Acute Aortic Disease.. - Index of

340 Elefteriades
of physicians on the front lines of chest pain evaluation— especially
emergency physicians and primary care doctors. The very process of
including these diseases in the differential diagnosis of chest or abdominal
symptoms will suggest that studies be done to rule these diseases in
or out—the first step in preventing catastrophic oversight.
2. Perform simple pertinent blood tests, including a D-dimer. Creatine
phosphokinase isoenzyme and troponin levels are useful in ruling in or
out myocardial infarction. If these enzymes are negative, aortic disease
must rise in the differential diagnosis of acute chest pain (this is especially
true if the electrocardiogram (EKG) fails to show suspicious ST
or T-wave changes of ischemia or infarction). The D-dimer is another
useful test. D-dimer is a degradation product of fibrin crosslinking in
clot. This test is sensitive for detecting on-going intravascular thrombosis.
Emergency physicians are familiar with ordering this test to rule out
pulmonary embolism. This test has a high sensitivity for that purpose.
Less well known is the fact that D-dimer is nearly invariably elevated in
acute aortic dissection. The sensitivity of this test is 99% (16). If the Ddimer
is negative, acute aortic dissection is essentially ruled out. This is
probably true because significant amounts of clot form quite quickly in
the false lumen of any dissection, liberating D-dimer. In fact, the degree
of elevation of D-dimer correlates with the longitudinal extent of the
dissection, suggesting that surface area for contact of the bloodstream
with the dissection plane determines D-dimer release. A large body of
knowledge has now accumulated supporting the application of D-dimer
in aortic dissection (20–23). In fact, bedside kits are now available (24).
A recent paper has shown an extremely high sensitivity and specificity
(90% and 97%, respectively) for aortic dissection of a test called smooth
muscle myosin heavy chain assay (25). However, this test is not widely
and immediately available in the clinical setting.
3. Image freely, including the “Triple Rule-Out.” In many of the cases we
studied, no imaging studies whatsoever were done, not even a chest
X-ray. Had imaging been done, the lawsuit would have been prevented
and, quite possibly, the patient’s life saved.
a. Chest X-ray. The chest X-ray can certainly provide useful clues—
such as prominence of the ascending aorta to the right of the upper
mediastinal contour, indistinctness of the aortic knob, and widening
or distortion of the descending aortic stripe. Also, pulmonary congestion
can be a helpful indicator of cardiac issues. We suggest this test
as a minimum in patients with chest, or even abdominal, symptoms.
b. Echocardiogram. The transthoracic echocardiogram is available on
an urgent basis in nearly all emergency rooms. This test is highly
sensitive for ascending dissection. It may show enlargement of the
ascending aorta, a dissection flap, or aortic insufficiency—all clues
to the existence of an aortic dissection.