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Different types of bioprostheses for valve-in-valve transcatheter aortic valve replacement (TAVR) may need to be positioned differently, a study of simulated hemodynamics suggested.

CoreValve device sizes 23 and 26 mm performed optimally in the normal-to-slightly sub-annular (-3 mm) deployment range, reported , of George Institute of Technology and Emory University in Atlanta, and colleagues in a paper to be published in .

But the 23 mm Sapien valve exhibited its best performance at 6 mm above the annulus. This position was associated with a number of advantages, albeit with increased embolization risk (mean pullout force 5.54 N versus 7.09 N at normal position, P<0.01). Those included:

• Lower transvalvular pressure gradients (mean 9.31 mm Hg versus 11.66 mmHg, P<0.01)
• Reduced regurgitant fraction (0.95% versus 1.27%, P<0.01)
• Lower pinwheeling index (1.23% versus 3.46%, P<0.01)
• Higher effective orifice area (1.51 cm² versus 1.35 cm², P<0.01)

"Though all transcatheter heart valve deployments resulted in hemodynamics that would have been consistent with VARC-2 procedure success, we found significant differences between transcatheter heart valve type, size, and deployment position," the authors wrote. "Long-term studies are needed to understand the clinical impact of these hemodynamic performance differences in patients who undergo valve-in-valve TAVR."

"The lowest [paravalvular] leakage was observed at the same positions that resulted in the lowest transvalvular pressure gradient, further supporting our recommendation for a supra-annular deployment of the Sapien valve, and for a normal deployment of the CoreValve."

Yoganathan's in vitro model for a patient with a failing bioprosthesis used a physiological left heart simulator and a 23 mm Edwards Perimount surgical bioprosthesis into which new valves were deployed.

Among the devices tested at their ideal positions, the 26 mm CoreValve boasted the lowest mean gradient at 7.76 mm Hg versus 10.27 mm Hg for the 23 mm CoreValve and 9.31 mm Hg for 23 mm Sapien (P<0.01), the highest effective orifice area (1.66 versus 1.44 and 1.51 cm², respectively, P<0.01), and the lowest embolization risk (pullout force 10.65 versus 5.35 and 5.54 N, P<0.01).

Its weaknesses were the higher regurgitant fraction (4.79% versus 1.98% versus 0.95%, respectively, P<0.01) and pinwheeling index (29.13% versus 6.57% versus 1.23%, P<0.01).

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