Infective abdominal aortic aneurysms

　　First, the cause of the disease

　　1. The main causes of aneurysms are:Before the widespread use of antibiotics, the main pathogenic microorganisms were alpha-hemolytic streptococcus, pneumococcus, tuberculosis bacillus, and Treponema pallidum. With the increase in penetrating injuries of the abdominal aorta and the development of vascular surgery, the proportion of Staphylococcus infections has increased. Currently, the most common causes of disease are due to Staphylococcus aureus and Salmonella infection, accounting for about 40% and 20% respectively, with the remainder being infections by anaerobic bacteria, and there have been reports of pathogenic strains of resistant Staphylococcus. It is especially important to emphasize that Salmonella has a vascular affinity and can cause structural damage to the normal arterial wall, leading to pseudo-aneurysms.

　　2. Risk factors that increase the susceptibility to this disease include:Penetrating artery trauma (including accidental injury to arteries during drug injection), concurrent bacteremia and sepsis, infective endocarditis, congenital heart disease, immunosuppression due to malignant tumors or the use of certain drugs, and other factors. In addition to common pathogenic bacteria, such as Campylobacter, Pseudomonas, Brucella, Klebsiella, and Candida albicans, can also cause disease.

　　Infectious aneurysms can exist covertly. The First Affiliated Hospital of China Medical University once treated a female patient with a ruptured infectious abdominal aortic aneurysm, and the bacterial culture was Staphylococcus. Half a year after the successful rescue of the aneurysm rupture, a carotid artery aneurysm occurred again, and the bacterial culture was also Staphylococcus, causing staphylococcal sepsis. After rescue, the patient was cured.

　　Second, pathogenesis

　　Finseth and others classify infectious abdominal aortic aneurysms according to their causes and mechanisms as follows:

　　1. Primary infectious aneurysm:It is caused by direct or lymphatic infection of the abdominal aortic wall by adjacent infection foci, with a low incidence.

　　2. Embolic infectious aneurysm:It is caused by infection emboli from distant infection foci adhering to the arterial wall, forming infection foci and causing infectious damage to the arterial wall, forming an aneurysm. Among them, bacterial endocarditis is the most common cause, accounting for 80% of the causes of infectious aneurysms in the 1970s.

　　3. Traumatic infectious aneurysm:It is caused by bacterial contamination of the arterial wall due to penetrating trauma of the arterial wall or catheter placement, vascular surgery, and other iatrogenic causes.

　　4. Cryptogenic infectious aneurysm:The primary infection focus is unclear. During sepsis or bacteremia, bacteria in the blood pass through the inner membrane damage caused by atherosclerosis or through the nutrient vessels to cause infectious necrosis of the aortic wall, forming an aneurysm.

　　This disease mainly has infectious factors, so it can cause infections in other tissues or organs due to infection entering the blood circulation, such as secondary abscesses of the skin, infectious endocarditis, and bacterial empyema in lung infections. At the same time, infection can also act directly on the angioma, causing the angioma to enlarge, and rupture can lead to massive hemorrhage. The amount and speed of hemorrhage are quite rapid, and it can directly enter a shock state in a short period of time.

　　Patients may have abdominal pain or lumbar back pain, which can be quite severe. About 94% of patients have unexplained fever, and 77% of patients have blood white cell counts above 10,000/mm3. About 53% of patients can feel abdominal pulsatile masses, which may be accompanied by tenderness and can increase in a short period of time. However, only 18% of patients with fever, recurrent bacteremia, and rapid appearance of abdominal pulsatile masses have the 'triad' of fever, abdominal pain, or lumbar back pain, and abdominal pulsatile masses. Therefore, for patients with unexplained fever, recurrent bacteremia, and rapid appearance of abdominal pulsatile masses, if they also have spondylomyelitis, endocarditis, or valvular disease, they should consider this disease and need detailed examination.

　　The etiology of infectious abdominal aortic aneurysm patients mainly includes infections by pathogenic microorganisms such as alpha-hemolytic streptococcus, pneumococcus, tuberculosis bacilli, and syphilis spirochete. Therefore, the preventive methods are to minimize infections, avoid contact with radiation and other harmful substances, especially drugs that suppress the immune function; to engage in appropriate exercise, enhance physical fitness, and improve one's own ability to resist diseases.

　　Blood routine often indicates an elevated white blood cell count, visible accelerated erythrocyte sedimentation rate, and an increased level of C-reactive protein, indicating inflammatory reactions; the positive rate of blood bacteriology culture (especially from the distal lower limb artery) is not more than 50%, but it can support the diagnosis.

