Abdominal aortic aneurysms: a review of current problems

Abdominal aortic aneurysm: an illustrated narrative review

OBJECTIVE

To present a descriptive review of abdominal aortic aneurysm (AAA), including a review of risk factors for and case finding in AAA for chiropractors as primary contact health care practitioners.

DATA SOURCES

Clinical and scientific literature identified through various sources including MEDLINE and citation tracking.

DATA SYNTHESIS

Selective narrative review of relevant literature.

RESULTS

AAA may be asymptomatic; however, back pain is a common presenting feature. Risk factors include male gender, increasing age, cigarette smoking, hypertension, chronic obstructive airway disease, claudication, and AAA in a first-degree relative. AAA should be considered in the differential diagnosis of older white patients, especially males, with low back pain. Estimated prevalence for AAAs in older males is in the order of 3% to 5%; rupture accounts for 1.7% of deaths in men aged 65 to 75 years. Elective surgical resection of AAAs (prior to rupture) offers a low operative mortality and good prognosis.

CONCLUSION

AAA should be considered in the differential diagnosis of older patients presenting with low back pain and those with risk factors for AAA. Chiropractors, as primary contact health care practitioners, have a responsibility to refer patients suspected of having AAA for appropriate imaging and, where indicated, vascular surgical opinion.

Abdominal aortic aneurysm: association between haptoglobin phenotypes, elastase activity, and neutrophil count in the peripheral blood

To investigate the role of genetic factors on susceptibility to atherosclerotic arterial disease, the influence of haptoglobin phenotypes (Hp) on serum elastase activity, neutrophil count, and elastin concentration in the aorta was measured in patients with abdominal aortic aneurysm (AAA; n=52) and aortoiliac atherosclerotic occlusive disease (AOD; n=37). Findings (serum elastase activity, peripheral blood neutrophil count) were compared to a control group (CG) of 37 subjects without atherosclerosis. Hp phenotyping performed by starch-gel electrophoresis produced a haptoglobin-hemoglobin complex of three phenotypes: Hp1-1, Hp2-2, and Hp2-1. Distribution of Hp phenotypes was similar in the three study groups (AAA, AOD, CG). Significant increases in serum elastase activity and neutrophil count was measured in Hp2-1 phenotype of AAA patients. Although the aorta wall of aneurysm patients contained less (p<0.001) elastin than that of AOD patients, no significant difference of aorta elastin concentration between the three Hp phenotypes, including Hp2-1, was measured. The postulated association of AAA susceptibility with Hp2-1 phenotype was supported by the study data that demonstrated an increase in serum elastase activity in patients undergoing AAA repair.

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.

Influence of selective management on the prognosis and the risk of rupture of abdominal aortic aneurysms

A total of 199 patients with abdominal aortic aneurysms were followed up to investigate the influence of selective management on the prognosis and the risk rupture of abdominal aortic aneurysms. Decisions to operate or to continue watchful waiting with treatment of risk factors for expansion were based on aneurysm size, expansion rate, aneurysm-related symptoms, and individual operative risk. Rupture occurred in eight cases. All aneurysms were larger than 5 cm, and six were larger than 6 cm in diameter at the last measurement before rupture. The resulting overall 5-year cumulative rate of rupture was 7.3% (Kaplan Meier). The 134 patients who underwent more than one ultrasound examination were observed for an average of 4.0 years (536 patient-years). The expansion rate was significantly correlated with the initial diameter and the diastolic blood pressure (best subset multiple regression analysis: r = 0.403; P < 0.001). A correlation with the systolic blood pressure was found only in univariate analysis (r = 0.236; P = 0.011). Amplitude of blood pressure, serum cholesterol level, low-density and high-density lipoproteins, ratio of low- to high-density lipoproteins age, and the extent of smoking habits were not correlated with the expansion rate. Our conclusion is that larger diameter and higher diastolic blood pressure are important risk factors for expansion of abdominal aortic aneurysms. Selective management of abdominal aortic aneurysms based on aneurysmal size, expansion rate, and patient characteristics may result in a low rate of rupture.

