1. Abdominal Aortic Aneurysm
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R3 김민경/prof. 김 원

2. Definition Abdominal Aortic Aneurysm
Aneurysm occurring in any portion of the infradiaphragmatic aorta
In 1991, Aortic diameter > 1.5 times measured at the level of the renal arteries
J Vasc Surg 1991;13:452-48
Normal value: 2cm (1.4-3cm)
Most AAAs are infrarenal –
patients often have other aneurysms,
including iliac (41%) and femoropopliteal (15%) lesions

3. Epidemiology In USA
Incidence of AAA has increased during the past twe decades and Over the last three decades, incidence has tripled
1% - 5% of general population affected
4% - 8% of the male population aged 60 years or older
1.5 million people have AAAs
15,000 deaths annually due to ruptured AAAs in the US  13th leading cause of death
> 50,000 procedures per year for AAA repair
100,000 – 250,000 new cases discovered each year
Prevalence increases with age
4.8% in men aged years
10.8% in men aged years
% in women

4. Etiology and Risk Factors
Specific cause
Trauma, infection, inflammatory disease(Behcet, Takayasu) connective tissue disorder
Most AAA are non-specific  risk factor*(odds ratio, OR)
Protease-TIMP-2, PAI-1, smoking(5.6), Male sex(4.6), Family history(2)
Atherosclerosis, Hypertension
In smokers, AAA vs Coronary artery dis. = 3:1
In smokers, AAA vs cerebrovascular dis. = 5:1
*Odds Ratios From Aneurysm Detection and Management (ADAM) Veterans Affairs Cooperative Study Group, Ann Inter Med 1997

5. Clinical feature
No obvious symptoms of the disease  detected as an incidental
If symptoms present, the risk of rupture increases
Abdominal pain, Lower Back pain extended to the buttocks, groin or legs, Pulsating sensation in the abdomen
Symptoms indicating a rupture may include:
Sudden onset of severe back or abdominal pain
Dizziness, fainting and/or sudden weakness
Rupture carries a 90% mortality
Approximately 40% of patients with ruptured AAAs die prior to presentation to the emergency department
Only 10% to 25% of individuals with ruptured AAAs survive until hospital discharge

6. Abdominal Aortic Aneurysms How Big is the Problem?
Natural history of AAA
Although, small AAA can become enlarged with time
Mean expansion rate is initially slow and then increases exponentially
Finally RUPTURE or REPAIR may be occur
In US, ruptured AAA : 4 to 5% of sudden deaths, 13th most common cause of death
5 year cumulative rupture rate of incidentally diagnosed AAA : 25 to 40% for > 5cm, compared with 1to 7% for 4.0 to 5.0 cm
Elective repair of AAA is performed with mortality rates averaging less than 5%

7. Risk for rupture Annual rupture risk Rate of expansion
- Ruptured VS non-ruptured: 0.82 vs 0.42cm
Baseline diameter
rate per year
2.8 to 3.9 cm
0.19 cm
4.0 to 4.5 cm
0.27 cm
4.6 to 8.5 cm
0.35 cm

8. Risk for rupture
Rupture risk

9. Why Screen for AAA at All?
The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised controlled trial
Lancet 2002; 360
65-74 aged men
randomised
Control group
Screening group
Mortality follow up
AAA
Not AAA
Screening tool: US
Prevalence of AAA : 4.9%
Repair : 1) diameter ≥ 5.5cm 2) expansion rate ≥ 1cm/year 3) symptomatic AAA
Mean follow up: 4 years
Conclusion: significant reduceds the risk of AAA related mortality by about 50% in men
 Screening for High risk population is recommended
Aneurysm related death
control:screen  0.86:0.49/1000personyears
HR 0.58

10. Screening Guideline United States Prevention Services Task Force
Ann Intern Med. 2005;142
Men and ages 65 to 75, who ever smoked: should be screened on time for AAA by US
ACC/AHA guidelines
Circulation. 2006;113(11):e
Men, 60 years or older, who are either siblings or offspring with AAAs should PEx and US
Men, age 65 to 75, who ever smoked

