Increased plasma levels of metalloproteinase-9 are associated with abdominal aortic aneurysms

Purpose: Previous investigators have identified disease-specific elevations of metalloelastase-9 (MMP-9) in aneurysm tissue biopsies. We hypothesized that circulating MMP-9 might also be elevated in patients with aneurysms. The purpose of this study was to compare plasma and aortic tissue MMP-9 levels in patients with infrarenal aneurysms (AAAs), patients with symptomatic aortoiliac occlusive disease (AOD), and healthy patients. Methods: A sandwich enzyme-linked immunosorbent assay was used to measure plasma MMP-9 in patients with AAA (n = 22; mean age, 72.7 years), with AOD (n = 9; mean age, 60.5 years), and without disease (n = 8; mean age, 35.3 years). The MMP-9 levels also were measured in 48-hour supernatants of organ culture tissue explants from patients with AAA (n = 10; mean age, 66.2 years) and AOD (n = 5; mean age, 50.4 years) and organ donors (n = 7; mean age, 48.1 years). The results were reported as the mean ± the standard error of the mean and analyzed with analysis of variance with multivariate regression. Results: The plasma MMP-9 levels were significantly higher in the patients with AAA (85.66 ng/mL ± 11.64) than in the patients with AOD (25.75 ng/mL ± 4.159; P < .001) or the healthy patients (13.16 ng/mL ± 1.94; P < .001). No significant difference in plasma MMP-9 levels between patients with AOD and healthy patients was identified. The patients with multiple aneurysms had significantly higher levels of plasma MMP-9 than did the patients with an isolated AAA (134.68 ng/mL ± 17.5 vs 71.03 ng/mL ± 10.7; P < .04). In organ culture, AAA and AOD tissue explants produced significantly higher levels of MMP-9 (3218.5 ng/gm ± 1115.2 and 1283.1 ng/gm ± 310.6 aortic tissue) than did disease-free explants (6.14 ng/gm ± 2.3 aortic tissue; P < .0001). No significant difference in MMP-9 production between AAA and AOD explants was identified. Conclusion: Plasma MMP-9 levels are significantly higher in patients with AAA than in patients with AOD or in healthy volunteers. The patients with multiple aneurysms have higher levels than those patients with an isolated AAA. Organ culture studies suggest that diseased aortic tissue is the source of MMP-9. (J Vasc Surg 1999;29:122-9.)     

Intraluminal thrombus is associated with early rupture of abdominal aortic aneurysm

Background

The implications of intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) are currently unclear. Previous studies have demonstrated that ILT provides a biomechanical advantage by decreasing wall stress, whereas other studies have associated ILT with aortic wall weakening. It is further unclear why some aneurysms rupture at much smaller diameters than others. In this study, we sought to explore the association between ILT and risk of AAA rupture, particularly in small aneurysms.

Statins are associated with a reduced infrarenal abdominal aortic aneurysm growth.

OBJECTIVE: To evaluate the effect of statins on aneurysm growth in a group of consecutive patients under surveillance for infrarenal aortic aneurysms (AAA). MATERIALS AND METHODS: All patients (59 statin users, 91 non-users) under surveillance between January 2002 and August 2005 with a follow-up for aneurysm growth of at least 12 months and a minimum of three diameter evaluations were retrospectively included in the analysis. Multiple regression analysis, weighted with the number of observations, was performed to test the influence of statins on AAA growth rate. RESULTS: During a median period of 3.1 (1.1-13.1) years the overall mean aneurysm growth rate was 2.95+/-2.8 mm/year. Statin users had a 1.16 mm/year lower AAA growth rate compared to non-users (95% CI 0.33-1.99 mm/year). Increased age was associated with a slower growth (-0.09 mm/year per year, p = 0.003). Female gender (+1.82 mm/year, p = 0.008) and aneurysm diameter (+0.06 mm/year per mm, p = 0.049) were associated with increased AAA growth. The use of non-steroidal anti-inflammatory drugs, chronic lung disease, or other cardiovascular risk factors were not independently associated with AAA growth. CONCLUSIONS: Statins appear to be associated with attenuation of AAA growth, irrespective of other known factors influencing aneurysm growth.     

Chronic rupture of abdominal aortic aneurysm

Although the mortality rate after abdominal aortic aneurysm rupture approximates 90% despite the urgent management, a few cases of chronic rupture and delayed repair have been reported in the world literature; anatomic and hemodynamic reasons occasionally allow for the fortunate course of these patients. We report in this article the case of 76-year-old man with a ruptured abdominal aortic aneurysm who was transferred to our facility 4 weeks after his initial hospitalization in a district institution and who finally had a successful open repair.     

Arteriovenous fistaul from rupture of abdominal aortic aneurysm.

