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.     

Lack of association between Chlamydophila pneumoniae seropositivity and abdominal aortic aneurysm

Chronic Chlamydophila pneumoniae infection has been suggested as a possible contributing factor for the development and expansion of abdominal aortic aneurysm (AAA). The relevance of C pneumoniae involved in the processes underlying aneurysmal rupture is unknown. The aim of this study was to examine the relationship between C pneumoniae seropositivity and AAA rupture. In a case-control study, 119 patients with AAA and 36 matched controls were prospectively investigated with C pneumoniae serology. Patients with ruptured AAA have similar levels of IgG antibodies against C pneumoniae as patients with an electively operated AAA, a small AAA, and controls. In conclusion, this study fails to demonstrate a connection between C pneumoniae seropositivity and AAA rupture.     

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.     

Infective abdominal aortic aneurysm due to Haemophilus influenza identified via the polymerase chain reaction.

Infective abdominal aortic aneurysms due to Haemophilus influenza are rarely reported. We report a case in a 65 year old female presenting with abdominal pain, weight loss, pyrexia and elevated inflammatory markers. The patient was found to have an abdominal aortic aneurysm clinically and on CT scanning. At surgery, an inflammatory aneurysm was successfully repaired using an autogenous vein panel-graft. Tissue samples were analysed using the polymerase chain reaction, identifying H. influenza as the causative organism. H. influenza is a scarcely reported cause of infective aortic aneurysms. The mechanism of infection is unknown. Reference is made to existing reports of such infection.     

Prevalence of abdominal aortic aneurysm in the offspring of patients dying from aneurysm rupture.

The prevalence of abdominal aortic aneurysm (AAA) is high in the brothers of patients with aneurysm. A genetic component in the development of AAA has, therefore, been postulated. In this study the offspring of patients who had died from AAA rupture were invited to undergo ultrasonography of the abdominal aorta. The attendance rate was 69 per cent. Thirty-nine sons of median age 60 (range 45-75) years and 23 daughters of median age 62 (range 42-80) years were examined. Abdominal aortic dilatation was found in eight men and one woman. The presence of aortic dilatation in these nine cases was not related to age, hypertension, smoking or symptoms of occlusive arterial disease. It is concluded that the sons of those who have died from ruptured AAA constitute a high-risk group for the development of this condition and should be considered for further screening.     

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.     

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.