Fusion of real-time 3D transesophageal echocardiography and cardiac fluoroscopy imaging in transapical catheter-based mitral paravalvular leak closure

Safety, Efficacy and Long-Term Outcomes of Patients Treated with the Occlutech Paravalvular Leak Device for Significant Paravalvular Regurgitation

Between December 2014 and March 2021, 144 patients with aortic (Ao) or mitral (Mi) paravalvular leaks (PVLs) were enrolled at 21 sites in 10 countries. Safety data were available for 137 patients, who were included in the safety analysis fraction (SAF), 93 patients with Mi PVLs and 44 patients with Ao PVLs. The full analysis set (FAS) comprised 112 patients with available stratum (aortic/mitral leak) as well as baseline (BL), 180-day or later assessments (2 years). Procedural success (implantation of the device with a proper closure of the PVL, defined as reduction in paravalvular regurgitation of ≥one grade as assessed by echocardiography post implantation) was achieved in 91.3% of FAS patients with Mi PVLs and in 90.0% of those with Ao PVLs. The proportion of patients suffering from significant or severe heart failure (HF), classified as New York Heart Association (NYHA) class III/IV, decreased from 80% at baseline to 14.1% at 2-year follow-up (FAS). The proportion of FAS patients needing hemolysis-related blood transfusion decreased from 35.5% to 3.8% and from 8.1% to 0% in Mi patients and Ao patients, respectively. In total, 35 serious adverse events (SAEs) were reported in 27 patients (19.7%) of the SAF population. The SAEs considered possibly or probably related to the device included device embolization (three patients), residual leak (two patients) and vascular complication (one patient). During follow-up, 12/137 (8.8%) patients died, but none of the deaths was considered to be device-related. Patients implanted with the Occlutech Paravalvular Leak Device (PLD) showed long-lasting improvements in clinical parameters, including NYHA class and a reduced dependency on hemolysis-related blood transfusions.

Technical Recommendations for Real-Time Echocardiography and Fluoroscopy Imaging Fusion in Catheter-Based Mitral Valve Paravalvular Leak and Other Procedures

Widespread catheter-based interventions for structural heart disease have overtaken the treatment of paravalvular leaks (PVL). Multimodality imaging techniques play a crucial role in accurate diagnosis, procedure planning and performance. However, PVL closure is often technically challenging due to the complex anatomy of the defects and their relation to surrounding anatomical structures. The application of echocardiography and fluoroscopy imaging fusion (EFF) may simplify challenging imaginative three-dimensional reconstruction of the intracardiac anatomy and facilitate the procedure. To master new technology, personnel must make cognitive changes, overcome a learning curve, and obtain adequate theoretical knowledge. Main aim of this manuscript is to present basic recommendations for EFF application in practice, alongside, each scenario is supported by technically challenging clinical examples. We may conclude that our manuscript may provide useful information for physicians on EEF application in clinical practice.

Real-time intraoperative co-registration of transesophageal echocardiography with fluoroscopy facilitates transcatheter mitral valve-in-valve implantation in cases of invisible degenerated bioprosthetic valves

OBJECTIVES

Transcatheter mitral valve-in-valve (TMViV) implantation is an alternative treatment to surgery for high-risk patients with degenerated bioprosthetic mitral valves. Some types of bioprostheses are fluoroscopically translucent, resulting in an 'invisible' target deployment area. In this study, we describe the feasibility and outcomes of this procedure using intraoperative fusion of transoesophageal echocardiography (TEE) and live fluoroscopy to facilitate valve deployment in cases of invisible bioprosthetic valves.

METHODS

We reviewed all TMViV implantations at our centre from July 2014 to July 2019. Patient, procedure and outcome details were compared between those with a visible bioprosthesis (N = 22) to those with an invisible one (N = 12). Intra-operative TEE and live Fluoroscopy co-registration were used for real-time guidance for all invisible targets.

RESULTS

All valve implantations were completed successfully in both groups without cardiovascular injury, valve migration or left ventricular outflow-tract obstruction. Technical success was 100% in both groups. One-year survival was 83% [95% confidence interval (CI) 70-96] for the entire cohort, with 79% (95% CI 63-100) survival for the visible group and 92% (95% CI 77-100) for the invisible group. Probability of 1-year survival free from mitral valve reintervention, significant valve dysfunction, stroke or myocardial infraction was 78% (95% CI 63-93) for all patients whereby the probability was 72% (95% CI 54-97) in the visible group and 80% (95% CI 59-100) for the invisible group.

