclusion: This study shows that AAA in this Asian population is not uncommon and the incidence is comparable to the Western world.     

Matrix metalloproteinase 2 polymorphisms in a caucasian population with abdominal aortic aneurysm

BACKGROUND: The formation of sporadic abdominal aortic aneurysm (AAA) is explained by remodeling of the extracellular matrix (ECM) and breakdown of structural components of the vascular wall. Matrix metalloproteinase 2 (MMP2) is one of the principal matrix-degrading proteases and is known to play a major role in the remodeling of the extracellular matrix in arterial vessels. Increased MMP2 expression in the extracellular matrix of the walls of AAAs has been shown in several studies. To investigate the possible impact of genetic variants of the MMP2 gene in the etiology of AAA, we conducted this case-control study. PATIENTS AND METHODS: We analyzed MMP2 single-nucleotide polymorphisms (SNPs) in 51 patients with AAA and 48 controls. Differences in genotype and allele frequencies of identified polymorphisms were determined after sequencing the entire coding region and three selected parts of the promoter. RESULTS: Eighteen polymorphisms were identified, 6 of which are newly described, with 3 located in the introns (c.IVS1+31C>G, c.IVS7-18G>A, c.IVS10+26C>T) and 3 located in the coding region (c.124G>A, c.1368C>T, c.1860C>T). There were no statistically significant differences in genotype or allele frequencies between the two groups. CONCLUSIONS: Our analysis of the entire coding region and three parts of the promoter of the MMP2 gene failed to show an association between genetic polymorphisms and AAA, suggesting that variations in the MMP2 gene do not contribute to the development of AAA.     

Genetic and environmental contributions to regional cortical surface area in humans: a magnetic resonance imaging twin study

Cortical surface area measures appear to be functionally relevant and distinct in etiology, development, and behavioral correlates compared with other size characteristics, such as cortical thickness. Little is known about genetic and environmental influences on individual differences in regional surface area in humans. Using a large sample of adult twins, we determined relative contributions of genes and environment on variations in regional cortical surface area as measured by magnetic resonance imaging before and after adjustment for genetic and environmental influences shared with total cortical surface area. We found high heritability for total surface area and, before adjustment, moderate heritability for regional surface areas. Compared with other lobes, heritability was higher for frontal lobe and lower for medial temporal lobe. After adjustment for total surface area, regionally specific genetic influences were substantially reduced, although still significant in most regions. Unlike other lobes, left frontal heritability remained high after adjustment. Thus, global and regionally specific genetic factors both influence cortical surface areas. These findings are broadly consistent with results from animal studies regarding the evolution and development of cortical patterning and may guide future research into specific environmental and genetic determinants of variation among humans in the surface area of particular regions.     

Genetic variants of collagen III and abdominal aortic aneurysm.

Collagens provide the tensile strength of the aortic wall. Variations in collagen structure are recognised in Ehlers Danlos syndrome type IV and could also be associated with a predisposition to aortic aneurysm. The frequency of some minor genetic variants of type III collagen, present in the normal population, can be detected by restriction enzyme digestion of genomic DNA from peripheral leucocytes. The frequency of a minor collagen type III allele demonstrated with the restriction enzyme Ava II was compared in patients with abdominal aortic aneurysm (n = 70) and aortoiliac stenosis (n = 47). The frequency of the minor allele was significantly higher in aneurysm patients (0.30) compared with patients with aortoiliac stenosis (0.17), p less than 0.05. The presence of the minor allele was associated with a less elastic aneurysm wall (median pressure strain elastic modulus 4575, n = 7), compared with patients homozygous for the common allele (median pressure strain elastic modulus 1990, n = 6), p less than 0.05. These results indicate that genetic variants of type III collagen may influence the extensile properties of the aortic wall and that mutations in the type III collagen gene may be associated with aortic aneurysms.     

Screening study of abdominal aortic aneurysm in a general population: lipid parameters

The level of blood lipids and apolipoproteins in subjects being screened for abdominal aortic aneurysms have been investigated. As part of an ultrasound screening programme in a population of 65- to 75-year-olds, blood samples were collected from 1460 of 1504 subjects with a normal aorta (97.1%) and 69 of 70 patients with an abdominal aortic aneurysm >29 mm (99%). Samples were also taken from 22 of 27 patients (81%) with an ectatic aorta (26–29 mm). Total cholesterol, HDL-cholesterol, LDL-cholesterol, Apo-AI and Apo-B levels were significantly higher in women than in men (P < 0.01). Levels of HDL-cholesterol and Apo-AI were significantly lower in patients with an abdominal aortic aneurysm than in normal subjects (P < 0.001). The mean (s.d.) body mass index was 25.1 (3.9) in women and 25.5(3.2) in men with aneurysms and not significantly greater than that of normal subjects (25.2(3.61) and 25.2(3.38) respectively). Copyright © 1996 The International Society for Cardiovascular Surgery.     

