Aortic dissection: Difference between revisions

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(Created page with "'''Arterial dissection''' occurs when there defect in the arterial tunica intima, leading to blood entering a virtual space between the tunica intima and tunica media. This forms a so-called ''false lumen'' inside this space. Unlike what the image at the top of the page shows, the false lumen may become larger than the true lumen. Blood may flow out of the false lumen through a second intimal tear. The aorta is the artery most often affected by dissection. Aortic dissec...")
 
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'''Arterial dissection''' occurs when there defect in the arterial tunica intima, leading to blood entering a virtual space between the tunica intima and tunica media. This forms a so-called ''false lumen'' inside this space. Unlike what the image at the top of the page shows, the false lumen may become larger than the true lumen. Blood may flow out of the false lumen through a second intimal tear.
<section begin="A&IC" /><section begin="radiology" />'''Aortic dissection''' refers to the [[arterial dissection]] of the aorta and is, like [[aortic aneurysm]], mostly a disease of older men. It’s a quite deadly condition, with high mortality rate even with treatment. It's one form of [[acute aortic syndrome]].<section end="radiology" />
 
The aorta is the artery most often affected by dissection. Aortic dissection is, like [[aortic aneurysm]], mostly a disease of older men. It’s a quite deadly condition, with high mortality rate even with treatment.


Aortic dissection is problematic because it may rupture the aorta, or it may cause downstream ischaemia. If the dissection occurs above where a branching artery originates, the branching artery will no longer be supplied by blood from the true lumen but rather from the false lumen. Circulation in the false lumen is worse than in the true lumen or even completely absent, which may cause ischaemia of supplied tissues. Thrombi may also form in the false lumen, which may embolise.
Aortic dissection is problematic because it may rupture the aorta, or it may cause downstream ischaemia. If the dissection occurs above where a branching artery originates, the branching artery will no longer be supplied by blood from the true lumen but rather from the false lumen. Circulation in the false lumen is worse than in the true lumen or even completely absent, which may cause ischaemia of supplied tissues. Thrombi may also form in the false lumen, which may embolise.
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* [[Cocaine]] use
* [[Cocaine]] use
* [[Thoracic aortic aneurysm]] (especially >6 cm)
* [[Thoracic aortic aneurysm]] (especially >6 cm)
 
<section begin="radiology" />
== Classification ==
== Classification ==
[[File:Stanford types of aortic dissection..png|thumb|290x290px|Stanford types of aortic dissection. The arrows show where the intimal rupture can be.]]
[[File:Stanford types of aortic dissection..png|thumb|290x290px|Stanford types of aortic dissection. The arrows show where the intimal rupture can be.]]
Two classification systems exist for aortic dissections, the Stanford classifications and DeBakey classifications, but the Stanford classification is the one which is used. Stanford type A aortic dissection originates from the ascending aorta and may extend all the way to the iliac bifurcation. Stanford type B aortic dissection originates from the beginning of the descending aorta and may also extend to the bifurcation. Stanford type A is the worst type.
Two classification systems exist for aortic dissections, the Stanford classifications and DeBakey classifications, but the Stanford classification is the one which is used. Stanford type A aortic dissection originates from the ascending aorta and may extend all the way to the iliac bifurcation. Stanford type B aortic dissection originates from the beginning of the descending aorta and may also extend to the bifurcation. Stanford type A is the worst type.
 
<section end="radiology" />
== Clinical features ==
== Clinical features ==
Rupture usually causes sudden severe pain in the chest, back (interscapular), abdomen, or neck. Depending on the complications of the dissection, symptoms of ischaemia of other organs as well as bleeding may also be present:
Dissection usually causes sudden severe pain in the chest, back (interscapular), abdomen, or neck. Depending on the complications of the dissection, symptoms of ischaemia of other organs as well as bleeding may also be present:


* [[Acute myocardial infarction]] – due to involvement of right coronary artery
* [[Acute myocardial infarction]] – due to involvement of right coronary artery
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There are no specific clinical signs. Involvement of the subclavian artery may cause falsely low blood pressure when measured at the affected arm. Difference in radial pulse and brachial blood pressure between the two arms is relatively specific but only occurs in 30% (if the subclavian artery is affected). Absent pulse in carotid or iliac arteries may be a sign that these arteries are blocked by the false lumen. A diastolic murmur may be audible if aortic regurgitation has occured. Absent bowel sounds may be a sign of intestinal ischaemia.  
There are no specific clinical signs. Involvement of the subclavian artery may cause falsely low blood pressure when measured at the affected arm. Difference in radial pulse and brachial blood pressure between the two arms is relatively specific but only occurs in 30% (if the subclavian artery is affected). Absent pulse in carotid or iliac arteries may be a sign that these arteries are blocked by the false lumen. A diastolic murmur may be audible if aortic regurgitation has occured. Absent bowel sounds may be a sign of intestinal ischaemia.  
 
<section begin="radiology" />
== Diagnosis and evaluation ==
== Diagnosis and evaluation ==
[[Chest x-ray]] may be the initial evaluation and may show widened mediastinum and it may be normal.
[[Chest x-ray]] may be the initial evaluation and may show widened mediastinum and irregular contour of the aorta.


