The “untimely bomb” in the belly 1.The patient had back pain a month ago and was suspected of having an abdominal aortic aneurysm by ultrasound, I wonder if there is any danger? A: There is danger! Because abdominal aortic aneurysm is caused by arteriosclerosis and other reasons that make the arterial wall become less elastic and expand outward. As the pressure of arterial blood continuously impacts the weak aneurysm wall, it makes the aneurysm likely to rupture, resulting in intra-abdominal hemorrhage, severe pain in the abdomen, shock, and serious life-threatening conditions. Therefore, some people have called abdominal aortic aneurysms “untimely bombs” in the abdominal cavity. 2.What is abdominal aortic aneurysm? A: We usually define aneurysm as a permanent, limited dilatation of an artery. Then abdominal aortic aneurysm should be a permanent, persistent dilatation of the abdominal aorta. Although the diagnostic criteria for abdominal aortic aneurysms are not uniform, the vast majority of physicians consider a permanent, limited dilatation of the abdominal aorta greater than or equal to 1.5 times the normal diameter to be an abdominal aortic aneurysm. The average CT measurement of the diameter of the abdominal aorta below the opening of the renal artery in adult men is 2.0 cm, while in women the corresponding diameter is approximately 1.8 cm. Therefore, a diameter of 3 cm should be used as a starting point for the diagnosis of abdominal aortic aneurysm. The size of the aneurysm is often indicated by the maximum external transverse diameter of the aorta (measured by ultrasound, CT, MRI or directly during surgery). 3.What kind of people are prone to abdominal aortic aneurysm? A: Abdominal aortic aneurysms are most common in older men, with a male to female ratio of about 4:1. In the West, the incidence rate for men over 60 years of age is 2.5%. In recent years, the incidence of abdominal aortic aneurysm in China has increased year by year. Two reports from a hospital in the United States show that from 1951 to 2010, the incidence rate rose from 12.2/100,000 residents to 36.2/100,000 residents, a threefold increase, and the aging growth of the population has played a role in the increase in incidence. Therefore, as the aging process in China continues to accelerate, the incidence of abdominal aortic aneurysm in our population will also increase. 4.What factors can cause abdominal aortic aneurysm? A: Because most patients with abdominal aortic aneurysms have atherosclerosis in the arterial wall, abdominal aortic aneurysms used to be called atherosclerotic aneurysms. Atherosclerosis is thought to be the primary cause of aneurysmal degeneration. Obesity, smoking and hypertension are common risk factors for abdominal aortic aneurysms and obstructive vascular disease, but it is uncommon for abdominal aortic aneurysms to be combined with obstruction of the main-iliac aorta; therefore, it is more appropriate to call atherosclerotic aneurysms degenerative and nonspecific abdominal aortic aneurysms. 5.Can young people get abdominal aortic aneurysm? A: Young people may also have abdominal aortic aneurysms, but the causes of abdominal aortic aneurysms in young people are different from those in older people. Most abdominal aortic aneurysms in the elderly are related to atherosclerosis and hypertension, while most abdominal aortic aneurysms in the young are related to congenital abnormalities and degeneration of the smooth muscle fibers of the arterial vessels. In fact, the chances of abdominal aortic aneurysm in young people are extremely low and generally there is nothing to fear. 6.What types of abdominal aortic aneurysms are there? A: Abdominal aortic aneurysm can be divided into three types according to the location: above renal artery, flat renal artery and below renal artery, and the vast majority of abdominal aortic aneurysms are below renal artery type. According to the pathological changes, they can be divided into true aneurysm, pseudoaneurysm and intercalated aneurysm. A true aneurysm is a limited abnormal dilatation of an artery formed by lesions in the arterial wall, reduced elasticity, and structural weakness. In true aneurysms, the wall is intact and all layers of the vessel wall are preserved; in pseudoaneurysms, the whole layer of the arterial wall is often destroyed due to injury, and blood rushes out of the vessel lumen but is wrapped by surrounding tissues to form a pulsatile hematoma; in pseudoaneurysms, there is no complete three-layer structure of the vessel, covered by fibrous tissue, and there is no arterial structure in the wall of the aneurysm; in sandwich aneurysms, the intima of the artery is torn, and blood flow enters and separates the vessel through the rupture The tearing of the intima and the middle layer of the artery forms a pseudocavity, which leads to the compression of the true cavity of the vessel while the pseudocavity continues to expand into an aneurysm. 7.Will abdominal aortic aneurysm be passed on to me or the next generation? A: This is a rather specialized question. Simply put, there is a possibility of inheritance, but it is actually not very common. In Ehler-Danlos syndrome, a rare genetic deletion of type III collagen, which forms the main structure of the arterial wall, causes multiple aneurysms. Patients with Mafan syndrome present with dilated arteries and whole aortic coarctation due to a mutation in the protofibrillin-Ⅰ gene on chromosome 15. In the 1980s, several studies showed a familial predisposition to abdominal aortic aneurysms, with at least 18% of patients with abdominal aortic aneurysms having close relatives involved. 8. What are the other causes of abdominal aortic aneurysms? A: Atherosclerotic degenerative abdominal aortic aneurysms account for 90% of infrarenal abdominal aortic aneurysms. Other causes include cystic mesangial necrosis, arteritis, injury, hereditary connective tissue disease, disruption of anatomic structures, and infection can also lead to abdominal aortic aneurysms. Infectious abdominal aortic aneurysms originate from local infection of the arterial wall. Most infectious abdominal aortic aneurysms develop from bacteremia caused by distant lesions (e.g., endocarditis) and are the most common type of aortic aneurysm in children. Infected abdominal aortic aneurysms due to syphilis infection have a tendency to resurface in recent years and should be given our utmost attention.