Familial abdominal aortic aneurysms

Risk factors associated with abdominal aortic aneurysm: a population-based study with historical and current data

OBJECTIVES

To define risk factors associated with the development of abdominal aortic aneurysm (AAA) in a population-based case-control study.

MATERIAL AND METHODS

Thirty-five patients found to have AAA at screening were compared with 140 age- and sex-matched controls. Three distinct comparisons were made. Current risk factors in both cohorts were compared. Because data were also available for both cohorts from a study conducted 12 years previously, a historical comparison was made between risk factors identified at the time of this initial evaluation. A longitudinal comparison was made between historical and current risk factors.

RESULTS

Elevated low-density-lipoprotein cholesterol, total cholesterol, and triglyceride levels 12 years before AAA screening were associated with current AAA with an odds ratio (OR) of 2.3 (95% confidence interval [CI], 1.2 to 4.4); OR, 1.9 (95% CI, 1.3 to 2.8); and OR, 1.9 (95% CI,1.2 to 3.1)/mmol/L, respectively. Current variables assessed at AAA screening that were associated with AAA were: A history of atherosclerotic disease, OR, 3.8 (95% CI, 1.7 to 8.5); having a first-degree relative with AAA, OR, 4.4 (95% CI, 1.5 to 13.0); current smoking, OR, 5.2 (95% CI, 1.6 to 16.8); high-density-lipoprotein cholesterol level, OR, 0.1 (95% CI, 0.02 to 0.7)/mmol/L; and high-sensitivity C-reactive protein (hsCRP) level, OR, 1.1 (95% CI, 1.01 to 1.2)/mg/L. Hypertension and diabetes were not associated with AAA. A significant increase of hsCRP over time (12 years) was observed in AAA patients ( P = .039) but not among controls. The variables of a history of atherosclerosis, smoking, and family history of AAA appear to interact synergistically to increase the prevalence of AAA ( P < .001).

CONCLUSION

Among traditional risk factors for atherosclerosis, some were associated with AAA and others were not, indicating complex and partly different causes. Inflammation and heredity appear to be important factors in the development of AAA.

Abdominal aortic aneurysm

Abdominal aortic aneurysms cause 1.3% of all deaths among men aged 65-85 years in developed countries. These aneurysms are typically asymptomatic until the catastrophic event of rupture. Repair of large or symptomatic aneurysms by open surgery or endovascular repair is recommended, whereas repair of small abdominal aortic aneurysms does not provide a significant benefit. Abdominal aortic aneurysm is linked to the degradation of the elastic media of the atheromatous aorta. An inflammatory cell infiltrate, neovascularisation, and production and activation of various proteases and cytokines contribute to the development of this disorder, although the underlying mechanisms are unknown. In this Seminar, we aim to provide an updated review of the pathophysiology, current and new diagnostic procedures, assessment, and treatment of abdominal aortic aneurysm to provide family practitioners with a working knowledge of this disorder.

A genealogical assessment of heritable predisposition to aneurysms

OBJECT

This study was conducted to investigate the familial and genetic contribution to intracranial, abdominal aortic, and all other types of aneurysms, and to define familial relationships among patients who present with the different aneurysm types.

METHODS

The authors used a unique Utah resource to perform population-based analysis of the familial nature of aneurysms. The Utah Population Data Base is a genealogy of the Utah population dating back eight generations, which is combined with death certificate data for the state of Utah dating back to 1904. Taking into account the genetic relationships among all aneurysm cases derived from this resource, the authors used a previously published method to estimate the familiality of different aneurysm types. Using internal, birth-cohort-specific rates of disease calculated from the database, they estimated relative risks by comparing observed to expected rates of aneurysm incidence in defined sets of relatives of probands.

CONCLUSIONS

Each of the three aneurysm types investigated showed significant evidence for a genetic component. Relatives of patients with intracranial aneurysms do not appear to be at increased risk for abdominal or other lesions, but relatives of patients with abdominal aortic aneurysms appear to be at increased risk for other types of these lesions.