The gold standard is [[CT angiography]]. Visualisation of two lumen or an intimal dissection flap gives the diagnosis. [[Echocardiography]] should always be performed to look for cardiac complications.
The gold standard is [[CT angiography]]. Visualisation of two lumen separated by an intimal dissection flap gives the diagnosis. The true lumen is often the smaller of the two. The true and false lumen can also be distinguished based on that the great arteries (coeliac trunk, SMA) usually originate from the true lumen. [[Echocardiography]] should always be performed to look for cardiac complications.


[[ECG]] should always be performed to look for inferior [[AMI]].
[[ECG]] should always be performed to look for inferior [[AMI]].
 
<section end="radiology" />
== Treatment ==
== Treatment ==
Aortic dissection is an emergency and so the patient must be admitted.
Aortic dissection is an emergency and so the patient must be admitted, usually to the ICS.


So-called ''anti-impulse therapy'', involving urgent intravenous antihypertensive treatment to decrease BP and HR (which reduces stress on the aortic wall), is always indicated. This involves [[Beta blocker|beta blockers]] and vasodilators (nitroprusside/nicardipine). The blood pressure should remain < 140/90 for life. Atherosclerotic risk factors should be treated.
So-called ''anti-impulse therapy'', involving urgent intravenous antihypertensive treatment to decrease BP and HR (which reduces stress on the aortic wall), is always indicated. This involves [[Beta blocker|beta blockers]] and vasodilators (nitroprusside/nicardipine). The blood pressure should be decreased to lower-normal ranges.  


Emergency surgery is indicated for Stanford type A dissections, and Stanford type B dissections with complications. Uncomplicated Stanford type B dissections has lower mortality when treated conservatively rather than with surgery.
Emergency surgery is indicated for Stanford type A dissections, and Stanford type B dissections with complications. Uncomplicated Stanford type B dissections has lower mortality when treated conservatively rather than with surgery.
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Possible procedures include Bentall procedure, Frozen elephant trunk, etc.
Possible procedures include Bentall procedure, Frozen elephant trunk, etc.
<noinclude>‎[[Category:Vascular surgery]]</noinclude>
 
For secondary prevention, atherosclerotic risk factors should be treated, and blood pressure should be kept < 140/90.<section end="A&IC" />
<noinclude>‎
[[Category:Vascular surgery]]
</noinclude>

Latest revision as of 12:58, 12 October 2024

Aortic dissection refers to the arterial dissection of the aorta and is, like aortic aneurysm, mostly a disease of older men. It’s a quite deadly condition, with high mortality rate even with treatment. It's one form of acute aortic syndrome.

Aortic dissection is problematic because it may rupture the aorta, or it may cause downstream ischaemia. If the dissection occurs above where a branching artery originates, the branching artery will no longer be supplied by blood from the true lumen but rather from the false lumen. Circulation in the false lumen is worse than in the true lumen or even completely absent, which may cause ischaemia of supplied tissues. Thrombi may also form in the false lumen, which may embolise.

Etiology

The biggest risk factors for aortic dissections are:

Classification

Stanford types of aortic dissection. The arrows show where the intimal rupture can be.

Two classification systems exist for aortic dissections, the Stanford classifications and DeBakey classifications, but the Stanford classification is the one which is used. Stanford type A aortic dissection originates from the ascending aorta and may extend all the way to the iliac bifurcation. Stanford type B aortic dissection originates from the beginning of the descending aorta and may also extend to the bifurcation. Stanford type A is the worst type.

Clinical features

Dissection usually causes sudden severe pain in the chest, back (interscapular), abdomen, or neck. Depending on the complications of the dissection, symptoms of ischaemia of other organs as well as bleeding may also be present:

There are no specific clinical signs. Involvement of the subclavian artery may cause falsely low blood pressure when measured at the affected arm. Difference in radial pulse and brachial blood pressure between the two arms is relatively specific but only occurs in 30% (if the subclavian artery is affected). Absent pulse in carotid or iliac arteries may be a sign that these arteries are blocked by the false lumen. A diastolic murmur may be audible if aortic regurgitation has occured. Absent bowel sounds may be a sign of intestinal ischaemia.

Diagnosis and evaluation

Chest x-ray may be the initial evaluation and may show widened mediastinum and irregular contour of the aorta.

The gold standard is CT angiography. Visualisation of two lumen separated by an intimal dissection flap gives the diagnosis. The true lumen is often the smaller of the two. The true and false lumen can also be distinguished based on that the great arteries (coeliac trunk, SMA) usually originate from the true lumen. Echocardiography should always be performed to look for cardiac complications.

ECG should always be performed to look for inferior AMI.

Treatment

Aortic dissection is an emergency and so the patient must be admitted, usually to the ICS.

So-called anti-impulse therapy, involving urgent intravenous antihypertensive treatment to decrease BP and HR (which reduces stress on the aortic wall), is always indicated. This involves beta blockers and vasodilators (nitroprusside/nicardipine). The blood pressure should be decreased to lower-normal ranges.

Emergency surgery is indicated for Stanford type A dissections, and Stanford type B dissections with complications. Uncomplicated Stanford type B dissections has lower mortality when treated conservatively rather than with surgery.

Surgery involves the replacement of the affected part of the aorta with a prosthesis, or the insertion of a stent graft, or a combination of the two. An affected aortic valve must be replaced.

Possible procedures include Bentall procedure, Frozen elephant trunk, etc.

For secondary prevention, atherosclerotic risk factors should be treated, and blood pressure should be kept < 140/90. ‎