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.

Influence of gender on intraluminal thrombus of abdominal aortic aneurysms

BACKGROUND: The mechanisms of formation of intraluminal thrombus (ILT) of abdominal aortic aneurysms (AAA) remain unknown. The aim of this study was to investigate the pathogenesis of AAA by analysis of ILT. METHODS: We retrospectively analyzed the size of ILT in 98 consecutive patients with AAA undergoing abdominal computed tomography (CT) examination. The volume of ILT was estimated by the area ratio of ILT in CT images. Important baseline variables related to small ILT were determined using logistic-regression analysis. RESULTS: There were two apparent peaks in the distribution of ILT ratio. Thirteen of 98 patients had negligible ILT with ratio < or = 0.1. Female gender was the only patient characteristic independently significantly correlated with small ILT (odds ratio 5.214, P = 0.0096). CONCLUSION: Our findings provide important evidence that AAA is formed by at least two different pathogenic processes. It is likely that this difference in mechanisms may be caused partly by sex hormones.     

Size and location of thrombus in intact and ruptured abdominal aortic aneurysms

PURPOSE: This study compared the volume and morphology of intraluminal thrombus (ILT) in intact and ruptured abdominal aortic aneurysms (AAAs). METHODS: ILT volume in 67 intact AAAs and in 31 ruptured AAAs was assessed by using computed tomography (CT) angiography to measure the major and minor diameter of the outer wall and lumen of AAA as outlined by contrast at multiple sites. ILT thrombus morphology was recorded by AutoCAD 2000 software. Four equidistant images traced from the CT scan were recorded along the length of AAA. Thrombus volume was categorized as anterior-eccentric if the calculated area of thrombus was greater anteriorly, posterior-eccentric if greater posteriorly, eccentric-equal if the difference between the anterior and posterior thrombus was 相似文献   

Inflammatory abdominal aortic aneurysms

In a series of 517 operations for abdominal aortic aneurysm from 1971 to 1988 there were 45 cases (8.7%) with an inflammatory aneurysm with a typical thick glistening whitish fibrous layer. Almost two-third of the patients had rather severe chronic or acute progressive pain in the abdomen, the back or the flank. Unilateral (7) or bilateral (2) hydronephrosis due to ureteral compression occurred in 9 patients (20%). A diagnosis of inflammatory aneurysm was made preoperatively only in 10 patients. In 8 of the 9 patients with hydronephrosis ureterolysis was done, unilaterally (6) or bilaterally (2). After ureterolysis all had complete resolution of the hydronephrosis. Preoperative diagnostic methods are excretory urography, showing medial deviation, ultrasonography and CT-scanning of the abdominal aorta. All patients with an inflammatory aneurysm should undergo aortic replacement to prevent rupture and achieve pain relief. Ureterolysis in cases of hydronephrosis is strongly recommended and may be performed safely and with excellent results.     

Familial abdominal aortic aneurysms

The case histories of three brothers, the only siblings of one family, all of whom underwent surgery for the treatment of a previously asymptomatic ruptured abdominal aortic aneurysm, are recorded. The possibility of underlying constitutional and hereditary factors is discussed and the suggestion of a primary familial incidence of atheromatous, nondissecting aortic aneurysm is raised.     

Ruptured abdominal aortic aneurysms

Eighty two aortic replacements of ruptured abdominal aortic aneurysms have been performed during the last 6 years. There were 72 male and 10 female patients, and the average age was 71.33 years. Hemorrhagic shock on the admission was observed in 45 patients, and 13 have been operated urgently without any diagnostic procedures. The transperitoneal approach have been used for the operation. Two aorto duodenal and one aorto caval fistulas, have been found. Only exploration (three patients died immediately after laparotomy and 6 after cross clamping) has been done in 9 cases, and the aortic replacement in 70 cases (27 with tubular, and 43 with bifurcated graft). In 3 cases and axillobifemoral bypass had to be done. During the operation eleven patients died, and 30 in postoperative period, during the period between one and 40 days. Total intrahospital mortality rate was 50%, compared with 3.5% for 250 electively operated patients with abdominal aortic aneurysms in same period. In postoperative period the most important cause of death was multiple organs failures. Statistically significant greater mortality rate (p > 0.01%) was found in cases of late operative treatment, hemorrhagic shock, intra-operational bleeding, ruptured front wall, suprarenal cross clamping and in patients older than 75 year. In complicated cases such as juxtarenal aneurysm, 3 sutures parachute technique for proximal anastomosis, a temporary transection of the left renal vein, and intraaortal balloon occlusive catheter for proximal bleeding control are recommended.     

