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Papers of the Month - October 1997
I am reporting briefly on a paper from our lab, presented in
October at the Surgical Forum of the American College of Surgeons
meeting in Chicago. It was presented by Jim Knoetgen, who did the
work. Also, I will briefly summarize the findings of the largest
program to date (73,271 subjects) for AAA screening (The Aneurysm
Detection and Management [ADAM] Veterans Affairs Cooperative
Study). Finally, there will be comments on two recent papers
reflecting progress in the field of bifurcated endovascular grafts.
1. Knoetgen J, Chew DKW, Xia S, and Tilson MD. Detection of
autoantibodies against an aortic antigenic protein as a screening
test for abdominal aortic aneurysm disease. Surgical Forum 48:
401-402, 1997.
Our laboratory has cloned and expressed the cDNA for a recombinant
protein that appears to be "aorta-specific," hereafter called r-
clone 1. Although it is detectable in some tissues other than
aorta, it is abundant only in the aorta. Preliminary experiments
with Western blotting suggested that some patients with AAA have
antibodies against this protein. The present work was done to
develop a screening test by ELISA that would be safe, sensitive,
specific, and inexpensive.
Eighteen of 20 patients tested positive, and none of 10 controls
(with p for the difference in means between the groups = .000006.
Thus, the results with this initial small group (Phase I) are
encouraging. 90% sensitivity is substantially higher than the 65%
sensitivity of the prostate-specific antigen (PSA) test for
detecting curable carcinoma of the prostate. Additional studies
are planned to evaluate the test with a larger number of subjects
(Phases II and III).
2. Lederle FA, et al. Relationship of age, gender, race, and body
size to infrarenal aortic diameter. J Vasc Surg 1997; 26: 595-
601.
All active patients at 15 VA medical centers who were 50-79 years
old were invited by mail to undergo ultrasound measurement of their
aortic diameters as part of the Aneurysm Detection and Management
study. A total of 73,943 subjects (with no known history of AAA)
underwent screening. After excluding the unsuccessful studies,
3366 of 73,271 subjects ( 4.6%) were found to have AAA's, defined
by an aortic diameter of 3 cm or greater. The remaining, 69,905
subjects, are analyzed in the present report.
Age, gender, black race, height, weight, body mass index, and body
surface area were assoicated with aortic diameter by multivariate
linear regression (all p <.001), but the effects were small. The
authors conclude that the use of these parameters to define AAA may
not offer sufficient advantages over the simpler definition of 3 cm
or greater.
Comment by mdt: *Nice* work. The VA ADAM trial is going to produce
a great deal of useful information.
3. Chuter TAM et al. Bifurcated stent-graft for AAA.
Cardiovascular Surgery 1997; 5: 388.
and
Mialhe C, Amicabile C, Becquemin JP. Endovascular treatment of
infrarenal abdominal aneurysms by the Stentor system: Preliminary
results of 79 cases. J Vasc Surg 1997; 26: 199.
Chuter analyzes the results in 57 patients, stratified as first 20,
second 20, and last 17. The AAA was successfully excluded in 55%
of the first 20, 70% of the second 20, and 100% of the last 17.
The steady improvement in the short-term success rate is attributed
to improvements in technique and patient selection.
Mialhe and colleagues report on 71 bifurcated grafts and 8 straight
grafts. There were no surgical conversions. There were four post-
operative deaths (4.8%). 45 patients (57%) had postoperative
fever. In 62 (78%) the exclusion was immediate and definitive.
Seven of the leads were treated successfully by an additional
endovascular graft. During followup, at the time of writing there
had been no ruptures.
Comment by mdt: These improving results are encouraging, but, as
Larry Hollier likes to say, "Don't throw away your scalpels yet."