腹主动脉瘤(AAA)

腹主动脉瘤(AAA)

Abdominal aortic aneurysm (also known as AAA) is a localized ballooning of the abdominal aorta exceeding its normal diameter by more than 50 percent, 是动脉瘤最常见的形式. Approximately 90 percent of abdominal aortic aneurysms occur below the kidneys, but they can also occur at the level of the kidneys or above the kidneys.

Such aneurysms can extend to include one or both of the iliac arteries in the pelvis. Abdominal aortic aneurysms occur most commonly in individuals between 65 and 75 years old and are more common among men and smokers. 它们往往不会引起任何症状, although occasionally they cause pain in the abdomen and back (due to pressure on surrounding tissues) or in the legs (due to disturbed blood flow).

腹主动脉瘤的主要并发症是破裂, which can be life-threatening as large amounts of blood spill into the abdominal cavity, 能在几分钟内致死. 有症状的大动脉瘤(1.e.大于5的.5 cm in diameter) are considered for repair by one of several surgical methods. There is moderate evidence to support screening in individuals with risk factors for abdominal aortic aneurysms.

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左侧动脉瘤 右侧动脉瘤

 

症状

绝大多数动脉瘤是无症状的. 然而, 当腹主动脉瘤扩张时, they may become painful and lead to pulsating sensations in the abdomen or pain in the chest, 下背, 或阴囊. 有症状的动脉瘤破裂的风险很高, 因此哪一个被认为是Surgery的指征.

并发症包括破裂, 外围栓塞, 急性主动脉阻塞, 以及腹主动脉或十二指肠瘘管. 体格检查时,腹部可触及肿块. Bruits can be present in case of renal or visceral arterial stenosis.

The clinical manifestation of ruptured AAA usually includes excruciating pain of the 下背, 侧面, 腹部及腹股沟. 出血通常导致低血容量性休克并伴有低血压, 心动过速, 黄萎病, 精神状态的改变. AAA破裂的死亡率高达90%. 65-75% of patients die before they arrive at hospital and up to 90% die before they reach the operating room. 出血可发生在腹膜后或腹膜内, or the rupture can create an aortocaval or aortointestinal (between the aorta and intestine) fistula. Flank ecchymosis (appearance of a bruise) is a sign of retroperitoneal hemorrhage, 也被称为格雷·特纳的标志.

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成因及危险因素

Cigarette smoking: More than 90% of people who develop an AAA have smoked at some point in their life.

基因的影响: 遗传因素的影响是极有可能的. The high familial prevalence rate is most notable in male individuals. There are many theories about the exact genetic disorder that could cause higher incidence of AAA among male members of the affected families.

Some presumed that the influence of alpha 1-antitrypsin deficiency could be crucial, 一些实验工作支持x连锁突变理论, 这就解释了杂合子女性发病率较低的原因吗. 遗传病因学的其他理论也已形成. 结缔组织紊乱, 比如马凡氏综合征和埃勒斯-丹洛斯综合征, 也与AAA密切相关. Both relapsing polychondritis and pseudoxanthoma elasticum may cause abdominal aortic aneurysm.

动脉粥样硬化: 长期以来,AAA被认为是由动脉粥样硬化引起的, 因为AAA的壁经常受到严重影响. 然而, this theory cannot be used to explain the initial defect and the development of occlusion, 在这个过程中观察到什么.

其他原因: 其他 causes of the development of AAA include: infection, trauma, arteritis, cystic medial necrosis.

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诊断

An abdominal aortic aneurysm is usually diagnosed by physical exam, ultrasound, or CT. Plain abdominal radiographs may show the outline of an aneurysm when its walls are calcified. 然而,只有不到一半的动脉瘤会出现这种情况. Ultrasonography is used to screen for aneurysms and to determine the size of any present. 此外,可以检测到游离腹膜液. It is noninvasive and sensitive, but the presence of bowel gas or obesity may limit its usefulness. CT scan has a nearly 100% sensitivity for aneurysm and is also useful in preoperative planning, 详细介绍解剖结构和血管内修复的可能性. In the case of suspected rupture, it can also reliably detect retroperitoneal fluid. Alternative less often used methods for visualization of the aneurysm include 核磁共振成像 and angiography.

An aneurysm ruptures if the mechanical stress exceeds the local wall strength; consequently, peak wall stress (PWS) and peak wall rupture risk (PWRR) have been found to be more reliable parameters than diameter to assess AAA rupture risk. Medical software allows computing these rupture risk indices from standard clinical CT data and provides a patient-specific AAA rupture risk diagnosis.

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治疗方案

Surgery for an abdominal aortic aneurysm is known as AAA surgery or AAA repair. The threshold for repair varies slightly from individual to individual, depending on the balance of risks and benefits when considering repair versus ongoing surveillance. 个体原生主动脉的大小可能会影响这一点, along with the presence of comorbidities that increase operative risk or decrease life expectancy.

打开修复

打开修复 is indicated in young patients as an elective procedure, 或成长或变大, 有症状的或破裂的动脉瘤. It was the main surgical intervention used from the 1950s until other procedures developed.

血管内修复

血管内修复 first became practical in the 1990s and although it is now an established alternative to open repair, 它的作用还有待明确界定. It is generally indicated in older, high-risk patients or patients unfit for open repair. 然而, 血管内修复只有一部分AAAs是可行的, 取决于动脉瘤的形态. The main advantages over open repair are that there is less peri-operative mortality, 减少重症监护的时间, less time in hospital overall and earlier return to normal activity. Disadvantages of endovascular repair include a requirement for more frequent ongoing hospital reviews, 而且更有可能需要进一步的治疗. 根据最新的研究, the EVAR procedure does not offer any benefit for overall survival or health-related quality of life compared to open surgery, 虽然动脉瘤相关的死亡率较低. 不适合开放式修复的患者, EVAR加保守治疗没有任何益处, 更多的并发症, subsequent procedures and higher costs compared to conservative management alone. Endovascular treatment for paraanastomotic aneurysms after aortobiiliac reconstruction is also a possibility.

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先生,Sateesh C., MD
Sateesh先生,医学博士
主治医师,血管外科
  • 血管Surgery
  • 普通外科
戈亚尔,阿伦,医学博士
  • 血管Surgery
  • 普通外科
伊戈尔·拉斯科夫斯基., MD
  • 血管Surgery
  • 普通外科
马特奥,罗密欧., MD
  • 血管Surgery
  • 普通外科