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Aortic dissection: Difference between revisions
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'''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 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" /> | ||
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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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 | [[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 | 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. | ||