Assessment
of mortality in infrarenal abdominal aortic aneurysm repair
(Portuguese
PDF version)
Mônica
Becker1, Telmo Pedro Bonamigo, MD2, Felipe Puricelli
Faccini, MD3
1.
Vascular surgeon, Teaching Hospital of Universidade de Santa Maria,
State of Rio Grande do Sul, Brazil.
2. Associate professor of Vascular surgery, Fundação
Faculdade Federal de Ciências Médicas de Porto Alegre
(FFFCMPA); head of the Division of Vascular Surgery, Hospital Santa
Casa, Porto Alegre, State of Rio Grande do Sul, Brazil.
3. Resident , Hospital Santa Casa, Porto Alegre, State of Rio
Grande do Sul, Brazil.
The present
article is based on the main author's dissertation, and was presented
in November 2001, at FFFCMPA, Porto Alegre, State of Rio Grande do
Sul, Brazil.
Correspondence:
Telmo Pedro Bonamigo
Rua Coronel Bordini, 675/303
CEP: 90440-001 - Porto Alegre - RS
Tel./Fax: +55 51 3333.1642
ABSTRACT
Objective:
Abdominal aortic aneurysm is a disease whose elective surgical treatment
has been widely accepted, since it significantly reduces the rate
of postoperative mortality and increases the patient's life expectancy,
as observed in most specialized services. The present article aims
at assessing the postoperative mortality rate of 600 patients who
had been submitted to elective surgery due to infrarenal abdominal
aortic aneurysm, in addition to assessing the complications, intercurrent
diseases and risk factors associated with mortality in the first
30 days after surgery.
Methods:
The data obtained from the medical records and standard protocols
of 600 consecutive patients with infrarenal abdominal aortic aneurysm,
operated on between 1973 and 1999 were revised and statistically
analyzed.
Results:
The mortality rate in the first 30 days after surgery was 3.3%.
Complications occurred in 142 (23.7%) patients. Bronchopneumonia
was the most frequent complication. The mortality rate in patients
older than 80 years was 13.5%. There was no specific correlation
between associated diseases and risk factors with mortality. Patients
with inflammatory aneurysms showed a 12.1% mortality rate, whereas
those with noninflammatory aneurysm had a mortality rate of 2.8%.
Conclusions:
The results obtained in this study confirm that elective surgery
for infrarenal abdominal aortic aneurysm by the conventional method
offers a low rate of mortality and complications, providing patients
with a longer life expectancy.
Key
words: aneurysm, mortality, abdominal aorta
Palavras-chave: aneurisma, mortalidade, aorta abdominal.
J
Vasc Br 2002;1(1):15-21.
INTRODUCTION
Infrarenal
abdominal aortic aneurysm has become increasingly important, with a
prevalence rate around 2% in male patients older than 60 years. This
prevalence rate has increased in the last few years as people are now
expected to live longer. The mortality rate among patients with aortic
aneurysms may be related to their rupture, which causes abdominal hemorrhage
and requires prompt surgical correction. Therefore, the disease must
be treated in an elective fashion before the aneurysm ruptures so that
complications can be avoided and mortality can be reduced.
The abdominal
aortic aneurysm should be surgically treated by replacing the aneurysmal
dilatation with a vascular prosthesis. The surgical treatment is widely
accepted and yields results in the long run that are already clearly
defined and acceptable for patients at a higher risk of aneurysm rupture.
Patients at higher risk are those whose aneurysm is larger than 5 cm
in diameter, whose obstructive pulmonary disease shows a FEV1 less than
50 %, and those who have diastolic hypertension.
Improved
intraoperative and postoperative care in the last few years contributed
towards the recommendation of this surgery for patients with medium
risk of aneurysm rupture, as those mentioned above. The reduction of
surgical mortality is confirmed by several studies. Among these studies,
the most important was the one published by Crawford et al.,1
who found out a reduction in mortality from 18% in 1960 to 1.4% in 1980
(Table 1).
