Guidelines
for the management of abdominal aortic aneurysm: comparing the 1992
and the 2003 recommendations
(Portuguese
PDF version)
Américo
Dinis da Gama1
1.
Vascular Surgery Clinic, Hospital de Santa Maria, University of Lisbon,
Portugal.
Correspondence:
Américo Dinis da Gama
Av. das Forças Armadas, 133 Lote D 16º E
1600-081 - Lisbon, Portugal
E-mail: dinisdagama@clix.pt
ABSTRACT
In
this article, a comparison is made between the 1992 and the 2003
recommendations for the management of abdominal aortic aneurysm,
which were published by different subcommittees of the Society for
Vascular Surgery and the American Association for Vascular Surgery.
Substantive differences, both in format and content, can be found
due to the enormous progress and technical achievements which occurred
between 1992 and 2003. The most relevant improvement was the introduction
of the endovascular treatment, which is not yet regarded as a valid
alternative to the conventional surgical treatment, being indicated
only in particular and well defined circumstances. Furthermore,
the spirit of the 2003 recommendations seems to be heavily influenced
by the large transformations in the organization and management
of health care services, as well as the powerful influences and
interests around the medical practice. This fact allows us to conclude,
following Sigerist, that "... changes in medical concepts are
tightly connected to the culture as a whole, and are influenced
by the changes of the ideas of each epoch".
Key-words:
aortic aneurysm, guidelines, therapeutics.
Palavras-chave: aneurisma da aorta abdominal, diretrizes,
terapêutica.
J
Vasc Br 2004;4(1):38-42
In 1992,
a subcommittee assigned by the Society for Vascular Surgery and the
North American Chapter of the International Society for Cardiovascular
Surgery, formed by Larry Hollier, Lloyd Taylor and John Ochsner,1
published a set of recommendations for the surgical management of abdominal
aortic aneurysms (AAA), giving special emphasis to relative or absolute
indications and contra-indications for surgery.
Approximately 10 years later, the same institutions decided to indicate
a new subcommittee for the same purpose as the previous one. It was
then formed by David Brewster, Jack Cronenwett, John Hallet, Wayne Johnston,
William Krupski and John Matsumura.2
Throughout this decade, there have been enormous changes in the clinical
and therapeutic practice in the field of vascular surgery. Undoubtedly,
the most relevant of them was the introduction and diffusion of the
endovascular repair technique, which had a strong impact in the therapeutic
approach to aortic aneurysms, causing a huge debate, which is still
going on, about the advantages and validity of the procedure.
However, there are other aspects which had a relevant role in changing
the criteria and attitude towards the treatment of abdominal aortic
aneurysms which deserve to be emphasized as well. First, some highly
reliable prospective randomized trials were reported comparing results
of the surgical repair with those of the conservative treatment 3,4
in order to establish a better definition for the risk of rupture in
terms of aneurysm diameter; that is, in order to establish the threshold
diameter for surgery, from which the surgical repair is justified and
recommended. There has been significant improvement in imaging diagnosis,
in the study and selection of patients in order to develop a careful
identification of patients at high risk of rupture; methods for previous
or concomitant control and treatment of diseases and comorbid conditions
have been developed as well. Improvements in anesthesia and analgesia,
perioperative and postoperative control and care, cardiovascular pharmacotherapy,
anticoagulant drugs and antibiotic therapy certainly had a marked influence
in the treatment of the aortic aneurysm. Finally, the introduction of
new prostheses, surgical instruments and suture materials also had a
relevant importance in this process and should not be neglected.
Such contributions allowed for more safety and efficacy in the performance
of the surgical procedure, and consequently, had an inevitable impact
in the process of clinical decision-making.
Thus, it is an enticing exercise to compare the 1992 and 2003 recommendations
in order to check what has changed, how it has changed and what impact
they had in current therapeutic indications.
CURRENT
RECOMMENDATIONS FOR TREATMENT OF ABDOMINAL AORTIC ANEURYSM - 1992
Recommendations
for the treatment of abdominal aortic aneurysm were the following in
1992:1
"1. Ruptured AAA:
Indications: any patient with documented or suspected rupture.
Relative contraindications: underlying medical condition that would
otherwise preclude any significant long-term survival (e.g. terminal
cancer); underlying issues relating to quality of life that make repair
unreasonable (e.g. demented elderly nursing home patient).
2. Symptomatic or rapidly expanding aneurysm:
Indications: any patient, regardless of aneurysm size, should be considered
for aneurysm repair.
Relative contraindications: preterminal condition, overwhelming medical
problems, or unacceptable quality of life.
3. Asymptomatic aneurysms:
Indications: aneurysms greater or equal to 4 cm in diameter or a diameter
twice the diameter of the normal infrarenal aorta.
