Neo-annulus: a reference plane in a surgical heart valve to facilitate a valve-in-valve procedure.

Objectives: To determine the level of the narrowest plane (neo-annulus) of a surgical heart valve (SHV), which could be used for sizing and securing a transcatheter heart valve (THV) during a valve-in-valve (VIV) procedure and define its relationship with the fluoroscopic markers of the SHV.

Background: In the native aortic valve, the aortic annulus is used as a reference plane for sizing and deployment of THV as it provides the narrowest dimension to securely anchor the THV. However, the reference level for different models of SHV that are currently treated by a VIV procedure remains unknown.

Methods: We studied 13 aortic SHVs from all major heart valve manufacturers (labeled size 21, 22, or 23). A 26cc valvuloplasty balloon was inflated with contrast within each SHV under fluoroscopy to achieve a 'waist'. The level of the 'waist' was compared with the SHV and its fluoroscopic markers to identify the level of the neo-annulus.

Results: In all SHVs tested, the balloon 'waist' or 'neo-annulus' was at the level of the sewing ring. When the fluoroscopic marker of the SHV was the sewing ring, the level of the neo-annulus was also at that level, irrespective of supra-annular or intra-annular design. However, when the fluoroscopic marker was the stent frame, the relationship between the fluoroscopic marker and the level of the neo-annulus was different for supra-annular and intra-annular designs. This correlation was not possible in two models of SHV as neither the stent nor the sewing ring was radio-opaque.

Conclusions: We have demonstrated that the narrowest portion of all SHVs is at the level of its sewing ring, which can be identified fluoroscopically and should be used as a reference level during a VIV procedure.