I. Causes 1. What is the main cause of abdominal aortic aneurysm? The exact cause of abdominal aortic aneurysm is still unclear. Most scholars now believe that an inflammatory response in the aortic wall can trigger an aneurysm, which in turn leads to a weakness of the vessel wall to the point of rupture. This inflammatory response is closely related to atherosclerosis (also known as arteriosclerosis) and its risk factors, which include high blood pressure, smoking, and high blood lipids. Atherosclerosis causes lipids in the blood to be deposited on the walls of blood vessels, which then form hardened plaques. This lesion will lead to hardening of the arteries as well as weakening of the walls, which over time may lead to the formation of aneurysms. In addition to atherosclerosis, other factors that increase the risk of abdominal aortic aneurysm include age over 60 years, being male, having a history of abdominal aortic aneurysm in the immediate family, high blood pressure, and smoking. Symptoms 1. What are the symptoms of abdominal aortic aneurysm? What are the secondary symptoms? In the early stages of abdominal aortic aneurysm, or in the case of small aneurysm diameter (less than 4-5 cm), patients usually have no obvious symptoms. Sometimes there is simply an unintentional palpation of a throbbing mass in the abdomen, which is usually the case when the patient discovers the aneurysm early. As the aneurysm increases in size, other symptoms may occur, most notably pain in the abdomen or lower back. Sometimes the patient may feel a twinge of pain, which is caused by the enlarged mass pressing on some of the organs in the abdominal cavity, thus causing discomfort. In larger diameter abdominal aortic aneurysms, the shell becomes so thin that even pressure can be painful. Sudden, severe pain often signals that the aneurysm is about to rupture, or even has ruptured. When an aneurysm ruptures, the patient may suddenly feel very weak, dizzy or even completely unconscious. At these life-threatening junctures, immediate medical attention should be sought. In less common cases, the patient may feel pain in the toes or feet and a change in color, which is due to an arterial embolism caused by a dislodged blood clot in the wall attached to the aneurysm. 3. How is an abdominal aortic aneurysm diagnosed? Since the vast majority of patients with abdominal aortic aneurysms have no clinical symptoms, the disease is generally difficult to detect. According to statistics, only 10% of abdominal aortic aneurysms are detected by physicians during physical examination, and most abdominal aortic aneurysms are detected incidentally during abdominal imaging for other reasons. Therefore, for elderly patients, especially those with concomitant risk factors for atherosclerosis, regular physical examinations and abdominal vascular ultrasound should be performed for screening. When a pulsating abdominal mass or painful discomfort is detected, as well as sudden chills and pain in both lower extremities, the possibility of abdominal aortic aneurysm should be more alert. The diagnosis of this disease is mainly based on the results of ultrasound, CT and other imaging examinations. 4.With which diseases should the differential diagnosis of abdominal aortic aneurysm be made? The diagnosis of abdominal aortic aneurysm is usually not difficult to establish based on medical history, symptoms and imaging examinations. (1) Aortic coarctation aneurysm: The first presentation is usually severe pain in the abdomen or low back, which occurs in middle-aged people aged 40-50 years old, younger than patients with abdominal aortic aneurysm. The disease is often associated with a history of hypertension and unsatisfactory blood pressure control, and the onset of the disease is usually accompanied by a sudden increase in blood pressure. (2) Iliac aneurysm or other visceral aneurysm: The pulsatile mass of abdominal aortic aneurysm is usually palpated above the level of the navel, while iliac aneurysm is usually below the level of the navel. Other visceral aneurysms such as mesenteric aneurysms, splenic aneurysms or renal aneurysms may also present as pulsatile abdominal masses, which can be differentiated by imaging. It is often accompanied by systemic symptoms such as weight loss, appetite, nausea and vomiting or jaundice. (1) What are the treatment modalities for abdominal aortic aneurysm? The former is mainly applied to patients with asymptomatic early aneurysms and small aneurysm diameters (<5cm), including control and treatment of atherosclerotic risk factors (such as lowering blood pressure, lipids, sugar and smoking cessation) and regular follow-up observation (every 6-12 months) to understand the degree of aneurysm progression; the latter is mainly used for symptomatic abdominal aortic aneurysms and aneurysms with small diameters (<5cm). The latter is mainly used for symptomatic abdominal aortic aneurysms and patients with large aneurysm diameters (>5 cm) and a greater risk of rupture, including both open surgical treatment and endoluminal intervention. (2) Surgical problems? Not all patients diagnosed with an abdominal aortic aneurysm will require surgery. Treatment options should be determined on a case-by-case basis, the most important of which is whether the patient is symptomatic and the diameter of the aneurysm, in addition to whether the patient’s health can tolerate surgery. In general, patients with small aneurysms (<5 cm) and no symptoms can be treated conservatively without surgery for the time being, but ultrasound or CTa examinations should be repeated every six months to a year to see how fast the aneurysm is progressing. Surgery should be considered for patients with rapid aneurysm expansion (aneurysm diameter increase of 0.5 cm or more per year) who can generally tolerate surgery. In addition, surgical intervention should be considered for patients with larger diameter (>5 cm) or symptomatic abdominal aortic aneurysms. This is because at this time, the chances of aneurysm rupture are higher and the risk is high if surgery is not performed.