Aortic dissection is the most common form of the acute aortic syndromes and a type of arterial dissection. It occurs when blood enters the medial layer of the aortic wall through a tear or penetrating ulcer in the intima and tracks along the media, forming a second blood-filled channel within the wall.

主动脉夹层是急性主动脉综合征最常见的形式，也是动脉夹层的一种。当血液通过内膜的撕裂或穿透性溃疡进入主动脉壁的内侧层，并沿着介质流动，在壁内形成第二个充满血液的通道时，就会发生这种情况。

Epidemiology 流行病学

The majority of aortic dissections are seen in elderly hypertensive patients. In a very small minority, an underlying connective tissue disorder may be present. Other conditions or predisposing factors may also be encountered, in which case they will be reflected in the demographics. Examples include :

主动脉夹层多见于老年高血压患者。在极少数情况下，可能存在潜在的结缔组织障碍。还可能遇到其他条件或诱发因素，在这种情况下，它们将反映在人口统计资料中。例子包括:

• structural aortic abnormalities 结构性主动脉异常 ： bicuspid aortic valve | 二叶主动脉瓣aortic coarctation |主动脉缩窄abnormal connective tissues | 不正常的结缔组织Marfan syndrome： 马凡氏综合症Ehlers-Danlos syndrome
• Turner syndrome 特纳综合征
• pregnancy 怀孕
• intra-aortic balloon pumps 主动脉内气囊泵
• ciprofloxacin use (unclear if class effect for fluoroquinolone agents) 使用环丙沙星(氟喹诺酮类药物的类效应不清楚)fluoroquinolones seem to promote loss of extracellular matrix integrity, by several mechanisms 氟喹诺酮类药物似乎通过几种机制促进细胞外基质完整性的丧失in the UK caution is now advised in using these agents in high risk patients 21 在英国，现在建议对高危患者慎用这些药物

Clinical presentation 临床表现

The duration of aortic dissection is arbitrarily categorized into three phases : 主动脉夹层的持续时间可分为三个阶段:

• acute: within 14 days of first symptom onset 急性:首次症状出现后14天内
• subacute: between 14 days to 3 months 亚急性期:14天至3个月
• chronic: more than 3 months from initial onset of symptoms 慢性:从症状开始算起超过3个月

Patients are often hypertensive (although they may be normotensive or hypotensive) and present with anterior or posterior chest pain and a tearing sensation in the chest. There may be a difference in blood pressure between the two arms depending on where the dissection occurs.

患者通常为高血压(尽管他们可能是正常血压或低血压)，并表现为前后胸痛和胸部撕裂感。根据撕裂部位的不同，两臂之间可能存在血压差异。

Depending on the extent of dissection and occlusion of aortic branches, end-organ ischemia may also be present (seen in up to 27% of cases) , including:

根据主动脉分支剥离和闭塞的程度，也可能出现终末器官缺血(高达27%的病例)，包括:

• abdominal organ ischemia 腹部器官缺血
• limb ischemia 肢体缺血
• ischemic or embolic stroke 缺血性或栓塞性卒中
• paraplegia: involvement of the artery of Adamkiewicz 截瘫:腰膨大动脉

If the aortic dissection involves the aortic root it may result in involvement of the coronary arteries and can present similarly to ST-elevation myocardial infarction on an ECG. However, treating these patients with antiplatelets/anticoagulation could be disastrous in aortic dissection.

如果主动脉夹层累及主动脉根部，则可能导致冠状动脉受累，心电图上的表现与st段抬高心肌梗死相似。然而，用抗血小板/抗凝治疗这些病人在主动脉夹层中可能是灾难性的。

Some cases of aortic dissection may result in rupture, causing collapse and often death. Signs of cardiac tamponade ( ) may also be encountered if rupture occurs into the pericardial space.

一些主动脉夹层的病例可能会导致主动脉破裂，导致主动脉塌陷，甚至死亡。心脏填塞( )的迹象也可能遇到，如果破裂发生在心包空间。

There have been efforts to construct a clinical decision rule stratify risk of acute aortic dissection and avoid over-investigation. The aortic dissection detection risk score (ADD-RS) combined with a negative d-dimer test has been demonstrated to be effective in reducing unnecessary exams, however, it has not been widely accepted into clinical practice and requires further validation .

