Human aorta; Aging; Aneurysm; Dissection; Marfan syndrome; Bicuspid aortic valve; Elastin; Collagen; Microstructure; Architecture; Multiphoton microscopy; Custom image-based analysis; Computational modeling
Stearns-Reider K.M., D'Amore A., Beezhold K., Rothrauff B., Cavalli L., Wagner W.R., Vorp D.A., Tsamis A., Shinde S., Zhang C., Barchowsky A., Rando T.A., Tuan R.S., Ambrosio F. (2017), Aging of the skeletal muscle extracellular matrix drives a stem cell fibrogenic conversion, in Aging Cell
, 16(3), 518-528.
Pasta Salvatore, Phillippi Julie A, Tsamis Alkiviadis, D'Amore Antonio, Raffa Giuseppe M, Pilato Michele, Scardulla Cesare, Watkins Simon C, Wagner William R, Gleason Thomas G, Vorp David A (2016), Constitutive modeling of ascending thoracic aortic aneurysms using microstructural parameters., in Medical engineering & physics
, 38(2), 121-30.
Tsamis Alkiviadis, Phillippi Julie A, Koch Ryan G, Chan Patrick G, Krawiec Jeffrey T, D'Amore Antonio, Watkins Simon C, Wagner William R, Vorp David A, Gleason Thomas G (2016), Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy., in The Journal of thoracic and cardiovascular surgery
, 151(6), 1718-1728.
Hemmasizadeh Ali, Tsamis Alkiviadis, Cheheltani Rabee, Assari Soroush, D'Amore Antonio, Autieri Michael, Kiani Mohammad F, Pleshko Nancy, Wagner William R, Watkins Simon C, Vorp David, Darvish Kurosh (2015), Correlations between transmural mechanical and morphological properties in porcine thoracic descending aorta., in Journal of the mechanical behavior of biomedical materials
, 47, 12-20.
Koch Ryan G, Tsamis Alkiviadis, D'Amore Antonio, Wagner William R, Watkins Simon C, Gleason Thomas G, Vorp David A (2014), A custom image-based analysis tool for quantifying elastin and collagen micro-architecture in the wall of the human aorta from multi-photon microscopy., in Journal of biomechanics
, 47(5), 935-943.
Pal Siladitya, Tsamis Alkiviadis, Pasta Salvatore, D'Amore Antonio, Gleason Thomas G, Vorp David A, Maiti Spandan (2014), A mechanistic model on the role of "radially-running" collagen fibers on dissection properties of human ascending thoracic aorta., in Journal of biomechanics
, 47(5), 981-988.
Tsamis Alkiviadis, Pal Siladitya, Phillippi Julie A, Gleason Thomas G, Maiti Spandan, Vorp David A (2014), Effect of aneurysm on biomechanical properties of "radially-oriented" collagen fibers in human ascending thoracic aortic media., in Journal of biomechanics
, 47(16), 3820-4.
Tsamis Alkiviadis, Pocivavsek Luka, Vorp David A (2014), Elasticity and geometry: a computational model of the Heineke-Mikulicz strictureplasty., in Biomechanics and modeling in mechanobiology
, 13(6), 1185-98.
Koch Ryan G., Tsamis Alkiviadis, D’Amore Antonio, Wagner William R., Vorp David A. (2013), A Custom Image-Based Analysis Tool for Quantifying Elastin and Collagen Fiber Micro-Architecture in the Wall of the Human Aorta From Multi-Photon Microscopy Images, in ASME 2013 Summer Bioengineering Conference
, Sunriver, Oregon, USA.
Tsamis Alkiviadis, Phillippi Julie A, Koch Ryan G, Pasta Salvatore, D'Amore Antonio, Watkins Simon C, Wagner William R, Gleason Thomas G, Vorp David A (2013), Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media., in Journal of biomechanics
, 46(16), 2787-2794.
Tsamis Alkiviadis, Phillippi Julie A., Koch Ryan G., Krawiec Jeffrey T., D’Amore Antonio, Watkins Simon C., Wagner William R., Vorp David A., Gleason Thomas G. (2013), Region-Specific Medial Fiber Micro-Architecture in the Longitudinal-Radial and Circumferential-Radial Planes of Ascending Thoracic Aortic Aneurysm Among Bicuspid and Tricuspid Aortic Valve Patients, in ASME 2013 Summer Bioengineering Conference
, Sunriver, Oregon, USA.
Aortic disease is a significant cause of death in developed countries. The most common forms of aortic disease are aneurysm, dissection, atherosclerotic occlusion and a general stiffening of the normally-elastic aorta that is thought to be a natural consequence of aging. There are many co-morbid conditions that can lead to one or more of these diseases, including hypertension, genetic mutations (such as Marfan syndrome), and developmental defects (such as bicuspid aortic valve). The aorta is elastic and this design aids in the propulsion of blood downstream to the systemic vasculature. Connective fibers within the aortic wall impart these elastic properties, and it is often alteration of the quantity and/or architecture of these fibers that lead to mechanical and hence functional changes associated with aortic disease. The aorta also has distinct regions or segments that are more susceptible to certain types of disease than others. At present, the regional variation in aortic wall fiber content and architecture in aging and disease - including co-morbid conditions such as Marfan syndrome and bicuspid aortic valve - and the associated biomechanical behavior of the aorta over the lifespan are still not fully understood. This work will attempt to shed light on the interrelation among the aforementioned processes. That is, I will: (1) Assess the regional variation in elastin and collagen content and fiber distributions in 6 specified segments of the human aorta obtained from subjects within a wide age range; (2) Correlate the nature of the fiber architecture and content with the formation of ascending and descending thoracic aortic aneurysm or dissection; (3) Seek associations of Marfan syndrome and bicuspid aortic valve with regional alterations in the fiber architecture and mechanical properties of the aortic wall; and (4) Synthesize these observations into a consistent computational model to simulate aging, aneurysm formation and dissection in the human aorta. An expected long-term outcome of such work would be a subject-specific simulation tool that would enable the precise prediction of aortic remodeling in health and disease, and could possibly guide the decision-making in clinical diagnosis and treatment.