Application of Optical Coherence Elastography to characterize elastic properties of human pericardium samples used for fabrication of cardiac-valve prostheses

Abstract

Application of Optical Coherence Elastography to characterize elastic properties of human pericardium samples used for fabrication of cardiac-valve prostheses
V.Y. Zaitsev, A.A. Sovetsky, L.A. Matveev, A.L. Matveev, D.V. Shabanov, V.Y. Salamatova, P.V. Karavaikin, Y.V. Vassilevski

1 Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod
2 Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russia
3 Central Clinical Hospital of the Presidential Administration of the Russian Federation,
4 Sechenov First Moscow State Medical University

In this study for the first time we applied quantitative compressional optical coherence elastography (C-OCE) to characterize samples of human pericardium used for fabrication of auto-prostheses of cardiac valves. The typical thickness of such pericardium samples is ~200-400 micrometers, such that C-OCE is very well suited to characterize the elastic properties of the entire thickness of the samples. During the prosthesis preparation, the pericardium sample excised from the patient is subjected to chemical and mechanical processing (stretching), which significantly alters the tissue elasticity. The latter in turn is important for the fabricated-valve functionality. The latter can be optimized by choosing the most appropriate elastic modulus of the processed pericardium based on numerical simulations of the valve behavior in the blood flow. Presently, there are no convenient and reliable standard means to quantitatively characterize the pericardium elasticity. The C-OCE method in our study demonstrated the ability to easily detect the difference in the elastic properties of differently prepared pericardium samples. Furthermore, the possibility to obtain nonlinear stress-strain curves for compressive strains up to 10-15% was shown. The elastic modulus was shown to vary several times in this strain range. The most linear and soft (with typical Young’s modulus ~50kPa and lower) were the unprocessed samples, whereas for those processed according to typical protocols of preparation, the modulus was ~200-800 kPa and pronouncedly nonlinear. For chemically processed but over-stretched samples, the modulus could be even higher, ~1 MPa. Mechanical heterogeneity (layered structure) of the samples could also be readily seen, which is inaccessible to existing characterization methods. Overall, it has been demonstrated that C-OCE enables previously unavailable possibilities for quantitative characterization of pericardium, which is important for improving the fabricated valve prostheses.


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V.Y. Zaitsev
Institute of Applied Physics RAS
Russia

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