已经有努力构建一个临床决策规则分层急性主动脉夹层的风险，并避免过度调查。主动脉夹层检测风险评分(ADD-RS)联合阴性d-二聚体检测已被证明可以有效地减少不必要的检查，然而，它尚未被临床广泛接受，需要进一步的验证。

Pathology 病理学

The normal lumen lined by intima is called the true lumen and the blood-filled channel in the media is called the false lumen. In most cases the vessel wall is abnormal. Causes include:

正常内膜排列的管腔称为真管腔，充满血液的中腔称为假管腔。在大多数情况下，血管壁是异常的。原因包括:

• hypertension (pathogenesis: medial degeneration) 高血压(发病机制:内侧变性)
• inherited connective tissue disorders (pathogenesis: medial degeneration) 遗传性结缔组织疾病(发病机制:内侧变性)Marfan syndrome 马凡氏综合症Ehlers-Danlos syndrome 恰当牵拉
• atherosclerosis (pathogenesis: penetrating ulcer) 动脉粥样硬化(发病机制:穿透性溃疡)
• vasculitis (pathogenesis: inflammation) 血管炎(发病机理:炎症)
• pregnancy (pathogenesis: unknown) 怀孕(发病机理:未知)
• iatrogenic: aortic catheterization, intra-aortic balloon pump 医源性:主动脉导管插入术，主动脉内球囊泵

Radiographic features 影像表现

Imaging is essential in delineating the morphology and extent of the dissection as well as allowing for classification (which dictates management). Two classification systems are in common usage, both of which divide dissections according to the involvement of the ascending aorta:

影像学对于描述夹层剖的形态和范围以及分类（这决定了管理）是必不可少的。有两种分类系统是常用的，它们都根据升主动脉的累及程度来划分夹层:

In recent years, the Stanford classification has gained favor with cardiothoracic surgeons. Approximately 60% of dissections involve the ascending aorta (Stanford A or DeBakey I and II) .

近年来，斯坦福的分类得到了心胸外科医生的青睐。大约60%的夹层涉及升主动脉(Stanford A或DeBakey I和II) 。

Aortic dissection are also sometimes classified as communicating versus non-communicating. 主动脉夹层有时也分为沟通型和非沟通型。

A new classification system was proposed which is referred with the acronym DISSECT (duration, intimal tear, size of dissected aorta, segmental extent of involvement, clinical complications, and thrombosis of the false lumen) . 提出了一种新的分型系统，即首字母缩略词DISSECT(病程、内膜撕裂、主动脉尺寸、节段累及程度、临床并发症、假腔血栓形成)。

Plain radiograph 普通x光照片

Chest radiography may be normal or demonstrate a number of suggestive findings, including: 胸部x片可能是正常的，也可能会有一些暗示性的发现，包括:

• widened mediastinum: >8.0-8.8 cm at the level of the aortic knob on portable anteroposterior chest radiographs , although this upper limit of normal varies (may be significantly larger) depending on projection, FFD and x-ray cassette positioning增宽纵隔:>8.0-8.8 cm，位于便携式胸片的主动脉结处，尽管这一正常的上限值根据投影、FFD和x线盒定位不同(可能更大)而不同
• double aortic contour 双主轮廓
• irregular aortic contour 不规则的主动脉轮廓
• inward displacement of atherosclerotic calcification (>1 cm from the aortic margin) 动脉粥样硬化钙化向内移位(距主动脉边缘1厘米)

Depending on ethology, there may be signs of periaortic or mediastinal hematoma which include:

根据动物行为学，可能有主动脉周围或纵隔血肿的迹象，包括:

• obscuration of the aortic knob 主动脉旋钮（结）模糊
• opacification of the AP window AP窗口的不透明
• deviation of mediastinal structures 纵隔结构的偏移esophagus or NGT to the right 食道或NGT向右trachea to the right 右边的气管left main bronchus inferiorly (decreased angle from the horizontal) 左主支气管下(与水平方向的角度减小)
• increased thickness of the left and/or right paratracheal stripe 增加左侧和/或右侧气管旁条纹的厚度
• apical capping, particularly on the left 顶端封顶，尤指左侧

CT

CT, especially with arterial contrast enhancement (CTA) is the investigation of choice, able not only to diagnose and classify the dissection but also to evaluate for distal complications. It has reported sensitivity and specificity of nearly 100%. CT，

特别是动脉造影(CTA)是首选的检查方法，不仅可以诊断和分类夹层，还可以评估远端并发症。报道的敏感性和特异性接近100%。

Non-contrast CT may demonstrate only subtle findings; however, a high-density mural hematoma is often visible. Displacement of atherosclerotic calcification into the lumen is also a frequently identified finding.

