00:01
When we talk about
aortic dissections,
we use the Stanford
Classification for the most part.
00:07
There is also something called
the DeBakey classification.
00:10
Let's start with the Stanford
classification which is shown here.
00:12
Stanford is divided into type
A and type B dissections.
00:17
So this means that we
involve if it's a type A,
the proximal aorta and it may involve the
distal aorta too but it doesn't have to.
00:26
Anytime we have a dissection
involving the proximal aorta,
above the levels or before
the great vessels of the arch,
that would be a
type A dissection.
00:35
And then, if it involves the
aorta distal to the great vessels
it's called a type B dissection.
00:42
Those two distinctions type
A and type B are important
because type A almost always
require surgical intervention.
00:49
And type B can usually not always
but can usually be managed medically.
00:55
Now DeBakey from Texas,
developed a slightly
different system,
which is not used
as much anymore,
but you may want
to be aware of it.
01:05
And in a Type l dissection.
01:09
It's the entire aorta that has
now got a dissection plane,
the blood gets into the
separating layers of the media
and just unzippers
it all the way down.
01:19
That's a Type l.
01:21
And Type ll dissections
involves the ascending aorta,
but it kind of stops
at the great vessels.
01:27
This may be due to scarring or other
things happening within the aorta.
01:32
And then Type lll is a
classical Stanford Type B.
01:36
Okay.
01:38
So signs and symptoms
of aortic dissection
and they're mostly
compression symptoms.
01:44
So if you have dissection,
you have expansion of the
thickness of the aorta.
01:49
In the same way aneurysms
can cause dysphagia,
so too, can aortic dissection.
01:55
So you can get esophageal
compression associated with that.
01:58
You can get hoarseness because of
impingement of a expanding aorta
and impacting the left
recurrent laryngeal nerve.
02:07
You can get Horner syndrome,
and this is the superior
cervical sympathetic ganglia,
and you get ptosis on that side and
you get anhidrosis and you get myosis.
02:17
So the classic Horner syndrome is
ptosis, that's the eyelid drooping.
02:21
Myosis,
so you get dilation constriction of the pupil,
and you get anhidrosis, you don't
get normal sweating on that side.
02:30
Sudden onset of severe
tearing chest pain is typical.
02:34
It's typically described
as a tearing chest pain
that starts either
in the anterior chest
or starts between the
scapulae in the back
and then progresses
to go more distally.
02:45
And it's described as severe,
terrible, tearing pain
as if you're being stabbed with a knife
and the knife has been dragged down.
02:53
Neurological symptoms can include
syncope, altered mental status, or stroke,
depending on the vessels
that are compromised.
03:00
Also, depending on the
degree of sympathetic tone
that's elicited,
because of the severe pain.
03:05
Painless dissection can occur.
03:08
And in about 10% of individuals,
usually with a connective
tissue disorder,
they may have a transient dissection
that gets initially into the media,
and then luckily finds its way
back in to the lumen of the aorta.
03:24
When that happens,
we don't have a dissection that
goes all the way down aorta,
it only goes for a
very limited period.
03:33
Other kinds of
signs and symptoms.
03:35
So patients will present
with asymmetric pulses.
03:38
Again, depending on where
the dissection occurs,
and the compromise
of vasculature,
you may have more
prominent bounding pulses
in the right side
versus the left side,
or you may have
differential pressure.
03:52
So if I measure blood pressure,
it should be the same in
the right and left arm.
03:56
And not only that, should be pretty
much the same in arms as in legs.
04:00
But if there's an
aortic dissection,
patients will typically have normal
pressure in the right limb,
diminished pressure in the left limb
and diminished pressures in the legs.
04:09
So asymmetric pulses
or asymmetric pressures
are a sign of
aorctic dissection.
04:15
Tachycardia.
04:16
This is in part due to the pain
but it's also because
we now have blood flow
that is not going to the
appropriate locations.
04:24
It's in a false lumen.
04:27
And that is reflected or is felt
by the heart as diminished volume.
04:34
So you can get tachycardia.
