MRI-Guided 3D Printed Training Model for Left Atrial Appendage Closure

Overview

A novel MRI-based 3D printed training model was developed to simulate left atrial appendage (LAA) closure procedures, incorporating multiple predetermined transseptal puncture (TSP) sites and interchangeable silicone LAA models. This approach enables patient-specific anatomical representation and training on optimal puncture site selection to improve procedural success and reduce complications.

Background

Percutaneous closure of the LAA is a key strategy for stroke prevention in atrial fibrillation patients, requiring precise transseptal puncture to access the LAA. Due to high anatomical variability in LAA shape and optimal puncture sites, individualized preprocedural planning is critical. While CT-based 3D printed models have been used for planning and training, they expose patients to radiation and contrast agents. MRI-based models offer a radiation-free alternative with potential for patient-specific customization and procedural training.

Data Highlights

The MRI datasets were acquired using a non-contrast-enhanced respiratory navigated 3D isotropic two-point mDixon technique at 3T with 1.3 mm3 spatial resolution. The nominal scan duration was 3–4 minutes, with actual scan times around 12 minutes depending on heart rate and respiration. The base model printing took approximately 19 hours using fused filament fabrication with PLA filament. Silicone LAA models were created using Dragon Skin® 10NV silicone with an elastic modulus of 0.19 N/mm2, closely mimicking myocardial tissue elasticity.

Key Findings

• The training model includes a rigid base with vena cava, right and left atria, and four anatomically based TSP sites derived from retrospective evaluation of 16 cases.
• Interchangeable silicone LAA models were fabricated from patient-specific MRI segmentations, allowing replication of various LAA shapes.
• The MRI-based approach avoids radiation and contrast exposure inherent to CT-based models while providing sufficient anatomical detail for segmentation and model construction.
• The model allows simulation of sheath passage through different TSP sites, demonstrating the impact of puncture location on access to the LAA.
• The 3D printed model is reproducible using widely available fused filament fabrication technology, facilitating adoption in diverse clinical settings.

Clinical Implications

This MRI-guided 3D printed training model offers a practical tool for interventionalists to practice and optimize transseptal puncture site selection tailored to patient-specific anatomy. It may reduce procedural complications by minimizing multiple punctures and device repositioning. Additionally, the model serves as an educational aid for patients and trainees, enhancing understanding of LAA closure techniques without radiation exposure.

Conclusion

The MRI-based 3D printed training model successfully integrates patient-specific LAA anatomy with multiple puncture sites to simulate and train for LAA closure procedures. This approach holds promise for improving procedural planning, training, and patient education in a radiation-free manner.

References

1. Various Authors 2024 -- MRI-guided training approach for closure of the left atrial appendage