Prospects for the medical management of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are a chronic degenerative disease with life-threatening implications. While AAAs are thought to arise through a localized form of arterial wall injury superimposed on various predisposing factors, their natural history is one of progressive structural deterioration, gradual expansion, and eventual rupture. Pathologic processes contributing to the changes observed in AAAs include chronic inflammation, destructive remodeling of the extracellular matrix, and depletion of vascular smooth muscle cells. These changes result in progressive aortic dilatation accompanied by alterations in vessel geometry, redistribution of hemodynamic wall stresses, and diminished tensile strength. As outlined in this review, better understanding of the biological mechanisms underlying these changes will allow design of novel therapeutic strategies to suppress the process of aneurysmal degeneration.

A family with abdominal aortic aneurysms

This investigation focused on 7 siblings to 2 brothers with abdominal aortic aneurysm (AAA), with respect to AAA, Chlamydia pneumoniae (CP) serology, serum cholesterol, and smoking habits. Five male and 4 female siblings were included. All siblings underwent ultrasonography, and surgical specimens from the aorta were prepared for immunohistochemical (IHC) analysis. Blood was obtained from all living siblings and serum cholesterol level was analyzed. Serologic analysis was done by microimmunofluorescence (MIF). Smoking habits were recorded. In addition to the 2 known siblings with AAA, 2 other brothers with AAA were found. Four of 8 siblings had IgG 1/512 or greater and 7 of 8 had IgA 1/64 or greater. Two of 3 were positive for CP in IHC obtained from aortic specimens. Two of 8 had hypercholesterolemia; 7 of 9 were smokers. C. pneumoniae as well as smoking seems to be important in the pathogenesis of AAA in this small cohort; however, larger patient cohorts are needed.

Familial abdominal aortic aneurysm: a systematic review of a genetic background

BACKGROUND

Familial clustering of the abdominal aortic aneurysm (AAA) is clear, 12-19% of AAA patients have one or more first-degree relatives with an aneurysm and 4-19% is detected with ultrasound screening.

OBJECTIVES

To review the genetic background of AAA. DESIGN, METHODS AND MATERIALS: Computer searches of the MEDLINE, EMBASE, SUMsearch database and the Cochrane Library and searched reference lists of English language articles concerning the genetics of AAA, candidate gene approach and linkage analysis.

RESULTS

Brothers of AAA patients are at high risk to develop an AAA. The candidate gene approach was performed to detect defects in one of the components of the connective tissue, i.e. type I and III collagen, elastin and fibrillin, the inflammatory cell-derived matrix metalloproteinase, there inhibitors, auto-immune components and components related to atherosclerosis.

CONCLUSION

These studies give us insight in the pathology but do not lead to the specific genetic factor(s) responsible for (familial) AAA. Considering the supposed autosomal dominant inheritance, a gene mutation in one of the structural proteins of the connective tissue is expected. In the future, linkage analysis may resolve the genetic background of AAA.

Ubiquitous elevation of matrix metalloproteinase-2 expression in the vasculature of patients with abdominal aneurysms

BACKGROUND

Patients with abdominal aortic aneurysms (AAAs) exhibit arterial dilation and altered matrix composition throughout the vasculature. Matrix metalloproteinase-2 (MMP-2) is the dominant elastase in small AAAs, and overexpression of MMP-2 in vascular smooth muscle cells (SMCs) may be a primary etiological event in aneurysm genesis. The aim of this study was to investigate MMP-2 production in vascular tissue remote from the abdominal aorta.

