Author + information
Transcatheter Aortic Valve Replacements (TAVR) are percutaneously implanted using fluoroscopic guidance, which makes precise positioning challenging. The location of the valve with respect to the annulus is expected to influence the sinus flow and coronary perfusion. The present study investigates the effect of TAVR positioning on flow characteristics in the aortic sinuses.
A commonly used TAVR design with an aortic stabilization section was investigated using qualitative and quantitative flow visualization in the Georgia Tech left heart simulator under physiological flow and pressure conditions. A bioprosthetic valve was used as control and also mimicked the presence of the native aortic valve. The valve assembly was mounted in a custom designed chamber with an axisymmetric sinus, designed based on anatomic dimensions. The TAVR was deployed in high and low positions with respect to the aortic annulus and studied at 2 cardiac outputs (2.5 L/min; 5.0L/min).
The TAVR showed good systolic flow characteristics with wide forward flow jets in the ascending aorta (V=1.5m/s at 5.0 L/min; V=1.0m/s at 2.5 L/min). Sinus vortices are created by flow reversal near the walls of the aorta, resulting in entrainment of this fluid into the sinuses. These vortices are critical for washout of fluid near the annulus, to prevent thrombosis & platelet activation. In the high position of TAVR, physical spacing between the leaflet free edge and sino–tubular junction is reduced (<10mm), causing a weaker sinus vortex and lower washout. A larger region of low velocity (< 0.1m/s) near the annulus is observed at high positioning, particularly at 2.5 L/min, where flow stagnation and recirculation can be higher. When the commissures of the TAVR are aligned with those of the native valve in the radial direction, sinus washout is further reduced.
For optimal sinus washout, subvalvular deployment of the TAVR and anti–positioning of the TAVR commissures with the native valve is necessary. The present study indicates need for careful positioning of TAVR during deployment, as incorrect valve positioning can reduce coronary perfusion and cause potential regions of stasis near the aortic annulus.
West, Room 2010
Sunday, March 10, 2013, 8:15 a.m.–8:30 a.m.
Session Title: Valvular Heart Disease: Year in Review, Functional MR, E–Clip Updates and MR in the Context of AS
Abstract Category: 32. Valvular Heart Disease: Therapy
Presentation Number: 922–4
- 2013 American College of Cardiology Foundation