 Table
1 - Results of abdominal aortic aneurysm surgery in different periods
 |
| Author |
Year |
Initial
Mortality |
Intermediate
period |
Current mortality |
|
| Szilagyi
et al.2 |
1966 |
21%(1952-1955) |
7.2%(1964-1965) |
- |
| Thompson
et al.3 |
1975 |
17%(1954-1961) |
7.4%(1962-1967) |
5.5%(1968-1974) |
| Baird
et al.4 |
1978 |
11%(1955-1964) |
9.8%(1965-1970) |
1.2%(1971-1979) |
| Darling
& Brewster5 |
1980 |
9.6%(1953-1960) |
4.7%(1961-1970) |
1.7%(1971-1979) |
| Crawford
et al.1 |
1981 |
18%(1955-1960) |
4.5%(1966-1975) |
1.4%(1976-1980) |
|
PATIENTS
AND METHODS
The protocols
and medical records of all the patients submitted to elective surgery
of Infrarenal abdominal aortic aneurysm between 1973 and 1999 were
revised. A total of 600 surgeries were performed during that period
by the same surgeon (TPB) and all the patients were included in the
analysis for this retrospective study of mortality. The recommendation
for surgical treatment was based upon the risks each patient presented.
The surgery was indicated for patients with moderate and high surgical
risk whose aneurysms had 6 cm in anteroposterior diameter or whose size
increased by 0.5 cm within one year. Low-risk patients were submitted
to surgery when their aneurysm exceeded 4.5 cm in diameter or had up
to 4 cm in cases in which atherosclerosis was the major reason for surgical
recommendation. The diameter of aneurysms was determined by abdominal
sonogram or computed tomography. Arteriography was used in cases of
suspected distal arterial disease or renal artery disorders.
The surgery
was contraindicated for patients with acute myocardial infarction in
less than six months, decompensated cardiac failure, dyspnea at rest,
permanent neurological deficit, associated kidney disease or other diseases
that suggest a life expectancy lower than two years. The assessment
of risk factors and early morbidity and mortality (30 days after surgery
or during the same hospital admission) was made according to routine
procedures and statistically analyzed by means of a descriptive and
comparative analysis through Student t test and the chi-square test.
The continuous independent variables of the abnormal distribution were
compared with the U-test and the dependent variables were compared with
Wilcoxon test.
RESULTS
Among the
600 patients, 515 (85.8%) were males. The age of the patients ranged
from 40 to 89 years (mean 67.3 years, SD 7.6 ). The age of female patients
averaged 68 years with a 9.1 standard deviation, with no statistically
significant age difference between males and females. The correlation
between surgical mortality and age, and between mortality and gender
was not statistically different up to the age of 75. Patients older
than 80 years showed a mortality rate significantly higher: 13.3% of
a total of 30 patients versus 2.8% among 570 patients (P=0.014).
When the
influence of risk factors on mortality was analyzed, there was no statistically
significant increase in the mortality of patients with renal insufficiency,
smoking habit, chronic obstructive pulmonary disease, systemic hypertension,
stroke, diabetes mellitus, and myocardial infarction (Table 2). Different
causes of death were found, but the major ones were pulmonary embolism
and multiple organ failure (three cases each or 0.5%) (Table 3). The
subgroup of inflammatory aneurysms was associated with a mortality rate
higher than that of noninflammatory aneurysms, that is, 12.1% (four
among 33 patients) versus 2.8% (16 among 567 patients). The comparison
was statistically significant (P=0.004).
Table
2 - Assessment of risk factors and mortality rate in patients submitted
to surgical treatment due to abdominal aortic aneurysm
|
| Associated
factors |
Factors
presence |
Death |
Survival |
Total
|
P* |
|
| Chronic
renal insufficiency |
yes |
3
(8.1%) |
34 |
37 |
|
|
no |
17
(3.0%) |
546 |
563 |
0.231 |
| Smoking
habit |
yes |
14
(3.6%) |
372 |
386 |
|
|
no |
6
(2.8%) |
208 |
214 |
0.764 |
| Chronic
obstructive |
yes |
5
(3.7%) |
129 |
134 |
|
| Pulmonary
disease |
no |
5
(3.7%) |
451 |
466 |
0.985 |
| Systemic
hypertension |
yes |
15
(4.1%) |
348 |
363 |
|
|
no |
5
(2.1%) |
232 |
237 |
0.264 |
| Stroke |
yes |
0
(0%) |
11 |
11 |
|
|
no |
20
(3.4%) |
569 |
589 |
0.821 |
| Diabetes |
yes |
1
(2.8%) |
35 |
36 |
|
|
no |
19
(3.4%) |
545 |
564 |
0.774 |
| Myocardial
infarction |
yes |
7
(4.8%) |
140 |
147 |
|
|
no |
13
(2.9%) |
440 |
453 |
0.535 |
|
*
chi-square test
Table
3 - Causes of early mortality in 600 patients
|
| Cause
|
n.