11. Diagnosis Physical examination: 52% sensitivity
Approximately 30% of asymptomatic AAA are discovered
Imaging studies
Plain abdominal radiograph: “eggshell” pattern of calcification
Ultrasonography: Sensitivity 100%
Iinitial evaluation, screening, surveillance in size
CT and MRI are better : Most precise test
Size of the aortic lumen, Amount and location of mural thrombus, Calcification
Choice for patients with renal insufficiency: MRI
But greater cost, contrast, radiation
arteriography

12. Treatment Medical therapy and surveillance Open repair
Endovascular aneurysm repair
Diameter < 5cm, the annual risk of rupture is similar to or lower than the risk of surgery
UK Small Aneurysm trial
83% men, AAA diameter 4.0 to 5.5cm, asymptomatic
Early elective surgery or surveillance every 6 month
Repair, when > 5.5cm, expansion ≥ 1cm/year, symptomatic
Initial survival disadvantage for early surgery because of a 30day operative mortality
BUT the need for surgical repair of an AAA increases over time

13. Medical therapy and surveillance
Small /intermediate size (< 5.5cm)
ACC/AHA guidelines
4.0 to 5.4: US or CT every 6 to 12 month
3.0 to 4.0: US every 2 to 3 years
Cessation of smoking: with AAA or Family Hx of AAA should be advised to stop smoking and offered cessation intervention
Risk factor reduction : HTN, dyslipidemia for reduction of all cause mortality
Beta blockers: mean expansion rate significant lower
Antibiotic therapy
Roxithromycin for 28days; mean annual expansion rate of the aneurysm was redued

14. When to intervene? Elective repair Symptom, size > 5.5cm,
Rapid expansion rate, Morphologoy (saccular, fusiform with distal embolization or complication)
Consider Risk Factors for Rupture
Size (it really does matter), Hypertension, COPD(smoking)

15. Endovascular versus Open Repair of Abdominal Aortic Aneurysm
The United Kingdom EVAR Trial Investigators*
N Engl J Med 2010;362:
Randomised controlled trial, AAA>5.5cm, Age >60 yrs
Baseline characteristics; no significant differences
Operative mortality: at 30 days after surgery
1.8% in EVAR vs 4.3% in OR

16. Long-Term Outcome of Open or Endovascular Repair of Abdominal Aortic Aneurysm
N Engl J Med 2010;362:
Six years after randomization
 The cumulative overall survival rates were 69.9% for open repair and 68.9% for endovascular repair, for a difference of 1.0 percentage point

17. How best to treatment? Open repair or Endovascular repair Surgery
Elective open repair: Average mortality 4%
Re-intervention rate is lower
Significant short & long-term morbidity and short term mortality
mortality : 3 - 5%, morbidity : %
High risk surgical group : comorbidity
Patients > 75 years of age have a higher perioperative mortality rate
Average 7 to 10 days hospitalization

18. Benefits of EVAR
Lower short term mortality rate and similar overall mortality
Overall lower morbidity
Shorter hospital stay: days vs days
Safer option for high risk patients: most have significant concomitant disease (e.g., CAD, COPD)
Minimal Anesthesia
Patient comfort

19. Summary Men who are 65 to 75 and who ever smoked
Screening for AAA at once by imaging modality
Only 1% of 65 year old men who have a negative US will develops AAA innext 5 years
AAA < 4cm are unlikely to rupture in the next five years
Incidentally diagnosed AAA in population based sample, rupture rate of AAA withdiameter 4 to 5cm : 1-7%
Screening for AAA at once by imaging modality
If Abdominal aorta aneurism present
Management according to guideline
CT angiograph: anatomy, complication, size, ect.
Indicated and if possible, consider endovascular aneurysm repair
Peri- and after- procedure, Risk factor and comorbidity(DM,HTN) control