To create or pull from the shelf?

Early Outcome of Simplified Standardized Trileaflet Polytetrafluoroethylene Valved Conduit Placement

Background

Use of the expanded polytetrafluoroethylene (ePTFE) valved conduit in the pulmonary position during the correction of congenital heart defects has significantly increased in popularity over the last decade due to its promising conduit longevity. We describe the standardized process to create and implant a trileaflet ePTFE pulmonary conduit along with the early outcomes of such procedures at our institute.

Methods

Records of 100 consecutive patients who underwent ePTFE valved conduit placement using our technique from April 2018 through February 2022 were retrospectively analyzed. The function of the conduit was evaluated by transthoracic echocardiography.

Results

The mean age of the patients was 28 ± 13.2 years old at the time of the operation. The conduit diameters ranged from 16 to 24 mm (mean 23.0 ± 1.9 mm). Conduit placement was utilized for pulmonary valve replacement in 68 patients, conduit change in 25 patients, and as a part of total repair in 7 patients. There were 2 in-hospital conduit-unrelated deaths from multi-organ dysfunction and pulmonary hypertensive crisis. From the postoperative echocardiography, the average peak pressure gradient across the conduit was 18.6 ± 9.0 mm Hg, and the conduit regurgitation was graded as none or trace in 81 patients, mild in 17 patients, and moderate in 2 patients. At 589 days of median follow-up, there was no conduit reoperation. Follow-up imaging of 60 available patients at a median time of 511 days did not show a significant change in conduit function.

Conclusions

Our standardized ePTFE valved conduit creation and placement demonstrated satisfactory clinical and echocardiographic outcomes.

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

Prosthetic pulmonary valves are widely used in the management procedures of various congenital heart diseases, including the surgical pulmonary valve replacement (PVR) and right ventricular outflow tract reconstruction (RVOT). The discouraging long-term outcomes of standard prostheses, including homografts and bioprosthetic, constrained their indications. Recent developments in the expanded-polytetrafluoroethylene (ePTFE) pulmonary prosthetic valves provide promising alternatives. In this study, the hemodynamic characteristics of bileaflet and trileaflet ePTFE valve designs were experimentally evaluated. The in vitro tests were performed under the right ventricle (RV) flow conditions by using an in vitro RV circulatory system and particle image velocimetry (PIV). The leaflet kinetics, trans-valvular pressure gradients, effective orifice areas, regurgitant fractions, energy losses, velocity fields, and Reynolds shear stress (RSS) in both prostheses were evaluated. The opening of the bileaflet and trileaflet valve takes 0.060 and 0.088 s, respectively. The closing of the former takes 0.140 s, in contrast to 0.176 s of the latter. The trans-valvular pressure is 6.8 mmHg in the bileaflet valve vs. 7.9 mmHg in the trileaflet valve. The effective orifice area is 1.83 cm2 in the bileaflet valve and 1.72 cm2 in the trileaflet valve. The regurgitant fraction and energy loss of bileaflet are 7.13% and 82 mJ, which are 7.84% and 101.64 mJ in its bileaflet counterpart. The maximum RSS of 48.0 and 49.2 Pa occur at the systole peak in the bileaflet and trileaflet valve, respectively. A higher average RSS level is found in the bileaflet valve. The results from this preliminary study indicate that the current bileaflet prosthetic valve design is capable of providing a better overall hemodynamic performance than the trileaflet design.

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

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.