“Cusp-overlap” technique simplifies the implantation of Chinese domestic transcatheter valve in transcatheter aortic valve implantation

Currently, transcatheter aortic valve implantation (TAVI) has become a feasible interventional technique for severe aortic stenosis in patients who deemed inoperable or are at high surgical risk. In China, the TAVI technique started from 2010. Until now two domestic devices J Valve (Jie Cheng Medical Technologies, Suzhou, China) and Venus A-Valve (Venus MedTech, Hangzhou, China) have been allowed access into the market in 2017, since then most centers began to set up TAVI programs. Venus A-Valve is the only transfemoral transcatheter valve in China which approximately has been implanted 4000 times, till VitaFlow (MicroPort, Shanghai, China) and SAPIEN 3 (Edwards Lifesciences, Irvine, CA, USA) entered the market in China a few months ago.

Concerning the intraoperative technique, an optimal projection of the aortic root enables the exact positioning of the prostheses. The standard position of deployment is at an alignment of the right cusp between the left and the noncoronary cusps, which is the current standard in China.^[1] However, as for self-expanding Venus A-Valve, we recommend using a “Cusp-Overlap” view for deployment. This technique was firstly described by Gilbert Tang, which is a coplanar projection overlapping the right coronary cusp (RCC) and left coronary cusp (LCC).^[2] With a different design of the Venus A-Valve, compared to other self-expandable transcatheter heart valves, potential advantages may be obtained with isolation of the non-coronary cusp (NCC) in addition to the known advantages:

• 1.It simplifies the implantation with a short learning curve and reproducibility
• 2.It reduces the pacemaker implantation rates
• 3.It reduces the paravalvular leakage (PVL).

An isolation of NCC with en-face view provides a better anatomical reference for the deployment depth, which supports the radiopaque markers design of the Venus-A Valve at 0.5 cells above the inflow end, to indicate the optimal landing zone [Supplementary Figure 1A and 1B]. It may reduce the parallax of delivery catheter and radiopaque markers. The Venus A-Valve device has a quicker valve frame flowering time [Supplementary Figure 2A–2D] and the delivery system lacks 1:1 response, providing delayed feedback between the deployment knob and the movement of the capsule compared to the Evolut Pro (Medtronic, Minneapolis, MN). This may increase the possibility of diving into the left ventricular outflow tract (LVOT). An extreme slow deployment of the first 2/3 part of the valve flame is mandatory. Meanwhile, a better nadir of NCC contributes to a higher and more accurate valve position to start the deployment with avoidance of pacemaker and PVL. Isolation of NCC also assists with depth visualization near the non-right commissure and membranous septum.

A sample of Evolut Pro (Medtronic, Minneapolis, Minnesota) implantation is illustrated by using 3Mensio Valves software (Pie Medical Imaging, Maastricht, the Netherlands) analysis of multidetector computed tomography (MDCT). The standard 3-cusp view of the left anterior oblique (LAO) is 20°, caudal 2°, and aortic annulus projected in a long axis [Figure 1A and 1C]. By applying the cusp-overlap view, RCC and LCC overlap in the right anterior oblique (RAO) 4°, caudal 25° and the aortic annulus is projected in a short axis [Figure 1B and 1D]. When the delivery catheter is sent, a standard 3 cusp view presents with a longer distance for the valve frame to engage with the LCC [Figure 1E and 1G] while a cusp-overlap view provides a more centered delivery catheter and perceives a short distance of valve frame flowering from the NCC to the LCC. [Figure 1F and 1H] With a short projection axis, cusp-overlap view may reduce the parallax of delivery catheter, radiopaque markers and valve flame, compared with standard 3-cusp view [Figure 1I and 1J].

Figure 1.

Standard 3-cusp view versus cusp-overlap view. Red, green, and yellow dots show the nadir of left coronary cusp, right coronary cusp, and the non-coronary cusp. Blue eye illustrates the projection (A-H). The blue dot and stripe simulate the delivery catheter. The white dotted arrow shows the distance between the delivery catheter and the left coronary cusp.

Given that the “Cusp-Overlap” view permits a higher implant depth to decrease the incidence of pacemaker implantation, patients with high risk of conduction disturbances are principal candidates for this technique. The pre-procedural anatomic risk factors include “short” membranous septum, LVOT calcification (particularly below the non-coronary cusp), and severe mitral annular calcification.^[3] A baseline right bundle branch block is regarded as a clinical risk factor. Bicuspid aortic valve and incompatible C-arm projection (extreme RAO and caudal angle) are a contraindication for this technique.

The “Cups-Overlap” technique has been well applied in self-expandable transcatheter valves worldwide. It may be an alternative view for the deployment process to accomplish a simpler and more accurate implantation for the Chinese domestic self-expanding Venus A-Valve.

Acknowledgement

A special thanks to Oliver Kuratli, M.D. for his English expertise.

Funding

This study was supported in part by the grant from the National Key Technologies Research and Development Program (No.2015BAI12B03)

Conflicts of interest

None.