Advancing Surgical Arrhythmia Ablation: Novel Insights on 3D Printing Applications and Two Biocompatible Materials

Abstract

To date, studies assessing the safety profile of 3D printing materials for application in cardiac ablation are sparse. Our aim is to evaluate the safety and feasibility of two biocompatible 3D printing materials, investigating their potential use for intra-procedural guides to navigate surgical cardiac arrhythmia ablation. Herein, we 3D printed various prototypes in varying thicknesses (0.8 mm-3 mm) using a resin (MED625FLX) and a thermoplastic polyurethane elastomer (TPU95A). Geometrical testing was performed to assess the material properties pre- and post-sterilization. Furthermore, we investigated the thermal propagation behavior beneath the 3D printing materials during cryo-energy and radiofrequency ablation using an in vitro wet-lab setup. Moreover, electron microscopy and Raman spectroscopy were performed on biological tissue that had been exposed to the 3D printing materials to assess microparticle release. Post-sterilization assessments revealed that MED625FLX at thicknesses of 1 mm, 2.5 mm, and 3 mm, along with TPU95A at 1 mm and 2.5 mm, maintained geometrical integrity. Thermal analysis revealed that material type, energy source, and their factorial combination with distance from the energy source significantly influenced the temperatures beneath the 3D-printed material. Electron microscopy revealed traces of nitrogen and sulfur underneath the MED625FLX prints (1 mm, 2.5 mm) after cryo-ablation exposure. The other samples were uncontaminated. While Raman spectroscopy did not detect material release, further research is warranted to better understand these findings for application in clinical settings.

Keywords: ablation; additive manufacturing; cardiac; epicardial; material testing; three-dimensional printing (3D printing).

Figure 1

3D-printed prototypes for in vitro ablation experiments: (A) An eyelet for the ablation catheter (black circle) placed centrally. Two 1 mm internal lumens were created for thermocouple insertion at distances of 1 mm (D1) and 11 mm (D2) from the energy source. (B) Computerized blender samples for 3D printer. (C) 3DP samples, with different thicknesses and materials (TPU: black; MED625FLX: transparent).

Figure 2

Assessment of geometric integrity of various 3D-printed designs before and after sterilization. (A–C) Pre-sterilization models; (D,E) two failed post-sterilization designs (orange circles highlight the areas of damage). (A) a 3D-printed guide of ventricular tachycardia-inducing scar substrate located in the left ventricle, 3D printed in MED625FLX (2.5 mm thickness); (B) 3D-printed model revealing coronary stenosis in a NSTEMI patient, printed in MED625FLX (3 mm thickness) [8]; (C) 3D-printed model of arrhythmogenic substrate in Brugada Syndrome (TPU; 1 mm); (D) example of material breakage (orange circle) after sterilization on the coronary model shown in panel (B); (E) area of damage (orange circle) following sterilization on a Brugada Syndrome model in MED625FLX (0.8 mm thickness).

Figure 3

A segment of the wet-lab experiment. The ablation catheter is placed in the central eyelet of the 3DP prototype. The temperature beneath the 3DP material is measured during the ablation using thermocouples, at distances of 1 mm and 11 mm from the energy source.

Figure 4

(A) Scanning electron microscopy with energy-dispersive X-ray showing control tissue samples (ablated porcine tissue without 3D printing material). The main components detected include carbonium (C) and oxygen (O). (B) Higher magnification confirming that the main components detected in the three measurements include carbonium (C) and oxygen (O).

Figure 5

Left panel: 3D print in MED625FLX was assessed using an electron microscope. Right panel: Raman spectrum measured centrally (4 measurements). The same spectrum was obtained for all measured positions, and no material damage (due to the laser irradiation (max. power) was observed.

Figure 6

Left panel: 3D print in TPU95A was evaluated using an electron microscope. Right panel: Raman spectrum was measured centrally (4 measurements). The same spectrum was obtained for all measured positions; at a high laser power (>1 mW), the material was damaged in the irradiated area, compatible with the information reported on the datasheet. Laser power < 1 mW used for the analysis.

Figure 7

Images obtained, through an electron microscope, of biological tissue beneath MED625FLX prototypes (1 mm; 2.5 mm) after cryo-ablation. Particles of nitrogen and sulfur were identified (EDX) (red circles), which are not typically present in biological tissue.

Figure 8

Scanning electron microscopy with energy-dispersive X-ray spectroscopy of biological tissue below MED625FLX material after cryo-ablation. Traces of nitrogen were detected.

Figure 9

Comparison between Raman spectroscopy results for reference tissue sample (blue) and MED625FLX material (green).