Chris Imray
Consultant Vascular, Endovascular and Renal Transplant Surgeon,
University Hospitals Coventry and Warwickshire NHS Trust
Abdominal aortic aneurysms – A silent killer
Recent developments and their implications
Aims
The brief is for me was to present to you on
- aortic aneurysm, morbidity and mortality
- how modern treatments might influence these
- the implications of a national screening
programme producing an overall improvement in
mortality
- the possibility of non-disclosure of the
condition in its early stages to an insurance company
Deaths due to cancer and CVD by decade
Aortic aneurysm, morbidity and mortality
• An abdominal aortic aneurysm (AAA) is a
permanent dilation of the abdominal aorta
greater than 3 cm in diameter
• The natural course is one of progressive
enlargement, and maximum aortic diameter
is the strongest predictor of aneurysm
rupture
Aortic aneurysm, morbidity and mortality
• The reported incidence of AAA is 4.9-9.9%
and mortality after rupture exceeds 80%,
accounting for 8000 deaths annually in the
United Kingdom
• Elective surgical repair has an operative
mortality of 1-5% in the best centres, and
several countries have implemented
population screening programmes to
reduce aneurysm related mortality
AAA ESSENTIALS
Definition
•
Diameter of the aorta 1.5 times (3.0cm)
greater than normal.
•
Most are infrarenal, and a significant
number extend down into one or
both iliac arteries.
Incidence and Mortality in the UK
Around 6,000 deaths each year in England and Wales from
ruptured AAA
Deaths from AAA account for around 2% of all deaths in men
aged 65 and over
Around 4% of men aged between 65 and 74 in England have an
AAA (approx. 80,000 men)
Incidence in women much lower (1/3-1/4)
Vascular disease (including death from ruptured AAA) accounts
for 40% of UK deaths
Diagnosis
•
•
•
•
History
Examination
Ultrasound
CT / MRA
Natural history of the disease
La Place’s Law
Annual rupture rates of abdominal aortic aneurysms according to size
(based on pooled available data).
Thompson M M , Bell P R F BMJ 2000;320:1193-1196
©2000 by British Medical Journal Publishing Group
AAA Surgery
• Performed because of natural history of
AAA expansion and risk of death
• There is also morbidity due to arterial
thromboembolism to legs
• Therefore surgery is recommended in
AAA over 5.5 cm
• 2002 study showed no benefit to
surgery on small (4-5.5) aneurysms
History of treatment options
•
•
•
•
Ligation
Coil
Wrap
Graft
• Inlay graft
• Endoluminal
Modern treatments
REPAIR OPTIONS
Open Surgery
•
•
•
Requires large abdominal or flank incision
Retroperitoneal dissection and exclusion of the aneurysm by clamping
the aorta
Removal of the affected aorta and replacement with surgical graft
Average hospital stay: 7-14 days
Average recovery time: 1-3 months
3-6% mortality
REPAIR OPTIONS
Endovascular Surgery
•
•
Requires two small incisions in the groin area.
An endovascular graft is inserted through the femoral artery
via a catheter and deployed inside the lumen, relining the aorta.
Average hospital stay: 2-3 days
Average recovery time: 1-2 weeks
1% mortality
Fitness for surgery
VO2 Max and anaerobic threshold
• VO2 Max: Maximum uptake of oxygen (ml/kg/min).
• AT:
Level of physical performance at which lactic acid
production exceeds clearance by the liver and muscle enzyme
systems.
Cardio pulmonary exercise testing and surgical outcome
• A minimum aerobic (AT) capacity is required to survive the
stress of a major operation
• Anaerobic threshold < 11ml/kg/min is associated with poor
outcome from surgery
Deaths AT< 11
Deaths AT>11
Risk Ratio
18%(10/55)
0.8%(1/32)
24(3.1-183)
Old et al Chest 1993
Mortality (%) at one month following elective AAA surgery
60
Mortality at one month %
50
40
95% confide
95% confide
30
Mortality
20
10
0
6.7
7.5
8.3
9
9.7
10.5 11.3
12
12.7
13.5 14.3
15
15.7
16.5 17.3
Anaerobic threshold mls O2/kg/min
Carlisle and Swart BJS 2007
18
18.7
19.5 20.3
Pre-operative Cardiopulmonary Exercise Test stratification in
Elective Abdominal Aortic Aneurysm Surgery reduces length of
inpatient stay and costs.
Data on 237 consecutive patients considered for elective
(open/EVAR) AAA repair between November 2007-July 2011
were compared with a control group of 128 consecutive
unselected elective AAA repair patients.
CPEX-failed patients suffered higher mortality than the CPEXpass cohort (21.6% vs 8.9%; p<0.05) although aneurysmrelated mortality was equivalent (5.4% vs 2.2%; p=NS).
Selected CPEX-fail patients were offered EVAR.
CPEX-pass open AAA patients required a significantly shorter
ITU stay (3.5 vs 12.9 days; p<0.01) and total length of inpatient
stay (12.8 VS 16.5 days; p<0.05) than unselected elective open
AAA patients between 2003-2007.
World Health Organization —Principles of Screening
• The condition should be an important health problem.
• There should be a treatment for the condition.
• Facilities for diagnosis and treatment should be
available.
• There should be a latent stage of the disease.
• There should be a test or examination for the condition.
• The test should be acceptable to the population.
• The natural history of the disease should be adequately
understood.
• There should be an agreed policy on who to treat.
• The total cost of finding a case should be economically
balanced in relation to medical expenditure as a whole.
Advantages vs Disadvantages
•
False positives.
•
Screening involves cost and use of medical resources on a majority of
people who do not need treatment.
•
Adverse effects of screening procedure (e.g. stress and anxiety,
discomfort, radiation exposure, chemical exposure).
•
Unnecessary investigation and treatment of false positive results.
•
Stress and anxiety caused by prolonging knowledge of an illness
without any improvement in outcome.
MASS Trial
Analysis of the 10-year Multicentre Aneurysm Screening Study
(MASS) data shows that the NHS AAA Screening Programme will
prevent significant numbers of AAA ruptures and AAA deaths.
It also proves that the number of lives saved will greatly outweigh
the number of post-elective surgery deaths.
The following figures use the 10-year MASS data and assume an
80% attendance for screening and a 5% post-elective surgery
mortality:
240 men need to be invited (192 scanned) to save one AAA death
over 10 years
Thompson S G et al. BMJ 2009;338:bmj.b2307
Cumulative deaths related to abdominal aortic aneurysm, by time since
randomisation.
Thompson S G et al. BMJ 2009;338:bmj.b2307
©2009 by British Medical Journal Publishing Group
Impact of screening
The screening process
All men living in an area covered by the screening
programme are automatically invited for screening in the
year they turn 65. Men who are older than 65, and who have
not previously been screened or treated for an abdominal
aortic aneurysm, can opt-in through self-referral direct to the
screening programme.
Men receive an invitation leaflet with an appointment time
three weeks in advance.
If the man accepts the invitation an ultrasound scan of the
abdomen is carried out and the aortic diameter measured.
Results are provided verbally immediately after the scan and
in the post shortly afterwards.
Non-disclosure
Rupture >80% mortality
AAA Summary
1. Aortic aneurysm, morbidity and mortality
2. Modern treatment might influence these
3. National screening programme producing an
overall improvement in mortality
4. Possibility of non-disclosure to an insurance
company.
Thank you