Non-invasive methods of <i>in vivo</i> functioning analysis of the “TiAra” stentless valve prosthesis

Abstract

Highlights. Non-invasive method for the assessment of the mobility and deformation of the wire element of the bioprosthesis in the cardiac cycle based on the developed mathematical algorithm is presented. Numerical analysis of the behavior of the wire element of the “TiAra” bioprosthesis is shown for the first time. The developed method can be used for other medical devices as well.Aim. To develop a method for non-invasive assessment of the mobility and deformation of the wire element of the aortic heart valve bioprosthesis in the cardiac cycle based on mathematical processing of visual medical data.Methods. Multidetector computed tomography data of patient P. (male, 66 years old), who received the “TiAra” aortic bioprosthesis (NeoCor CJSC, Kemerovo), were used for the study. Using the built-in tools in the Mimics Medical Image Processing Software (Materialize, Belgium), based on the radio density, 5 stages of movement of  the  wire  element  of  the  bioprosthesis  were  reconstructed  in  the  form  of 3D-models.  The  differences between  the  models,  characterizing  deformation in the cardiac cycle, were quantitatively assessed using a proprietary Matlab algorithm (The MathWorks, USA), calculating the distance between similar points. Moreover, obtained data on displacements was used in the numerical study of the stress-strain state of a 3D-model of the wire element by the finite element method in the Abaqus/CAE software (Dassault Systèmes SE, France).Results. The proposed method for assessing the mobility of the wire element made it possible to quantitatively evaluate the biomechanics of the “TiAra” stentless bioprosthesis based on multidetector computed tomography, a non-invasive clinical tool. The movements that the bioprosthesis undergoes during the cardiac cycle (the maximum value is 2.04 mm in the radial direction) are comparable to the movement of the aortic root of a healthy patient. The results of the numerical modeling of the stress state of the wire element did not indicate high amplitudes (peak value – 564 MPa) that would be capable of causing critical damage to the wire. It allows us to confirm the clinical safety of the bioprosthesis in real conditions like asymmetric and uneven loads. Moreover, deformations observed in the bioprosthesis are similar in the amplitude to the displacements of the aortic root described in the literature, which highlights the main feature of the bioprosthesis – ensuring the physiological biomechanics throughout the cardiac cycle.Conclusion. The presented method of qualitative computer assessment of the movement of the wire element of heart valve prosthesis using the “TiAra” bioprosthesis as an example demonstrates its validity as a tool for studying prosthesis functioning.