METHODS AND RESULTS

Inferior mesenteric vein (IMV) was harvested from patients undergoing aneurysm repair (n=21) or colectomy for diverticular disease (n=13, control). Matrix composition of the vessels was determined by stereological techniques. MMPs were extracted from tissue homogenates and quantified by gelatin zymography and ELISA. MMP-2, membrane type-1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinases type 2 (TIMP-2) expression were determined by Northern analysis. SMCs were isolated from IMV, and the production and expression of MMP-2 and TIMP-2 in the SMC lines were quantified. Tissue homogenates and isolated inferior mesenteric SMCs from patients with aneurysms demonstrated significantly elevated MMP-2 levels, with no difference in TIMP-2 or MT1-MMP. These differences were a result of increased MMP-2 expression. Histological examination revealed fragmentation of elastin fibers within venous tissue obtained from patients with AAA and a significant depletion of the elastin within the media. In situ zymography localized elastolysis to medial SMCs.

CONCLUSIONS

Patients with AAA have elevated MMP-2 levels in the vasculature remote from the aorta. This finding is due to increased MMP-2 expression from SMCs, a characteristic maintained in tissue culture. These data support both the systemic nature of aneurysmal disease and a primary role of MMP-2 in aneurysm formation.

Abdominal aortic aneurysm

Abdominal aortic aneurysm is a chronic dilation of the aorta with a natural history toward enlargement and rupture. Its pathogenesis is believed to be multifactorial and complex. Clinical presentation may be asymptomatic, symptomatic, or as rupture. Elective surgery by open transperitoneal or retroperitoneal approach is the most common repair intervention. However, placing an endoluminal stent graft within the aneurysm is currently being evaluated as an alternative to open repair. Nursing care of the patient with abdominal aortic aneurysm involves intensive care skills as well as a foundation in chronic illness management. This article presents information on pathogenesis, natural history, clinical presentation, surgical interventions, and postoperative complications.

The role of type III collagen in family members of patients with abdominal aortic aneurysms

OBJECTIVES

type III collagen is responsible for the tensile strength of the aorta-wall. To determine if genetic defect in the type III collagen production is associated with familial clustering of AAA.

METHODS

fifty-six patients with AAA and 82 first-degree family members participated. The medical and family histories were obtained. All these relatives were screened by ultrasound for AAA. In 58 relatives of 20 families, skin biopsies were taken for protein analysis to measure type III collagen production in cultured fibroblasts.

RESULTS

only one new AAA was detected in a brother of a patient. Four other relatives were already known with AAA. Three AAA patients had a type III collagen deficiency, but type III collagen was normal in all family members.

CONCLUSION

type III collagen deficiency does not appear to be an aetiological factor in the development of AAA.

Natural history, pathogenesis, and etiology of thoracic aortic aneurysms and dissections

The natural history of thoracic aortic aneurysms and dissections is diverse, reflecting a broad spectrum of etiologies which include increasing aortic size, hypertension, and genetic factors. The pathogenesis is related to defects or degeneration in structural integrity of the adventitia, not the media, which is required for aneurysm formation. The ascending and descending aorta appear to have separate underlying disease processor that lead to a weakened vessel wall and an increased susceptibility for dissection. Etiologic factors for aortic aneurysms and dissections are multifactorial, reflecting genetic, environmental, and physiologic influences.

Ruptured versus elective abdominal aortic aneurysm repair: outcome and cost

During a recent 30-month period, we repaired 10 ruptured abdominal aortic aneurysms (RAAA) at our institution. To evaluate the survival, postoperative morbidity, and financial impact of treating RAAA, we compared these patients with 10 randomly selected patients undergoing elective AAA (EAAA). Both groups were comparable for age, gender, and incidence of diabetes, hypertension, coronary artery disease, chronic obstructive pulmonary disease (COPD), and renal failure. Although we have noted a dramatic increase in survival for RAAA (90%), the morbidity continues to be unacceptably high (60%). Efforts should be made toward better detection of AAA prior to rupture as well as development of strategies to minimize or prevent these major complications. Potential average savings accrued from one patient undergoing EAAA repair rather than RAAA repair ($93,139. 21) can be used to perform screening abdominal ultrasound tests in patients at increased risk of having an AAA.

