3分鐘,認識主動脈夾層

熱愛醫學英語，置頂醫學英語詞彙

編輯/校審/拓展 | 馬金傑

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An aortic dissection is where part of the tunica intima (which is the endothelial, or the innermost layer of a blood vessel) of the aorta is ripped off.

主動脈夾層是主動脈內膜撕裂形成的。

（tunica intima是指內膜，血管最裡面那層膜。）

What happens is a tear in the tunica intima of the aorta forms, and the high-pressured blood flowing through the aorta begins to tunnel between the tunica intima and the muscular tunica media, separating the two layers. This is widely accepted as an unideal situation.

在主動脈內膜撕裂時，高壓的血流進入主動脈，開始在內膜和肌性中膜之間形成通道，將內膜與中膜分離。這是一個不理想的情形。

 

Now as the high-pressured blood continues to shear more and more of the tunica intima off the tunica media, blood starts to pool between the two layers, increasing the outside diameter of the blood vessel. The area where blood collects between the intima and the media is called a false lumen, and the true lumen is the regular lumen of the blood vessel.

隨著高壓血流不斷地將越來越多的內膜撕裂，血液開始在兩層膜之間聚集，增加了兩層膜之間的血管直徑。在內膜與中膜之間，由血液聚集形成的腔隙稱為假腔，原來的那個正常的血管腔稱為真腔。

 

Since high pressure is a cause of aortic dissection, it’s no surprise that the aorta is the prime target for this problem.

由於高血壓是主動脈夾層的病因之一，主動脈成為主要的攻擊目標就不驚訝了。

So what causes aortic dissections? Well, chronic hypertension is the major cause, whether the hypertension is caused by stress or from increased blood plasma volume like in pregnancy. Blood vessel coarctation, which is the narrowing of a blood vessel, also can cause a dissection.

那麼，是什麼導致主動脈夾層的？

慢性高血壓是主要的病因，不管高血壓是由於應激還是在妊娠期血漿容量的增加引起，都可引起主動脈夾層。

血管狹窄也是主動脈夾層的病因之一。

 

Aortic dissections most often happen in the first 10 cm of the the aorta closest to the heart. In order for an aortic dissection to occur, an underlying condition usually has to exist that weakens the aorta’s wall. Connective tissue disorders like Marfan’s and Ehlers-Danlos syndrome can cause a dissection, as well as decreased blood flow in the vasa vasorum.

主動脈夾層在主動脈最靠近心臟的10cm最容易發生。主動脈夾層的出現，經常會存在潛在的疾病，它能使主動脈壁減弱。結締組織病，如 Marfan’s and Ehlers-Danlos syndrome可以引起夾層，同樣地，在小血管的血流減少也會導致夾層。

Aneurysms can be a cause of aortic dissection as well, and incidentally dissection can also cause aneurysms because again, the dissection weakens the blood vessel wall.

動脈瘤也可能是主動脈夾層的病因之一，而主動脈夾層也可能導致動脈瘤，因為夾層使血管壁被削弱。

 

In other words, weak walls can lead to outpouching of the blood vessel or a break in the tunica intima, and both of these weaken the walls further.

換言之，被削弱的血管壁可以導致血管外翻或內膜的撕裂，反過來，這兩者也可進一步使血管壁被削弱。

Aortic dissections cause a whole wack load of problems too.

A lot of complications are related to where the blood in the false lumen flows. The blood could flow back up the aorta to the heart and enter the heart’s pericardial space, filling it with blood and causing pericardial tamponade, a really really bad and potentially fatal situation.

主動脈夾層也可以引起很多問題。血液在假腔裡流動，引起可很多併發症。

血液可以回流到主動脈，通向心臟，引起心包填塞，這真的是一個致命的疾病。

The blood flowing through the false lumen could also puncture a hole through the tunica media and tunica externa and bleed into the mediastinum, which would kill you really fast cause that’s a lot of blood leaving the vascular system quickly.

血流通過假腔也可以穿破引起一個孔，通過內膜進入真腔。也可以向縱膈方出血，這可以快速致死，因為大量的血液快速離開血管系統。

 

The tunneling blood could also puncture a hole in the tunica intima and return into the true lumen which isn’t great but hey all things considered, it could be worse.

假腔裡的血液也可以在內膜穿破一個孔，進入真腔，這是一個不好的情況，綜合所有情況，這可能更糟。

Yet another possibility is the blood could continue to tunnel between the tunica intima and the tunica media until it reaches another artery that branches off the aorta, like the renal arteries or the subclavian arteries.

然而，還有一個可能，血液可以一直在假腔裡流動，直到到達主動脈的另一個動脈分支才停止，像腎動脈或鎖骨下動脈。

The blood in the false lumen can put pressure on these branching arteries decreasing blood flow to the kidneys and arms, causing a whole new mess to deal with.

在假腔的血液可壓迫這些動脈分支，導致通向腎臟和手臂的血流減少，引起一個全新的問題來處理。

 

And there you have it. That’s how aortic dissections happen!

你就明白了，這就是主動脈夾層發生的原理。

在人民衛生出版社第八版內科學中：

疼痛是本病最主要和最常見的表現。約90%患者以突發前胸或胸背部持續性、撕裂樣或刀割樣劇痛引起的。

本文僅對視頻內容進行中文翻譯以及進行稍延伸，更多詳情請諮詢醫生或查看教科書。 

參考資料：

人民衛生出版社第八版內科學，主編：葛均波，徐永健

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