The Effect of Valve-in-Valve Implantation Height on Sinus Flow

Abstract

Valve-in-valve transcatheter aortic valve replacement (VIV-TAVR) has proven to be a successful treatment for high risk patients with failing aortic surgical bioprostheses. However, thrombus formation on the leaflets of the valve has emerged as a major issue in such procedures, posing a risk of restenosis, thromboembolism, and reduced durability. In this work we attempted to understand the effect of deployment position of the transcatheter heart valve (THV) on the spatio-temporal flow field within the sinus in VIV-TAVR. Experiments were performed in an in vitro pulsatile left heart simulator using high-speed Particle Image Velocimetry (PIV) to measure the flow field in the sinus region. The time-resolved velocity data was used to understand the qualitative and quantitative flow patterns. In addition, a particle tracking technique was used to evaluate relative thrombosis risk via sinus washout. The velocity data demonstrate that implantation position directly affects sinus flow patterns, leading to increased flow stagnation with increasing deployment height. The particle tracking simulations showed that implantation position directly affected washout time, with the highest implantation resulting in the least washout. These results clearly demonstrate the flow pattern and flow stagnation in the sinus is sensitive to THV position. It is, therefore, important for the interventional cardiologist and cardiac surgeon to consider how deployment position could impact flow stagnation during VIV-TAVR.

Transcatheter aortic valve deployment influences neo‐sinus thrombosis risk: An in vitro flow study

“…A higher implantation depth was also associated with reduced pressure gradients and greater EOA in the CoreValve regardless of annular expansion. This finding, which is in agreement with recent valve‐in‐valve studies, suggests that higher valve placement yields fuller leaflet opening and less resistance to flow through the valve (pressure gradients).…”

Characterization of aortic root geometry in transcatheter aortic valve replacement patients

“…A wide range of material properties and geometries have been used in past studies, from rigid idealized to compliant patient specific . Since postprocedural aortic root dimensional relationships were uninvestigated to date, the same relationships for healthy or stenotic valves were used in idealized models.…”

“…As newer TAVR devices emerge and are increasingly considered for implantation in younger lower-risk patients, rigorous performance A wide range of material properties and geometries have been used in past studies, from rigid idealized to compliant patient specific. [31][32][33][34] Since postprocedural aortic root dimensional relationships were uninvestigated to date, the same relationships for healthy or stenotic valves were used in idealized models. As this study suggests, aortic root dimensions change after implantation of the replacement device.…”

Three-dimensional extent of flow stagnation in transcatheter heart valves

“…Additionally, substantial focus is on identifying and defining metrics that characterize flow-mediated thrombogenic potential in the cardiovascular system. Novel metrics developed include characterization of wall shear stress vector [5], blood residence time [23,24] and three-dimensional flow-based metrics [25,26]. However, little is known about the flow-mediated mechanisms responsible for the recently revealed issue of bioprosthetic and transcatheter heart valve (THV) hypo-attenuated leaflet motion caused due to thrombosis [16,17], and this is the primary motivation for this study.…”