The role of type III collagen in the development of familial abdominal aortic aneurysms

OBJECTIVES

to evaluate the prevalence of familiar abdominal aortic aneurysm (AAA) and the role of type III collagen deficiency.

METHODS

fifty-six consecutive patients coming for aneurysm repair were asked if one or more first-degree relatives had an AAA. During operation, a skin biopsy was taken from the patients for protein analysis to measure the type III collagen production in cultured fibroblasts.

RESULTS

a positive family history was found in 28.6% of the AAA patients. Six (10.7%) of the AAA patients had a type III collagen deficiency (mean 4.3% (S.D.+/-0.5)). In this group three men, mean age 65.3 years (S.D.+/-5.0), had a positive family history and a type III collagen deficiency. Segregation analysis with an intragenic marker in the type III collagen gene in a single family was in favour of linkage with the gene for type III procollagen (COL3A1) locus.

CONCLUSIONS

the high prevalence of familial AAA suggests a genetic aetiology. A small group of patients have a type III collagen deficiency. Linkage with the COL3A1 gene could not be proven or excluded in the families studied.

Plasma endothelin levels in patients with abdominal aortic aneurysms

OBJECTIVES

endothelin 1,2 plays a significant role in the process of atherogenesis and vascular wall injury. The aim of this study was to assess whether plasma endothelin 1,2 levels were elevated in patients with large or symptomatic abdominal aortic aneurysms (AAAs).

DESIGN

a prospective open study.

MATERIALS AND METHODS

plasma endothelin 1,2 levels were measured in 65 consecutive patients with infrarenal aortic aneurysms and compared with the levels in 44 healthy volunteer controls. The data for abdominal aneurysm patients was analysed in four subgroups: (i) small aneurysms (<5 cm), (ii) large aneurysms (>/=5 cm), (iii) asymptomatic aneurysms and (iv) symptomatic aneurysms. Comparisons were made between endothelin 1,2 levels in aneurysm patients and controls and between the different aneurysm subgroups.

RESULTS

a highly significant difference (p<0.0001) was found between aneurysm patients and controls. Patients with large aneurysms had significantly higher levels than patients with small aneurysms (p<0.01). There was no statistical difference in endothelin 1,2 levels between symptomatic and asymptomatic patients; however, the highest levels were found in large, symptomatic aneurysms and the lowest in small, asymptomatic aneurysms.

CONCLUSIONS

plasma endothelin 1,2 is an endogenous marker of aneurysm diameter. Further studies are required to determine whether it relates to the rate of growth of aneurysms.

Atherosclerotic aneurysms of the superficial femoral artery: report of two ruptured cases and review of the literature

Isolated arteriosclerotic aneurysms of the superficial femoral artery are rare. In citing the literature a total of 30 cases in 28 patients in the last 25 years were found. In addition to the above cases, two aged patients with ruptured aneurysms of the superficial femoral artery are reported; these were managed successfully with partial aneurysmectomy and restoration of the circulation of the extremity with a synthetic graft. The prognosis for this type of aneurysm following surgical therapy is good, despite the advanced age of the patients, and amputation is relatively rare, occurring in only two out of the 30 aneurysms (6.6%) reported. The risk of rupture is 46.6% (14/30) and is greater than that found in peripheral aneurysms. This, in association with the possibility of the creation of thrombosis (5/30; 16.6%) or embolization (1/30; 3.3%), threatens the extremity itself as well as the life of the patient, increasing the risk of complications and even death at a rate of 66.6% (20/30). Timely diagnosis, immediate surgical reconstruction and prompt mobilization, however, can guarantee a good prognosis for these aged patients.

