Document 9396

Annals of the Royal College of Surgeons of England (1983) vol. 65
ASPECTS OF TREATMENT*
Unoperated Abdominal Aortic Aneurysm:
Presentation and Natural History
E. M. WALKER FRC'S
Senior Registrar
B. R. HOPKINSON FRCS
Consultant Surgeon
G. S. MAKIN FRCS
Consultant Surgeon
University Hospital Nottingham
Key words: ABDOMINAL AORTIC ANEURYSM; RUPTURE; GRAFT; ELECTIVE OPERATION
Summary
The natural history of abdominal aortic aneurysm (AAA) is death
from rupture unless the patient diesfrom another cause prior to rupture.
Elective aortic grafting is the treatment of choice. Following
rupture, emergency operation is the only treatment which will prolong
the patient's survival. Controversy still exists as to the optimum
management in poor risk patients and in those with a small aneurysm.
This paper describes the presentation and natural history of 65
patientis presenting with a ruptured abdominal aortic aneurysm who did
not have an emergency operation, and afurther 27 patients in whom the
diagnosis of intact AAA was made who did not have an elective aortic
replacement graft.
The correct diagnosis was made at the time of admission in only 43
of the 65 patients with ruptured aneurysms. The diagnostic errors and
appropriate investigations in cases of doubt are discussed. The mean
time from admission to hospital to death was 8 hours.
The reasons for not performing an elective operation in the 27
patients known to have AAA are given. .Nine have subsequently died
from rupture. There have been 7 deaths from other causes.
Clinical experience
The incidence of intact abdominal aortic aneurysm (AAA)
found at autopsy is approximately 2°o (1). The natural
history of AAA is death from rupture unless the patient dies
from other causes prior to rupture. Most clinical studies of
patients with unoperated AAA cite a 30-60% incidence of
rupture (2-5), McGregor (6) reported 41 deaths from
ruptured AAA in 9894 consecutive autopsies (0.41o ).
Despite recent advances in the treatment of patients with
AAA the mortality is still 40-600o in those patients operated
on after rupture (4, 7). In contrast the mortality following
elective resection is 2-50O (8). In poor risk patients or those
with small aneurysms controversy still exists as to the
optimum management. In addition there is a small group of
patients who will not accept an operation. Accurate diagnosis is an essential pre-requisite to early operation. In a
retrospective study of 42 ruptured AAA 15 died without the
diagnosis being suspected, and in only half the remainder
was the correct diagnosis made at the time of admission to
hospital (9).
This paper presents details of 65 patients presenting with
ruptured AAA and the natural history of a further 27
patients in whom the diagnosis of AAA had been confirmed
but who did not have an elective operation.
GROUP I 65 PATIENTS PRESENTING WITH RUPTURED
ABDOMINAL AORTIC ANEURYSM AND NOT UNDERGOING
SURGERY
Sixty-five patients presented to hospital during the period
1971-81 and subsequently died from ruptured AAA without
undergoing aortic graft replacement. During the same
period, a further 68 patients were operated on for ruptured
AAA. Of the 65 patients who did not have a graft 53 were
male and 12 female, age range 51-88 years.
Table 1 details the principle presenting symptoms in the
65 patients. Abdominal pain and circulatory collapse were
the two most common presenting symptoms. Back pain was
not a common feature, and no patient presented with lower
limb ischaemic pain. In only 16 was the classical triad of
circulatory collapse, abdominal pain, and an expansile
abdominal swelling present. Thirteen of the patients had a
systolic blood pressure above 100mm/Hg, and in 23 the
systolic pressure was below 70 mm/Hg.
In 43 the correct diagnosis was made at the time of
admission, of whom 6 were previously known to have an
aneurysm. Two had previously refused elective operation,
and 4 had been refused on the grounds of age (82-85 years).
In all but 6 patients some abdominal tenderness was elicited,
TABLE I Presenting symptoms in
65 patients with ruptured aortic
aneurysm
Circulatory collapse
Abdominal pain
Back pain
Vomiting
Shortness of breath
Chest pain
Renal failure
The Editor would welcome any comments on this paper by readers
Fellows and Members interested in submitting papers for consideration for publication
should first write to the Editor
*
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E Al Walker, B R Hopkinson and G S Makin
312
but an expansile abdominal mass was only felt in 29. The
reason for no operation being performed in the 43 patients in
whom the correct diagnosis had been made are given in
Table II. The 2 patients previously known to have an aortic
aneurysm who had refused elective operation also refused an
emergency operation. The most common reason for refusal of
emergency surgery was age. Many of these patients had a
previous history of cardiovascular disease.