Two patients with spontaneous aortocaval fistulas are described and compared with 67 cases reported in the English literature. Symptoms may vary widely; however, the presence of an expansile abdominal mass with a continuous bruit is usually diagnostic. The only successful management is promt repair of the vena caval defect and the aortic aneurysm. A third patient with spontaneous rupture of an abdominal aortic aneurysm into the left renal vein is alos described. Only five similar cases could be found in the work literature. Left flank pain, pulsatile abdominal mass, continuous bruit, and hematuria is the usual clinical picture. All of these cases involved an anomalous left retroaortic renal vein and all patients survived the necessary surgical correction. The operation of choice is closure of the defect in the retroaortic left renal vein and repair of the aneurysm.     

Biomechanical factors in abdominal aortic aneurysm rupture

Hitherto the size of abdominal aortic aneurysms (AAA) has been considered the most important factor in determining the risk of rupture. For this reason most interest had been devoted to physical, echographic and tomographic analyses of the shape of AAA. However, its is known that rupture can also occur in small AAA. Other factors must be considered to have an important role in the natural history of aneurysms. The aim of t his study was to characterise the mechanical stress in the wall of an AAA due to pressure in the presence of atherosclerosis, intraluminal thrombus and anatomical restraints. The Finite Elements Method (FEM) was used to determine wall stress distribution. Due to the simplicity of the AAA structure an axisymmetric model has been built. The results of the structural analysis confirms that maximum stress increases with diameter. These effects may be reduced by the presence of intraluminal thrombus, which in the models reduces maximum stress by up to 30%; however this is not the case for dissecting thrombus. On the other hand atherosclerotic plaques cause stress concentration and a significant increase in maximum wall stress. The risk of rupture can increase by about 200%. Finally the investigation shows the FEM is a versatile tool for studying the mechanics of vascular structures. It enables the influence of various parameters on wall stress to be quantified in diagnostic settings, and so could be useful for predicting the rupture of AAA, although at present such predictions are limited by data leakage and by the approximations used in the model.     

Activated forms of MMP2 and MMP9 in abdominal aortic aneurysms

Purpose: The consistent observation of a reduction of the elastin concentration in abdominal aortic aneurysms (AAAs) has led us to investigate in AAA specimens two metalloproteinases that display elastase activity, MMP₂ (gelatinase A/72 kDa) and MMP₉ (gelatinase B/92 kDa).Methods: Samples of full-thickness aortic wall, adherent thrombus, and serum were collected in 10 patients with AAAs. Samples of normal aortic wall and serum were taken from 6 age-matched control patients. Quantitative gelatin-zymography and gelatinolytic soluble assays after acetyl-phenyl mercuric acid activation were performed on serum and tissue extracts, and the results were expressed in units on a comparative wet-weight basis. Histologic analysis was performed in parallel to score the inflammatory infiltrate.Results: The luminal and parietal parts of the thrombus contained, respectively, 20- and 10-fold more gelatinolytic activity than the serum. The predominate form was MMP₉. Although the total gelatinolytic activity was in the same range both in AAAs and in normal walls, a significantly higher proportion of MMP₉ was found in the aneurysmal aortic walls. Furthermore, a significant proportion of MMP₉ was under its processed active form, which was never observed in normal samples. A significantly higher proportion of MMP₂ was also present as processed active form in AAA wall. This latter parameter positively correlated with the inflammatory score.Conclusions: The presence of activated MMP₉ and MMP₂ might contribute to the degradation of the extracellular matrix proteins that occurs during the development of aneurysms. (J Vasc Surg 1996;24:127-33.)     

Immunoglobulin A antibodies against Chlamydia pneumoniae are associated with expansion of abdominal aortic aneurysm.

BACKGROUND: The aim of this study was to examine the possible association between the progression of small abdominal aortic aneurysm (AAA) and chronic infection with Chlamydia pneumoniae. METHODS: Patients from a hospital-based mass screening programme for AAA with annual follow-up (mean 2.7 years) were included. After initial interview, 139 men aged 65-73 years with a small AAA underwent examination and blood sampling. Immunoglobulin (Ig) G and IgA titres against C. pneumoniae were measured by a microimmunofluorescence test. RESULTS: Some 83 (95 per cent confidence interval 74-93) per cent of the men had an IgA titre of 20 or more, or an IgG titre of 32 or more. Men with an IgA titre of 20 or more had a 48 per cent higher AAA expansion rate than those with a titre of less than 20 (3.1 versus 2.1 mm/year; P < 0.05). Multiple linear and logistic regression analyses showed that an IgA titre of 20 or more was a significant independent predictor of increased AAA expansion, adjusted for known risk factors of expansion. Initial AAA size and serum total cholesterol level were also predictors of expansion. CONCLUSION: A high proportion of men with a small AAA had signs of chronic infection with C. pneumoniae. Aneurysm progression correlated with evidence of chronic C. pneumoniae infection.     

Proteolysis of the abdominal aortic aneurysm wall and the association with rupture.

