Imaging in Transcatheter Mitral Valve Replacement: State-of-Art Review

Utility of Multidetector Computed Tomographic Angiography as an Alternative to Transesophageal Echocardiogram for Preoperative Transcatheter Mitral Valve Repair Planning

BACKGROUND

Three-dimensional (3D) transesophageal echocardiogram (TEE) is the gold standard for the diagnosis of degenerative mitral regurgitation (dMR) and preoperative planning for transcatheter mitral valve repair (TMVr). TEE is an invasive modality requiring anesthesia and esophageal intubation. The severe acute respiratory syndrome coronavirus 2 pandemic has limited the number of elective invasive procedures. Multi-detector computed tomographic angiography (MDCT) provides high-resolution images and 3D reconstructions to assess complex mitral anatomy. We hypothesized that MDCT would reveal similar information to TEE relevant to TMVr, thus deferring the need for a preoperative TEE in certain situations like during a pandemic.

METHODS

We retrospectively analyzed data on patients who underwent or were evaluated for TMVr for dMR with preoperative MDCT and TEE between 2017 and 2019. Two TEE and 2 MDCT readers, blinded to patient outcome, analyzed: leaflet pathology (flail, degenerative, mixed), leaflet location, mitral valve area (MVA), flail width/gap, anterior-posterior (AP) and commissural diameters, posterior leaflet length, leaflet thickness, presence of mitral valve cleft and degree of mitral annular calcification (MAC).

RESULTS

A total of 22 (out of 87) patients had preoperative MDCT. MDCT correctly identified the leaflet pathology in 77% (17/22), flail leaflet in 91% (10/11), MAC degree in 91% (10/11) and the dysfunctional leaflet location in 95% (21/22) of patients. There were no differences in the measurements for MVA, flail width, commissural or AP diameter, posterior leaflet length, and leaflet thickness. MDCT overestimated the measurements of flail gap.

CONCLUSIONS

For preoperative TMVr planning, MDCT provided similar measurements to TEE in our study.

Transcatheter mitral valve replacement: there is still work to be done

Transcatheter mitral valve replacement (TMVR) is a novel therapeutic option for patients with severe mitral regurgitation (MR) at high or prohibitive surgical risk. Most TMVR technologies under investigation use either a trans-apical or a trans-septal approach via dedicated multistep anchoring systems. Transcatheter mitral valve replacement offers several potential advantages over transcatheter repair, notably a greater and more sustained MR reduction. At the same time, significant engineering challenges and potential disadvantages must be acknowledged. Preclinical and clinical studies have shown promising results, demonstrating TMVR feasibility. Nevertheless, further development, testing, and trials are needed before considering TMVR as a definitive therapeutic option for MR in a wide range of anatomical scenarios.

Mitral and tricuspid valve disease: diagnosis and management. Consensus document of the Section on Valvular Heart Disease and the Cardiovascular Imaging, Clinical Cardiology, and Interventional Cardiology Associations of the Spanish Society of Cardiology

The diagnosis and management of mitral and tricuspid valve disease have undergone major changes in the last few years. The expansion of transcatheter interventions and widespread use of new imaging techniques have altered the recommendations for the diagnosis and treatment of these diseases. Because of the exponential growth in the number of publications and clinical trials in this field, there is a strong need for continuous updating of local protocols. The recently published 2021 European Society of Cardiology guidelines for the management of valvular heart disease did not include some of the new data on these new therapies and, moreover, the number of mitral and tricuspid interventions varies widely across Europe. Therefore, all this information must be summarized to facilitate its use in each specific country. Consequently, we present the consensus document of the Section on Valvular Disease, Cardiovascular Imaging, Clinical Cardiology, and Interventional Cardiology Associations of the Spanish Society of Cardiology for the diagnosis and management of mitral and tricuspid valve disease.

Imaging in transcatheter native mitral valve replacement with Tendyne mitral valve system: Echocardiographic pathway for the interventional imager

The interaction between the implanter team and the imager team is critical to the success of transcatheter native mitral valve replacement (TMVR), a novel interventional procedure in the therapeutic arsenal for mitral regurgitation. This imaging scenario necessitates the addition of a new dedicated professional figure, dubbed "the interventional imager," with specific expertise in structural heart disease procedures. As its clinical application grows, knowledge of the various imaging modalities used in the TMVR procedure is required for the interventional imager and beneficial for the interventional implanter team. The purpose of this review is to describe the key steps of the procedural imaging pathway in TMVR using the Tendyne mitral valve system, with an emphasis on echocardiography. Pre-procedure cardiac multimodality imaging screening and planning for TMVR can determine patient eligibility based on anatomic features and measurements, provide measurements for appropriate valve sizing, plan/simulate the access site, catheter/sheath trajectory, and prosthesis positioning/orientation for correct deployment, and predict the risks of potential procedural complications and their likelihood of success. Step-by-step echocardiographic TMVR intraoperative guidance includes: apical access assessment; support for catheter/sheath localization, trajectory and positioning, valve positioning and clocking; post deployment: correct clocking; hemodynamic assessment; detection of perivalvular leakage; obstruction of the left ventricular outlet tract; complications. Knowledge of the multimodality imaging pathway is essential for interventional imagers and critical to the procedure's success.

Segmentation of Echocardiography Based on Deep Learning Model

In order to achieve the classification of mitral regurgitation, a deep learning network VDS-UNET was designed to automatically segment the critical regions of echocardiography with three sections of apical two-chamber, apical three-chamber, and apical four-chamber. First, an expert-labeled dataset of 153 echocardiographic videos and 2183 images from 49 subjects was constructed. Then, the convolution layer in the VGG16 network was used to replace the contraction path in the original UNet network to extract image features, and depth supervision was added to the expansion path to achieve the segmentation of LA, LV, and MV. The results showed that the Dice coefficients of LA, LV, and MV were 0.935, 0.915, and 0.757, respectively. The proposed deep learning network can achieve simultaneous and accurate segmentation of LA, LV, and MV in multi-section echocardiography, laying a foundation for quantitative measurement of clinical parameters related to mitral regurgitation.