The list of erroneous diagnosis which were confused with
ruptured AAA is shown in Table III. In the patient with
renal failure and ischaemic colitis, AAA was the underlying
cause of these conditions, but was unrecognised at the time.
TABLE II Reasons for no operation in patients with the correct
diagnosis of ruptured aneurysm
Age
Died awaiting emergency operation
Died on induction of anaesthetic
Possible dissecting aneurysm
Congestive cardiac failure
Renal failure
Earlier elective operation aborted
Not recorded
Patient refused operation
22
3
3
2
3
Range 76-88
I
I
6
2
TABLE IV Reasons for no definitive operation bein, performed in patients known to
have an intact abdominal aortic aneurysm
Age
Congestive cardiac failure
Patient refused operation
Operation aborted
Small aneurysm
Multiple medical problems
Known carcinoma of stomach
12
5
4
4
2
2
I
grafted. The fourth patient also had an inflammatory sugaricing aneurysm in which the inferior vena cava and the left
renal vein were incorporated in the dense inflammatory
tissue surrounding the aneurysm. Nine of these 27 patients
have subsequently died from rupture of their aneurysm. The
time from diagnosis to rupture varied from 3 months to 6
years (mean 21 months). Six patients have died from causes
unrelated to their aneurysm and in 1 the cause of death was
unknown. Four patients have been lost to follow up and 7
remain alive, 3 of whom have survived more than 6 years
since the diagnosis was made. Of these 3, 2 are the patients
with inflammatory aneurysms, and the third has persistently
refused operation despite the fact that his aneurysm has
slowly been getting larger for 8 years.
TABLE iII Diagnoses confused with ruptured aortic
aneurysm
Myocardial infarction
Carcinoma of stomach
Abdominal tumour
Mesenteric infarction
Cerebrovascular accident
Renal failure
Renal failure and ischaemic colitis
Diverticular disease
Congestive cardiac failure
Gastro-intestinal tract bleeding
Chronic bronchitis
Perforated duodenal ulcer
Ureteric colic
No diagnosis made
4
2
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5
In one of the patients diagnosed as having carcinoma of the
stomach, this diagnosis was confirmed at post-mortem in
addition to his undiagnosed ruptured AAA. In the 3 patients
diagnosed as having mesenteric infarction, gastro-intestinal
bleeding and perforated duodenal ulcer, surgery might have
been undertaken, but none of the patients was referred to a
surgeon.
GROUP 2 27 PATIENTS WITH INTACT AORTIC ANEURYSM WHO
DID NOT HAVE AN OPERATION
In 27 patients a diagnosis of intact AAA was made in whom
elective operation was not performed. The most common
presentations in these patients were abdominal pain (7),
abdominal mass (6), and back pain (3). Seven were found
on routine clinical examination in patients presenting with
unrelated symptoms. The reason for elective operation not
being performed in these patients is shown in Table IV. Age
was again the most common reason for refusal (range 77 to
90 years). In 2 the aneurysm was considered too small to
warrant operation but one of these died 2 years later from
rupture.
In 4 more patients in whom an operation was attempted
and abandoned 1 had multiple congenital venous anomalies,
including a bilateral vena cava. In 1 the aneurysm was
thought to involve the renal arteries, but adhesions from a
previous gastrectomy prevented full dissection. One patient
presented with bilateral hydronephrosis due to retroperitoneal fibrosis. His ureters were freed but the aneurysm
which was of the inflammatory sugar-icing type, was not
Discussion
There must always be some limitations on the conclusions
drawni from retrospective studies, but we believe this study
shows some interesting and important aspects of AAA.
Mortality following rupture of an AAA is so high that no
properly controlled trial of operation versus conservative
management of AAA either ruptured or intact is possible. Of
the 23 patients in whom follow up is available, and are known
to have had an aneurysm managed conservatively 8 (35%/)
died from rupture within 3 years.
Darling (2) from a series of 16483 consecutive autopsies
reported 83 deaths from ruptured AAA (0.50/), and intact
AAA in 199 patients dying from other causes (1.20o)
indicating that fewer than 300, of patients with an AAA
died from rupture. Very few of the patients in this series were
known to have an aneurysm prior to death, and no mention
is made of the number who had had an elective operation for
their aneurysm.
