Hemodynamic assessment of extra-cardiac tricuspid valves using particle image velocimetry.

There has not been much progress in the development of transcatheter tricuspid valves to treat tricuspid regurgitation because of the difficulty in anchoring a stented valve onto the complex tricuspid annulus. Hence, the concept of heterotopic implantation of the transcatheter tricuspid valve onto the cavo-atrial junction was proposed. However, to date there has been no detailed in vitro investigation of the hemodynamic performance of this new device. The study utilises both 2-D and 3-D particle image velocimetry (PIV) to interrogate the flow patterns in the vicinity of the extra-cardiac tricuspid valves in an in vitro physiological flow loop, specifically at four measurement locations in the cavo-atrial anatomy. Comparison of the 2-D and 3-D PIV results revealed that accuracy of 2-D PIV would be acceptable at time point and at measurement locations where the velocity was mostly planar with minimal or low out-of-plane flow such as at the outlet of the superior vena cava valve at the point of valve closure. The results also showed that the RSS in the vicinity of the valves were relatively low (∼150 dynes/cm) with the exception of that in the leakage jet at the upstream of the valve. The leakage in the leaflets could be a result of the use of aortic valve leaflets which was more suited for the higher pressured environment of the left side of the heart. The stent design could also be customised for implantation in the vena cava. In summary, these issues could be eradicated with improvements to the leaflet and stent design which would enhance the haemodynamics of the post-implantation flow performance.