In Vitro Investigation of the Hemodynamics of Transcatheter Heterotopic Valves Implantation in the Cavo-Atrial Junction.

Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve. This may be due to the complex tricuspid valve anatomy, which lacks an anchorage zone for the percutaneous valves. In view of this drawback, we have recently developed and tested two percutaneous caval heart valves that are designed to deploy at the vena cava and atrium junction. The hemodynamic characteristics of these valves are tested in a mock circulatory system with patient-specific silicone atrium and vena cava, which emulates the physiological pressure and flow conditions at the right side of the human heart. Particle imaging velocimetry results showed that flow velocity and the associated Reynolds shear stress (RSS) and the turbulent kinetic energy (TKE) downstream of the valves increased after the implantation of the valves. A maximum flow velocity of 0.94 m/s was observed at the region downstream of the percutaneous valve at the superior vena cava (SVC). Maximum RSS value of 2076.1 dynes/cm(2) was observed downstream of the valve at the inferior vena cava during the deceleration phase while maximum TKE measured was 572.6 J/m(3) at the upstream of the valve in the SVC during the peak flow phase. While these values appear high, they are significantly lower than those reported in prosthetic mitral and aortic valves. Hence, caval stented valves can be potentially considered as a minimally invasive option to treat TR.