What is unfolded aorta?

What is unfolded aorta?

In unfolding of aorta, there is apparent widening of the mediastinum as the curvature of the aortic arch decreases in the frontal plane. This is seen in elderly due to the disproportionate increase in length of ascending aorta compared to its diameter.

Aortic unfolding is often associated with aortic calcification and implies aortic degeneration [1]. Increase in length of ascending aorta with aging is disproportionate to increase in aortic diameter. This appears like a dilated ascending aorta and causes mediastinal widening. Sugawara J et al evaluated arterial lengths using 3-dimensional transverse magnetic resonance imaging in 256 apparently healthy adults with age range 19 to 79 years [2]. They showed that aorta lengthens with age even in healthy persons, primarily due to elongation of ascending aorta.

Lee JW et al evaluated aortic unfolding using non contrast cardiac computed tomography and correlated with age and coronary artery calcium score [3]. It was a retrospective chart review of 219 subjects who had undergone coronary artery calcium scoring during routine health check up. Aortic unfolding was defined by measuring aortic width on non contrast cardiac CT. It was associated with age, body surface area and hypertension.

Coronary artery calcium score which is an established surrogate marker of cardiovascular disease was also associated with aortic unfolding. They noted that though aortic unfolding increased progressively with age, it plateaued at 60 years of age. Aortic unfolding index (aortic unfolding indexed for body surface area) plateaued at age 70 years or more. The authors suggested further evaluation of aortic unfolding as potential predictor of cardiovascular risk.

References

1. O’Rourke M, Farnsworth A, O’Rourke J. Aortic dimensions and stiffness in normal adults. JACC Cardiovasc Imaging. 2008 Nov;1(6):749-51.
2. Sugawara J, Hayashi K, Yokoi T, Tanaka H. Age-associated elongation of the ascending aorta in adults. JACC Cardiovasc Imaging. 2008 Nov;1(6):739-48.
3. Lee JW, Hur J, Kim YJ, Lee HJ, Nam JE, Kim HY, Hong YJ, Ko SM, Kim TH, Choi BW. Aortic unfolding determined using non-contrast cardiac computed tomography: correlations with age and coronary artery calcium score. PLoS One. 2014 Apr 22;9(4):e95887.