A novel useful 3D multiplanar reconstruction algorithm to detect the optimal transseptal puncture positioning in percutaneous mitral valve repair
Authors: Mariani M , Bonanni M , D'agostino A , Berti S 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
in transcatheter edge to edge mitral repair (TEER), the use of transesophageal echocardiography (TEE) guidance is mandatory in every procedural step. The transseptal puncture (TPS) height is measured by TEE using a four chamber view (4CV) in mid-upper esophagus between the catheter tenting in fossa ovalis and the coaptation of the mitral valve (MV) and its correct positioning influence procedural outcome. However, TSP can represents a tricky step, because of poor images, challenging interatrial septa or a malalignment of TEE probe, catheter and mitral coaptation.

Aim
In this abstract we describe an alternative TEE 3D technique to measure TSP height.

Methods
Between August 2022 and December 2022 we performed 18 cases of TEER. In all cases we obtained a measure of the height of tenting (HT) with two different techniques: the 2D view (2DV) in 4CV and the 3D reconstruction algorithm (3DA) (fig.1). This 3DA starts with a real-time single-beat 3D volume acquisition from a mid esophagus at 0 degrees view. The 3D dataset should include IAS, aortic valve, and MV. In multiplanar reconstruction (MPR), three 2D planes are reconstructed from the 3D dataset. These MPR planes must be positioned in a predefined manner with the cursors correctly aligned on the catheter tip at the level of the fossa ovalis. The first plan (P1) is an off axis 4CV oriented perpendicular to the IAS exactly on the height of the catheter tip and serves as the orientation plane. This plane allows the exact location of the tenting point and the positioning of the other two MPR planes. The crossing of the axes should be positioned in all planes at the center of the left atrium. The second plane (P2) and the third plane (P3) are oriented perpendicular to the previous one (fig.1) and each other. Rotating and moving those two planes in a stepwise manner a 4CV, including the plane passing by catheter tip and MV coaptation is obtained in P1. In order to identify the exact plane of the coaptation, while in P1 the axis passing through the MV is positioned at the center of the MV, in P2 the axis is adjusted at the point of leaflet coaptation (fig.1). The HT is then measured in P1 thus avoiding the possible foreshortening affecting a simple 2DV.

Results
In all cases the 3D measure was accomplished but in 3 of 18 cases the 2DV was difficult to obtain because of loss of contact between the esophagus and the probe in retroflection, in those cases the HT was measured in a 0 degrees off axis view from the tenting of the fossa to a very anterior part of the coaptation line or to anterior leaflet. In all those cases the height of tenting was underestimated (fig.2).

Conclusion
The 3DA described can be useful in obtaining a more precise and reliable measure of the HT even in anatomical challenging patients. A comparative study that consents to investigate the correlation between the two methods and the inter and intra observer agreement is mandatory and planned at our institution.