Ruptured abdominal aortic aneurysms

A series of 180 consecutive patients with ruptured aortic aneurysms has been studied to determine the causes of death. 18% died before operation could be carried out, 8% proved inoperable and a further 10.5% died before operation could be completed. Overall mortality was 75%. By multivariate analysis, the most significant preoperative features influencing survival were a systolic BP less than 80 mmHg on admission and a history of hypertension, angina or myocardial infarct. The mortality increased with increasing age. Administration of fresh frozen plasma preoperatively significantly increased survival. However, we could not identify a single group of patients for whom the outcome was inevitably fatal.     

Anticoagulants and reduced thrombus load in abdominal aortic aneurysms assessed with three-dimensional contrast-enhanced ultrasound examination

ObjectiveThe relationship between intraluminal thrombus (ILT) and abdominal aortic aneurysm (AAA) growth and rupture risk remains ambiguous. Studies have shown a limited effect of antiplatelet therapy on ILT size, whereas the impact of anticoagulant therapy on ILT is unresolved. This study aims to evaluate an association between antithrombotic therapy and ILT size assessed with three-dimensional contrast-enhanced ultrasound (3D-CEUS) examination in a cohort of patients with AAA.MethodsIn a cross-sectional study, 309 patients with small AAAs were examined with 3D-CEUS. Patients were divided into three groups based on prescribed antithrombotic therapy: anticoagulant (n = 36), antiplatelet (n = 222), and no antithrombotic therapy (n = 51). Patient ILT size was calculated in volume and thickness and compared between the three groups.ResultsPatients on anticoagulants had a significantly lower estimated marginal mean ILT volume of 16 mL (standard error [SE], ±3.2) compared with 28 mL (SE, ±2.7) in the no antithrombotic group and 30 mL (SE, ±1.3) in the antiplatelet group when adjusting for AAA volume (P < .001) and comorbidities (P < .001). In addition, patients on anticoagulant therapy had significantly lower estimated marginal mean ILT thickness of 10 mm (SE, ±1.1) compared with 13 mm (SE, ±0.9) in the no antithrombotic group of and 13mm (SE, ±0.4) in the antiplatelet group when adjusting for AAA diameter (P = .03) and comorbidities (P = .035).ConclusionsA 3D-CEUS examination is applicable for ILT assessment and demonstrates that patients with AAA on anticoagulant therapy have lower ILT thickness and volume than patients with AAA on antiplatelet therapy and those without antithrombotic therapy. Causality between anticoagulants and ILT size, and extrapolation to AAA growth and rupture risk, is unknown and merits further investigations, to further nuance US-based AAA surveillance strategy.     

Homocysteine and abdominal aortic aneurysms

There is evidence to suggest that increased levels of homocysteine play a significant role in vascular disease. It has been suggested that lowering homocysteine levels by dietary folate supplementation may reduce the risk of stroke and coronary heart disease. It is plausible that homocysteine may also play a role in the pathogenesis of abdominal aortic aneurysms (AAA) and that patients with this disease may benefit from folate supplementation. Our objective was to review the published work with regard to the role of homocysteine in the pathogenesis of AAA. Searches were carried out in published work in English with the keywords 'abdominal aortic aneurysm' and 'homocysteine'. There is evidence from in vitro and animal model studies that activation of metalloproteinases by homocysteine can influence aortic wall structure. Several case-control studies report an association between increased levels of homocysteine and the presence of an AAA. There are conflicting genotypic data concerning the association between methylenetetrahydrofolate reductase gene variants and AAA. Although there is evidence for an association between homocysteine and AAA, it is not strong enough to conclude that it plays a causal role in the pathogenesis of AAA. Further research is needed, given the potential benefit that simple vitamin supplementation may have for patients with AAA.