A novel technique to optimize implantation of the Navitor valve in transcatheter aortic valve replacement

The Navitor valve (Abbott Structural Heart, Santa Clara, CA, USA) is a new self-expanding valve for transcatheter aortic valve replacement (TAVR).

We previously used a conventional technique in which we opened the valve at a higher position (3–4 mm), similar to the Evolut FX valve (Medtronic, Minneapolis, MN, USA) (Panel A). However, owing to the flexible nature of the delivery catheter, the device axis tends to be horizontal; thus, the conventional technique may fail to achieve valve coaxiality and symmetrical depth implantation (Panel B). Furthermore, lower radial force of this device occasionally results in asymmetric and insufficient expansion of the inflow of the valve, known as ‘non-uniform expansion (NUE)’ (Panel C), which may be a cause of valve migration (Panels D and E).

Therefore, we propose a novel ‘distal opening’ technique, to avoid NUE and achieve accurate device implantation. We initiated valve expansion in a deeper position (7–8 mm) inside the left ventricle (Panel F) and opened the inflow until it reached an angle of 45–60° (Panel G). Next, we pulled the entire device until it reached the target depth (3–5 mm) (Panel H). For cases with optimal positioning and confirmed symmetrical valve opening from the multiple views, we maintained the position and completed valve opening (Panel I). We confirmed the uniform expansion of the stent frame with this technique (Panel J), compared with that of the conventional technique (Panel E).

The distal opening technique offers several advantages: (i) symmetrical valve opening, which reduces interference with valve calcification, resulting in decreased risk of NUE and subsequent migration; (ii) reduced risk of migration, because of the downward friction against the pulling force between the valve and the annulus; and (iii) centralized delivery of the catheters, by efficiently pulling the device, enabling an equal implantation depth in all cusps.

After implementing this technique, we successfully prevented NUE in all 60 consecutive cases; this technique is currently widely accepted in many institutes in Japan. This technique generally applies to all cases, excluding those of horizontal aorta, since pulling the whole system will not improve valve coaxiality and symmetrical depth implantation.

We firmly believe that this concept streamlines the Navitor valve implantation process.

Graphical comparison between the conventional and distal opening approaches. (A) Conventional approach: the valve is opened at a higher position (3–4 mm). (B) During opening of the valve, the system tends to be horizontal, resulting in shallower positioning in the left coronary cusp and deeper positioning in the non-coronary cusp. (C) Further pushing the system prevents coaxial alignment of the system, resulting in non-uniform expansion (NUE). (D) NUE results in an unexpected upward motion of the valve. (E) Computed tomography (CT) images demonstrate NUE of the frame bottom (nine red dots). (F) Distal opening approach: initiating the valve expansion at a 7–8 mm depth in the left ventricle (LV). (G) The distal part is opened to 45–60° in the LV and pulled back to the target depth (3–4 mm) using a cusp-overlap view. (H) Multiple views are used to confirm optimal implantation depth and symmetrical valve expansion. (I) Symmetrical valve opening and optimal implantation depth are maintained, with no apparent tilting. (J) CT confirming uniform expansion of the inflow of the valve (nine red dots). White dotted line: annulus plane; arrows indicate the implantation depth in Panels (A) and (F) and the valve width in Panels (B) and (G).

 

Consent: All study participants provided informed consent for the use of their data.

Funding: None declared.

Data availability

The data underlying this article will be shared on reasonable request to the corresponding author.