　　First, ultrasound examination:Abdominal ultrasound can show abnormal hyperechoic areas around the aorta and cystic aneurysms, and the wall of the aneurysm usually lacks calcification. M-mode echocardiography may detect vegetations of infectious endocarditis or patent ductus arteriosus and other congenital heart disease changes.

　　Second, CT scan:It is valuable and often visible:

　　1. Localized irregular aortic dilation without calcification of the aneurysm wall.

　　2. Lobulated cystic aneurysms.

　　3. Multifocal cystic aneurysms.

　　4. The surrounding soft tissue mass shadow of cystic aneurysm can be dilated by contrast medium.

　　Third, MRI examination:Not sensitive to calcification, but it is convenient to show the details of the lesion and distinguish inflammatory tissue from hematoma. On T1-weighted images, the former shows low signal and the latter high signal.

　　Fourth, aortography:Characteristic lobulated cystic aneurysms can be seen, and they are usually multiple or continuous. The aortic wall may or may not show signs of atherosclerosis. The thrombus in the aneurysm may be irregular due to thrombosis or coverage by surrounding tissues. When the thrombus fills the aneurysm cavity, it may not be visible.

　　Fifth, radioactive isotope examination:If 67Ga-citrate scan or 131In-labeled leukocytes can show local radioisotope accumulation in the abdominal aorta, indicating the presence of an infectious aneurysm, it is often used in cases with recurrent bacteremia and unclear infection site.

　　First, postoperative dietary formula for infectious abdominal aortic aneurysm

　　1. Red date and brown sugar cooked pumpkin

　　[Formula] 500g of fresh pumpkin, 20g of red dates, an appropriate amount of brown sugar.

　　[Preparation] Peel the pumpkin, cut into small cubes, add red dates and brown sugar, and cook in water until done.

　　[Usage] Serve with meals, it is better to eat on an empty stomach.

　　[Indication] Suitable for those with deficiency of both Qi and blood after surgery and those with weak physique.

　　2. Black sesame bean milk

　　[Formula] 30g of black sesame seeds, 40g of soybean powder.

　　[Preparation] Roast black sesame seeds over low heat until they are done, grind them into fine powder for later use. Put soybean powder in a pot, add an appropriate amount of water, stir to form a thin paste, soak for 30 minutes, then simmer over low heat until boiling. Filter the soy milk with a cloth and add it back to the pot. Simmer over low heat until boiling again, add the black sesame powder, and stir well to combine.

　　[Usage] Take in the morning and evening, and you can add brown sugar as desired.

　　[Indication] Especially suitable for those with deficiency of both Qi and blood after surgery, and those with insufficient liver blood.

　　3. Astragalus and perch soup

　　[Formula] One perch (200g), 30g of astragalus, 30g of hawthorn yam, 6g of tangerine peel, 4 slices of ginger.

　　[Preparation] Remove impurities from the perch, wash and cut into pieces. Wash astragalus, yam, and tangerine peel, and put all the ingredients in a pot. Add an appropriate amount of water, bring to a boil over high heat, then simmer over low heat for 1 hour.

　　[Usage] Drink the soup and eat the meat.

　　[Indication] Strengthen the spleen and Qi, improve appetite, and harmonize the middle. It is especially suitable for the recovery of physical condition after surgery.

　　4. Chinese date stewed rabbit meat

　　[Ingredients] 60g of Chinese dates, 250g of rabbit meat.

　　[Preparation] Clean the rabbit meat, blanch it in a pot of boiling water, remove it and cut it into small pieces, then put it in a pot with Chinese dates. Add an appropriate amount of water, bring to a boil over high heat, add cooking wine, then turn to low heat and simmer for 40 minutes. After the rabbit meat is cooked, add scallions, ginger, salt, monosodium glutamate, and five-spice powder, mix well. Boil again and add sesame oil before serving.

　　[Usage] Serve as a side dish with meals, take freely.

　　[Indication] Tonify both Qi and blood, restore physical and mental strength after surgery.

　　Two. Foods that are good for infectious abdominal aortic aneurysm

　　1. Cancer patients have a high energy consumption, so their diet should be increased by 20% more than that of normal people.If malnutrition has occurred, more protein should be supplemented. The intake of protein should be plant protein and some animal protein. In addition, it is necessary to choose low-fat, low-salt foods rich in vitamins and inorganic salts, which are beneficial for the treatment and recovery of cancer patients.