非对比CT只能显示细微的表现；然而，高密度的壁血肿常可见。动脉粥样硬化钙化转移到腔内也是一个常见的发现。

Dissections involving the aortic root should ideally be assessed with ECG-gated CTA which nearly totally eliminates pulsation artefact. Pulsation artefact can mimic dissection, is very common and seen in up to 92% of non-gated CTA studies

理想情况下，涉及主动脉根部的夹层应采用心电图门控CTA进行评估，这几乎完全消除了脉搏跳动的人为因素。搏动伪影可以模拟夹层，非常常见，在92%的非门控CTA研究中可以看到。

Contrast-enhanced CT (preferably CTA) gives excellent detail. Findings include: 对比增强CT(最好是CTA)提供了极好的细节。结果包括:

• intimal flap 内膜的皮瓣
• double lumen 双腔
• dilatation of the aorta 主动脉扩张
• complications (see below) 并发症(见下文)
• an atypical variant that may be seen is an aortic intramural hematoma 主动脉壁内血肿是一种非典型的变异
• Mercedes-Benz sign in the case of a "triple-barreled" dissection 梅赛德斯-奔驰的标志在一个“三桶”的情况下夹层
• windsock sign 风向标信号

An essential part of the assessment of aortic dissection is identifying the true lumen, as the placement of an endoluminal stent graft in the false lumen can have dire consequences. Distinguishing between the two is often straightforward, but in some instances, no clear continuation of one lumen with normal artery can be identified. In such instances, a number of features are helpful:

评估主动脉夹层的一个重要部分是识别真正的腔，因为在假腔内放置腔内支架可能会产生可怕的后果。两者之间的区别通常是直接的，但在某些情况下，一个腔与正常动脉的清晰连续性是无法确定的。在这种情况下，一些表现是有帮助的:

• true lumen 真腔

1. ten compressed by the false lumen and the smaller of the two 常被假腔和较小的假腔所压缩
2. outer wall calcifications (helpful in acute dissections) 外壁钙化(有助于急性夹层)
3. origin of celiac trunk, SMA and right renal artery usually from true lumen 腹腔干、颈动脉和右肾动脉的起源多为真腔

• false lumen 假腔

1. o larger lumen size due to higher false luminal pressures 通常由于假腔压力较大，腔体积较大
2. at risk for rupture due to reduced elastic recoil and dilation 由于减少弹性反冲和膨胀而有破裂的危险
3. beak sign 喙的迹象
4. cobweb sign (as slender linear areas of low attenuation specific to the false lumen due to residual ribbons of media that have incompletely sheared away during the dissection process) .蜘蛛网标志(由于在剥离过程中残留的媒体带未完全剪切掉，所以对假腔具有较低衰减的细长线性区域)
5. often of lower contrast density due to delayed opacification 通常由于延迟混浊而导致对比度较低
6. maybe thrombosed and seen as mural low density only (more common in chronic dissections) 可能只是因为血栓形成和壁状低密度(在慢性夹层中更常见)
7. origin of left renal artery usually from false lumen左肾动脉通常起源于假腔
8. surrounds true lumen in Stanford type A 围绕真正的腔在斯坦福A型

Chronic dissection flaps are often thicker and straighter than those seen in acute dissections.

慢性夹层瓣通常比急性夹层瓣更厚、更直。

Transesophageal echocardiography 经食管超声心动图

Transesophageal echocardiography (TOE) has very high sensitivity and specificity for assessment of acute aortic dissection, but due to limited access and its invasive nature, it has largely been replaced by CTA (or MRA in some instances) .

经食管超声心动图(TOE)对急性主动脉夹层的评估具有很高的敏感性和特异性，但由于其局限性和侵袭性，其在很大程度上已被CTA(或在某些情况下为MRA)所取代。

MRI 核磁共振成像

Although in general MRA has been reserved for follow-up examinations, rapid non-contrast imaging techniques (e.g. true FISP) may see MRI having a larger role to play in the acute diagnosis, particularly in patients with impaired renal function 4. It has similar sensitivity and specificity to CTA and TOE 5 but suffers from limited availability and the difficulties inherent in performing MRI on acutely unwell patients.

