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AorticDissection.com-D-Dimer Test |
Just thought that you should get the word
out that there is a recent blood test that is great for aortic
dissection. Most of the work on this was in Europe.
Basically, it has been found that all acute aortic dissections thus
far checked have an elevated d-dimer blood test and there have been no
acute aortic dissections that have had negative d-dimer tests.
This was discovered recently by Weber and others. It was
discovered because a d-dimer test was developed to detect blood
clotting such as in pulmonary emboli and DVT (deep venous thrombosis)
in the legs. The current procedure to rule out a pulmonary
embolism is a Chest CT (done for a positive d-dimer) with a number of
dissections then discovered by accident. They then checked autopsy
records of people sent home that died of a dissection and then checked
hospital records, and sure enough, those that had a d-dimer test were
positive. Many of those people had a nuc med lung scan instead
of a CT to exclude PE (only the CT will discover the dissection
by accident).
Dean Easton MD, Radiologist
Las Vegas, NV
http://www.labtestsonline.org/understanding/analytes/d_dimer/test.html
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Hi,
Here are some articles on the d-dimer test
now being a good test for aortic dissection. Basically, if
positive, DVT, PE, and aortic dissection need to be excluded with a CT
of the chest and Doppler venous study of the legs.
Dean Easton MD
http://www.aemj.org/cgi/content/abstract/11/4/397
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Brian,
An elevated d-dimer can also be reflective of other medical
conditions/illnesses. Thus, although it can suggest the possibility
of an acute dissection, it is certainly not diagnostic of one and
other tests (CT, TEE) would be necessary to confirm the diagnosis.
The most impt thing at this point in time for diagnosing a
dissection is a high index of suspicion on the part of the ER doc.
Ed Chen
Hi,
--I agree. A positive test can be positive for a number of
other reasons, but if you have a positive d-dimer, a TEE or CT
should be done to exclude dissection, along with a CT to exclude
PE, and a Doppler venous ultrasound of the legs to exclude DVT.
--The major impact of this test is to prevent people with
subtle aortic dissection symptoms from being sent home from the ER
as "OK". Vague or no chest pain and a number of other
subtle symptoms of aortic dissection can bring one to the ER, and
without a family history or Marfans look or hypertension or other
more classic clues, aortic dissection can be missed (historically
up to 1/3 in the past). The people with the classic severe
"tearing" or "ripping pain" always get scanned. It is the
more vague presentations that tend to fall through the cracks.
Hence the need for an extremely high level of suspicion or
paranoia by the ER doc that any seemingly innocent symptom might
be a dissection (as a way catching some of that 1/3).
Routine d-dimer blood tests on all vague chest symptoms will help
prevent that 1/3 from being sent home, without a lot of expensive
testing on normal people due to that healthy high level of
paranoia on the part of the ER doc. Thus far all
acute aortic dissections that have also had a d-dimer test done
(in the literature) have had positive d-dimers. No acute
aortic dissections (in the literature) have thus far had negative
d-dimers.
--Chronic dissections seem to have lower and possible eventually
normal d-dimer levels, and there was a Japanese article, saying
that a d-dimer level may be useful in following Standford B (DeBakeyIII)
dissections for possible signs of re-activation or progression
despite medical therapy (another red flag for ordering a repeat CT
to assess for interval change).
--A negative test however does not mean that you won't get
an acute aortic dissection tomorrow, it only means that you
probably do not have one right now.
Dean Easton MD, Radiologist
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D-dimer in acute aortic dissection.
Weber T, Hogler S, Auer J, Berent R, Lassnig E, Kvas E, Eber B.
Cardiology Department, General Hospital of the Barmherzigen
Schwestern, Wels, Austria. webertom@aon.at
STUDY OBJECTIVE: Laboratory testing plays a minor role in the
assessment of aortic dissection. Its main value is in the
exclusion of other diseases. Following an incidental observation,
we systematically investigated the relationship between elevated
d-dimer levels and acute aortic dissection. DESIGN: We
prospectively tested d-dimer levels in patients with suspected
acute aortic dissection (10 patients). In addition, we
investigated 14 patients who had received a confirmed diagnosis of
thoracic aortic dissection during the previous 5 years, in whom d-dimer
testing had been performed for differential diagnosis. Thirty-five
patients with acute chest pain of other origin served as a control
group. SETTING: Tertiary referral hospital. PATIENTS: Twelve
patients had type A dissection (Stanford classification), and 12
patients had type B. MEASUREMENTS AND RESULTS: A d-dimer analysis
was performed (Tina-quant assay; Roche Diagnostics; Mannheim,
Germany) [normal limit of the assay, 0.5 micro g/mL]. The result
of the d-dimer test was positive (ie, > 0.5 micro g/mL) in all
patients (sensitivity of the test, 100%) with a mean value of 9.4
micro g/mL and a range of 0.63 to 54.7 micro g/mL. The degree of
the elevation was correlated to the delay from the onset of
symptoms to laboratory testing (mean, 12.6 h; range, 1 to 120 h)
and showed a trend to the extent of the dissection, but not to the
outcome (14 patients could be discharged; 10 patients died).
CONCLUSIONS: Based on our observation, we suggest that testing for
d-dimer should be part of the initial assessment of patients with
chest pain, especially if aortic dissection is suspected. A
negative test result makes the presence of the disease unlikely.
PMID: 12740250 [PubMed - indexed for MEDLINE]
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Hi Brian,
On researching aortic dissection, I did come
across something that might be important.
There is a food that is associated with
aortic dissection: sweat peas.
If rats are given a diet of 50% sweat peas,
many will get aortic dissections.
The cause has actually been well studied and
is well known in poorer areas of the world where in times of
drought, the peas are often the only thing left in the fields
that are still green and edible.
Grass peas (Lathyrus sativus even causes
neurologic symptoms).
Sweet peas (Lathyrus odoratus) contain a
toxic nonprotein amino acid (beta amino-proprionitrile) that
affects the cross-linking of the molecules of collagen, (making
aortas and tendons weaker).
So for what it’s worth, it might be a good
idea to stay away from sweat peas.
Later,
Dean
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