Inflammatory abdominal aortic aneurysm

The inflammatory abdominal aortic aneurysm has received little attention in the literature. To date only four reports have addressed the subject specifically. Controversy remains as to whether this is a variant of the usual atherosclerotic aneurysm or a separate entity. The operative reports of 24 patients with inflammatory abdominal aortic aneurysms are reviewed; 21 were intact and 3 ruptured. Intact aneurysms ranged in diameter from 5 to 12 cm and the ruptured ones from 5 to 10 cm. Nine patients with intact aneurysms had symptoms of abdominal or back pain. Of 13 patients who underwent excretory pyelography before operation, only 3 had evidence of obstruction. Nine patients had tube grafts placed, 10 had aortoiliac grafts and 5 aortofemoral grafts. There was one intraoperative duodenal injury and in another patient it was necessary to divide the left renal vein for proximal exposure. No attempt was made to expose the ureters at operation. All patients were discharged from hospital. The authors believe that the inflammatory aneurysm is a variant of the abdominal aortic arteriosclerotic aneurysm. Intraoperative complications can be avoided by the recognition of the pathological features.     

Congenital abdominal aortic aneurysm

The authors report the extremely rare occurrence of a congenital abdominal aortic aneurysm, 6 cm in diameter, found in a 1-month-old infant. Prenatal ultrasonography at 34 weeks' gestation had shown the aneurysm, which at that time was interpreted as a renal cyst. At operation, an 8-mm polytetrafluoroethylene tube graft was interposed between the infrarenal aorta and the bifurcation. Cardiopulmonary bypass facilitated operative management by permitting return of blood lost and by maintaining body temperature. In a review of the literature, the authors could not find any report of a neonatal aneurysm of this magnitude. Regrettably, the cause of this true aneurysm remains obscure.     

Ruptured abdominal aortic aneurysm: endovascular program development and results

Improvements in endovascular technology and techniques have allowed us to treat patients in ways we never thought possible. Today endovascular treatment of ruptured abdominal aortic aneurysms is associated with markedly decreased morbidity and mortality when compared to the open surgical approach, yet there are several fundamental obstacles in our ability to offer these endovascular techniques to most patients with ruptured aneurysms. This article will focus on the technical aspects of endovascular aneurysm repair for rupture, with particular attention to developing a standardized multidisciplinary approach that will help ones ability to deal with not just the technical aspects of these procedures, but also address some of the challenges including: the availability of preoperative CT, the choice of anesthesia, percutaneous vs. femoral cut-down approach, use of aortic occlusion balloons, need for bifurcated vs. aorto-uniiliac stentgrafts, need for adjunctive procedures, diagnosis and treatment of abdominal compartment syndrome, and conversion to open surgical repair.     

Haematuria and abdominal aortic aneurysm

Haematuria and left loin pain in a patient with abdominal aortic aneurysm and associated with the radiological finding of a poorly or non-functioning left kidney are the pathognomonic features of aorto-left renal vein fistula, a condition in which the aneurysm leaks into an anomalous retro-aortic left renal vein.     

Genes and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since the first candidate gene studies were published 20 years ago, approximately 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. These studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, only when appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called contactin-3, which is located on chromosome 3p12.3. However, two follow-up studies could not replicate this association. Two other SNPs, which are located on chromosome 9p21 and 9q33, were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense ribonucleic acid that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute toward AAA pathogenesis.     

Ruptured abdominal aortic aneurysm

Between 1974 and 1984, 174 patients with ruptured abdominal aneurysms have been treated by three vascular surgeons. The 11-year period showed a dramatic increase in the number of patients presenting with ruptured aneurysms. The overall operative survival, including patients who died before a graft could be inserted, was 67 per cent with improvement from 60 per cent in the first half of the period to 69 per cent in the second. The overall survival rate for the 162 who had a completed graft was 72 per cent. Reference to data from the Lothian area surgical audit showed that there has been a transfer of responsibility from general to vascular surgeons with an increase in the proportion of patients treated by operation. Concentration of care within a single specialized unit appears to have had a favourable effect on survival.