Infected abdominal aortic aneurysm

Introduction to infectious abdominal aortic aneurysm Infectious abdominal aortic aneurysm (infectious abdominal alaneurysm) is caused by bacterial infection of the abdominal aorta. It was reported by Whillian Osler in 1885 that it has a sharp tendency to increase compared with arteriosclerotic abdominal aortic aneurysm, which is prone to rupture and is difficult to diagnose early. basic knowledge Sickness ratio: 0.001%-0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: bacteremia, sepsis, infective endocarditis

Causes of infectious abdominal aortic aneurysm

(1) Causes of the disease

The main cause of aneurysm is that a-hemolytic streptococcus, pneumococcus, tubercle bacillus and even treponema pallidum are the main pathogenic microorganisms before the antibiotics are widely used. With the increase of abdominal aortic penetrating injury, the development of vascular surgery, grapes The proportion of cocci infection has increased. At present, the most common cause of infection is Staphylococcus aureus and Salmonella infection, accounting for about 40% and 20% respectively. The rest are infections such as anaerobic bacteria, and there are a few strains of Staphylococcus aureus. Reports of disease, in particular, it is important to emphasize that Salmonella has a vascular effect that can cause structural destruction of the normal arterial wall and form a pseudoaneurysm.

Risk factors that increase the susceptibility to this disease include: penetrating arterial trauma (including injury to the artery by accidental drug abuse), bacteremia and sepsis, infective endocarditis, congenital heart disease, due to malignancy or application of a certain Some drugs cause low immunity, etc., in addition to common pathogenic bacteria, Campylobacter, Pseudomonas, Brucella, Klebsiella, Candida albicans can also cause disease.

Infectious aneurysms can be occult. A hospital in Beijing has treated a female infected abdominal aortic aneurysm. The bacterial culture is staphylococci, and the common carotid aneurysm occurs half a year after the successful treatment of the aneurysm rupture. The bacterial culture is Staphylococcus, and staphylococcal sepsis occurs, which is cured by rescue.

(two) pathogenesis

Finseth et al. classify the causes and mechanisms of infectious abdominal aortic aneurysms as follows:

1. Primary infectious aneurysm: caused by infection of the adjacent aortic lesion directly or through the lymphatic pathway, the incidence is not high.

2. Embolization of infectious aneurysms: Infected emboli from the distant part of the infected area adheres to the arterial wall, forming an infected lesion and causing infectious damage to the arterial wall to form an aneurysm, of which bacterial endocarditis is the most common The reason was that in the 1970s it accounted for 80% of the causes of infectious aneurysms.

3. Traumatic infectious aneurysm: caused by bacterial contamination of the arterial wall due to penetrating trauma or indwelling catheter of the arterial wall, iatrogenic causes such as vascular surgery.

4. cryptogenic infectious aneurysm: the primary infection is not clear, in the case of bacteremia or sepsis, blood bacteria formed by intimal injury caused by arteriosclerosis or by infectious necrosis of the aortic wall caused by nourishing blood vessels Aneurysm.

Infectious abdominal aortic aneurysm prevention

For patients with cystic abdominal aortic aneurysm, if there is long-term unexplained fever, repeated bacteremia, rapid tumor enlargement, and lack of calcification of the tumor wall, infectious abdominal aortic aneurysm should be considered.

Infectious abdominal aortic aneurysm Complications, bacteremia, sepsis, infective endocarditis

The disease mainly has infectious factors, so it can cause infection of other tissues or organs due to infection into the blood circulation, such as secondary abscess of the skin, infective endocarditis, pulmonary infection can form bacterial empyema. . At the same time, the infection can also directly affect the hemangioma to cause an increase in hemangioma, and the rupture will form a large hemorrhage. The amount of bleeding and the bleeding rate are quite rapid, and can directly enter the shock state in a short time.

Infectious abdominal aortic aneurysm symptoms Common symptoms Abdominal pain calcification triad bacteremia

Patients may have abdominal pain or low back pain, sometimes more intense, about 94% of patients have unexplained fever, and 77% of patients have blood white blood cells up to 10000/mm3 or more, and about 53% of patients can touch abdominal pulsating mass, sometimes accompanied by It is tender and can be enlarged in a short time, but at the same time it has fever, abdominal pain or low back pain. The "triad" of the abdominal pulsation mass is only 18%, so the fever of the unexplained, repeated bacteremia and Rapidly occurring abdominal pulsatile masses, if patients with spinal osteomyelitis, endocarditis or valvular disease should consider this disease and need to be investigated.

Examination of infectious abdominal aortic aneurysm

Blood routine often indicates an increase in white blood cell count, showing an increase in erythrocyte sedimentation rate, an increase in C-reactive protein levels, and other inflammatory reactions; blood bacteriological culture (especially from lower extremity arteries at the distal end of the tumor) is less than 50%, but can be Support for diagnosis.

1. B-ultrasound: Abdominal B-ultrasound can show abnormal hypoechoic area around the aorta and aortic saccular aneurysm, the tumor wall usually lacks calcification, and cardiac M-mode ultrasound may find infective endocardial neoplasm or Congenital heart disease such as end-to-end catheterization.

2. CT scan: more valuable, often visible:

1 limited irregular aortic dilatation and lack of tumor wall calcification;

2-lobulated saccular aneurysm;

3 multifocal saccular aneurysms;

4 Around the saccular aneurysm, the soft tissue mass can be enlarged by the contrast agent.

3. MRI examination: not sensitive to calcification, but easy to display the details of the lesion, and can distinguish between inflammatory tissue and hematoma. On the T1-weighted image, the former shows low signal and the latter is high signal.

4. Aortic angiography: a characteristic lobulated saccular aneurysm can be seen, usually with multiple or continuous, aortic wall with or without arteriosclerosis, tumor thrombus can be covered by thrombus or surrounding tissue Regularly, the thrombus may not develop when it is filled with the tumor cavity.

5. Radionuclide examination: such as 67Ga-citrate scan or 131In-labeled leukocytes can show local nuclides concentration in the abdominal aorta, suggesting the presence of infectious aneurysms, mostly used for repeated bacteremia and infection Clear cases.

Diagnosis and diagnosis of infectious abdominal aortic aneurysm

The preoperative diagnosis rate of infectious abdominal aortic aneurysm is less than 50%. Because the tumor often increases rapidly and can suddenly rupture and die, early diagnosis is essential for improving the curative effect. Therefore, for patients with cystic abdominal aortic aneurysm, if there is a long-term Unexplained fever, repeated bacteremia, rapid tumor growth, lack of calcification of the tumor wall should consider infectious abdominal aortic aneurysm, B-ultrasound, CT scan, angiography, etc. can help early diagnosis.

Generally not confused with other diseases.

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