Growth curve of ruptured aortic aneurysm.

OBJECTIVE

We hypothesized that the aortic aneurysm might grow biexponentially. The object of this study was to determine the biexponential growth curve of aortic aneurysm.

DESIGN

A fifteen-year retrospective review of CT images of aortic aneurysm.

SETTING

Major cardiovascular referral center.

PATIENTS

Patients with true aortic aneurysm who were followed up with CT and performed CT at their aneurysmal ruptures.

MEASURES

The largest short-axial diameters of the outer contour of the aneurysms were measured. Aortic aneurysmal diameters were normalized by those at ruptures, and the plots were fitted to the biexponential curve.

RESULTS

Eight patients out of 1481 had been followed up with CT scans. In regression analysis, the values fit well to the biexponential equation: d(t) = 0.8345 exp (0.0052 t) + 0.1653 exp (0.8275 t), r = 0.934 where d(t) is the normalized diameter, and t is months before rupture. The first part of the equation mainly expresses the slow growth, and the second expresses the rapid growth shortly before rupture.

CONCLUSIONS

Aortic aneurysm began to grow faster at about three months before rupture. It is important to find out the point that the growth of aortic aneurysm changes its rate faster than before, and once the point is observed, elective repair should be considered.