Relative contraindications: life expectancy of less than 2 years, overwhelming
medical problems; unacceptable quality of life.
Relative contraindications to repair of small (smaller than 5 cm) AAAs
- Recent
myocardial infaction (less than 6 months);
- Intractable
congestive heart failure;
- Severe
angina pectoris;
- Severe
renal dysfunction;
- Decreased
mental acuity;
- Markedly
advanced age.
4. Complicated aneurysms:
Indications: embolism, thrombosis, fistulization, or aneurysms associated
with symptomatic intraabdominal occlusive disease, regardless of size.
Relative contraindications: life expectancy of less than 2 years; overwhelming
medical problems; unacceptable quality of life.
5. Atypical aneurysms:
Indications: Dissecting, mycotic, false, or saccular aneurysms, as well
as penetrating ulcers may represent indications for surgical treatment
regardless of size.
Relative contraindications: life expectancy of less than 2 years; overwhelming
medical problems; unacceptable quality of life."
Comments
Indications
for surgical repair of abdominal aortic aneurysms in this set of recommendations
were essentially based on objective data, of morphologic, clinical and
etiopathogenic character.
Documented or suspected rupture was the first indication for surgery;
for elective repair of asymptomatic aneurysms, the threshold diameter
for intervention was 4 cm. However, the presence of symptoms or the
rapid expansion of the aneurysm was a formal indication for intervention,
which, at that time, was exclusively restricted to conventional surgery.
Other indications for surgery included the occurrence of natural complications,
such as peripheral thromboembolism, coexistence of symptomatic intraabdominal
occlusive disease or etiopathogenic factors in which dissecting, mycotic
or false aneurysm were evident (considered formal indications for surgery).
Along with this set of indications, there was a systematic list of random
and imprecise absolute or relative contra-indications, which evidently
depended on medical judgment and which included "life expectancy
of less than 2 years", "overwhelming medical problems"
and "unacceptable quality of life".
It is relevant to mention that the skill and experience of the surgeon,
as well as the will or choice of the patient were not considered as
intervening factors in the process of clinical decision-making.
CURRENTt
RECOMMENDATIONS FOR TREATMENT OF ABDOMINAL AORTIC ANEURYSM - 2003
The recommendations
reported in 2003 are the following:2
"1. The arbitrary setting of a single threshold diameter for elective
AAA repair applicable to all patients is not appropriate, as the decision
for repair must be individualized in each case.
2. Randomized trials have shown that the risk of rupture of small (<
5 cm) AAA is quite low, and that a policy of careful surveillance up
to a diameter of 5.5 cm is safe, unless rapid expansion (> 1 cm/year)
or symptoms develop. However, early surgery is comparable to surveillance
with later surgery, so that patient preference is important, especially
for AAA 4.5 cm to 5.5 cm in diameter.
3. Based upon the best available current evidence, 5.5-cm diameter appears
to be an appropriate threshold for repair in an 'average' patient. However,
subsets of younger, low-risk patients, with long projected life-expectancy,
may prefer early repair. If the surgeon's personal documented operative
mortality rate is low, repair may be indicated at smaller sizes (4.5-5.5
cm) if that is the patient's preference.
4. For women, or AAA with greater than average rupture risk, elective
repair at 4.5 cm to 5.0 cm is an appropriate threshold for repair.
5. For high-risk patients, delay in repair until larger diameter is
warranted, especially if endovascular aneurysm repair is not possible.
6. In view of its uncertain long-term durability and effectiveness,
as well as the increased surveillance burden, endovascular aneurysm
repair is most appropriate for patients at increased risk for conventional
open aneurysm repair.
7. Endovascular aneurysm repair may be the preferred treatment method
for older, high-risk patients, those with 'hostile' abdomens, or other
clinical circumstances likely to increase the risk for conventional
open repair, if their anatomy is appropriate.
8. Use of endovascular aneurysm repair in patients with unsuitable anatomy
markedly increases the risk of adverse outcomes, need for conversion
to open repair, or AAA rupture.
9. At present, there does not appear to be any justification that endovascular
aneurysm repair should change the accepted size threshold for intervention
in most patients.
10. In choosing between open repair and endovascular aneurysm repair,
patient preference is of great importance. It is essential that the
patients be well informed to make such choices."
COMMENTS
As it
can be noted above, recommendations published in 2003 were substantially
different, both in form and content, from those reported in 1992. The
former did not allude to rupture, morphology, natural complications
or etiopathogenic circumstances related to the aneurysm as deciding
factors for surgical intervention.