The mean time from diagnosis to death in the present
series of ruptured AAA in whom the correct diagnosis was
made was 8 hours, excluding 3 patients who survived more
than 24 hours. Thus ample time was available to assess the
fitness for operation in the patient with ruptured AAA.
The diagnosis of ruptured AAA is often difficult. In the 16
patients presenting with the classical triad of circulatory
collapse, abdominal pain and an expansile abdominal mass
the diagnosis was made without difficulty. Circulatory collapse may be due to many causes, but in elderly men careful
examination of the abdomen is imperative. An abdominal
mass was not felt in over half the patients. This may be due to
obesity, guarding of the abdominal musculature, or leakage
from a small aneurysm. Some abdominal tenderniess was
almost always present.
The lack of tamponade provided by the retroperitoneal
structures when the rupture is into the peritoneal cavity,
usually results in such profound shock that the patients do
not reach hospital alive, but abdominal distention due to
haemoperitoneum may produce tenderness with no palpable
mass.
Only 3 patients died before emergency operation could be
performed, and in the 22 in whom the wrong diagnosis or no
diagnosis was made, 19 survived more than 2 hours. Ample
time was therefore available for plain abdominal x-ray or
ultrasound examination which might have helped in making
the diagnosis (10).
Linoperated abdominal aortic aneurysm
Janover (11) found that in 18 out of 20 patients with
ruptured AAA the radiographs were diagnostic. The lateral
views of the abdomen are the most valuable, but unless the
possibility of an aneurysm is borne in mind, the radiographs
may be misinterpreted. The more important radiographic
findings in cases of ruptured aneurysm include obliteration of
the psoas shadow, hazy and indistinct margin of the mass
with extension beyond the calcified rim, and displacement of
the bowel gas anteriorly on the lateral film.
The list of diagnostic errors made in the patients with
ruptured AAA is similar to that reported elsewhere (6, 9).
A high index of suspicion is essential if the diagnosis is not to
be missed.
In the 27 patients knowin to have an intact AAA who did
not have an elective operation, the most common reason was
again age (440w). Chang et al. (12) reported a mortality of
1400 in patients undergoing elective operation for AAA over
the age of 70 compared with 4.800 for patients under 70. If
the patient was over 70, had symptoms from his aneurysm
and had 3 or more 'risk factors' (cardiac disease, hypertension, chronic obstructive airways disease, peripheral vascular
disease, cerebro-vascular disease, diabetes, chronic renal
failure, previous pulmonary embolism) the mortality rose to
44()0.
Esselstyne (13) comparing the mortality in elective
on patients over or under the age of 75 found that
olperation
thie operative mortality was not related to age, but was
related to whether or not the patietnt had symptoms from his
aneurvsm (490) vs 12
Man\y authors have reported that the risk of rupture is
related to size (2, 6, 14). Clinical estimation of the size of an
aneurysm by palpation has been shows\n to correlate poorly
with measurement by ultrasound or at operation; whereas
ultrasound and measurement at operaton have been found
to correlate w%-ell (15).
Shumacker (16), and WValker (17) have described dense
peri-anieurvsmal fibrosis. The aneurysmns have a thick firm
smooth w all which is shiny white in appearance. The
histology showed dense inflammatory tissue. The incidence
of rupture was 15"O (3/19) compared with 400O (65/168) in
arteriosclerotic aneurysms. Darke (18) reviewed 27 patients
with ureteric obstruction and aortic aneurysm. Advocating
aneurysmectomy and ureterolysis this group of workers
reported that the ESR fell to normal postoperatively, suggesting that the aneurysm was the primary pathology.
Grafting of these inflammatory aneurysms may, however, be
technically difficult as was the case in two patients presented
hiere.
Conclusions
Approximately half the patients who presented with an
abdominal aortic aneurysm in a 10 year period did not
present uiitil the aneurysm had ruptured.
Thle diagnosis of ruptured abdominal aortic aneurysm will
be missed unless it is specifically considered, and should be
thoughlt of in all elderly patients presenting with abdominal
pain and circulatory collapse, or in whom no other positive
diagnosis can be made.
313
If there is doubt about the diagnosis of ruptured abdominal aortic aneurysm time is available for simple investigations such as plain abdominal radiographs before
irreversible deterioration takes place.
The mortality from rupture in patients known to have an
abdominal aortic aneurysm is so high that conservative
management is unacceptable in all but the very poor risk
patient.
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