of patients |
Percentage |
|
| Pulmonary
embolism |
3 |
0.5 |
| Multiple
organ failure |
3 |
0.5 |
| Myocardial
infarction |
2 |
0.3 |
| Stroke
|
2 |
0.3 |
| Prosthesis
infection |
2 |
0.3 |
| Mesenteric
thrombosis |
2 |
0.3 |
| Coagulopathy
|
2 |
0.3 |
| Peritonitis |
1 |
0.2 |
| Renal
insufficiency |
1 |
0.2 |
| Bronchopneumonia
|
1 |
0.1 |
Renal
abscess
|
1 |
0.2 |
| Total
|
20 |
3.3 |
|
Surgical
complications were presented in 142 (23.7%) patients. Of these, 91(15.2%)
had only one complication, 37 (6.2%) had two complications, and 2.4%
presented more than two complications. Postoperative complications were
more frequent among patients with inflammatory aneurysms: 12 patients
(36.4%) versus 130 (22.9%) in patients with noninflammatory aneurysms
(P=0.039). Bronchopneumonia occurred with higher frequency, affecting
4.5% of the patients. Other complications are listed in Table 4.
Table
4 - Complete list of complications and frequency of each complication
|
| Complication |
n.
of patients |
% |
|
| Bronchopneumonia |
27 |
4.5 |
| Pulmonary
embolism |
3 |
0.3 |
| Atelectasis
|
7 |
1.1 |
| Myocardial
infarction |
9 |
1.5 |
| Hypertensive
crisis |
9 |
1.5 |
| Arrhythmia
|
11 |
1.8 |
| Decompensated
cardiac failure |
2 |
0.3 |
| Acute
edema |
2 |
0.3 |
| Stroke |
4 |
0.6 |
| Medullary
ischemia |
1 |
0.2 |
Transient
brain ischemia
|
3 |
0.5 |
| Chronic
renal insufficiency |
16 |
2.7 |
| Urethral
trauma |
2 |
0.3 |
| Vesical
atony |
1 |
0.2 |
| Severe
digestive hemorrhage |
8 |
1.3 |
| Mesenteric
thrombosis |
2 |
0.3 |
| Mild
ischemic colitis |
12 |
2.0 |
| Peritonitis |
1 |
1 |
| Evisceration |
1 |
0.2 |
| Intestinal
obstruction |
1 |
0.2 |
| Infection |
15 |
2.5 |
| Sepsis |
2 |
0.3 |
| Prosthesis
infection |
2 |
0.3 |
|
Of the
600 patients submitted to surgery, twenty-two (3.7%) had to be reoperated;
12 because of bleeding, five due to thrombosis of a prosthetic limb,
two cases due to mesenteric thrombosis and one case because of intestinal
obstruction and evisceration, respectively. The causes for reoperation
of patients with bleeding were splenic trauma (three patients), hepatic
trauma (one), loose sutures (two) and iliac vein injury (one). Two patients
had diffuse bleeding caused by coagulopathy. Three other patients revealed
residual hematoma with no laparatomy-related active bleeding source.
DISCUSSION
AThe surgical
treatment of abdominal aortic aneurysm aims at preventing its rupture,
thus extending patient's life and improving the life expectancy of patients,
which becomes similar to that for individuals in the same age group1.
In addition, it is important to mention that mortality rates related
to elective surgery are approximately 5% at the best centers, rising
to 40-60% in case of surgery of ruptured aneurysm.1-8
The recommendation of elective surgery to treat aortic aneurysm should
take two important aspects into consideration: (1) not every patient
will have a ruptured aneurysm, since most of them die from different
diseases before that happens; (2) a significant number of them die from
a ruptured aneurysm because the aneurysm was not diagnosed and treated
promptly. In another group, the diagnosis had not been previously made
and the rupture may have been the first sign. Therefore, it is important
to identify the patients who are at a greater risk of aneurysm rupture
and at a lower risk of death so that the surgical treatment can bring
real benefits, such as improved life expectancy. The good outcome of
the surgical treatment for patients with aneurysms larger than 6 cm,
symptomatic or with a diameter greater than 0.5 cm in six months, has
been confirmed.9-11 However, the benefits
of a successful surgical treatment are restricted in patients with associated
comorbidities.