CONCLUSIONS

The use of intraoperative TEE and live fluoroscopy image fusion facilitates accurate TMViV among patients with a fluoroscopically invisible target-landing zone.

Catheter segmentation in X-ray fluoroscopy using synthetic data and transfer learning with light U-nets

Background and objectivesAutomated segmentation and tracking of surgical instruments and catheters under X-ray fluoroscopy hold the potential for enhanced image guidance in catheter-based endovascular procedures. This article presents a novel method for real-time segmentation of catheters and guidewires in 2d X-ray images. We employ Convolutional Neural Networks (CNNs) and propose a transfer learning approach, using synthetic fluoroscopic images, to develop a lightweight version of the U-Net architecture. Our strategy, requiring a small amount of manually annotated data, streamlines the training process and results in a U-Net model, which achieves comparable performance to the state-of-the-art segmentation, with a decreased number of trainable parameters. MethodsThe proposed transfer learning approach exploits high-fidelity synthetic images generated from real fluroscopic backgrounds. We implement a two-stage process, initial end-to-end training and fine-tuning, to develop two versions of our model, using synthetic and phantom fluoroscopic images independently. A small number of manually annotated in-vivo images is employed to fine-tune the deepest 7 layers of the U-Net architecture, producing a network specialized for pixel-wise catheter/guidewire segmentation. The network takes as input a single grayscale image and outputs the segmentation result as a binary mask against the background. ResultsEvaluation is carried out with images from in-vivo fluoroscopic video sequences from six endovascular procedures, with different surgical setups. We validate the effectiveness of developing the U-Net models using synthetic data, in tests where fine-tuning and testing in-vivo takes place both by dividing data from all procedures into independent fine-tuning/testing subsets as well as by using different in-vivo sequences. Accurate catheter/guidewire segmentation (average Dice coefficient of  ~ 0.55,  ~ 0.26 and  ~ 0.17) is obtained with both U-Net models. Compared to the state-of-the-art CNN models, the proposed U-Net achieves comparable performance ( ± 5% average Dice coefficients) in terms of segmentation accuracy, while yielding a 84% reduction of the testing time. This adds flexibility for real-time operation and makes our network adaptable to increased input resolution. ConclusionsThis work presents a new approach in the development of CNN models for pixel-wise segmentation of surgical catheters in X-ray fluoroscopy, exploiting synthetic images and transfer learning. Our methodology reduces the need for manually annotating large volumes of data for training. This represents an important advantage, given that manual pixel-wise annotations is a key bottleneck in developing CNN segmentation models. Combined with a simplified U-Net model, our work yields significant advantages compared to current state-of-the-art solutions.

Retrospective analysis of single-center early and midterm results of transapical catheter-based mitral paravalvular leak closure with a purpose-specific device

Introduction

Due to the recent lack of definitions to establish the severity of paravalvular leak (PVL) and endpoints for its treatment, the effectiveness and safety of a new device for PVL closure have not been comprehensively analyzed.

Aim

To analyze a single center’s experience of mitral PVL closure in a surgical transapical catheter-based fashion with a purpose-specific device.

Material and methods

This is a retrospective cohort study of patients following transapical catheter-based mitral PVL closure with a purpose-specific device. Data were analyzed at baseline, perioperatively, at discharge, at six months and annually after the procedure.

Results

Nineteen patients underwent surgical transapical catheter-based mitral PVL closure with the Occlutech PLD Occluder. Mean follow-up time was 20 ±7 (range: 9–33) months. The patients’ mean age was 64 ±7 years, and 11 (58%) were male. Technical, device and individual patient success at follow-up was achieved in 18 (95%), 16 (84%) and 16 (84%) patients respectively. Median intensive therapy unit stay was one day (1–4) and mean hospital stay was 11 ±4 days. A reduction of paravalvular regurgitation to a mild or lesser degree was achieved in 18 (95%) patients. There were no strokes or myocardial infarctions at follow-up. There were no deaths at 30 days after the procedure. One (5%) patient expired due to progression of heart failure 12 months after surgery. None of the patients required immediate conversion to full sternotomy.

Conclusions

Surgical transapical catheter-based mitral PVL closure with the Occlutech PLD Occluder is a safe and clinically effective treatment.