Effects of longitudinal pre-stretch on the mechanics of human aorta before and after thoracic endovascular aortic repair (TEVAR) in trauma patients
Thoracic endovascular aortic repair (TEVAR) has evolved as a first-line therapy for trauma patients. Most trauma patients are young, and their aortas are compliant and longitudinally pre-stretched. We have developed a method to include longitudinal pre-stretch in computational models of human thoracic aortas of different ages before and after TEVAR. Finite element models were built using computerized tomography angiography data obtained from human subjects in 6 age groups 10–69 years old. Aortic properties were determined with planar biaxial testing, and pre-stretch was simulated using a series of springs. GORE C-Tag stent-graft was computationally deployed in aortas with and without pre-stretch, and the stress–strain fields were compared. Pre-stretch had significant qualitative and quantitative effects on the aortic stress–strain state before and after TEVAR. Before TEVAR, mean intramural aortic stresses with and without pre-stretch decreased with age from 108 kPa and 83 kPa in the youngest age group, to 60 kPa in the oldest age group. TEVAR increased intramural stresses by an average of 73 ± 15 kPa and 48 ± 10 kPa for aortas with and without pre-stretch and produced high stress concentrations near the aortic isthmus. Inclusion of pre-stretch in young aortas increased intramural stresses by 30%, while in > 50-year-old subjects it did not change the results. Computational modeling of aorta-stent-graft interaction that includes pre-stretch can be instrumental for device design and assessment of its long-term performance, and in the future may help more accurately determine the stress–strain characteristics associated with TEVAR complications.
KeywordsPre-stretch Aorta Computational modeling Thoracic endovascular aortic repair Stent-graft
The authors wish to acknowledge Live On Nebraska for their help and support and thank tissue donors and their families for making this study possible.
Research reported in this publication was supported in part by the National Heart, Lung, And Blood Institute of the National Institutes of Health under Award Numbers HL124905, HL147128, and HL125736.
Compliance with ethical standards
This manuscript does not study living human or animal subjects. Cadaveric specimens were obtained after receiving consent from next of kin.
Conflict of interest
Authors declare that they have no conflict of interest.
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