Risk factors for abdominal aortic aneurysms in older adults enrolled in The Cardiovascular Health Study

B-mode ultrasound examinations of the abdominal aorta were performed from 1990 to 1992 to evaluate the prevalence of abdominal aortic aneurysm (AAA) in a subgroup of the Pittsburgh cohort (656 participants, aged 65 to 90 years) of the Cardiovascular Health Study (CHS). In this pilot study, we evaluated various definitions of aneurysm and the reproducibility of the measurements. In year 5 (1992 to 1993) of the CHS, the entire cohort (4741 participants) was examined. AAA was defined as an infrarenal aortic diameter of > or= 3.0 cm, or a ratio of infrarenal to suprarenal diameter of > or= 1.2, or a history of AAA repair. For the entire CHS cohort, prevalence of aneurysms was 9.5% (451/4741) overall, with a prevalence among men of 14.2% (278/1956) and prevalence among women of 6.2% (173/2785). Variables significantly related to AAA were older age; male sex; history of angina, coronary heart disease, and myocardial infarction; lower ankle-arm blood pressure ratio; higher maximum carotid stenosis; greater intima-media thickness of the internal carotid artery; higher creatinine; lower HDL levels and higher LDL levels; and cigarette smoking. The study has documented the strong association of cardiovascular risk factors and measures of clinical and subclinical atherosclerosis and cardiovascular disease and prevalence of aneurysms. We used a definition that is more sensitive than previously reported (diameter or ratio), which allowed the detection of smaller aneurysms and possibly those at an earlier stage of development. Follow-up of this cohort may lead to new criteria for determining the risk factors for progression of aneurysms.

Sibling risks of abdominal aortic aneurysm

There is evidence that the risk of abdominal aortic aneurysm (AAA) is greater in first-degree relatives of patients with the disorder than in the same age group of the general population. We conducted a 3-year study of siblings of AAA probands and siblings of a control group (cataract surgery patients) of the same age. Genetic information was obtained by interview from 126 probands and 100 controls; another family member was present at the interview. Medical records were obtained and further information verified before a sibling (over age 50) was assigned affected status. Of 427 siblings of probands, 19 (4.4%) had probable or definite AAA, compared with five (1.1%) of 451 siblings of controls. The lifetime cumulative risks of AAA at age 83 were 11.7% (SD 3.1) and 7.5% (4.1), respectively. The risk of AAA began at an earlier age and increased more rapidly for probands' siblings than for controls' siblings (p < 0.01, log-rank test). A risk comparison, based on the results of ultrasound screening of 54 geographically accessible siblings of probands and the 100 controls showed a similar pattern. Ten (19%) siblings of probands and eight (8%) controls had AAA on ultrasound (lifetime cumulative risk 60.8% [18.9] vs 14.9% [5.1], p = 0.01). These results show that familial factors influence the age of onset of AAA. We recommend routine ultrasound examination of siblings of patients with AAA.

Aneurysms of the abdominal aorta: familial and genetic aspects in three hundred thirteen pedigrees

PURPOSE

Familial clustering of abdominal aortic aneurysm was first noticed in 1977.

METHODS

Through questionnaire and phone inquiry, familial data on 324 probands with abdominal aortic aneurysms allowed the establishment of 313 multigenerational pedigrees including 39 with multiple affected patients.

RESULTS

There were 276 sporadic cases (264 men, 12 women); 81 cases belonged to multiplex pedigrees (76 men; 5 women). We compared familial and sporadic male cases; the ages at diagnosis were 64.1 +/- 7.9 years and 66.0 +/- 7.3 years (p < 0.05), respectively, the ages at rupture were 65.4 +/- 6.6 years and 75.2 +/- 8.6 years (p < 0.001), and the rupture rate was 32.4% and 8.7% (p < 0.001). Survival curves were computed. Relative risk for male siblings of a male patient was 18. We performed a segregation analysis with the mixed model, the most likely explanation for occurrence of abdominal aortic aneurysm in our families was a single gene effect showing dominant inheritance. The frequency of the morbid allele was 1:250, and its age-related penetrance was not higher than 0.4.

