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ASAIO CARDIAC ABSTRACT

TISSUE MECHANICAL AND HISTOLOGICAL PROPERTIES IN CO-ARCTATION OF THE AORTA (COAO)

Briceno, J C1,2; Garcia-Torres, A E1; Navas, P1,2; Gaitan, D M1,2

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Due to its viscoelastic properties, the diameter of the coarctated aorta after angioplasty decreases from that of the balloon to a final unknown diameter. We have developed a mathematical model that predicts the diameter of the aorta after angioplasty. The model depends on the mechanical properties of the CoAo tissue, which are not known and may differ from those of normal aorta. The purpose of this project is to study the mechanical and histological properties of the CoAo tissue. Methods: Fresh samples of human CoAo tissue discarded during surgery were subjected to circumferential tensile tests and the modulus of elasticity (El calculated. The smaller samples unsuitable for tensile tests were subjected to histological analysis. Results: E was 189 ±148 kPa (mean ± SD, n = 7). In 4 samples E was 192 ±19 kPa, in 2 samples E was 38 ±24 kPa, and in 1 sample E was 480 kPa. Histology (n=8) showed important differences in tissue composition: 2 samples presented fibrosis (Fib) and complete transmural loss of elastic fibers (LEF), 3 samples showed Fib and severe LEF, 1 sample had mild LEF, and two samples were normal. In conclusion, the elasticity of CoAo tissue varied in a wide range starting from values close to normal aortic tissue. Histological characteristics also differed between samples. The mechanical properties and CoAo tissue composition seem to he related: Fib and complete trans-mural LEF results in highly increased tissue rigidity, Fib and severe LEF causes an increase in tissue rigidity, and normal composition of CoAo tissue leads to an E similar to that of normal aortic tissue.

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