PURPOSE: to investigate proteolysis of the abdominal aortic aneurysm (AAA) wall and the association with rupture. METHODS: levels of matrix metalloproteinases (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) were measured in the walls of medium-sized (5-7 cm in diameter) ruptured AAA (rAAA) (n =30) and large (> or = 7 cm in diameter) asymptomatic AAA (aAAA) (n=30). RESULTS: MMP-2 levels (median, range) were significantly higher in the walls of large aAAA (165 ng/g AAA tissue, 50-840) than from medium-sized rAAA (110 ng/g AAA tissue, 47-547, p=0.007). MMP-9 levels were significantly higher in the walls of medium-sized rAAA (107 ng/g AAA tissue, 19-582) than from large aAAA (55 ng/g AAA tissue, 11-278, p=0.012). TIMP-1 and TIMP-2 levels were equivalent. There was a positive correlation between MMP-2 and the diameter of aAAA (r=0.54, p=0.002), but a negative correlation with MMP-9 (r= -0.44, p=0.017). No significant correlations were found between aAAA diameter and TIMP-1 or TIMP-2. CONCLUSION: AAA rupture is associated with higher levels of MMP-9. There is no association with TIMP-1 or TIMP-2 levels. MMP-2 levels are positively, whereas MMP-9 levels are negatively, correlated with aAAA size. MMP-9 may play a role in the progression towards rupture, whereas MMP-2 may play a role in expansion.     

Double left renal vein associated with abdominal aortic aneurysm.

Double left renal vein is a rare venous anomaly. We operated on 72-year-old man of abdominal aortic aneurysm (AAA) with double left renal vein. Massive hemorrhage was encountered during encircling the tape around the abdominal aorta. One vein passing posterior to the aorta was injured. Further dissection revealed the presence of double left renal vein forming a ring around the aorta. The patient underwent an abdominal aortic replacement following prompt repair of the injured vein. He had an uneventful postoperative course without renal complication. We missed that preoperative computed tomographic (CT) scan had demonstrated double left renal vein. Preoperative contrast-enhanced CT scan is useful and essential not only for evaluation of AAA, but also for establishing the presence of venous anomalies. Venous anomalies should be taken into consideration on the AAA operation.     

Prediction of outcome after abdominal aortic aneurysm rupture

BACKGROUND: Most vascular surgeons practice a selective policy of operative intervention for patients with ruptured abdominal aortic aneurysm (AAA). The evidence on which to justify operative selection remains uncertain. This review examines the prediction of outcome after attempted open repair of ruptured AAA. METHODS: The Medline and EMBASE databases and Cochrane Database of Systematic Reviews were searched for clinical studies relating to the prediction of outcome after ruptured AAA. Reference lists of relevant articles were also reviewed. RESULTS: The last 20 years has seen >60 publications considering variables predictive of outcome after AAA rupture. Four predictive scoring systems are reported: Hardman Index, Glasgow Aneurysm Score, Physiological and Operative Severity Score for Enumeration of Mortality and Morbidity (POSSUM), and the Vancouver Scoring System. No scoring system has been shown to have consistent or absolute validity. Of the remaining data, there are no individual or combination of variables that can accurately and consistently predict outcome. CONCLUSIONS: Little robust evidence is available on which to base preoperative outcome prediction in patients with ruptured AAA. Experienced clinical judgement will remain of foremost importance in the selection of patients for ruptured AAA repair.     

Severe jaundice after rupture of abdominal aortic aneurysm

Eight patients after operation for ruptured abdominal aortic aneurysm developed severe jaundice. The jaundice became clinically apparent by the sixth postoperative day, and the average peak total bilirubin level reached 28.4 mg/100 ml, alkaline phosphatase level 8.6 BL units/l, and SGOT 95 Karmen units/ml. In addition to the hepatic dysfunction, all patients developed acute renal failure, seven of eight patients experienced hypovolemic shock, and six of eight patients had respiratory insufficiency requiring ventilatory support. The overall mortality was 83 per cent. The most probable causes for the severe jaundice were increased bile pigment load and hepatocellular dysfunction due to ischemic hypoxic injury of hepatocytes secondary to shock. Morphologically, a picture of cholestasis existed with severe bile-staining of hepatocytes and intracanalicular and intraductal bile thrombi. No evidence of recent or resolving hepatic necrosis was observed.     

Chronic contained rupture of an abdominal aortic aneurysm

The operative treatment of chronic contained rupture of a saccular abdominal aortic aneurysm (AAA) with retroperitoneal haematoma is reported. A 62-year-old man presented with a painless abdominal mass and intermittent claudication. He had an episode of severe abdominal pain about 2 years before admission. A giant retroperitoneal neoplasm was initially suspected, based on computed tomography. However, magnetic resonance imaging, angiography and colour Doppler sonography demonstrated chronic contained rupture of an AAA. A punched-out oval defect (width 3.5 cm × length 4.5 cm) that was thought to connect the thrombosed aneurysm to an organized retroperitoneal haematoma was discovered in the posterior wall of the bifurcation of the aorta at laparotomy. An infrarenal aortobiexternal iliac Y-graft with bypass to the left femoral artery was placed without removing the aneurysm or haematoma. Recovery was uneventful. The retroperitoneal haematoma appeared smaller on computed tomography about 1 year after operation. This case fulfulled the criteria for chronic contained rupture of an AAA proposed by Jones and associates.