CONCLUSION

This analysis indicates the preeminence of genetic factors on multifactorial/environmental effects of the pathogenesis of abdominal aortic aneurysm.

Abdominal aortic aneurysm in the Irish population: a familial screening study

A pilot screening programme was undertaken in Ireland to determine the incidence of abdominal aortic aneurysm (AAA) (diameter 3 cm or greater) in the siblings of 120 patients known to have AAA. There were 621 siblings; 270 of them were dead, 32 were over 80 years old and 85 lived outside Ireland, leaving 234 under 80 years of age still living in Ireland who were invited to attend for ultrasonographic screening. Of the 270 siblings who had died, 102 were women and 168 men; eight men (4.8 per cent) had died from ruptured AAA. Only 125 (53.4 percent) of the 234 siblings agreed to participate in the screening programme, 60 brothers from 31 families and 65 sisters from 35 families. Fifteen (12.0 per cent) of the 125 siblings had an AAA (median size 4.2 (range 3.1-6.8) cm), 13 (22 per cent) of the 60 male siblings and two (3 per cent) of the 65 female siblings. The prevalence of AAA among siblings was not affected by the age or sex of the patient with aneurysm. Seven of the 14 male siblings with hypertension had an AAA, compared with only six of the 46 who were normotensive (P = 0.01). The high incidence of AAA in brothers of affected patients highlights the need to counsel this group on their risk of aneurysm. The relatively low participation rate by siblings in this screening programme indicates that a hospital-based unit is unlikely to be effective in recruiting all patient siblings at risk from an AAA.

Biochemical and molecular genetic studies of abdominal aortic aneurysm in an Irish population

Abdominal aortic aneurysm (AAA) is a common disease of the elderly exhibiting a complex aetiology. In a survey of 82 Irish aneurysm patients, compared to 79 age- and sex-matched control subjects, we have investigated a number of potential biochemical and molecular genetic markers which are amenable to analysis from blood specimens and which might have predictive value for AAA. No significant differences were observed between patients and control subjects in relation to serum lipids, leucocyte elastase activity or serum alpha 1-antitrypsin concentration. We have used the polymerase chain reaction to screen the patient and control groups in search of disease-associated genetic variation on chromosome 16, particularly in the region of the Cholesteryl Ester Transfer Protein (CETP) gene. Although variation in allele frequencies was detected between patients and controls at the four marker loci studied, no significant gene-disease associations were detected. The absence of gene-disease associations in our study may indicate that the genetic component in the aetiology of AAA in Ireland differs from that in the UK. Alternatively, it may indicate that the high degree of polymorphism at microsatellite loci may make them unsuitable as markers for the study of gene-disease associations in moderately sized populations. We therefore conclude that the biochemical and molecular genetic markers which we have examined are of no predictive value, and that ultrasonography remains the screening modality of choice for abdominal aortic aneurysm.

Pathogenesis of abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm involves many factors acting over time. However, destruction of elastin in the aortic wall is a key event that shifts the load produced by blood pressure on to collagen. This is exacerbated in the presence of hypertension. Smoking and age are further important factors, as is the site; elastic lamellae are relatively less common in the abdominal aorta. Once the shielding effect of elastin is lost, further dilatation and rupture of the aorta depend on the physical properties of the collagen present.

Sequencing of cDNA from 50 unrelated patients reveals that mutations in the triple-helical domain of type III procollagen are an infrequent cause of aortic aneurysms

Detailed DNA sequencing of the triple-helical domain of type III procollagen was carried out on cDNA prepared from 54 patients with aortic aneurysms. The 43 male and 11 female patients originated from 50 different families and five different nationalities. 43 patients had at least one additional blood relative who had aneurysms. Five overlapping asymmetric PCR products, covering all the coding sequences of the triple-helical domain of type III procollagen, were sequenced with 28 specific sequencing primers. Analysis of the sequencing gels revealed only two nucleotide changes that altered the structure of the protein. One was a substitution of threonine for proline at amino acid position 501 and its functional importance was not clearly established. The other was a substitution of arginine for an obligatory glycine at amino acid position 136. In 40 of the 54 patients, detection of a polymorphism in the mRNA established that both alleles were expressed. The results indicate that mutations in type III procollagen are the cause of only about 2% of aortic aneurysms.

