Key result
In an in vitro mock bench model, percutaneous pulmonary valved stents drastically reduced regurgitant flow compared to no valve, with mean regurgitant fractions varying from 5% to 7.3% across different RVOT geometries.
Why the study?
Does a percutaneous pulmonary valved stent reduce regurgitant flow across different right ventricular outflow tract morphologies in an in vitro model?
Does a percutaneous pulmonary valved stent reduce regurgitant flow across different right ventricular outflow tract morphologies in an in vitro model?
In vitro testing shows that right ventricular outflow tract geometry significantly influences the competency and regurgitant fraction of percutaneous pulmonary valved stents.
Bench data indicate percutaneous pulmonary valved stent competency across RVOT geometries; leaves open in vivo validation before clinical translation.
Percutaneous pulmonary valve implantation is a potential treatment for right ventricular outflow tract (RVOT) dysfunction. However, RVOT implantation site varies among subjects and the success of the procedure depends on RVOT morphology selection. The aim of this study was to use in vitro testing to establish percutaneous valve competency in different previously defined RVOT morphologies. Five simplified RVOT geometries (stenotic, enlarged, straight, convergent, and divergent) were manufactured by silicone dipping. A mock bench was developed to test the percutaneous valve in the five different RVOTs. The bench consists of a volumetric pulsatile pump and of a hydraulic afterload. The pump is made of a piston driven by a low inertia programmable motor. The hydraulic afterload mimics the pulmonary input impedance and its design is based on a three element model of the pulmonary circulation. The mock bench can replicate different physiological and pathological hemodynamic conditions of the pulmonary circulation. The mock bench is here used to test the five RVOTs under physiological-like conditions: stroke volume range 40-70 mL, frequency range 60-80 bpm. The valved stent was implanted into the five different RVOT geometries. Pressures upstream and downstream of the valved stent were monitored. Flow rates were measured with and without the valved stent in the five mock RVOTs, and regurgitant fraction compared between the different valved stent RVOTs. The percutaneous valved stent drastically reduced regurgitant flow if compared with the RVOT without the valve. RVOT geometry did not significantly influence the flow rate curves. Mean regurgitant fractions varied from 5% in the stenotic RVOT to 7.3% in the straight RVOT, highlighting the influence of the RVOT geometry on valve competency. The mock bench presented in this study showed the ability to investigate the influence of RVOT geometry on the competence of valved stent used for percutaneous pulmonary valve treatment.
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Vismara et al. (2009) studied Right ventricular outflow tract (RVOT) dysfunction. Percutaneous pulmonary valved stent vs. RVOT without the valve was evaluated on Regurgitant fraction. In an in vitro mock bench model, percutaneous pulmonary valved stents drastically reduced regurgitant flow compared to no valve, with mean regurgitant fractions varying from 5% to 7.3% across different RVOT geometries.
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