Pitt | Swanson Engineering
Variation of Regional Fiber Architecture Within the Thoracic Aorta

Our lab has used our image-based analysis of aortic microarchitecture to look at fiber variation in several different “coordinate systems” of the thoracic aorta. One area of inhomogeneity we have investigated is the transmural transition from the vascular intima to the media, then to the adventitia. From this work, we have identified the presence of radially-oriented fibers which could reduce the likelihood of dissection between layers. The amount of these fibers differs between two clinically distinct aortic valve morphologies - the natural tricuspid valve and the bicuspid valve (BAV) seen in 1-2% of the population. From our work, we hypothesize that the reduced undulation of collagen fibers in the aorta of BAV patients could predispose them to the formation of an intimal tissue tear, and ensuing dissection. The second area of inhomogeneity we are investigating is the variation that occurs around the circumference of the aorta, with respect to landmarks such as the left and right coronary arteries. Our initial data suggests that additional radially-oriented fibers in the region coincident with the left coronary artery, solely in the case of BAV, could provide extra strength and explain the circumferentially asymmetric geometry of aneurysms in BAV patients.

Related Publications

1.    Tsamis A, Krawiec JT, Vorp DA, "Elastin and collagen fibre microstructure of the human aorta in ageing and disease: a review”, J R Soc Interface, 2013 Jun 6, 10(83):20121004, PMID 23536538, PMCID: PMC3645409

2.    Tsamis A, Phillippi JA, Koch RG, Pasta S, D’Amore A, Watkins SC, Wagner WR, Gleason TG, Vorp DA, “Fiber Micro-Architecture in the Longitudinal-Radial and Circumferential-Radial Planes of Ascending Thoracic Aortic Aneurysm Media”, J Biomech, 2013 Nov 15; 46(16):2787-94 PMID 24075403, PMCID: PMC3898198

3.    Pal S, Tsamis A, Pasta S, D’Amore A, Gleason T, Vorp DA, Maiti S, "A mechanistic model on the role of “radially-running” collagen fibers on dissection properties of human ascending thoracic aorta", J Biomech, 2014 Mar 21; 47(5):981-8 PMID 24484644

4.    Tsamis A, Pal S, Phillippi JA, Gleason TG, Vorp DA, “Effect of aneurysm on biomechanical properties of “radially-oriented” collagen fibers in human ascending thoracic aortic media collagen fibers in human ascending thoracic aortic media”, Journal of Biomechanics, 2014 Dec 18;47(16):3820-4, PMID:25468299, PMCID: PMC4278426

5.    Tsamis A, Phillippi JA, Koch R, Chan PG, Krawiec JT, D’Amore A, Watkins SC, Wagner WR, Vorp DA, Gleason TG, “Extracellular Matrix Fiber Microarchitecture is Region-Specific in Bicuspid Aortic Valve-Associated Ascending Aortopathy”, Journal of Thoracic and Cardiovascular Surgery, 2016 Feb 13 (Epub ahead of print), PMID: 26979916