Abdominal aortic aneurysm and associated colorectal carcinoma: a management problem

The increasing age of the population has led to the more common occurrence of multi-organ disease. Colorectal cancer (CRC) and abdominal aortic aneurysm (AAA) in the same patient is a difficult management problem. Over 10 years, 23 patients with CRC and AAA were treated at Concord Hospital. The management and outcome of these patients was reviewed to identify an optimum plan for patients with both conditions. The average age of patients was 71 years, ranging from 52 to 90 years. There was only one female patient in the series. In 19 of the patients, the AAA and CRC were synchronous, while in the other four patients the AAA and CRC were remote events. Within the group of patients with synchronous AAA and CRC. 12 had the diagnosis of both conditions made pre-operatively. However, in seven cases an unexpected AAA or CRC was found at operation for the other condition. Sixteen patients underwent resection of the CRC, while only eight underwent repair of the AAA. There were three deaths following CRC resection, two following AAA resection, and one following simultaneous CRC resection and AAA repair. Two of 10 patients with large (> 6 cm) AAA, who underwent CRC resection, ruptured the AAA in the postoperative period. A further patient ruptured 10 months following CRC resection. Colorectal cancer was given priority over AAA when these conditions were found simultaneously. The present study suggests that a large AAA (> 6 cm) should be either given preferential treatment, or resected simultaneously, in view of the high risk of rupture.

Screening for abdominal aortic aneurysm in Northumberland

A study was carried out to examine the feasibility of setting up a community-based screening programme for abdominal aortic aneurysm (AAA) in men aged 65-79 years served by a district general hospital. A pilot project was run in two general practices from which 800 men were invited to undergo ultrasonography of the abdominal aorta. Of these, 628 (78.5 per cent) attended; 42 (6.7 per cent) were found to have an aneurysm (aortic diameter greater than 29 mm), ten (1.6 per cent) had a large aneurysm (diameter above 49 mm) and seven (1.1 per cent) received aortic grafts. On the basis of these findings it was felt that to screen all men aged 65-79 years (n = 12,800) or aged 65-74 years (n = 10,300) would lead to more operations than local facilities could handle. A more practical option would be to target annually men aged 65 years, with rescreening at intervals of 5 years until age 75 years, but even this would eventually lead to an unmanageable number of operations.

Abdominal aortic aneurysm in the elderly

Thirty-five patients over the age of 80 years underwent surgery for abdominal aortic aneurysm between January 1985 and December 1990. Of these, 25 had surgery for ruptured aneurysm (mortality rate 56 per cent) and ten had surgery for symptomatic or asymptomatic aneurysm (mortality rate zero). The mortality rate for patients with rupture aged over 80 years was considerably greater than that for those under 80 years of age (56 versus 36 per cent). The mortality rate in the elderly population was zero for elective surgery but in those under 80 years it was 5 per cent. During the study period a prospective analysis of all referrals with aortic aneurysm was carried out, whether or not they underwent surgery and whether or not they were admitted to hospital. The ratio of patients accepted for operation to those not accepted for operation was 92:59 (1.56:1) in the under 80-year-old age group and 12:34 (0.35:1) in those aged over 80 years.

Concomitant abdominal aortic aneurysm and colorectal cancer: a decision analysis approach to a therapeutic dilemma

The therapeutic approach to a patient with concomitant abdominal aortic aneurysm and colorectal carcinoma is not clear. Decision analysis helps clarify decision options and quantify therapeutic outcomes. Variables used in decision analysis include life expectancy after resection for colorectal cancer and abdominal aortic aneurysm, rupture rate of abdominal aortic aneurysm, complications of colorectal The results support the concept that the symptomatic lesion should be treated first. When both lesions are asymptomatic and the aneurysm is 4-5 cm in diameter, it should be resected first, if the colorectal cancer has a less than 5% chance of obstruction or perforation, as is found in noncircumferential lesions. When the aneurysm is greater than 5 cm, it should be resected first if the cancer has a less than 22% chance of obstructing or perforating, as with circumferential lesions. Simultaneous resection should be considered for patients with aneurysms greater than 5 cm and cancers with a greater than 75-80% chance of obstruction or perforation, provided the dual procedures can be performed with a less than 10% operative mortality and less than 50% complication rate.