INVESTIGATION OF THE HYDRODYNAMIC PERFORMANCE OF THE MINIMALLY INVASIVE AORTIC VALVE PROSTHESIS

Abstract

Purpose . The article is to demonstrate the possibility of manufacturing a prototype of transcatheter aortic valve prosthesis, followed by evaluation of its hydrodynamic performance under conditions simulating physiological blood flow. Materials and methods. In this paper we used the model of self-expanding transcatheter valve obtained on the basis of previous studies. The physical model of the prosthesis are made by high-precision laser cutting of tubes SE508 nickel-titanium alloy (Nitinol) with a further shape training under the control of differential scanning calorimeter (DSC). On the support frame were mounted xenopericardial leaflets stabilized with ethylene glycol diglycidyl ether (EGDE). Thus it was produced a working prototype of self-expanding aortic valve prosthesis. Research was performed in the pulse duplicator Vivitro-Systems (Vivitro Labs inc, Canada) while simulating the physiological mode of heart function: cardiac output of 5 L/min, the frequency of 70 beats/min, the average pressure heart rate in the aorta 100 mmHg, systolic contraction relative duration of 35 %. Results. The prototype of the transcatheter bioprosthesis showed the average value of the transprosthesis pressure gradient 18.01±0.55 mmHg, vs. 19.72±0.16 mmHg – for control (3F Enable, Medtronic Inc, USA) (p=0.37). Also, the prototype demonstrated lower transvalvular flow: the average value 253.62±3.88 ml/s vs. 272.3 1.18 ml/s (control, p=0.29). The regurgitation fraction, calculated as paravalvular and transvalvular leaks for the prototype was 5.08±1.06 %, the amount of leakage was 2.40±0.78 ml, and the closing volume was 1.67±0.15 ml. Similar rates were not significantly different to the control sample: 3.66±0.81 %; 1.28±0.51 ml and 1.57±0.12 ml, respectively (p=0.19; p<0.1; p=0.56). Conclusion. This work demonstrates the feasibility of manufacturing the prototype of transcatheter aortic valve prosthesis with Nitinol frame, having hydrodynamic performance, comparable to those used in clinical bioprostheses with seamless method of fixation. However, the evaluation of the possibility of clinical application of applied chosen design requires further research in durability, biocompatibility, and its in-depth study in vivo experiments, but the results and evaluation methods used may be useful in creating new transcatheter heart valve bioprosthesis.