Surgical
mortality is a crucial point for the current recommendation of abdominal
aortic aneurysm surgery. The mortality rate varies on a surgeon-to-surgeon
and service-to-service basis. The number of surgeries performed by a
surgeon during one year has been regarded as an important factor for
the reduction of surgical mortality.12-14
The period of time at which the surgeries are performed has been shown
by several authors to reduce the mortality rate (Table 1). Crawford
et al.1 published a study on the improvement of survival rate over time,
showing a reduction in the surgical mortality rate from 18% between
1955 and 1960 to 1.9% in 1979-80. Among the factors that influenced
the reduction of the mortality rate, namely: inclusion technique proposed
by Creech15 in opposition to aneurysmectomy,
systematization of the procedure and constantly updated knowledge about
the ventilatory support of severely ill patients, blood transfusion
and management of postoperative acidosis.
The case
series presented in this article started in the 1970's. Aneurysmectomy
was used in the first 12 cases, whereas the inclusion technique was
used in the remaining cases (588). Over the years, several procedures
were added to the routine of abdominal aortic aneurysm surgery, such
as reduction of blood loss, selective hydration, intraoperative autotransfusion
and standardization of routine intensive care procedures. The case series
was split into two time periods, with the aim of having a current estimation
of mortality and of the different results obtained throughout the years.
The mortality rate in the first 13 years (10 patients operated on per
year) was 4.9%. In the second time period (36 patients operated on per
year), the mortality rate was 2.9% (Table 5). The reduced mortality
rate probably results from the surgeon's experience and from the improvement
of intraoperative and postoperative care. Our study population is similar
to that in several excellent quality services found around the world
in the 1990's.
Table
5 - Mortality in surgery of abdominal aortic aneurysm in two different
periods of time
|
| Period
|
n.
of surgically treated patients |
Average
n. of surgically treated patients/year |
n.
of deaths |
Death % |
|
| 01/12/1973
to 01/12/1986 |
123 |
10 |
6 |
4.9 |
| 02/12/1986
to 01/12/1999 |
477 |
37 |
14 |
2.9 |
| 01/12/1973
to 01/12/1999 |
600 |
23 |
20 |
3.3 |
|
*
chi-square test
Complications
and deaths among our patients have different causes, as shown in Tables
4 and 5. Respiratory diseases are the most common complications, and
they are caused by pulmonary embolism, hyperhydration during blood volume
restoration, postoperative hypoventilation, history of smoking, and
chronic obstructive pulmonary disease. The adequate use of subcutaneous
heparin at low doses, respiratory and motor physical therapy, and analgesia
should be used to minimize the risk factors for pulmonary disease in
the postoperative period.
Cardiac
diseases are quite common in the postoperative period. Some authors
state that 40% of these patients suffer from coronary diseases and that
10% of them should receive previous treatment before aortic aneurysm
surgery.16 The mortality of patients with
severe coronary disease (coronary artery disorders, three vessel disease,
and unstable angina) is three times higher if compared to patients without
such condition.17 Cardiological and hemodynamic
assessment of patients before they are submitted to abdominal aortic
aneurysm surgery is of paramount importance and can reduce the incidence
of complications. Cardiac arrhythmia was observed in 11 patients (1.8%),
who required special heart care. According to Johnston,18,
chronic obstructive pulmonary disease and angina pectoris increase the
incidence of arrhythmia. Therefore, the patients must be monitored and
receive proper cardiological care in the perioperative period.
The complications
or deaths in the postoperative period of AAA surgeries with gastrointestinal
etiology mainly occurred due to the interruption of intestinal vascularization,
of which mesenteric ischemia accounted for two deaths (10% of total
deaths). This complication can be avoided by revascularizing the left
colon through the reimplantation of the inferior mesenteric artery when
it is tortuous and dilated. It is also important to keep the patency
of at least one hypogastric artery. Mild ischemic colitis was observed
in 12 (2%) patients, who responded well to the continuous clinical support
follow-up. Our patients were not submitted to routine colonoscopy; hence,
the 2% prevalence rate might have been underestimated. Ernst performed
routine colonoscopy and diagnosed colonic ischemia in approximately
5% of surgically treated patients.19 Upper
gastrointestinal bleeding from stress ulcer was observed in eight patients,
with no associated death. Such intercurrent disease occurred in the
first years of the series, but drastically decreased with the regular
use of ranitidine in the postoperative period. Atheroembolization of
the superior mesenteric artery branches occurred in one of the patients
in our series, resulting in death.
Prosthetic
vascular graft infection was diagnosed on the 10th and 16th days after
the surgery and accounted for 10% of the deaths (two patients). In both
cases, the prosthesis was removed and the aortic stump was sutured with
axillobifemoral bypass. This severe complication occurred in only 0.3
% of the patients.
