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| Journal of the New Zealand Medical Association,
23-March-2007, Vol 120 No 1251
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Endoluminal repair of abdominal aortic aneurysm: the
Middlemore Hospital experience
Janaka
Wickremesekera, Wilbur Farmillo, Stewart Hawkins, Homayoun Zargar, Anwar
Choudhary, Peter Vanniasingham
Endoluminal stent grafting (ESG) has extensively studied
since Juan Parodi’s first report of abdominal aortic aneurysm (AAA)
stenting in 1991.1 There has been much debate
about whether endoluminal or open repair of AAA is superior technique in term of
risks to the patient and longevity. Most vascular surgeons would agree that both
procedures have an important place in the armamentarium to treat AAA. With the
recent conclusion of randomised trials many of these issues would be shelved,
however there seem to be more questions than answers when looking through the
literature.2–5
Open repair has a proven track record and though has
increased early morbidity and mortality in comparison to ESG, there is no
difference in the mortality figures in the longer
term.5,6 In addition, after open repair there
is little need for long-term surveillance and the associated costs. In other
words, once open repair is performed, the problem usually remains
“fixed”. With ESG complication, the need for reintervention is
required in up to 40% of patients4. It has,
however, been shown that good case selection and planning reduces the risk for
secondary intervention.
The approach at Middlemore Hospital has been of strict
morphological selection criteria of AAA for ESG and a multidisciplinary approach
to planning. The aim of this audit is to show that this policy produces good
results in terms of morbidity and mortality.
MethodsMiddlemore Hospital is a tertiary centre serving a
population of approximately 450,000 people in the south Auckland region. Three
surgeons perform ESG on their patients at Middlemore with respective teams which
include interventional radiologists, nursing and theatre staff. All patients are
discussed at the multidisciplinary planning meeting prior to undergoing
treatment which involve all the above members.
Strict morphological criteria are adhered to including
neck diameter <28 mm or less, neck length >20 mm, and angulation ≤60
degree angle. No circumferential mural thrombus should be present. Iliacs had to
be >7 mm in diameter with minimal tortuosity. On CT there should be no
significant horizontal portion , splaying, or S shape. There should be good
landing zone with a vessel diameter not <22 mm and >20 mm length. Iliac,
or common femoral artery (CFA) aneurysm were excluded. Anything more than
minimal iliac calcification was also excluded.
All patients having had ESG of AAA at Middlemore
Hospital were retrospectively identified from the hospital database. Forty
patients were found to have had ESG and their medical records were reviewed.
Relevant data were collected, particular those
emphasising consistency in preoperative assessment
ResultsAll 40 patients received elective AAA repairs; their
procedures were performed between 1998–2005.
Most patients were male (5:1 male:female ratio); mean age
73.4 yrs (65–88 yrs). All patients were given Anaesthesiology Society of
America (ASA) criteria by the attending anaesthetist. Most (80%) patients were
classified as ASA III (Figure 1). Not surprisingly the most common patient
comorbidities were ischaemic heart disease (IHD), hypertension (HT), and
respiratory problems (Table 1; Figure 2).
Figure 1. Anaesthesiology Society of America
(ASA) criteria
(MMH=Middlemore Hospital; ASERNIP–S=Australian Safety and Efficacy Registry for New Interventional Procedure–surgical)  Figure 2. Comorbidity
distribution
(IHD=ischaemic heart disease; MI=myocardial infarction; HT=hypertension; Pulm(onary); CVA=cerebrovascular accident; DM=diabetes mellitus; CRF=chronic renal failure; Smok(ing)  Table 1. Patient characteristics
Morphology AAA—The majority of AAA were
fusiform morphology (90%)with mean diameter of 5.2 cm(4.3–6.7). The grafts
were bifurcated in the vast majority (39/40) and all were Zenith Cook grafts
(Figure 3).
Preoperative evaluation was extensive and included CT
aortography with 3D reconstruction (Figure 4). Subsequently their case and
investigations were discussed at the multidisciplinary planning meeting.
Figure 4. CT Aortography with 3-D
reconstruction
 All procedures were performed by multidisciplinary team
(MDT) which always included a vascular surgeon and interventional radiologist.
Most procedures were performed in theatre (33/40) and more recently with the
opening of angiography-suite remaining cases were performed there. All patients
had general anaesthetic (GA) for the procedure. All patients had surgical common
femoral artery (CFA) access for their procedures (Figure 5). Procedure time was
variable mean 149 minutes (57–222 min).
Hospital stay was a mean of 5.5 days (vs 7.4 days for ESG
recorded in the Australian safety and efficacy registry for new interventional
procedure-surgical (ASERNIP-S) database) with no patients requiring ICU
admission.
