A 14 year-old boy is brought into the Emergency 
Department just after midnight after having woken from 
sleep approximately ten minutes ago because of severe 
back pain and abdominal pain radiating into his throat. 
The pain is also described as "pressure" pain.  No 
history of trauma or similar attacks of pain in the past.  
No other concurrent illnesses or symptoms.
     Exam:  VS T35.8 C, P86, R32, BP 110/74, O2 
saturation 100% on room air.  Weight approximately 70 
kg.  He is obviously writhing in intense pain.  Heart 
regular without murmurs.  Lungs sounds are clear on 
auscultation with equal breath sounds bilaterally.  
Peripheral pulses are normal and equal bilaterally.  
Skin is warm and dry.  Abdominal exam is also 
unremarkable with good bowel sounds, and no palpable 
masses or costovertebral tenderness.

     What would you do next?

     At this point, the father settles down enough to be 
able to give you more of a coherent history.  He relates 
to you that he had another son who had died at about 
12 years of age from an aortic dissection and 
subsequent rupture.  A chest radiograph is obtained.

View CXR.

     The CXR is read as being relatively normal although 
there may be a suggestion of some mediastinal 
widening.  A CT of the chest and abdomen is ordered.

View CT.

     The CT of the thorax shows an aortic dissection 
extending from the aortic root to at least the level of the 
renal arteries. In the upper image taken through the 
aortic arch, an intimal flap is visible in the aortic arch 
(black arrow).  In the lower image taken through the 
abdomen, the intimal flap is more obvious in the 
descending aorta (black arrow).  There also appears to 
be an infarcted area in the left kidney.  An aortogram is 
ordered.

View aortogram.

