Aortic sinus flow stasis likely in valve-in-valve transcatheter aortic valve implantation

Abstract

Objective: Valve-in-valve procedures using transcatheter aortic valves are increasingly performed to treat degenerated bioprosthetic surgical aortic valves because they are less invasive than redo aortic valve replacement. The objective of this study is to quantify the changes in aortic sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets.

Methods: A detailed description of the sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary sinuses in vitro.

Results: Velocity and vorticity within the surgical valve sinuses reached peak values of 0.7 m/s and 1000 s^-1, with a 70% decrease in peak fluid shear stress near the aortic side of the leaflet in the noncoronary sinus. With the introduction of transcatheter aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s^-1 and 0.58 m/s and 653 s^-1 without coronary flow and 0.60 m/s and 631 s^-1 and 0.81 m/s and 669 s^-1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the aortic side of the coronary versus noncoronary transcatheter aortic valve leaflet.

Conclusions: Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary sinus.

Keywords: aortic sinus; calcification; thrombosis; transcatheter aortic valve implantation.

Figure 1

Snapshots from streak plot videos generated by time bin averaging raw images of non-coronary sinuses for (a) BPV (b) ViV with CoreValve and (c) ViV with Sapien and of coronary sinuses for (d) BPV, (e) ViV with CoreValve and (f) ViV with Sapien. Arrows are manually drawn (not computed vectors) to help depict trends in the videos.

Figure 2

Velocity vectors and vorticity contours within the non-coronary sinus for (a) BPV (b) ViV with CoreValve and (c) ViV with Sapien for each case at selected time points throughout the cardiac cycle.

Figure 3

Velocity vectors and vorticity contours within the coronary sinus for (a) BPV (b) ViV with CoreValve and (c) ViV with Sapien for each case at selected time points throughout the cardiac cycle.

Figure 4

Shear stress contours within the non-coronary sinus of (a) BPV (b) ViV with CoreValve and (c) ViV with Sapien for each case at selected time points throughout the cardiac cycle.

Figure 5

Shear stress contours within the coronary sinus of (a) BPV (b) ViV with CoreValve and (c) ViV with Sapien for each case at selected time points throughout the cardiac cycle.

Figure 6

Probability Density function in log scale of varying shear stress distribution values along a sub-region near the isolated bioprosthetic and ViV configurations leaflets during (a) systole and (b) diastole.