Figure 5. Open common femoral artery
access
All patients were followed up in clinic under strict CT and
Ultrasound-based protocol (see Figure 6) with a mean follow-up 37.9 months
(2–88 months).
Morbidity was categorised into local/graft related and
systemic complications (Table 2). There were 2 patients with endoleak that
required further intervention. Both were type II endoleaks that were sealed with
angiographic coil embolisation. Both patients had successful treatment of
backbleeding vessels.
Three patients had minor groin complications such as
cellulitis and lymph leak that settled again with antibiotics and non-operative
treatment;2 patients returned to theatre for distal embolic complication of
lower limbs. Both had embolectomy which was successful. There was one death
secondary to myocardial infarction giving mortality rate of 2.5%.
Primary technical success was 95%. Secondary technical
success 100%. There were no conversions to open surgery and there were no
procedural-related deaths.
Table 2. Post procedural morbidity of
Middlemore Hospital’s AAA patients
Figure 6. Surveillance protocol for AAA at
Middlemore Hospital
 DiscussionESG of AAA repair has become part of the important part of
the armamentarium of vascular surgeons and interventionalist throughout world.
In larger tertiary institutions ESG is being performed more frequently and with
that experience more challenging cases are
selected.6 However the question is in centres
that are selecting increasingly complex cases is there an associated increase in
procedural related complications and poorer outcomes?
Middlemore Hospital’s AAA patient male:female ratio,
age distribution, and patient comorbidities are similar to other
centres.7–9 It is well known that the
majority of AAA are fusiform, but in our study several patients had saccular
aneurysms.
These aneurysms have a tendency to rupture at smaller
diameters than fusiform aneurysms.10 Also these
patient saccular aneurysms seem to have a higher predicted mortality if their
aneurysms rupture so there is greater benefit to operate on them
early.11 This along with female patient
population caused our mean diameter of operated aneurysms to be at the lower end
of those normally offered surgery. The recent UK Aneurysm Study showed patients
with aneurysms measuring 5.5cm should be offered
surgery.12 However other factors need to be
taken into consideration such as sex of the patient, rate of expansion of the
aneurysm, patient age and comorbidities, life expectancy, and the patient
preferences.13
This audit of experience in a tertiary centre like
Middlemore Hospital where vascular surgeons and their teams have chosen a more
conservative approach shows that with good selection criteria and despite small
numbers good results can be achieved. Low morbidity and primary and
secondary technical success of 95% and 100% respectively, with no conversion to
open surgery or procedural-related deaths (or more importantly no
aneurysm-related deaths) shows good practice at Middlemore Hospital.
The endoleak rate in this series that required further
intervention was 5%. Endoleak can be categorised into five types (see Table 3).
The most clinically relevant are type I and III leaks that result in failure of
exclusion of the aneurysm once the graft is in place.
Type I can occur if there is failure to properly seal the
proximal or distal ends of the graft. Type III is due leakage between modules of
the graft. Endoleak of this nature results in failure of exclusion of the
aneurysm and the sac will continue to expand and risk of rupture persists if the
endoleak is not corrected. These endoleaks should be recognised and corrected
(ideally at the time of the procedure).
Interventionalists debate the significance of type II
endoleaks, as many of these leaks will spontaneously resolve, regardless of
graft type. Additionally, some patients will demonstrate stability or even
shrinkage of the aneurysm sac in the presence of a patent type II endoleak. The
rate of endoleak and the lack of more serious type I and III compares well with
larger randomised series.4 In the EVAR I study
there was 23% rate of endoleak, with 8% requiring reintervention.
We can conclude that the practice in Middlemore Hospital a
tertiary centre with conservative selection and small numbers are good and
compare well with larger centres.
Table 3. Classification of
endoleak
Competing interests: None.
Author information: Janaka Wickremesekera,
Vascular Fellow, Capital Coast Health, Wellington; R Wilbur Farmillo, Vascular
and General Surgeon, Middlemore Hospital; Stewart Hawkins, Interventional
Radiologist, Middlemore Hospital; Homayoun Zargar, General Surgical Registrar,
Hutt Hospital; Anwar Choudhary, Vascular Surgical House Surgeon, Capital Coast
Health, Wellington; Peter Vanniasingham, Head of Vascular Surgery,
Middlemore Hospital, Auckland
Correspondence: Janaka Wickremesekera,
Capital and Coast District Health Board, PO Box 7343, Wellington. Fax: (04) 389
5318; email:Janaka.Wickremesekera@ccdhb.org.nz
References:
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