04:36
You can get a murmur of aortic
insufficiency or aortic regurgitation,
and that's when you get
dilation of the aortic root
due to the dissection plane.
04:47
That aortic regurgitation
murmur is in a typical location
for the aortic valve left
of the sternal border.
04:54
And it's usually a very soft, high-pitched,
early diastolic decrescendo murmur.
05:00
You also have wide
pulse pressures.
05:02
What does that?
Well it actually means that
the pressure differential
which is normally 120 mm of mercury
systole versus 80 mm of diastole,
that pulse pressure
is 40 mm of mercury.
05:15
When the aortic
valve is regurgitant,
now that pressure
rapidly runs off,
so you will have a peak of 120
and a bottom sometimes a 40.
05:26
So, you have a widened
pulse pressure.
05:30
And on X-ray you can
see sometimes not always
and you shouldn't count on it.
05:35
But you can see a widen mediastinum
and a very prominent aortic knob,
and this is because of
expansion of the aorta.
05:46
Other signs and symptoms depend
on where the dissection plane goes
and depending on what
vessels are compromised
by the movement of
blood in the media,
you can have diminished or
absent peripheral pulses
in one or more extremities.
05:59
The tissue in that area may be very
pale because you're not perfusing it.
06:03
You may have pain associated not
only with the primary dissection,
but with the relative ischemia
of a particular tissue.
06:10
You may also have abnormal
paresthesias, a tingling sensation
because the nerves are not being
perfused and are not working.
06:17
And normal thermal
regulation may be compromised
depending on again where
the dissection is happening.
06:23
You may get motor deficits
affecting the nerves,
but also because of
ischemia of the tissue.
06:31
Long term not longer
term but important,
almost immediate consequences.
06:35
So depending again on where
the dissection plane goes,
if it goes retrograde
into the pericardial sac.
06:42
You will have hemopericardium,
which is demonstrated here.
06:46
That pericardial sac is
tense filled up with blood,
the oxygenated blood from a patient
who had an aortic dissection
that travelled retrograde
got into the pericardial sac
and quickly within about 10 sec,
filled up with 250 cc's of blood and
the patient died of cardiac tamponade.
07:06
You can also have retrograde
dissection around the coronary arteries
that are coming off
the ascending aorta,
in which case that dissection
may compromise the flow
of the coronary arteries giving
rise to a myocardial infarct.
07:19
You can have rupture of a
dissection into the thorax,
hemothorax and exsanguinate
into your thorax,
or exsanguinate
into the peritoneum.
07:28
Or if you're really
really lucky,
you have a dissection, and then it
finds its way back into the lumen,
the normal lumen of the
aorta and all you end up with
is a double-barreled
aorta with a true lumen
and a false lumen where you had
the dissection but you were lucky
and it came back
instead of going out.
07:50
Diagnostics for this and
basically that's going to be
an echocardiogram
or CT angiogram.
07:57
So computer tomography
takes longer
and by introducing dye you potentially
— depending on how the dye is installed —
you may or may not actually
make the dissection worse.
08:10
So echocardiogram is probably
the diagnostic imaging of choice
that can be done very
quickly at bedside.
08:20
The important thing is to be able to tell
the surgeons where is the intimal flap.
08:25
Where is the blood entering
this defective media
and where's the
dissection starting?
Because the surgeon needs to know
that so that when he or she goes in,
they can make sure that
flap is closed off.
08:38
X-ray is used.
08:39
X-rays, simple chest X-rays are
relatively insensitive and not useful
but CT, computerized
tomography angiography
such as what is shown here can
also be very, very helpful.
08:52
The laboratory workup is
basically looking for evidence of
activation of the
coagulation pathway.
08:58
So you look for D-dimers.
09:00
So if a patient has the
right kind of symptomatology
in terms of a tearing
acute onset chest pain.
09:06
Unequal pulses,
a flap that you can demonstrate by
echocardiogram and a positive D-dimer.
09:11
They've got an
aortic dissection,
you need to get them to the
operating room as soon as possible.
09:16
And with that,
we conclude our discussion
on dissections and aneurysms.