As to neurological
complications, two deaths occurred (one due to stroke and the other
one due to a fall). The patient who fell to the ground from his bed
was 83 years old and had subdural hematoma. This patient was operated
on, but died four days after the surgery. Stroke in the postoperative
period of AAA surgeries occasionally occur on patients with remarkable
stenosing lesions to the carotids and with reduced blood flow caused
by the surgical procedure.
Renal complications
are of extreme importance, since they increase mortality in aneurysm
surgeries. Patients with a high creatinine level in the preoperative
period or those who require suprarenal aortic clamping intraoperatively
are at a greater risk for renal insufficiency in the postoperative period.20
The ligation of the left renal vein may be absolutely necessary in some
cases and may determine a certain level of temporary loss of renal function.
Sixteen (2.7%) patients had acute renal insufficiency in our series,
three of them died due to renal insufficiency and multiple organ failure.
Two ureteral lesions were observed in patients with inflammatory aneurysms.
The first one was immediately identified and treated by direct suture,
with a good outcome. The second one was diagnosed on the sixth day after
the surgery and was attributed to late ischemia from electrocautery
burn. The patient needed a nephrectomy, but recovered well.
Age greater
than 80 years has not been regarded by some authors as a limiting factor
for surgical recommendation, since the mortality rate is approximately
5%.21-23 However, other published series
show a mortality rate between 7 and 10 %.24-27
In the present series, the mortality rate was 13,3%. Among the four
patients who died, two had inflammatory aneurysms, which will be discussed
next.
The mortality
rate related to inflammatory aneurysm surgeries has been described as
three times higher than that observed in noninflammatory aneurysm surgeries.
In the present series, the mortality rate for inflammatory aneurysms
was 12.1% in comparison with 2.8% in noninflammatory aneurysms (P=0,004).
The causes of death included mesenteric thrombosis in two cases, multiple
organ failure in one case and prosthetic infection in one case.
Our conclusion
is that infrarenal abdominal aortic aneurysm is a disease that requires
proper treatment and accurate and careful surgical procedures so that
good results can be obtained. The study presented here shows that the
good results depend on the commitment of surgeons, anesthesiologists,
and intensive care professionals towards the patient's well-being.
ACKNOWLEDGEMENTS
The second
author (TPB) would like to thank the following collaborators, who participated
of the surgical procedures as assistants: Clóvis A. Dihel, Ledo
J. Pinto, Airton D. Frankini, Neuza M. Furlan, João C. Martins,
Alexandre Copat, Lucio Siliprandi, Henrique Gude, Ana Lucia Cardoso,
Augusto Nienchenski, Claudia Bianco, Cláudia Milller, Marco A.
Cardoso, Luciano Strelow, Aparecido Lucin, Marcelo Rosa, Leila Funatsu,
Zygmunt Wojeieki, Luis F. Albernaz, Roberto Roncato, Edvaldo Paula Jr.,
Luciano Bazzanela, Esteban Kiss, Herton V. Lopes, Cíntia Schaeffer,
and Elton Weber.
REFERENCES
1.
Crawford ES, Saleh SA, Babb III JW, Glaeser DH, Vaccaro PS, Silvers
A. infrarenal abdominal aortic aneurysm: factors influencing survival
after operation performed over a 25-year period. Ann Surg 1981;193:699-709.
2.
Szilagyi DE, Smith RF, Derusso FJ, Elliott JP, Sherrin FW. Contribution
of abdominal aortic aneurysmectomy to prolongation of life. Ann Surg
1966;164:678-99.
3.
Thompson JE, Hollier LH, Patman RD, Persson AV. Surgical management
of abdominal aortic aneurysms: Factors influencing mortality and morbidity
- a 20-year experience. Ann Surg 1975;181:654-60.
4.
Baird RJ, Gurry JF, Kellam JF, Wilson DR. Abdominal aortic aneurysms:
Recent experience with 210 patients. Can Med Assoc J 1978;118:1229-35.
5.
Darling RC, Brewster DC. Elective treatment of abdominal aortic aneurysm.
World J Surg 1980;4:661.
6.
AbuRahma AF, Robinson PA, Boland JP, et al. Elective resection of
332 abdominal aortic aneurysms in a southern West Virginia community
during a recent five-year period. Surgery 1991;109:244-51.
7.
Bonamigo TP, Von Ristow A. Tratamento Cirúrgico do Aneurisma
da Aorta Abdominal: Indicações, Técnica Cirúrgica,
Intercorrências e Resultados. In: Bonamigo TP, Von Ristow A,
editores. Aneurismas. Porto Alegre: AGE; 1999.
