4.0-5.4 cm AAA
UK-SAT (Small Aneurysm Trial)
US-ADAM (Aneurysm Detection And Management)
Surveillance upto 4.9 years was a safe alternative to surgery
>60% of the surveillance group in both studies eventually underwent AAA repair because of expansion
and development of sptms
of these, 81% in the ADAM trial had AAA 5.0-5.4 cm
rupture risk was low in both studies (1%/yr)
74% of the total surveillance group ended up having AAA repair within 9 years
ASt 8 years, the estimated risk of death was 7.2% lower in the early-surgery group
however rupture of unrepaired AAA caused only a small proportion of deaths (5%) in men
buit ruptured AAA was the cause of 14% of deaths in women
the risk of rupture was 4 times as high in women than men
the threshold of 5.5 cm may be too high for women
trials for rupture risk by diameter:
-nevitt no rupture during 5 year follow up if < 5cm - 5% annual rupture risk if > 5 cm
-reed, annual rupture risk: 0% (<4 cm), 1% (4-4.9), 11% (5-5.9), 26% (6-6.9)
-UK-SAT, 0.3% <4, 1.5% 4-4.9, 6.5% 5-5.9
-cronenwett, diameter, HTN, COPD were independent risk factors for rupture
-smoking increased rupture by 4.6x fir cigarettes, 2.4x fir cigars, 14.6x for hand rolled cigarettes
-UK-SAT, female gender (3x), larger initial diameter (2.9x per cm), smoking (1.5x), COPD (0.6x per L
FREV1), MAP (1.02x per mm Hg)
Finland: a diameter of 5 cm in a woman is the equivalent of a 6 cm in a man
-Darling, rupture risk increases with family history of rupture (15% with 2 FDRs, 29% with 3 FDRs, 36%
with 4 FDRs
-Verloes, rupture rate was 32% in familial aneurysms, 9% in sporadics
-Rate of AAA to native aorta: a 4 cm AAAin a 1.5 cm native Ao is at greater risk of rupture than a 4 cm
AAA in a 2.5 cm native3 Ao
the validity of this concept however has not been proven
-Eccentric or saccular aneurysms more at risk of rupture than cylindrical
-Vorp et al, using computer modeling, stress is increased by asymetric bulge in AAAs
CAlculated wall stress may become a valuable predictor of rupture
-Faggioli, blebs observed intraop or on CT(5-30mm, areas of focal weakness, marked thinning of
medial elastin) increase rupture risk (71% vs 29%)
-Schurink, a thrombus within a AAA does not reduce either mean or pulse pressure near the aneurysm
and so does not affect rupture risk
-Increased thrombus content within an AAA and the extent of the aneurysm wall in contact with
thrombus appears to be associated with more rapid expansion