Aortic Elongation - Impact of Aging and Abdominal Aortic Aneurysm

An increase in both aortic diameter and length elevates the risk of catastrophic events in thoracic aortic aneurysms. It is unknown whether patients with abdominal aortic aneurysm (AAA) experience elongation of the infrarenal segment, potentially increasing the risk of rupture. Aortic elongation due to aging is a well-known phenomenon, but the extent to which different aortic segments contribute to the elongation is not well established. The aim of this study was therefore to explore the effect of AAA and aging on segmental and total aortic length, since increased aortic length may be associated with higher rupture risk in AAA.

Twenty-two AAA patients and 23 age- and sex-matched controls were recruited from a regional AAA screening program. Twenty-three sex-matched, young, healthy controls were enrolled through public advertising. All participants underwent whole-aorta contrast-enhanced magnetic resonance angiography (CE-MRA). Six landmarks were annotated in the CE-MRA images and were subsequently used to calculate the total aortic length and seven subsegments.

Total aortic length was significantly longer in AAA than in elderly controls (ECs) (57.9 ± 4.4 vs. 55.1 ± 4.2 cm, P = 0.035), with the elongated infrarenal segment (14.7 ± 1.7 vs. 11.9 ± 1.6 cm, P < 0.001) being the main contributor. EC presented with longer total aortic length compared to young controls (55.1 ± 4.2 vs. 47.8 ± 2.5 cm, P < 0.001), with the most pronounced age-related increase seen in the ascending aorta and the aortic arch (14.2 ± 1.8 vs. 9.9 ± 0.8 cm, P < 0.001).

AAA is associated with a pathological increase in the length of the infrarenal aorta at the site of the aneurysm, resulting in greater total aortic length compared to EC. Whether the elongation further increases the risk of aortic rupture beyond AAA diameter in patients with AAA remains to be elucidated.