High Transcatheter Valve Replacement May Reduce Washout in the Aortic Sinuses: an In-Vitro Study

Transcatheter aortic valve replacements (TAVRs) are performed using fluoroscopic guidance, which makes precise positioning challenging. The aim of the present study was to investigate the effect of TAV positioning on flow characteristics in the ascending aorta and sinuses.

A commonly used TAV design with a supra-annular support section was investigated using particle image velocimetry (PIV) under physiological flow and pressure conditions. A bioprosthetic valve served as a control and mimicked the native aortic valve. The valve assembly was mounted in a custom-designed chamber with an axisymmetric sinus, the design of which was based on anatomic dimensions. The TAV was deployed in the supra-annular (high) and sub- annular (low) implantation positions and studied at two cardiac outputs (5.0 and 2.5 l/min).

The TAV showed good systolic flow characteristics with wide forward flow jets in the ascending aorta (V = 1.5 m/s at 5.0 1/min; V = 1.0 m/s at 2.5 1/min). In the high implantation, the physical spacing between the leaflet free edge and sinotubular junction was reduced (< 10 mm), causing a weaker sinus vortex and a lower washout. A larger region of low velocity (< 0.1 m/s) in the sinus was observed at high implantation at all time points, particularly at a cardiac output of 2.5 l/min. In the low implantation, good sinus washout was observed.

For optimal sinus washout, sub- annular TAV deployment is recommended, particularly for patients with smaller sinuses. An impaired cardiac output may also require sub- annular deployment for adequate sinus washout. The study results confirmed the need for precise TAV deployment tailored to patient-specific annular and sinus dimensions, as sub-optimal positioning may inhibit coronary perfusion and cause potential regions of stasis near the aortic annulus.