虽然MRA一般用于随访检查，但快速非对比成像技术(如真FISP)可能使MRI在急性诊断中发挥更大的作用，尤其是对肾功能受损的患者。它与CTA和TOE 5具有相似的敏感性和特异性，但其有效性有限，并且在对病情严重的患者进行MRI检查时存在固有的困难。

DSA - angiography DSA -血管造影术

Conventional digital subtraction angiography has historically been the gold standard investigation. CTA has now replaced it as the first line investigation, not only due to it being non-invasive but also on account of better delineation of the poorly opacifying false lumen, intramural hematoma and end-organ ischemia.

传统的数字减影血管造影一直是黄金标准的调查。CTA现在已经取代了它作为一线检查，不仅因为它是非侵入性的，而且因为它能更好地描述不透明的假腔、壁内血肿和末端器官缺血。

Angiography still is required for endoluminal repair. 腔内修复仍需血管造影。

Risks of angiography include general risks of angiography plus the risk of catheterizing the false lumen and causing aortic rupture.

血管造影的风险包括血管造影的一般风险以及导管置入假腔和导致主动脉破裂的风险。

Treatment and prognosis 治疗和预后

• aggressive blood pressure control with beta blockers as they reduce both blood pressure and also heart rate hence reduce extra pressure on the aortic wall

积极的血压控制与受体阻滞剂，因为他们降低血压和心率，从而减少额外的压力对主动脉壁

• immediate surgical repair (for type A dissection or complicated type B dissection)

手术修复(用于A型剥离或复杂的B型剥离)

Complications 并发症

Complications of all types

• dissection and occlusion of branch vessels 分支血管的分离和闭塞abdominal organ ischemia 腹部器官缺血limb ischemia 肢体缺血ischemic stroke 缺血性中风paraplegia: involvement of artery of Adamkiewicz 截瘫:亚当维奇动脉受累
• distal thromboembolism 远端血栓栓塞
• aneurysmal dilatation: this is an indication for endovascular or surgical intervention 6 动脉瘤性扩张:这是血管内或外科介入治疗的指征
• aortic rupture 主动脉破裂

A Stanford type A dissection may also result in: 斯坦福A型夹层也可能导致:

• coronary artery occlusion 冠状动脉闭塞
• aortic incompetence 主动脉无能
• rupture into pericardial sac with resulting cardiac tamponade 破裂进入心包膜囊，导致心脏填塞

Although the combination of blood pressure control and surgical intervention has significantly lowered in-hospital mortality, it remains significant, at 10-35%. Over the 10 years following diagnosis another 15-30% of patients require surgery for life-threatening complications. 虽然血压控制和手术干预的结合显著降低了住院死亡率，但仍有显著性，为10-35%。在确诊后的10年里，另有15-30%的患者因危及生命的并发症需要手术治疗。

Differential diagnosis 鉴别诊断

The differential on chest x-ray is that of a dilated thoracic aorta. 胸片上的区别是扩张的胸主动脉。

On CT, a number of entities that can mimic a dissection should be considered: 在CT上，应考虑许多因素可以模拟夹层:

• pseudodissection due to aortic pulsation motion artefact (typically left anterior and right posterior aspects of the ascending aorta) 主动脉搏动造成的假性剥离(典型的升主动脉左前方和右后方)
• pseudodissection due to contrast streaks 由于对比条纹假剥离
• mural thrombus 附壁血栓
• intramural hematoma: really an atypical type of aortic dissection and part of the acute aortic syndrome 壁内血肿:一种非典型的主动脉夹层，是急性主动脉综合征的一部分
• penetrating atherosclerotic ulcer which is part of the acute aortic syndrome 穿透性动脉粥样硬化性溃疡，是急性主动脉综合征的一部分
• adjacent atelectasis 邻近肺不张

Clinically, a number of causes of acute chest pain are often considered:

在临床上，急性胸痛的许多原因通常考虑:

• acute coronary syndrome 急性冠脉综合征
• acute pulmonary embolism 急性肺栓塞
• pneumonia 肺炎
• Bornholm disease: a diagnosis of exclusion, rarely thought about. CT usually normal, or occasionally non-specific pleural inflammation and/or infiltrates. 博恩霍尔姆病:诊断排斥，很少考虑。CT通常正常，或偶尔非特异性胸膜炎症和/或浸润

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關鍵字: 高血压 夹层 主动脉