Based on the results of scientific studies already mentioned, the threshold
diameter for intervention was established as 5.5 cm for the "average"
patient, but intervention may be justified below that level if symptoms
appear or rapid expansion occurs, if the patient is young and has a
prolonged life expectancy or if this is the explicit will of the patient.
The fact that there were two options for treatment did not mean that
they were unequivocally similar. In fact, because of the uncertainties
of long-term results, endovascular repair was only recommended for high-risk
patients, and it may be the preferential approach to a particular subset
of older patients with a hostile abdomen or other relevant clinical
conditions, which restricts its scope. Furthermore, endovascular repair
required a favorable anatomy, which made its use even more restrict,
and, when such requirement were not followed, it may lead to adverse
outcomes, including conversion to open repair and aneurysm rupture.
According to such recommendations, surgical decision-making should also
take into consideration sex, given that the vulnerability of female
patients had already been demonstrated, as well as the experience of
the surgeon, based on her/his operative mortality rate - and such recommendations
are unique to the 2003 report.
Finally, patient preference was presented as an important deciding factor
in opting for one of the methods (which had been totally omitted in
the 1992 recommendations). Thus, it was essential that the patient be
well informed. However, the 2003 recommendations did not discuss who
would provide information to the patient, the degree of neutrality and
the limitations of such information in terms of scientific support,
communicative abilities of the informant or patient's ability to understand.
Such a recommendation was paradoxical given that the authors themselves
expressed their own doubts and uncertainties about the efficacy, risks
and long-term durability of endovascular repair.
DISCUSSION
Comparing
the 1992 and the 2003 recommendations, it is evident that the huge improvements
and achievements which took place during the 1990's lead to significant
changes in therapeutic treatment of abdominal aortic aneurysm . Among
such huge and varied technical progresses, endovascular aneurysm repair
evidently played a dominant role.
Despite accumulated experience and various contributions to the study
of endovascular repair, its efficacy and long-term durability are still
to be demonstrated - and thus it cannot be considered as a reliable
alternative to standard surgical treatment; its use is recommended preferably
to subsets of patients considered "unsuitable" to conventional
repair.
Given that we were devoted to eminently technical aspects of such controversy,
we have not considered that, throughout that period, simultaneous huge
transformations in the organization of medicine and medical care services,
in physician-patient relations and in society as a whole took place.
Such transformations also had a more or less intense impact on the content
of the 2003 therapeutic recommendations of abdominal aortic aneurism.
In fact, putting emphasis on patient preference as a relevant deciding
factor gives rise to a set of circumstances and interests (some of which
are powerful) relating to the patient, which are a paradigm to contemporary
medicine: the right of the patient to health and her/his legitimate
aspirations to a good quality of life and to full and unlimited access
to information; the interests of health insurance companies, of managed
care plans and medical industries; corporative interests of physicians
and their professional, civil and criminal responsibility; and last
but not least, intervention of the judiciary. Such new conditions and
constraints to the medical practice, which naturally influence the process
of decision-making, lead to the so-called defensive attitude of physicians,
which is evident in several of their attitudes and procedures. Among
them is the intension of making the patient participate and assume part
of the responsibility in choosing among the therapeutic options available.
Perhaps, this is the greater difference we could identify in comparing
the "spirit" of 1992 and 2003 recommendations for treating
abdominal aortic aneurysms.
Such a reflection recalls a statement by Sigerist from his Introduction
à la Medecine, published in 1932, with which I close this
article, praising its appropriateness in relation to the topic under
discussion:
"... changes in medical concepts are tightly connected to the culture
as a whole, and are influenced by the changes of the ideas of each epoch".5
REFERENCES
1.
Hollier LH, Taylor LM, Ochsner J. Recommended indications for operative
treatment of abdominal aortic aneurysms. Report of a subcommittee of
the Joint Council of the Society for Vascular Surgery and the North
American Chapter of the International Society for Cardiovascular Surgery.
J Vasc Surg 1992;15:1046-56.
2. Brewster DC, Cronenwett JL, Hallet Jr J, Johnston
KW, Krupski WC, Matsumura JS. Guidelines for the treatment of abdominal
aortic aneurysms. Report of a subcommittee of the Joint Council of the
American Association for Vascular Surgery and Society for Vascular Surgery.
J Vasc Surg 2003;37:1106-17.
3. Mortality results for randomised controlled trial
of early elective surgery or ultrasonographic surveillance for small
abdominal aortic aneurysms. The UK Small Aneurysm Trial Participants.
Lancet 1998;353:1649-55.
4. Lederle FA, Wilson SE, Johnson GR, et al. Immediate
repair compared with surveillance of small abdominal aortic aneurysms
N Engl J Med 2002;346:1437-44.
5. Sigerist HE. Introduction à la Médecine.
Paris: Payot; 1932.
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