     This contrast study shows the catheter tip at the 
aortic root.  The aortic root is irregular.  Since contrast 
does not enter the carotid vessels, the catheter is 
presumed to be in the false lumen of the aortic 
dissection which is dilated at the aortic root.  An imprint 
of the brachiocephalic artery (a non-contrast filled 
vessel impinging on the contrast filled false aortic 
lumen) is seen overlying the aorta.  Subsequent views 
revealed a complex flap of the dissection in the 
descending aorta.
     Aortic dissection is rare, but catastrophic when it 
occurs.  Therefore, a high index of suspicion and 
appropriate early intervention are paramount if the 
patient is to survive.  The majority of non-traumatic 
causes of aortic dissection occurs in the older 
population, and hypertension is the overwhelming 
leading risk factor.  Those who develop aortic 
dissections under 40 years of age more commonly have 
an underlying connective tissue disorder, congenital 
heart defect, or are pregnant.  For the purposes of this 
teaching case, most of the discussion will focus on the 
younger population.
     Classification of aortic dissection is either by the 
DeBakey or the Stanford types.  The former was 
classified first and divides the types into those involving 
the ascending, transverse, and/or descending aorta 
(Type I), those involving the ascending aorta only (Type 
II), and those involving the descending aorta only (Type 
III).  The latter classification distinguishes dissections 
mainly by the involvement of the ascending aorta:  any 
dissection involving the ascending limb is Type A, and 
those that involve just the descending aorta are Type B.  
Approximately 75% of the cases are of Type A, which 
also is more commonly associated with the younger 
patients and those with connective tissue and 
congenital heart disorders.
     Pathophysiology centers mainly on the integrity of 
the vessel wall. Most cases show a weakening in the 
media including lesions involving smooth muscle, 
elastin and collagen.  In Marfan's Syndrome, medial 
cysts with mucopolysaccharide deposits, disarray of 
muscle fibers, and fragmentation and loss of elastin 
fibers can be seen histologically in the face of 
dissection.  Furthermore, the aortic root is made up of 
approximately 60% elastin and is the most common 
point of dilatation and dissection in these patients.  In 
one study, up to 60% of infants and children under 4 
years old were found to have a certain degree of aortic 
dilatation (Sisk).  Other familial conditions without 
Marfanoid features but presenting with aortic dissection 
include anuloaortic ectasia, familial dissecting 
aneurysm, Ehlers-Danlos Syndrome, and osteogenesis 
imperfecta.  In addition, history of hypertension or a 
specific triggering event is often absent for this 
population.
     Patients may present with a wide range of signs and 
symptoms.  One of the most common (90%) as well as 
the most impressive complaints is excruciating pain.  
This is often described as being "cutting," "ripping," or 
"tearing," and originating in the anterior chest, although 
less commonly in the interscapular, epigastric, and 
lumbar areas.  Back pain also tends to correlate more 
with distal dissections.  Flank pain may suggest 
involvement of the renal arteries.  In addition, the pain 
will usually begin suddenly and will persist unremittingly, 
often inciting the fear of death in the patient.
     Cardiac involvement depends on the site of 
dissection and the location of the external rupture. One 
of the distinguishing features of aortic dissection is an 
elevated blood pressure, which may seem contradictory 
to what one would expect.  This is, in part, due to renal 
ischemia and severe stress.  Hypotension, on the other 
hand, occurs in approximately 20% of ascending 
dissections and is an ominous sign as it suggests a 
significant external rupture.  In fact, rupture into the 
pericardial sac is, unfortunately, relatively common and 
can result in pericardial tamponade.  Syncope may be a 
presenting symptom or sign and almost always reflects 
leaking into the pericardium.  Because of this, syncope 
is usually an ominous sign and, therefore, warrants 
prompt surgical intervention.  Aortic dissection also 
often leads to heart failure secondary to aortic 
incompetence. This may be exhibited by aortic 
regurgitation and can be appreciated as a new diastolic 
murmur.
     Peripheral pulses may also be affected, depending 
on the extent of the dissection.  Pulses in one or more 
extremities may be diminished or even absent.  It is 
important, therefore, to evaluate the quality of pulses 
(and, possibly, the blood pressure) in all four 
extremities.
     Neurologic changes are actually very common 
occurring approximately 40% of the time.  Dissections 
involving the carotid arteries may result in 
encephalopathy or even stroke.  Dissections extending 
through branches supplying the spinal cord may also 
lead to paraplegia.  Aortic dilatation or hematoma within 
a dissection may also compress the recurrent laryngeal 
nerve resulting in Horner's Syndrome and/or 
hoarseness.
     The most critical preliminary diagnostic test for 
suspected aortic dissection is a chest radiograph.  
Aortic shadows are seen in approximately 80-90% of 
the time.  Other initial tests may include a hemoglobin 
and hematocrit, with a low value suggesting an external 
rupture; a urinalysis, with hematuria reflecting renal 
ischemia; and an electrocardiogram to detect 
myocardial ischemia. 
     Once a dissection is suspected, it may be confirmed 
by one of the following tests.  Transesophageal 
echocardiography is gaining popularity as a quick and 
sensitive test that can be performed at the patient's 
bedside.  One study shows a sensitivity of 99% and a 
specificity of 98% with results of the test provided within 
20 minutes (2).  An echocardiogram will also provide 
information on myocardial function, valvular 
insufficiency, and any pericardial effusion.  
Computerized tomography is also gaining favor as it is 
highly sensitive and specific and readily accessible in 
most centers.  The main disadvantage concerns the 
time necessary to perform these tests.  However, 
ultrafast CT has improved the time factor as well as 
heightened the accuracy.  However, the traditional gold 
standard, has been retrograde aortography, which 
involves the use of contrast to determine the full extent 
of the dissection as well as involvement in arterial 
branches.  Magnetic resonance imaging also is an 
option, but the length of time necessary to perform the 
test and the accessibility are the main limiting factors.
     The mainstay of medical treatment revolves around 
controlling blood pressure (systolic and pulse pressure).  
Antihypertensives should be instituted immediately if 
the blood pressure is high, or as soon as possible once 
the pressure is stable and the diagnosis is confirmed.  
The combination of sodium nitroprusside and 
propranolol is most commonly used.  Labetolol can also 
be used as monotherapy or in place of propranolol. 
     Surgical intervention should be started emergently in 
aortic dissection if pericardial tamponade is suspected, 
if there are any signs of shock, or if the dissection is 
progressing.
     Outcome remains relatively poor, but is improving 
with a current mortality rate of 5-30%.  Death is mostly 
due to hemorrhage and heart failure with one study 
finding 93% of deaths secondary to cardiovascular 
complications (5).  For patients with Marfan's Syndrome 
and other connective tissue disorders and congenital 
heart diseases, prevention with routine cardiac 
evaluations as well as elective, prophylactic surgical 
intervention (when indicated) are currently the best 
means of minimizing poor outcome.
     In summary, aortic dissection and rupture is very 
rare, but must be considered in patients presenting with 
acute, intense chest pain.  A good history and physical 
exam should lead the examiner to suspect this 
diagnosis, and successful outcome will be determined 
by timely intervention.

References
     1.  Wernly JA.  Thoracic Aortic Dissection.  In:  
Crawford MH (ed).  Current Diagnosis and Treatment in 
Cardiology, 1st Ed., 1995, Norwalk, Appleton & Lange, 
pp. 456-468.
     2.  Erbel R et al.  Detection of Aortic Dissection by 
Transesophageal Echocardiogram.  Br Heart J 
1987;58:45.
     3.  Fuster V, Ip JH.  Medical Aspects of Acute Aortic 
Dissection.  Seminars in Thoracic and Cardiovascular 
Surgery 1991;3(3):219.
     4.  Roman MJ, Devereux RB.  Heritable Aortic 
 Diseasea.  In Lindsay J (ed).  Diseases of the Aorta. 
 1994, Philadelphia, Lea & Febiger, pp. 55-74, 127-143.
     5.  Murdoch JL et al.  Life Expectancy and Causes 
 of Death in the Marfan's Syndrome.  N Engl J Med 
 1972;286:804.
     6.  Sisk HE et al.  The Marfan Syndrome in Early 
 Childhood: Analysis of 15 Patients Diagnosed at less 
 than 4 Years of Age.  Am J Cardiol 1983;53:353.