Abdominal aortic aneurysm, glaucoma and deafness: a new familial syndrome

Several reports have suggested a genetic basis for the distribution of abdominal aortic aneurysm (AAA) in some families. The familial clustering of this disease is further demonstrated in this report of ten siblings, five of whom have confirmed AAA. This is the largest cluster so far reported. The majority of patients in this family group also have glaucoma and/or deafness.

Pathogenesis of acquired aneurysms of the abdominal aorta

The incidence of abdominal aortic aneurysm has recently increased. There is still no accurate definition of abdominal aortic aneurysm. The diameter of abdominal aortic aneurysms is the only factor permitting evaluation of the risk of rupture of aneurysms whose growth remains unpredictable. Abdominal aortic aneurysm is a multi-factorial disease associated with aortic aging and atheroma. It differs from stenotic disease by the intensity of degenerative or destructive phenomena in the media. Particular hemodynamic conditions in the infrarenal abdominal aorta seem to enhance the development of aneurysm at this level. While certain constitutional anomalies of the extracellular matrix of proteins seem to enhance the development of abdominal aortic aneurysm, protease activity of as yet undetermined origin also seems to play a prominent role. Family cases of abdominal aortic aneurysms have been reported but the mechanisms responsible remain to be determined. Several genetic markers have been suggested. The most reliable marker of aortic aneurysm is arteriomegaly.

Pathophysiology and pathogenesis of aortic aneurysms. Current concepts

From an engineering point of view, the development of an arterial aneurysm is a classic case of material failure that may involve two factors: excessive applied load and inadequate material strength. The author describes a hypothesis that explains how atherosclerosis could increase the pressure load on the vessel and at the same time decrease the capacity of the wall to bear that load. It will be of interest to learn precisely what the genetic trait is that causes the atherosclerotic aorta to fail structurally in some patients while allowing the vessel to remain intact and develop occlusive lesions in others.

Incidence and etiology of abdominal aortic aneurysms

Unlike coronary artery disease and cerebrovascular disease, the incidence of abdominal aortic aneurysms has increased dramatically over the past three decades. There appears to be a correlation between both hypertension and smoking and the development of aneurysms, and there is a substantial predominance of white men among the patients. Recent studies have also documented a strong genetic component to this disease. Several biochemical abnormalities have been noted in those with aortic aneurysms, including increased proteolysis (elastolysis and collagenolysis). At present, the precise etiology of aneurysmal disease remains unclear, but it will most likely turn out to be a heterogenous disease with several molecular forms.

Familial aortic aneurysms: serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol

Patients with abdominal aortic aneurysms (AAAs) have been compared with healthy controls with respect to the serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol. The concentrations of triglyceride and (VLDL + LDL)-cholesterol in serum were higher in the patients than in the controls, while the concentration of HDL-cholesterol in serum was lower in the patients than in the controls. There was no statistically significant difference in the serum concentration of total cholesterol between the patients and the controls. Twelve patients had first degree relatives (brothers, sisters and/or parents) with AAAs and six patients had second degree relatives (cousins or brothers and sisters of the parents) with AAAs. There was no statistically significant difference between the patients who had first degree relatives with AAAs and the patients without AAAs in the family in the serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol.

A personal view of abdominal aortic aneurysms

Based on the Surgikos Lecture delivered to the Association of Surgeons of Great Britain and Ireland, London 1983.