　　2. When arranging the diet for cancer patients, in addition to considering the above nutritional factors, attention should also be paid to fully utilizing the anticancer substances in food.Some foods can induce cancer, while others can prevent cancer. Cancer patients should try to avoid cancer-inducing foods and eat more cancer-preventing foods. According to research, common cancer-preventing foods include cruciferous vegetables (such as cabbage and cauliflower), radishes, garlic, umeboshi, soybeans, beef, mushrooms, asparagus, and Job's tears.

　　3. The dietary forms for cancer patients include ordinary rice, soft rice, semi-liquid food, and liquid food. They should be provided according to the specific condition of the patient and their digestive and absorption abilities.For example, some lung cancer patients in the late stage may easily have hiccups while eating, causing them to be afraid to eat. In this case, soft rice or semi-liquid food should be given. For patients with facial radiotherapy, saliva decreases, the throat becomes dry and painful, and swallowing is difficult. The diet should be more watery and cooler.

　　Three. Foods to avoid for infectious abdominal aortic aneurysm

　　1. Abstain from spicy and刺激性 foods in diet.

　　2. Reduce the intake of greasy and heavy foods.

　　3. Reduce the intake of warm-nourishing foods such as dog meat and mutton.

　　4. Reduce the intake of shellfish, bamboo shoots, taros, and other allergenic 'inducing' foods that are easy to cause allergic reactions.

　　5. Reduce the intake of beverages and snacks containing chemicals, preservatives, and additives.

　　6. Avoid overly sour, spicy, salty, and stimulating substances such as tobacco and alcohol.

　　For patients with cystic abdominal aortic aneurysm, if there are long-term unknown reasons for fever, recurrent bacteremia, rapid tumor growth, and lack of calcification in the tumor wall, it should be considered as an infectious abdominal aortic aneurysm.

　　Western treatment methods for infectious abdominal aortic aneurysm

　　Surgical Treatment:Infectious abdominal aortic aneurysm is an explosive infectious process that requires active early treatment to prevent rupture. Simple antibiotic treatment cannot reduce the occurrence of rupture, and effective antibiotics should be used in conjunction with active surgery. The surgical method involves the excision of the infectious aneurysm, complete removal of the adjacent necrotic tissue, and the use of either anatomical or non-anatomical artificial vascular grafting.

　　1. Surgical method:Using a median laparotomy, after opening the peritoneum, a cystic abdominal aortic aneurysm can be seen, and sometimes there is purulent accumulation around the tumor. The proximal abdominal aorta near the neck of the tumor is blocked because the tumor body is infected and fragile and easy to rupture. It is necessary to block the aorta at the crura of the diaphragm to reduce dissection if necessary. Then, the iliac artery is exposed and blocked, and the infectious aneurysm is resected. Bacterial culture of the aneurysm wall and thrombus adherent to the wall is performed to guide diagnosis and treatment. Thoroughly remove the infected necrotic tissue and rinse with saline containing antibiotics. It is currently believed that when visceral blood supply is damaged, anatomical vascular graft transplantation should be performed; for infrarenal abdominal aortic aneurysms, if Gram-negative and no periaortic abscess is found during surgery, anatomical vascular graft transplantation can be performed, but it requires 6-8 weeks of effective antibiotic treatment, and for Salmonella, antibiotics with a long half-life should be selected; if there is obvious periaortic abscess and (or) Gram-positive bacterial infection, the aneurysm should be resected and the necrotic tissue should be thoroughly removed. The residual aortic end should be sealed with non-absorbable suture lines, requiring that the residual aortic edge be free of infection. If necessary, frozen sections should be used to determine this, and the omentum should be covered, and then axillary-bilateral femoral bypass grafting should be performed to maintain blood supply to the lower limbs. The artificial blood vessel should be selected as ePTFE vessel, which has strong anti-infection ability.

　　2. Perioperative management:Once an infectious abdominal aortic aneurysm is diagnosed, it should be treated with effective antibiotics for empirical therapy. After surgery, more targeted treatment should be adopted based on bacterial culture and drug sensitivity test. For Salmonella infection, antibiotics with a long half-life should be selected, and there is no definite standard for the duration of treatment, it is generally believed that at least 4-6 weeks of medication is required. For some highly virulent pathogenic microorganisms, some even recommend lifelong drug treatment. Since most of these patients have low immunity and poor general condition, attention should be paid to correcting anemia, strengthening nutritional support, enhancing immune function, and strengthening the monitoring of important organ functions during the perioperative period.

　　In view of the possibility of recurrence of infectious aneurysms after surgery and the possible occurrence of various complications, close follow-up and observation are necessary to timely handle them.