Date Published: January 30, 2019
Publisher: Public Library of Science
Author(s): Guangyu Zhu, Munirah Binte Ismail, Masakazu Nakao, Qi Yuan, Joon Hock Yeo, Davide Pacini.
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.
Congenital birth defects such as aortic incompetence may lead to aortic failure. Nowadays, there have been a number of publications indicated the growing enthusiasm in the aortic valve repair techniques in children [1, 2]. Because of the encouraging mid- and long-term results in treating aortic stenosis or aortic regurgitation, percutaneous or surgical aortic valve repair is generally recommended as the primary management strategy in pediatric patients with aortic valve diseases [1, 3, 4]. Despite the fact that aortic valve repair has developed rapidly in pediatric patients, aortic valve replacement (AVR) may still be required in some cases, such as significant valve destruction and those after repair failure .
The goal of the current study was to develop a reliable bi-leaflet valve for patients who need AVR. A novel design of the bi-leaflet valve was proposed in the current study. The dynamic and hemodynamic performances of the newly designed valve were assessed in FEM simulations and in-vitro experiments. The results were compared with the reference valve that was tested under the same conditions.
In conclusion, this study presents a novel ePTFE bi-leaflet valve prosthesis for AVR, and the dynamic and hemodynamic performance of the proposed bi-leaflet valve under physiological aortic loading were evaluated by using numerical and in-vitro experimental methods. The preliminary results showed that the bi-leaflet valve design is not only capable of serving as an aortic valve substitute under aortic physiological loadings in terms of structural dynamic behaviors, but also shows encouraging outcomes in certain critical hemodynamic parameters, including EOA, TPG, and RF when comparing with its commercialized counterparts. These novel findings could have implications for the further studies on the use of the ePTFE bi-leaflet valve in the pediatric patients who need AVR.