Numerical and in-vitro experimental assessment of the performance of a novel designed expanded-polytetrafluoroethylene stentless bi-leaflet valve for aortic valve replacement

Abstract

The expanded polytetrafluoroethylene (ePTFE) heart valve can serve as a viable option for prosthetic aortic valve. In this study, an ePTFE bi-leaflet valve design for aortic valve replacement (AVR) is presented, and the performance of the proposed valve was assessed numerically and experimentally. The valve was designed using CAE software. The dynamic behavior of the newly designed bi-leaflet valve under time-varying physiological pressure loading was first investigated by using commercial finite element code. Then, in-vitro tests were performed to validate the simulation and to assess the hemodynamic performance of the proposed design. A tri-leaflet ePTFE valve was tested in-vitro under the same conditions as a reference. The maximum leaflet coaptation area of the bi-leaflet valve during diastole was 216.3 mm2. When fully closed, no leakage gap was observed and the free edges of the molded valve formed S-shaped lines. The maximum Von Mises stress during a full cardiac cycle was 4.20 MPa. The dynamic performance of the bi-leaflet valve was validated by the in-vitro test under physiological aortic pressure pulse. The effective orifice area (EOA), mean pressure gradient, regurgitant volume, leakage volume and energy loss of the proposed valve were 3.14 cm2, 8.74 mmHg, 5.93 ml/beat, 1.55 ml/beat and 98.99 mJ, respectively. This study reports a novel bi-leaflet valve design for AVR. The performance of the proposed valve was numerically and experimentally assessed. Compared with the reference valve, the proposed design exhibited better structural and hemodynamic performances, which improved valve competency. Moreover, the performance of the bi-leaflet design is comparable to commercialized valves available on the market. The results of the present study provide a viable option for the future clinical applications.

In vitro Assessment of the Impacts of Leaflet Design on the Hemodynamic Characteristics of ePTFE Pulmonary Prosthetic Valves

“…Though the direct quantitative comparison of the above hemodynamic parameters with those from other in vitro studies is limited by the lack of data acquired at corresponding conditions, the quantities of each parameter are still in line with their results (Nagy et al, 2000;Dur et al, 2010;Claiborne et al, 2013;Yamamoto et al, 2018;Pragt et al, 2019). Additionally, the superior performance of the same bileaflet valve design in terms of RF, EOA, pressure gradient, and E L was also found under the aortic flow conditions (Zhu et al, 2019).…”

“…The large leaflet area of the bileaflet design could be the main reason for these phenomena. Although there is a lack of detailed data on the kinematics of ePTFE prostheses under RV conditions, the similar dynamic behavior of the bileaflet valve has been observed under aortic flow conditions as well (Zhu et al, 2019).…”

“…The geometry of bileaflet prosthesis cusps was adopted from our previous design (Zhu et al, 2019), and the trileaflet cusps geometry was created based on the parameters from Thubrikar et al (Thubrikar, 2018). Both of the bileaflet and trileaflet prostheses were designed to incorporate with conduits of 25 mm in diameter.…”

The Comparison of Different Constitutive Laws and Fiber Architectures for the Aortic Valve on Fluid–Structure Interaction Simulation

“…The regurgitant fraction reflects the regurgitant degree during valve closure and leakage. The regurgitant fraction (RF) is calculated by (Zhu et al, 2019 ). in which V F is the forward volume, V R is the regurgitant volume during the valve closing, and V L is the leakage volume after the AV closes.…”

“…To evaluate the impedance of the AV, the effective orifice area (EOA) is introduced as follows (Zhu et al, 2019 ): where Q ( t ) is the flow rate through the AV during the systolic phase at the center of the AV orifice as shown in Figure 1 , Q rms is the root mean square volumetric flow rate, and Δ P is the mean systolic transvalvular pressure gradient.…”