8.
Ouriel K, Geary K, Green RM, Fiore W, Geary JE, Deweese JA. Factors
determining survival after ruptured aortic aneurysm: the hospital,
the surgeon, and the patient. J Vasc Surg 1990;11:493-6.
9.
Batt M, Staccini P, Pittaluga P, Ferrari E, Hassen-Khodja R, Declemy
S. Late survival after abdominal aortic aneurysm repair. Eur J Vasc
Endovasc Surg 1999;17:338-42.
10.
Brown PM, Pattenden R, Vernooy C, Zelt DT, Gutelius JR. Selective
management of abdominal aortic aneurysms in a prospective measurement
program. J Vasc Surg 1996;23:213-22.
11.
Scott AP, Tisi PV, Ashton HA, Allen DR. Abdominal aortic aneurysm
rupture rates: a 7-year follow-up of the entire abdominal aortic aneurysm
population detected by screening. J Vasc Surg 1998;28:124-8.
12.
Katz DJ, Stanley JC, Zelenock GB. Operative mortality rates for intact
and ruptured abdominal aortic aneurysms in Michigan: An eleven-year
statewide experience. J Vasc Surg 1994;19:804-15.
13.
Hannan EL, O'Donnell JF, Kilburn H, Bernard HR, Yazici A. Investigation
of the relationship between volume and mortality for surgical procedures
performed in New York State hospitals. JAMA 1989;262:503-10.
14.
Amundsen S, Skjaerven R, Trippestad A, Soreide O, and Members of the
Norwegian Abdominal aortic aneurysm trial. Abdominal aortic aneurysms.
Is there an association between surgical volume, surgical experience,
hospital type and operative mortality? Acta Chir Scand 1990; 156:323-8.
15.
Creech Jr O. Endo-aneurysmorraphy and treatment of aortic aneurysm.
Ann Surg 1966;164:935-46.
16.
Hallett Jr JW. Current role of coronary revascularization prior to
abdominal aortic aneurysm repair. In: Yao JST, Pearce WH, editores.
Aneurysms: new findings and treatments. New York: McGraw-Hill; 1994.
17.
Hallett Jr JW, Marshall DM, Petterson TM, et al. Graft-related complications
after abdominal aortic aneurysm repair: reassurance from a 36-year
population-based experience. J Vasc Surg 1997; 25:277-84.
18.
Johnston KW. Multicenter prospective study of non-ruptured abdominal
aortic aneurysm. Part II. Variables predicting morbidity and mortality.
J Vasc Surg 1989;9:437-47.
19.
Ernst CB. Prevention of intestinal ischemia following abdominal aortic
reconstruction. Surgery 1983;93:102-5.
20.
Diehl JT, Cali RF, Hertzer NR, Beven EG. Complications of abdominal
aortic reconstruction: An analysis of perioperative risk factors in
557 patients. Ann Surg 1983;197:49-56.
21.
O'Donnel TF, Darling RC, Linton RR. Is 80 years too old for aneurysmectomy?
Arch Surg 1976;111:1250-7.
22.
Petracek MR, Lawson JD, Rhea Jr WG, Richie RE, Dean RH. Resection
of abdominal aortic aneurysms in the over 80 age group. South Med
J 1990;73:579-81.
23.
Dean RH, Woody JD, Enarson CE, Hansen KJ, Plonk GW. Operative treatment
of abdominal aortic aneurysms in octogenarians. When is it too much
too late? Ann Surg 1993;217:721-8.
24.
Dardik A, Lin JW, Gordon TA, Williams M, Perler BA. Results of elective
abdominal aortic aneurysm repair in the 1990s: A population-based
analysis of 2335 cases. J Vasc Surg 1999;30:985-95.
25.
O'Hara PJ, Hertzer NR, Krajewski LP, Tan M, Xiong X, Beven EG. Ten-year
experience with abdominal aortic aneurysm repair in octogenarians:
Early results and late outcome. J Vasc Surg 1995;21:830-7.
26.
Kazmers A, Perkins AJ, Jacobs LA. Outcomes after abdominal aortic
aneurysm repair in those = 80 years of age: recent veterans affairs
experience. Ann Vasc Surg 1998;12:106-12.
27.
Treiman RL, Levine KA, Cohen JL, Cossman DV, Foran RF, Levin PM. Aneurysmectomy
in the octogenarian: A study of morbidity and quality of survival. Am
J Surg 1982;144:194-7.
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