Objectives: To study 40-55 mm aneurysms and calculate their size in relation to the individual predicted normal aortic diameter to see if this might add anything in the evaluation of treatment.
Material and methods: The anteroposterior diameter of 40-55 mm AAAs was measured with an echo-tracking ultrasonic technique in 147 consecutive patients. The weight and height were registered and body surface area calculated. The predicted normal aortic diameters were defined according to nomograms and the diameter increase from the predicted normal aortic size in the individual aneurysms calculated.
Results: The median AAA diameter was 48 mm (range 40-55), the BSA 1.85 m2 (1.42-2.37), and the predicted AO size 19.4 mm (14.3-21.6). The calculated increase of size in the individual aneurysms was 2.51 (1.9-3.53), that is the spread of data doubled as compared to conventional diameter measurements. When females and males were studied separately the AAA diameter was 46.5 mm (40-55) and 48 mm (40-55), respectively (NS). Since the BSA was significantly lower in women than in men, 1.63 (1.42-1.95) and 1.89 (1.47-2.37), respectively (p < 0.0001), also the predicted normal aortic size was lower, 16.4 (14.3-17.8) vs. 19.7 (18.0-21.6) (p < 0.0001). Thus, the AAA diameter increase from the predicted size was larger in women than in men; 2.93 (2.25-3.53) vs. 2.46 (1.90-2.94), respectively (p < 0.0001).
Conclusion: To define an aneurysm as a localised dilatation of an artery exceeding 50% of the expected normal diameter is now possible. This may facilitate how to treat especially smaller aneurysms and give new information concerning patterns of growth and risk of rupture.