Ultimate tensile strength and biaxial stress–strain responses of aortic tissues—A clinical-engineering correlation

For over a decade, the team from the Aortic Institute at Yale University has worked closely with the bioengineering team of Dr. Wei Sun at Georgia Tech University. This paper presents the products of that collaboration.

We provide clinical context by describing thoracic aortic dissection and its genesis as a prelude to the bioengineering findings. We discuss the genesis of aortic dissection, from the fundamental underlying genetic abnormality, through the degenerative aortic process, to the acute inciting factors and the dissection event itself. The inciting factor is usually an extreme hypertensive episode, occasioned by exertion or emotion.

The bioengineering findings include the following: The aortic wall is stronger in the circumferential direction than in the longitudinal. Bicuspid aortic valve and bovine aortic arch morphology do not compromise aortic strength. Biaxial testing reveals a non-liner stress-strain response of aortic tissues. Dissected tissues become stronger over time, reflecting fibrotic connective tissue ingrowth in response to the dramatic tissue injury from the dissection event. Human aortic tissues stiffen at advanced age, in contradistinction to those of aged animals (porcine).

Combining clinical and bioengineering perspectives yields a more complete and correlative understanding of the genesis of thoracic aortic dissection.