dissection occurs when the inner layer of the wall of the aorta tears
and splits open (dissects). This is more likely to occur where
pressure on the artery wall from blood flow is high. A common place is
the ascending aorta, where the aorta originates from the heart’s left
ventricle. When the aortic wall splits, the blood enters the artery
wall under the intima (inner layer). This makes the aorta split
further. The tear usually continues distally (away from the heart)
down the descending aorta and into its major branches. When the
cerebral arteries are involved this can lead to neurological symptoms.
When the visceral vessels are involved this can lead to ischemia of the
The presence of an intima flap is pathognomonic for a dissection.
there is a proximal and a distal tear, blood flows on either side of
the intima layer. Which is the case in the abdominal aorta in this
patient. Sometimes however there is antegrade flow in the true lumen
and retrograde flow in the false lumen. Several examples of antegrade
and retrograde flow in cases of a dissection of the aorta can be found
on www.ultrasoundcases.info category 1.6.5 Aortic dissection
there is no distal tear, blood pools behind the detached intima layer
which leads to a reduction of the lumen and eventualy an
occlusion.Which is the case in the common iliac artery in this patient.
In this case the dissection continued to the left external iliac
artery. In some cases the dissection continues ever more distally.
A case of iliac an femoral artery involvement with severe stenosis can be found on www.ultrasoundcases.info category 10.1.2 Peripheral arteries
The dissection weakens the wall of the aorta which can lead to an aneurysmal dilatation and rupture.
with Marfan's syndrome have a high incidence of developing an aortic
dissection and aneurysmal dilatation at a very young age. In category
1.6.5 of the above mentioned website is a case of a 37 year old patient
with an aortic and iliac dissection and aneurysmal dilatation.
aortic dissection usually causes sudden chest pain. This pain is often
described as very severe and tearing; it’s associated with cold sweat.
Typically the pain moves as the dissection extends distally. Other
symptoms and signs depend on the arterial branches involved.
dissection is more common in males than in females. The male-to-female
ratio ranges from 2:1 to 5:1. The peak age of occurrence of proximal
dissection is between ages 50 and 55. Distal dissection occurs most
often between ages 60 and 70. High blood pressure is the most common
factor predisposing the aorta to dissection. Dissection can also be the
result of a chest trauma
Several different classification systems
have been used to describe aortic dissections. A common classification
is the DeBakey classification system. It categorizes the dissection
based on where the original intimal tear is located and the extent of
the dissection (localized to either the ascending aorta or descending
aorta, or involves both the ascending and descending aorta).
In this patient the dissection originated in the ascending aorta and extended far distally so it is a DeBakey type 1
ultrasound doesn’t show the intrathoracic aorta, the full extend of an
aortic dissection can only be examined with CT or MRI. However since
the initial examination in many emergency departments is still
ultrasound, it is good to be aware of the signs of a dissection. Also
color doppler and spectral doppler can give information about the flow
(direction and velocity) in the true and false lumen.